I.M.D. Study Material Exam 2 PDF

Chapter 5: Development of Human Locomotion Pg. 147-199 Questions: What research Studies should we know for the exam? TYK 1. Describe the constraints that may act as rate controllers for specific locomotor Activities What is the difference between a rate limiter and rate controller? Notes:...

Chapter 5: Development of Human Locomotion Pg. 147-199 Questions: What research Studies should we know for the exam? TYK 1. Describe the constraints that may act as rate controllers for specific locomotor Activities What is the difference between a rate limiter and rate controller? Notes: Introduction ○ Locomotion is the act of moving, or the capability to move, from place to place ○ Type of locomotion used depends on interacting constraints - affordances ○ Rate limiters in childhood - height, weight, limb length ○ Rate limiters During life span- motivation, perceived gender association, structural constraints (physical characteristics, and functional constraints (fear of falling, loss of balance), and weather change (snow or ice) First Voluntary Locomotor effort: creeping and crawling ○ Motor milestones must be achieved before creeping and crawling can begin Enough strength to support and move himself and must uncouple his limbs, which have primarily moved in unison and the same direction Environment must allow for locomotion Must afford the infant certain things ○ Surface provide path to support body ○ Large enough to allow passage as body moves ○ Sturdy ○ Firm enough ○ Flat enough ○ sufficient friction to maintain balance Creeping: Moving on hands and knees Needs balance and strength to support themselves crawling Moving on hands and stomach in a combat crawl Progression of skills: Crawling with chest and stomach on floor Low creeping with legs working symmetrically Rocking back and forth in high creep position Creeping with legs and arms in opposition Gait pattern of hands and feet emerges from infrequently occurring interactions between constraints  Uncomfortable knee support, reinforcement from caregiver, above average strength Transition from crawling to walking ○ End of the first year, infants can crawl and navigate their environments. ○ Transition anyways to novice walkers. ○ Affordance for crawling doesn't automatically transfer for walking. ○ Persist in walking even in dangerous situations, because it allows them to go, see, play and interact more Walking across the lifespan ○ People continually change the way they walk as constraints change. ○ 50 % phasing between the legs when walking stays the same across the lifetime ○ Period of double support then single support Relative timing relationships (coordination) ○ As constraints change, absolute timing and placement can change. First Steps: Characteristics of Early Walking: ○ Short steps with little leg and hip extension. ○ Flat feet and points toes outward ○ Feets wide apart when planted to improve balance ○ No trunk rotation ○ High guard arm position Rate Limiters in Early Walking ○ Individual constraints must develop to certain levels before an infant can support their own body weight ○ Must be able to alternate legs movement ○ Have enough strength to support himself on a single limb ○ Must be able to balance on one leg and transfer weight onto other foot ○ Must have strength in trunk and extensor muscles to maintain posture Proficient Walking Patterns ○ Taking advantage of the principles of motion and stability ○ New walkers optimize balance with wide stance, increase stability not always desirable however ○ Decrease base of support to become more mobile ○ Developmental changes in walking Stride length increases Heel and forefoot pattern → increased rom Narrows base of support Pelvis rotation Balance improves Oppositional arm swing Developmental changes in walking during early childhood ○ Stride length increases throughout mid adolescence Due to fuller range of motion Increase in leg length ○ Velocity of walk increases between age 1-3.5  ○ Coordination of walk improves until age 5 or so. ○ Children usually achieve developmental changes in walking by an early age- age 4 Developmental changes in walking during older adulthood ○ Changes that do occur represent individual (rather than universal) differences. ○ Factors such as Weight loss or gain Changes in strength ot balance Injury Gait training ○ Changes in interacting constraints during walking ○ Adults that enter old age will change in more predictable ways ○ Change in adult walking pattern represent recalibration to the environment ○ Murray and coworkers conducted a series of studies on gait patterns in older men and women. Measured linear and rotary displacements and velocity of limbs during walking Differences in walking Shorter step length More toed out Reduced degree of ankle extension Pelvic rotation diminished ○ Older adults walk more slowly than younger adults Balance is key again as aging process tends to weaken stability Related to disease and injury, especially in loss of muscle strength. Changes are still minor Rate Controllers in Later Walking ○ Changes associated with aging process Structural constraints like osteoarthritis or decline in muscle mass Modify gait to accommodate pain or changes in balance Functional constraints such as fear of falling and balance. Rate limiters contributed to decline in walking For example, An older adult falling will result in a fear of falling, resulting in not wanting to walk long distances, leading to disease in walking, which leads to decrease in mobility and muscle mass. Running Across the LifeSpan ○ Running is more advanced motor skill but still similar to walking Both legs alternate moving ○ Running is different than walking Running has flight phase No period of double support like in walking ○ Children start to run 6-7 months after beginning to walk ○ When first learning to run, the child may adopt a wide base of support, a flat footed landing, leg extension at mid support, and high guard arm position.  ○ As child practices and gets used to balance demands, she begins to put arm swing back in the movement Characteristics of Early Running ○ Reflects the changes in speed between walking and running ○ Brief period of flight by limited range of motion ○ Arms swing to accompany the trunks rotation rather than drive forward and back ○ Elbows exerted when swinging back (unnecessary movement) ○ Arms swing out slightly to the side (waste of energy) Rate limiters in Early Running ○ Coordination patterns such as 50 percent phasing of legs when walking ○ Sufficient strength for flight phase ○ Balance important for weight shifting Proficient Running ○ Requires effective use of the biomechanical principles discussed in chapter 3 ○ Optimize movement forms that allow for quick movement even at expense of balance  Stride length increases–indicating greater force application Recovery leg swung forward in tucked position shows conserved energy Heel tucked close to buttocks Runner eliminated lateral leg movements Each foot strikes ground with heel first and then forefoot Runner eliminates out-toeing Trunk rotation increases Arms swing forward and back in sagittal plane Developmental changes in early running ○ Children growing will change running pattern ○ Increase in body size and strength and improved coordination results on improved running speed and time in flight. ○ Age alone does not guarantee perfect running form ○ Things could be affected from skeletal and muscular imbalances Developmental changes in Later Running ○ Individuals vary in how they change from walking to jogging. ○ Older women increase their walking speed by lengthening stride, but increased running speed by increasing stride frequency, as do young women ○ Differences in younger and older women Older women did not tuck recovering leg completely Older women had shorter stride Older women took fewer stride Rate Controllers in Later Running ○ Rate limiters for walking also affect running, but smaller changes in these constraints may lead to disappearance of this skill. ○ Lacking opportunity or desire to run. Observation plan for Running: ○ By observing a runner and making decisions about movements, you can establish developmental levels very efficiently Other Locomotor Skills ○ Jumping, hopping, galloping, sliding, and skipping Jumping ○ Individuals propel bodies from a surface with one or both feet, And land with both feet. ○ Specialized forms of jumping Hopping or leaping Characteristics of Early Jumping ○ Developmental changes determined in various ways; Age norms Distance or height of jump Jumping form or pattern ○ Early developmentalists determined age norms for jumping achievement Indicates children learn to step down off a higher surface with one foot to the other before jumping off the floor with both feet  ○ Basic skill development in children is a gradual process of refining skills ○ Qualitative change in skill ○ Two types of developmental sequences exist The whole body approach describes all characteristic positions of various body components The component approach follows each separate body component through whatever number of steps accounts for the qualitative changes observed over time. ○ Such sequences identify the steps that children achieve in making the transition from inefficient to proficient movement patterns ○ The advan,events reflect the child's adoption of movement that take advantage of the principles of motion ○ Most young jumpers begin by: Executing a vertical jump, even if intending to jump horizontally To jump a long distance, a skilled jumper leans trunk angle forward from the vertical. By age 3, children can change trunk angle at take off to make either vertical or horizontal jump Lack of coordinated arm action Proficient Jumping  ○ Preparatory crouch that allows maximal force as legs fully extend at moment of lift off ○ Take off for horizontal jump with heels coming off the ground, both feet leave ground at same time ○ Extend arms backward then initiate take off with vigorous arm swing forward to position overhead Jumping for height ○ Direct force downward ○ Trunk upright ○ Flex ankles, knees and hips on touch down to allow force absorption Jumping for distance ○ Direct force down and back ○ Heels leave ground ○ Trunk tips forward ○ Flex knees during flight ○ Flex ankles knees and heels to absorb force when landing Developmental Changes in Jumping ○ With practice children can eventually make refinements in their jumping pattern ○ Continuous growth in body size and strength contributes to quantitative improvement in how far children can jump ○ Differences between a vertical jump and a standing long jump involve position and movement speed. Standing long jump Hips ar more flexed Hips extend faster Vertical jump Knees and ankles extend faster ○ Children and adults use same pattern for standing long jump and vertical jump ○ Not all persons master jumping in childhood or adolescence Zimmerman found many inefficient jumping characteristics in college women Rate limiters in jumping ○ Be able to develop enough force to bring bodies in the air from still position ○ They cannot take advantage of the momentum or “fall and catch” motion Hopping ○ One must project and absorb body weight with just one limb and maintain balance on a small base of support that one foot provides. Characteristics of early hopping ○ Children may move through the levels of arm action and leg action at different rates Leg action can sometimes be ineffective as a force producer E.g. momentarily lifting the support leg from the floor by flexing it rather than projecting the body up by leg extension with swing leg inactive  ○ Review developmental steps of hopping - observation plan Proficient hopping ○ To become Proficient, children must: Swing leg lead the hip Support leg fully extending The arms must move in opposition to the leg The support leg must flex at landing to absorb force and prepare for extension at take off Developmental changes in Hopping ○ Few Children Under Age 3 can hop repeatedly ○ Most children show step 2 in arm and leg action ○ Hopping on non preferred leg was developmentally behind hopping on the preferred leg ○ Hopping continues to develop well past the age of 5 ○ Neuromuscular system contributes to advancement in hopping E.g. neuromuscular system prepares ahead of time when landing to absorb the force, leading to less flat foot landing when hopping An Integrated Approach to understanding Hopping ○ Interaction of individual constraints in the body within the framework of the principles of motion Swing leg held in front may react rather than contribute to the hop For a lightweight child, the stationary leg does not prevent hopping As the child grows older and adds body weight and size, these increase her inertia, so projecting downward from the stance leg is not enough to hop, so she adds swing leg movement to provide additional force Swing leg helps push the body down and back, the ground responds by pushing body up and forward (newton 3rd law) Child will return with greater force because of increased weight and height of the hop, resulting in a softer landing by flexing the leg. All examples of the body recalibrating and changing patterns to account for changing individual constraints Observing Hopping Patterns ○ Halverson suggests a systematic pattern of observation that focuses on the body parts one at a time Is the swing leg active? Does it move up and down or swing past the support leg? Does the support leg extend at take off? Does it flex on landing and extend on the next hop? Is arm movement bilateral or opposing Rate Controllers in Hopping ○ Depends on postural systems ability to balance the body on one limb for a succession of hops ○ Body must be able to generate enough force to lift the body with one limb, recover, and quickly generate enough force to hop again  In running legs alternate projecting on one limb and regain energy as they swing in flexed position, in the hop, legs stay extended, thus it requires more effort than running. Generating force can act as a rate controller. Galloping, sliding and skipping ○ Involve the fundamental movements of stepping, hopping and leaping ○ Galloping and slides are both asymmetric gaits, Consists of a step on one foot, then a leap on the same foot Same leg always leads with the step Difference is direction of movement In galloping, individual moves forward In sliding, individual moves sideways ○ Skipping is a step and a hop on the same foot, with alternating feet. Movement is forward Characteristics of Early Skill Patterns ○ Children's early attempts at these skills are usually arrhythmic and stiff ○ Arms are rarely involved in force generation ○ Arms may be held in high guard or out to the side for balance ○ Stride length is short and land is flat footed, ○ Little trunk rotation is used ○ Vertical lift is exaggerate ○ In galloping, child training leg may land ahead of the lead leg Proficient Skill Patterns ○ Proficiency in these skills includes the following: Arms no longer needed for balance In skipping, arms swing in opposition to the legs to provide momentum Child can use arms for other purpose in galloping and sliding Forefoot or heel to forefoot landings Knees give on landing, remaining flexed while they support the body weight, extend at take off Developmental Changes ○ Galloping is the first of these three bipedal patterns to emerge ○ Develops between 2 and 3 years of age after child develops running pattern and before hopping ○ Galloping is uneven as opposed to walking and running 50 percent phasing of the legs. The steps take longer than the leap-steps Two timing patterns: Step takes twice as long → 66 to 33 percent phasing Or 3 times as long → 75 to 25 percent phasing ○ Children master sliding next ○ Skipping is usually the last of the locomotor patterns to emerge, usually between 4-7 years of age ○ First, a child might perform a unilateral step hop  Which is A skip with the dominant leg and a running step with the other leg ○ Several changes are apparent Beginning skipper uses a high hop and knee lift Skip appears jerky which reflects the need for much effort to project the body off the ground for the hop Child will partially extend leg on the hop and use a lower but smoother knee lift. Greater leg strength allows child to get body off the ground with only partial leg extension Beginners use arms inconsistently Often swinging one or both arms Then arms are used bilaterally Then skilled skippers can use their arms in opposition to their legs Observing Galloping, sliding, and skipping PAtterns ○ Galloping- Take note of trailing foot in relation to the lead foot ○ Take a side view first ○ Arms can be viewed from any angle ○ Sliding best observed from the front Focus on knees Ar arms in guard position or relaxed ○ When watching skipping Does the child skip with one leg and runs with the other, or skips with both Watch the arm pattern to see if its bilateral or oppositional Rate Limiters for Galloping, Sliding, and Skipping ○ Galloping Generally follows running in the development of motor skills Individuals must uncouple their legs from the 50% phasing they use Rhythmic or coordination changes Different amounts of force in two legs ○ Sliding Individuals must turn to one side, neuromuscular system may limit the rate at which these two skills develop ○ Skipping Generation of force is not a limiter as skipping is done after hopping, same for balance Main limiter would neuromuscular system that coordinates the two limbs Summary and Synthesis ○ Locomotion is one of the first signs of an infant's independence ○ Creep, crawl is initial means of moving ○ And then walking which is the basic form of upright bipedal locomotion ○ Next, come running, and then comes the ability to jump, hop, slide and skip. ○ Constraints affect the timing and sequence they emerge, and can be traced further into adulthood.  ○ Form of skills changes as child becomes more proficient ○ Across all locomotor skills, similar patterns of change appear Individuals narrow their base of support to increase mobility, and may widen it to increase stability in older adulthood ○ Adults do not generally use the entire range of locomotor patterns. Due to sociocultural attitudes and energetic inefficiency Test Your Knowledge Questions Ch. 5: 1. Describe the constraints that may act as rate controllers for specific locomotor Activities. Specific Locomotor activities can include sports such as basketball and baseball, or physical education games directed at young children, or traveling from place to another place in a city. Rate Controllers For most sports can be related to functional or structural constraints in individuals such as Loss or decline of muscle, bone density, and cardiorespiratory health, as well as certain limb length and neuromuscular coordination, as these are required to have proficient form in running, throwing such as in baseball and basketball, and sliding, galloping and skipping that may be use in P.E games for children. Rate controllers in traveling outside from place to palace can also include the environmental constraints and their interaction with individual constraints, such as balance interacting with a steep terrain or loose gravel, or arthritis interacting with walking long periods of time, this can affect the walking form. Temperature may also constrain certain movements in activities that require locomotion like baseball, a muddy field in the rain may result in a slower and more cautious run as the athlete tries to travel between bases without slipping. 2. How can a teacher or therapist manipulate task constraints to help a child acquire the skill of galloping? They can Manipulate the task constraints by starting with foundational skills and allowing for aid where the child may be lacking when galloping. Galloping is asymmetrical and often occurs after having understood locomotor skills like running and walking, but in orde3r to move to a gallop, the childs must learn to change the phasing of the legs and sequence of the steps. First, the teacher or therapist can make sure there is plenty of space to practice the step and then leap with the same foot, and give the instructions or task to the child through familiar cues and example, and as they develop the rhythm or semi coordination, the teacher can place down visual markers on the floor and have the child try to get to the markers by “leading with the same foot,” and requiring a “a step then a leap” in order to travel successfully using the markers. By changing the environment and task of the child in that environment it will all interact with the child's individual constraints to help develop the skill of galloping. 3. What are some of the ways humans can move from place to place (without equipment)? Which ones are not currently observed in adults? Why are these locomotor forms rarely used?  Moving place to place without equipment such as cars, scooters, bikes, is essentially by using Locomotor skills such as running, walking, hopping, and jumping. These locomotor skills develop in childhood in a way that correlates with calibration of the environment through interacting constraints. Walking and running are some of the most used locomotor patterns used throughout the lifespan, as it is used to move yourself from place to place in an efficient way that conserves energy and time, however there are locomotor patterns not current observed in adults such as galloping or skipping, and sliding. Unless in a game-like setting or task specified to have an adult do anh of these locomotor skills, they are not used on a daily basis to carry out daily living activities. There is no need, or reason, for adults to use these locomotor skills because many require extra energy that either adults may not feel like using, or have any “motive” for using. Sociocultural factors also play a role in adults' lack of using certain locomotion because they are not deemed appropriate for an adult to be doing in an average setting such as the work place, public places, or at home, as we;; as not viewed as being needed when walking conserves more energy. 4. What movement characteristics might you see in an older adult who is galloping? Why? If an older adult is galloping, you may see arms up on high guard as balance is known to decline with older age because of muscle and strength loss, as well as possible bone disease and neuromuscular decline. With the decline of strength and muscle, lack of coordination may also be seen in the galloping form, due to the fact that the phasing of the legs is different than when running, as the older adults are not usually galloping, showing less experience in the form as well. There may be minimal trunk rotation and steps will be flat footed and short, because of the caution for falling, as older adults lack strength and reaction time leads to higher risk for falls. The reduced range of motion in the trunk and joints such as the knees, will also alter the galloping pattern and revert back to earlier more stiff movements seen in galloping in adolescence. Chapter 6: Development of Ballistic Skills Pg. 201-247 Introduction ○ Ballistic skills are those in which a person applies force to an object in order to project it ○ Throwing, kicking, and striking Have similar developmental patterns because mechanical principles are basically the same Skill studied most is the overhand throw for distance Overarm Throwing ○ Throwing takes many forms ○ Two hand underhand throw and one hand underhand throw are common in young children  ○ Type of throw depends on task constraints. ○ Researchers often make product assessments to determine skill development I.e measuring distance, accuracy or ball velocity ○ Task constraints must change depending on age ○ Individual factors can also affect distance, like size and strength Characteristics of early overarm throwing ○ Determining development is helpful when looking at child's early attempts at throwing ○ Young children , especially those that are under 3 years, tend to have restricted arm action. ○ Execute throw just by elbow extension Proficient Overarm Throwing ○ We can identify limitations in early throwing by studying a proficient throw ○ An advanced forceful throw for distance involved: Leg opposite of throwing arm stepping forward to increase distance of thrower applying force to ball and allow full trunk rotation Trunk rotates forward to add force to throw, trunk rotation is differentiated Trunk bends laterally, awat from throwing arm Upper arm forms right angle with the tunk and comes forward just as shoulders rotate to front facing Throwing holds elbow at a right angle during forward swing, extending arm when shoulders reach front facing. Forearm lags behind trunk and upper arm during forward swing Follow through with wrist flexion Thrower carries out the movements of the body segments sequentially, adding contributions of each part to the force of the throw 1. Forward step and pelvic rotation 2. Upper spine rotation and upper arm swing 3. Upper arm inward rotation and elbow extension 4. Release 5. Follow-through Developmental Changes in Overarm Throwing ○ Whole body component approach ○ Arm action and trunk action are validated developmental sequences Sequences of advances in the performance of a skill that have been determined by longitudinal study and shown to fall in the same fixed order for all individuals See Developmental sequence for throwing Pg 206 ○ Use an observation plan ○ Block rotation of the trunk is forward rotation of the lower and upper trunk as a unit. ○ In differentiated trunk rotation, the lower trunk (hip section) rotates forward while the upper trunk (shoulder section) is rotating backward, still preparing to rotate forward.  ○ To analyze arm movements Study the preparatory backswing Then the upper arm (humerus) And finally forearm motion Note. deepest lag of forearm comes before the front facing position of the shoulders ○ Letting distal body sections lag behind more proximal ones allows momentum to be transferred and distal sections to increase speed, providing the movements are well timed. ○ Most unskilled throwers throw without taking a step When they learn, the step may be homolateral which reduces the extent of the trunk rotation and range of motion available ○ Body component levels will vary ○ Structural constraints limit the movements that some body sections can make while other body sections are moving in a particular way ○ Tendency for children to go from no trunk rotation to trunk rotation before the upper arm and forearm advance to intermediate levels ○ Mechanical constraints and neurological development are rate limiters ○ Older children better coordinate their joint actions, using open kinetic chain ○ Girls progressed slower than boys in throwing Gender differences reflected a culture of discouraging girls to practice overarm throwing Boys more likely to develop advanced leg movement, trunk movement and forearm movement Instruction and practice may help girls in their skill development Gender differences also occurred in adulthood ○ Researchers examined if biological factors or environmental (sociocultural factors) are responsible Observing Overarm Throwing Patterns ○ Best observed from front or back Trunk to upper arm angle Elbow angle Lateral trunk bend ○ Best observed from the throwing side The step Trunk rotation Upper arm and forearm lag Throwing in Adulthood ○ Thrower must move many joint through a full range of motion with precise timing ○ In comparing younger and older adult throwers, we can observe both the movement patterns used and how the movements are controlled. ○ Sex differences were similar to adolescence, and most older throwers took a short contralateral step. ○ Almost all used block rotation.  ○ Those who participated in sports with over arm movement patterns at young ages were better throwers. ○ Actions during backswing in ballistic skills are related to ball velocity Those who used circular downward backswing threw faster than those using a upward (shorter) backswing Many older adults used backswing movement pattern that was different Many started with circular downward back swing but did not complete circle Bent elbow to bring ball behind the head This coil be due to change in musculoskeletal symptom such as decreased shoulder flexibility or loss of fast twitch muscle fibers Consistent decline with advancing age Decreases range of motion and slower movement speeds Small changes are more typical than large declines, however ○ Throwing movements of older adults are characterized more by stability in the developmental steps than by rapid decline. Change is more often typified by increased variability from throw to throw, a slight slowing of movement, or a more limited range of movement. ○ One or more body systems might regress, causing a slowing or limitation of movement Throwing for Accuracy ○ Task change causes change in movement pattern ○ Male throwers categorized as significantly lower developmental steps when throwing for accuracy ○ Female throwers tended toward lower steps but nt significantly different ○ In accuracy conditions, Throwes use movement patterns that are difference from those for distance conditions ○ Throwes use slower velocity in accuracy condition ○ Older adults changed little from one condition t the other, but most adapted their movements in at least one body component ○ Person-task interaction influences movement Kicking ○ Kicking projects an object, but with a strike ○ Children must have sufficient perceptual abilities ○ Eye foot coordination Characteristics of Early Kicking ○ Unskilled kickerfs tend to use a single action rather a sequence of actions ○ Trunk does not rotate and child holds arms stationary at sides ○ Just as young children throw with arm action alone, young kickers ○ use only leg action. ○ Just as young children throw with arm action alone, young kickers use only leg action Proficient Kicking ○ Advanced kickr does the following:  Preparatory wind up, trunk rotated back, kicking leg cocked, by keeping or running up to the ball Uses sequential movements of the kicking leg. Thigh rotates forward, then lower kef extends just before contact with the ball to increase radius of the arc through which the kicking leg travels Swings kicking leg through a full range of motion at the hip Uses trunk rotation to maximize the range of motion. To compensate for the complete leg swing, kicker leans back Uses arms in opposition to legs as a reaction to trunk and leg motion Developmental changed in kicking ○ Children do not automatically achieve proficient kicking ○ Distances act as control parameters for kicking, just as speed. ○ Individuals will change kicking patterns once a critical kicking distance is reached. ○ Children changed movement form when asked to kick longer distances much in the way children improve proficiency over their childhood ○ Ability to generate force may be key component driving developmental change in kicking Observing Kicking Patterns ○ From the side, a teacher or coach can look for Placement of the support foot Range of motion and precontact extension in the kicking leg Range of trunk motion and Arm opposition Punting ○ The ballistic skill of punting is mechanically similar to kicking, but is more difficult to learn. ○ To punt,a child drops the ball from the hands and must time the leg swing to the dropping ball Characteristics of early punting ○ Beginning punters tend to toss the ball up rather than drop it and will often release the ball after the support leg contacts the ground, if the child steps at all. ○ Arms drop to the sides ○ Child might rigidly extend the kicking-leg knee or bend it at a right angle. ○ Ball contacts the toes. Proficient Punting ○ Extend arms forward with the ball in hand before dropping it as final leg stride is taken ○ Move the arms to the side after releasing ball than move into arm opposition ○ Leap onto the supporting leg and swing the punting lef vigorously to contacts the ball such that he body leaves the ground with a hop ○ Keep the kicking leg knee nearly straight and toes pointed at time of contact Developmental Changes In punting  ○ Arm action is divided into two sequences, one for the ball-release phase and one for the ball-contact phase. ○ Sequence that moves from Tossing ball up to begin the punt Dropping the ball late And finally, timing the drop appropriately ○ Ball contact sequence shows arms go from no use to bilateral movement, and then to arm opposition that accompanies forceful lower trunk rotation ○ Leg action reflects a developmental transition from short step of non kicking leg, to a long step, to then a leap. ○ At contact the ankle of kicking leg changes from a flexed to an extended position ○ See developmental sequence for punting pg. 230 Observing Punting Patterns ○ Observing from the side offers you a view of the ball drop, the arm position, and foot position ○ You can clearly see the degree of foot extension at ball constant from this position Sidearm Striking ○ Striking encompasses numerous skills ○ Can be done with various body parts, such as the hands or the feet ○ Swinging a bat sidearm, a racket overhand, or golf club under hand. ○ Sidearm striking is a form of striking where the arm remains at or below shoulder level. One example of sidearm striking is a person swinging a baseball bat. ○ Striking involves the most difficult perceptual judgment ○ Teachers often adapt striking tasks for young children by making the ball stationary Characteristics of early sidearm striking ○ A child's first attempt to strike sidecar often look like unskilled attempts to throw overhand ○ Child chops at the oncoming ball by extending elbow, using little leg and trunk action Proficient sidearm striking ○ Incorporates many of the characteristics of an advanced overarm throw, such as Stepping into the hit, thus applying linear force to the strike Steps should cover a distance of more than half individuals standing height Using differentiated trunk rotation to contribute more force through rotary movement Swinging through full range of motion Swinging in a roughly horizontal plane and extending the arms just before contact Linking or chaining movements together to produce the greatest force possible Backswing and forward step  Pelvic rotation Spinal rotation and swing Arm extension Contact Follow through Developmental changes in sidearm striking ○ Apply the sequences for foot and trunk action in the overarm throw to striking ○ The arm action for sidearm striking is distinct from that for over arm and underarm striking, but all three forms share many of the same mechanical principles ○ First obvious change occurs when a striker stands sideways the path of the incoming ball By transferring the weight to the read foot, taking a step forward, and transferring the weight forward at contact, a striker is able to improve striking skills ○ Second change is the use of trunk rotation. Individuals usually use block rotation before advancing to differentiated rotation ○ Strikers also progressively change the plane of their swing from vertical chopi g to an oblique plane and finally a horizontal plane ○ Eventually they obtain a longer swing by holding their elbows away from their sides and extending arms before contact. ○ A beginner striker golds a racket or battle with a power grip, which makes the striker swikng and supinate the forearm, undercutting the ball. Observing Sidearm striking patterns ○ At the pitching position (directly in front of the child) you can observe The direction of the step The ;lane of the swing Arm extension ○ From the side You can check the step The trunk rotation And extent of the swing Overarm Striking ○ One can execute overarm striking without an implement (like a volleyball serve) or with an implement (a tennis serve) Characteristics of Early Overarm Striking ○ A beginner demonstrates limited pelvic and spinal movement, swings with collapsed elbow and swings the arm and racket forward in unison Proficient Overarm Striking ○ Skilled overarm striking: Rotates both the pelvis and spine more than 90 degrees Holds the elbow at an angle between 90 and 119 at the start of the forward movement Lets the racket lag behind the arm during forward swing  ○ Racket lag is consistent with the open kinetic chain principle, where force is generated by a correctly timed sequence of movements ○ The humerus and forearm lag is an example of an open kinetic chain. Humerus lags behind trunk rotation, the forearm lags behind humerus, racket lags behind forearm Developmental changes in overarm striking ○ Similar to overarm throwing and sidearm striking but also has unique features. ○ Trunk, humerus, forearm and le sequences are similar to overarm throwing ○ Pelvic range of motion, spinal range of motion, elbow angle and rocket action are unique to overarm striking Observing over striking ○ Observe from pitching position in addition to watching front he side Older Adult Striking ○ Tennis and gold are two contexts for older adult research because of the large senior following ○ Difference in rhythm when golfing Older golfers reaches peak force earlier Older golfers also had larger force changes in latter phases of the swing Strength and flexibility of this task were low, thus constraints like loss of strength and flexibility with advancing age would not have affected older golfers compared to younger ones ○ Many older performers can be as accurate as younger performers when strength and flexibility demands are not high, but it is likely that some performers in a group of elders will not be as accurate as the young. ○ Well-practiced movement patterns might be well maintained over the life span. ○ TGMD pg. 244 Interventions ○ Interesting in interventions that promote development of fundamental motor skills in preschool and early elementary school children ○ Motor skill competency is important for achieving lifelong health and wellness ○ A study of children 3 to 8 years of age demonstrated a higher improvement in both locomotor and object control skills for children in an intervention program supplementing regular physical education ○ Intervention in preschool ages girls for throwing overhand demonstrated short and long term improves in bal skills Summary and Synthesis ○ Proficient performance of ballistic skills requires movements that obey mechanical principles for maximizing force and speed ○ As children improve their skills, we see movements change that are consistent with these mechanical principles I.e. forward step that transfers momentum into the direction of the throw or strike Rotary motions of the trunk, usually sequences  Sequential movement of the projecting limb allow distal body components and striking implements to laf behind larger and more proximal body components so that momentum is transferred and speed is increases Task conditions and the interaction between the person and the task are important for determining what movement patterns emerge in performance Test Your Knowledge Questions 1. What distinguishes kicking from punting? 2. Identify four of the major qualitative changes in the development of each of the following ballistic skills: throwing, punting, and overarm striking. 3. What qualitative developmental changes are shared by throwing and overarm striking? Why might both skills change in these ways? 4. What characteristics of intervention programs result in the improved performance of young children? Chapter 7: Development of manipulative Skills Pg. 250-286 Introduction ○ Limb movements arise from the interaction of individual, task, and environmental constraints ○ The environment plays a role because gravity acts on the object Should I pick this up with one or two hands? ○ The task is a factor in several ways Consider the shape of the bowl Does the shape and the weight afford lifting the bowl with one hand or does it need two? Consider the person's strength - does this individual constraint interact with task and environment to afford lifting with one or two hands? ○ w/ growth and aging, many individual structural constraints change Length and size of the limbs change Strength changes Conditions like arthritis can make manipulative skills difficult Grasping and Reaching ○ When a skilled adults wants to obtain a small object, the arm reaches froward and the the hand grasps the object ○ Reach and grasp form a smooth movement unit ○ Prehension - is the grasping of an object, usually with the hand or hands. Grasping ○ In early grasping, the infant squeezes an object against the palm without the thumb providing opposition  Eventually, the infant uses the thumb in opposition but still holds the object against the palm These are called power grips The first year is characterized by a transition from power grips to precision grips ○ Transition from power to precision grips using a cube 1. Age - birth - no contact 2. 1 month - limited contact 3. 2 months - grasp with entire hand 4. 3 months - adjust hand position 5. 4 months - grasp with thumb on top 6. 5 months - grasp with fingers only ○ Shape and size of object influenced the specific type of grasp ○ By 9 months, infants reliably shake their hand in anticipation of an object's shape as they go to grasp it ○ The first year sees a transition from power grips to precision grips, but the particular grip used is influenced by the shape and size of the object grasped. ○ Devel[mentalists viewed pr4ehension as a behavior acquired in steps ○ Maturationists viewed these age related change in the same vein as motor milestones ○ Each progression linked to new stage with neuromotor maturation ○ interacting constraints in prehension movement ○ Neuromotor system must be mature enough to control precision grip ○ After infancy, visual information and body size appear to constrain the shape of the hands in grasping and the number of hands used to grasp a particular object. ○ Movement selected by individuals is related to their hand size compared with an object's size or movement reflect body scaling ○ Constant ratio of hand size to object size determined when individuals chose to use two hands to pick up an object instead of one ○ Vision also plays a role in this type of task ○ We select the grip appropriate for the size, weight, and shape of the object to be attained ○ Infants tend to knock an object before actually grasping it In contrast, adults shape their hands before making contact with an object They also make the decision to reach with one or two hands before making contact with an object Visual information is used in preparation for the grasp ○ 6-7 year olds were more dependant than adults on visual feedback during the reach to shape their hand for the grasp ○ Grasping is a very stable skill over the lab ○ Conditions such as arthritis or loss of strength in older age would influence hand configuration Reaching  ○ Infants make a transition during their first year from random arm movements to riches that allow them to grasp objects ○ Many developmentalists proposed that reaching and grasping required seeing both the object and the hand in the visual field so that vision and proprioception could be matched ○ Infants build a system of visually guided arm movements from initial poorly coordinated movements ○ Infants rely on vision to refine the path of the reach and configure the hand to the object ○ Infants make the transition from pre reaching to reaching at 3 to 4 months of age ○ To reach objects, infants learn to control their arms; they learn by doing. ○ Infants learned to align their gaze to w\here they reach ○ Infants begin reaching for stationary and moving objects at about the same age and have similar success in reaching ○ Use reaches that are bimanual and made with the arm on the same side as the object Hand-Mouth Movements ○ Arm movement brings the hand, with or without an object, to the mouth Between 3-4 months, infants become consistent bringing hand to mouth At 5 months, they open their mouth in anticipation Bimanual reaching and manipulation ○ Reaches discussed thus far are unimanual, or one arm ○ Infants also acquire bimanual reaching and grasping ○ Infants in their first year alternate between periods when unimanual reaches predominate and periods when bimanual reaches predominate. ○ Reaches begun with two hands usually result in one hand reaching and grasping the object first ○ Manual activities might be influenced by postural control ○ After 8 months, infants start to dissociate simultaneous arm activity so they can manipulate an object coorporevly with both hands ○ Late in the first year, infants learn to hold two objects one in each hand and bang them together ○ By 12 months, they can pull things apart and insert one object into another ○ Early in the second year, infants can use tools flexibly. The Role of Posture ○ Postural control i important in reaching ○ Infants typically sit index penalty by around 6 to 7 months Before this, their trunks must be supported for them to achieve a successful reach ○ Reaching improves when infants are able to maintain postural control ○ Shift to bimanual reaching at the end of the first year has been associated with the onset of walking with support through longitudinal observation of infants Manual performance in adulthood ○ Reaching and grasping remains important throughout the lifespan  ○ Many careers involve manipulation, and in older adults the ability to perform some ADL’s ○ Changes in individual constraints that accompany aging which could affect manipulative skills cross sectional study showed declining in scores on hand measures after 50, as wella s reaction, movement, and tapping times, and coordination ○ Grip strength decline with advancing age ○ Declining manual performance was associated with loss of strength and upper joint impairments resulting from musculoskeletal disease ○ In reaching, older adults slow down more than young adults at the end of the reach, presumably to make more correction in their trajectory ○ Older adults did not coordinate their finger and wrist movements well ○ Loss of speed in movement with aging is a common finding for large and fine motor movements ○ Disuse and disease affect it as it does locomotor and ballistic skills ○ Some aspects of older adults’ reach slow down, putting them at a disadvantage in making sequential movements, but accuracy of manipulation is stable, especially on well-known tasks. Rapid Aiming Movements ○ In some complex motor skills, participants make rapid aiming movements Arm movements involve an initiations and acceleration obhase from the start of the movement to the point when peak velocity of the arm movement is reached Then declaration and termination phase from peak velocity to the end of the movement Young adults make this moment symmetrically As in, the acceleration and deceleration phases are equal Older adults do not begin the movement as forcefully or travel as far in the acceleration phase Tend to have longe declaration phase to compensate because they need more adjustments in the final phase Especially because aiming needs to be accurate ○ Ram are involved in tasks requiring monitoring and manipulation of complex displays such as cockpits ○ In critical tasks, many such movements can be required in sequence, and any slowing effects can accumulate ○ Practice is important in older adults They can compensate for some slowing when they know the locations of buttons or levers very well Catching ○ Several manipulative skills are basic to sport performance A performer must gain possession or control of an object by reaching to intercept a moving object or stoping it with an implement ○ Is a relatively difficult task  ○ The interception aspect of catching makes it difficult ○ Goal of catching is to retain possession of the object you catc It is better to catch an object in the hands than tp trap it against to body or opposite arm Because if the object is caught in the hands, the catcher can quickly manipulate it- usually by throwing it ○ A child's initial catching attempts involve little force absorption ○ Beginning catching. This young boy holds his arms and hands rigidly rather than giving with the arrival of the ball to absorb its force gradually. ○ It is common to see children turn away and close their eyes in anticipation of the balls arrival Proficient Catching ○ In moving from novice to proficient catching, a child must: Learn to catch with the hands and give with the ball, thus gradually absorbing balls force Master the ability to move to the left or the right, or forward and back Point the fingers up when catching a highball and low when catching a low one Developmental Changes in Catching ○ It is more difficult to identify developmental sequences for catching skills than most locomotor or ballistic skills because the sequence is specific to the conditions under which the individual performs ○ Many factors are variable Balls size, shape, speed, trajectory, and arrival point ○ Gender differences might reflect patterns of participation in ball games ○ Developmental sequence pg. 269 ○ As a catcher improves they: Are better able to move their bodies in response to the oncoming ball Adjust their hands to anticipated location of the catch Catch the ball in their hands ○ Children over 8 made adjustments in body position in response to oncoming ball ○ A developmental profile is a combination of the developmental steps shown by a performer over all body components. For example, a developmental profile for catching could be arm 2, hand 3, body 2. ○ Catching, like striking, involves anticipating where a ball can be intercepted ○ And the ability to complete the movements that position the hands at that location ○ Children better predict the ball flight as they get older Observing Catching Patterns ○ Catching can be observed from the front, allowing you to toss the ball or from the side. ○ Easy to assess the product in catching task Record percentage of balls successfully caught ○ To assess catching skill, environmental and task constraints such as ball size and ball trajectory must be tracked and replicated.  ○ Observation plan page. 272 ○ For example, if you observe a child who extends her arms, palms up, and scoops a large ball thrown to her, trapping it against her chest, all without moving her feet, the developmental levels would be step 3 for arm action, step 1 for hand action, and step 1 for body action. Anticipation ○ Manipulative and interception skills involve anticipation ○ Ball or other moving object can approach at different speeds, from different directions along different trajectories and may be varying size and shape ○ To be successful, performers must initiate movements ahead of interception so that the body and hands can be in proper position when the object arrives ○ Reception skills through use of coincidence anticipation tasks It is easy to vary task characteristics and observe the effect on performance ○ A task can be defined as a requiring a simpler or more complex movement response and the characteristics of the ball can be varied to further contrarian the movement ○ Coincidence-anticipation tasks are motor skills in which one anticipates the completion of a movement to coincide with the arrival of a moving object. ○ Task constraints in coincidence-anticipation tasks Improves through childhood and adolescence Exact pattern of improvement with advancing age depends on task constraints Young children are less accurate as the movement required of them gets more complex = complexity influences how children perform Children's accuracy decreases if the intersection point is farther away = having to move to intercept Young children more successful catching larger balls High trajectory also makes interception more difficult because ball changes direction horizontal and vertically Ball and background combinations Speed of moving object ○ Interception success is often related to ball size, speed, trajectory, and other task and environmental constraints. ○ What underlies these age-related trends in coincidence anticipation? ○ Information processing perspective Performers were thought to receive visual and kinesthetic information and perform calculation on that data, like a computer,to project the future location of the moving object to intercept it ○ Perception-action perspective Holds that all needed information is in the environment and that no calculations are necessary Information of the environment specific the action or movement possibilities of that environment t- affordance  ○ Two important characteristics of the person- environment system are constant patterns of change, called invariants, and the expanding optic array. ○ Optic array refers to the visual picture falling on our retinas as we approach an object or as a moving object approaches us An affordance is an action or behavior provided or permitted for an actor by the places, objects, and events in an environment; it is often related to the relative sizes of the actor and the objects. Invariance is stability in the kinematic values of a set of movements (i.e., keeping patterns in the environment constant). An optic array consists of the light waves reverberating from surfaces in the environment—in other words, the stimulus for visual perception. ○ It is possible that we use the rate of expansion of this image on our retinas to know when arrival or collision will occur ○ To reach objects, the expansion rate of the image of a directly approaching ball on the retina could be used to time an interception. ○ Catchers can intercept a directly approaching high trajectory ball by keeping a ratio, based on the angle of the gaze, at or near zero If the ratio’s value is positive, the ball will land behind the catcher; if it is negative, the ball will land in front. By keeping the ratio near zero, the catcher knows whether to move forward or backward and how quickly to move ○ catchers could keep the vertical optical acceleration of the ball close to zero. This is called the optical acceleration cancellation (OAC) strategy. In this approach the catcher focuses on the ball’s acceleration in the vertical plane as the catcher views the ball. Both approaches tell a catcher whether to move forward or backward. ○ Many catches require sideways movement Strategy for this is keeping the lateral position of the ball constant with respect to the catcher Constant bearing angle strategy For example, soccer goalie could keep his angel constant by moving sideways to intercept a ball ○ Continuously moving to stay under balls trajectory ○ Catchers are able to intercept balls by keeping certain relationships between themselves and the ball constant. How do Children Learn to Arrive at the right place? ○ Children must learn to male more precise calculations to become proficient catchers ○ Errors made in early attempts serve as informative feedback that can be used to refine the calculation process ○ Children learn to catch fly balls from their experiences with catching. Both successful and unsuccessful catches contribute to learning a relationship between the visual display and the position of the body. ○ From perception-action perspective  Role of parents, teachers and coaches help children discover sources of perceptual information that constrain movement in interception tasks Training must be sports specific And must focus on factors known to limit novice performance Catching in Older Adulthood ○ Experienced older adults know the invariant patterns that provide information about intercepting balls ○ Factors that may change Quickness with which movement is initiated Maximum speed that could be achieved in moving to the ball Extent of reach if the catchability of a given ball were at the limit for an individual's speed in moving ○ Older adults are somewhat less accurate and more variable in their performance than younger performers and the differences are greater when the moving object moves faster and when the older adults are sedentary rather than active ○ Repetition of skills important for maintaining skill ○ Maintaining the speed of even fine movements could be related to older adults catching performance Summary and Synthesis ○ Manipulative skills set humans apart from other species ○ Infants become skilled at reaching and grasping stationary and moving objects early in life, during the first year, al;though using the two hands in complementary ways comes a little later ○ At any age, further the catcher travels, the more difficult the catch ○ Aging effects a catchers ability to get to a ball more than the ability to know where to be in order to catch the ball ○ When task demand gradespeed, older adults are disadvantaged compared with younger adults ○ Children need practice in order to learn, even if subconsciously the information available in the environment is important for catching success. Test Your Knowledge: 1. How does the size of an object affect the grip that an infant uses? How might this factor influence where an infant falls on Halverson’s prehension sequence? How does the shape of an object affect the grip used? 2. Do infants learn to reach for objects by better matching their hand position and the scene location of the object, or do they first learn to control the arm? Explain why you chose your answer. 3. How does reaching for stationary and moving objects compare in infants? 4. How does manipulative skill change in older adulthood, and how can older Adults adapt to these changes? 5. What are the major developmental trends we see in children as they  become increasingly proficient in catching? 6. When balls do not come directly to the catcher, what situations (environmental and task constraints) make catching success difficult for children? For adults? 7. Explain, from the information processing perspective and the perception– action perspective, how children learn to go to the proper place to catch a ball not traveling directly toward them. 8. What changing individual structural constraints might affect an older adult’s skill in driving or piloting? 9. Think about the term coincidence anticipation. Explain why someone who prefers the perception–action approach might consider this to be a misnomer for interception skills. Chapter 10: Development of Cardiorespiratory Endurance Pg.364-393 Introduction ○ Cardiorespiratory endurance reflects one's ability to sustain vigorous activity ○ It is important because Participation in many physical activities demands sustained vigorous exertion Health of cardiac, vascular, and respiratory systems is related to endurance level, largely because training that improves endurance makes these systems more efficient ○ Cardiorespiratory endurance has the greatest implications for lifelong health ○ Worldwide trend toward reduced fitness in children ○ Sedentary lifestyle that today's adults have adopted has spilled over to the l\ibves of their children ○ High percentage of teens and children are unable to sustain vidforu physical activity Exhibit risk factors for coronary heart disease and obesity  ○ Children in poor physical condition are likely to maintain that status through their adult lives Physiological responses to short term exercise ○ Vigorous activity can be: A short burst of intense exercise A long period of submaximal work Or a combination of these types ○ Bodies meet differing demands of bieg intensity and longer moderate activity with different physiological responses ○ During a brief period of intense activity body responds by depleting local reserves of oxygen and sources of energy stored in the muscles Creating deficit of oxygen that must eventually be replenished These are anaerobic systems Means without oxygen ○ Anaerobic system oer acne can be reflect in anaerobic power and anaerobic capacity ○ Anaerobic power is the rate at which a person’s body can meet the demand for short-term, intense activity. ○ Anaerobic capacity is the maximum oxygen deficit a person can tolerate. ○ As period of exercise grows longer, anaerobic systems contribute less and less to body's response ○ Respiration and circulation increase to bring oxygen to the muscles ○ 90 second into exercise, anaerobic and aerobic contribute equally ○ After 3 minutes (180 seconds ) aerobic processes meet the demands of exercise ○ Aerobic performance is sustained and less vigorous or intense Anaerobic Development and Training in Youth ○ At any age, anaerobic performance is related to Body size (fat free muscle mass and muscle size) Ability to metabolize fuel sources in muscles Quick mobilization of oxygen delivery systems ○ Young children have smaller absolute quantities of energy reserves than adults do because they have less muscle mass ○ Children attain less output of absolute anaerobic power than adults ○ As they grow, so does muscle mass, and therefore energy reserves ○ They can also tolerate by products of metabolic process such as katic acid in muscles ○ Total work output scores improve over entire adolescent period boys, but only until puberty in girls Reflects muscle growth patterns of the sexes ○ Maturity has a small effect Better neuromuscular coordination and skill contribute to anaerobic performance as children grow older and the capacity for energy production improves with age  ○ More mature children show better anaerobic performance despite similar body size to les mature children ○ Anaerobic fitness improves with growth but at a faster rate than can be explained by growth alone. Anaerobic training in youth ○ Children and adolescents of both sexes have higher peak power and mean power measures after training than untrained counterparts ○ Decrease in performance after detraining ○ Extent of differences between trained and untrained youths varies based on factors Length of training Similarity of training Testing activities Increased muscle mass Neurological adaptations Anaerobic development and Training in Adulthood ○ Once individuals attain adult body, anaerobic performance remained stable Any improved is achieved through training alone ○ Starting around 35 years, anaerobic capacity declines 6 -8 percent per decade until age 70 where decline is much sharper ○ Deline may start later in 40s ○ Anaerobic performance is related to a large number of factors in adults Muscle mass and fiber type Gender Training ○ Age related changes in any of these factors would contribute to a decline in anaerobic performance ○ Muscle mass declines in training and non training adults ○ Muscle mass can be maintained with strength training ○ Men maintain their edge in anaerobic performance over women Women decline faster despite similar declines at age 70 Anaerobic Training in Adulthood ○ 60-70 yo men engage in high intensity endurance training and negated an increase in work output during a 30 second anaerobic capacity test ○ Resistance training plus speed training improved their anaerobic performance ○ Specific training generally considered most beneficial ○ Anaerobic training improves the anaerobic performance of preadolescent children and resistance training improves anaerobic performance of masters athletes. Physiological responses to prolonged exercise ○ How do bodies sustain submaximal physical activity for prolonged periods? Energy for prolonged exercise is derived from aerobic system Oxidative breakdown of food stores  In addition to the local reserved depleted in first few minutes of exercise ○ Aerobic power is the rate at which long-term oxygen demand is met during prolonged activity. ○ Aerobic capacity is the total energy available to meet the demands of prolonged activity. ○ Sustained prolonged activity depends on the transportation of sufficient tongue to the working muscles for longer periods. ○ Needed oxygen delivered through increases in heart and respiratory rates, cardiac output, and oxygen uptake Increased respiratory rate brings more oxygen to the lungs, making it available to the bloodstream Increased cardiac output allows more oxygen to reach the muscles Achieved thru increases heart rate and stroke volume Changes in stroke volume during exercise are small but one of the long term benefits of training is longer stroke volume ○ Limiting factor to vigorous activity is heart's ability to pump enough blood to meet oxygen needs of the working muscles ○ When individual engages in heavy city, heart rate increases until exhaustion ends the activity When stopping, heart rate decrease for 2 to 3 minutes and then more gradually for time related to duration and intensity of activity Fit individuals regain their resting heart rates more quickly than unfit individuals Aerobic Development and Training in Youth ○ Children tend to have hypokinetic circulation Cardiac output is less than an adults ○ Children have a smaller stroke volume than adults, reflecting their smaller hearts ○ Compensate with higher heart rates than adults at a given level of exe3rcise But cardiac output still lower than adults ○ Children have lower hemoglobin concentrations than adults Related to blood's ability to carry oxygen Hemoglobin is the protein in the blood that carries oxygen ○ To compensate for these factors: children can extract relatively more of the oxygen circulation to the active muscles than adults can Result is comparatively effective oxygen transport system Children also mobilize aerobic systems faster than adults do ○ Children’s physiological response to endurance activity is very efficient, but children cannot exercise as long as adults can. ○ As children grow, their hypokinetic circulation is reduced and response becomes more similar to adults in prolonged exercise ○ Absolute peak oxygen uptake (VO2) increases linearly in children throughout childhood and adolescence ○ Peak VO2 in girls tends to plateru after 13 years of age  ○ Boys begin with slight edge over girls that widens during adolescence ○ Peak VO2 and body mass are strongly correlated, so boys greater muscle contribute to sex differences Larger muscle mass facilitates oxygen utilization ○ VO2 is the most common measure of fitness for endurance activities ○ Peak oxygen uptake ( O2) is the highest rate that oxygen can be consumed by the muscles during aerobic work. ○ Peak O2 increases in boys throughout childhood and adolescence and in girls until age 13, after which it plateaus. If peak O2 is expressed relative to body weight, it is stable in boys and declines slightly in girls. ○ Researches have divided peak VO2 by body mass, building a ratio ○ VO2 relative to body weight stays the same thru childhood and adolescence in boys, but declines in girls Due to increase in adipose tissue ○ Scores reflecting fat free mass show a slight decline during and after puberty and small sex differences remain ○ Peak VO2 and body mass ratios demonstrate the correlation between these two measures Ratio penalizes more mature or heavier individuals, to use of the rate for other purpose is limited ○ Body Mass tends to increase slightly faster than peak VO2 around puberty Might depend on mattury in addition to body size Comparisons of peak VVO2 with age show a relationships in adolescents who vary in age but are identical in size Two individuals identical in size could differ in peak VO2 ○ Peak O2 is related to body size, especially lean body mass, as well as to maturity status. ○ With body growth increases come lung volume, heart and stroke volume, total hemoglobin, and lean body mass ○ These foster cardiac output and improve exercise capacity ○ Exercise capacity is also related to maturation rate ○ In children, body size is a better predictor of endurance than the child's sex ○ After puberty, boys on average attain considerable edge over girls and potentially retain this throughout life ○ Factor to this sex differences is body composition Average man gains more lean body mass and less adipose tissue during adolescence than does the average woman Women are similar to men in peak VO2 per kilogram of fat free body mass, but when including adipose tissue, women have lower peak VO2 Women tend to have lower hemoglobin concentrations Aerobic Training in Youth ○ The result of aerobic training is predictable in adults ○ Adults improves peak VO2 by training 3 times a week for at least 20 minutes at an intensity 60-90 % of maximum heart rate  Stroke volume increases, maximal cardiac output increases Oxygen better extracted from blood at muscle sites Maximal ventilation per minute rises ○ Is the same true for children? ○ Necessary to include a control group not training but measured over the same time as training group ○ Comparing a group that contains early maturers with a group of late maturers can bias an investigation of training effects ○ 3 studies found significant increase in peak VO2 by training group over control group ○ Training didn't result in differences between groups until children reached peak height velocity ○ Suggest a maturational threshold before children are unable to respond to training ○ Hypothesis that until results of the hormones that initiate puberty are realized, effects if aerobic training on peak VO2 are minimal ○ Intensity of training appears to be major consideration in explaining mixed results ○ Sufficiently intense VO2 training can show an increase regardless of age, maturation or sex ○ Peak Vo2 might not be the best measure of training effects in children ○ The effect of growth and maturation on peak O2 must be distinguished from the effect of training. ○ Adolescents after puberty respond to aerobic training such as adults do Heart size and volume, blood volume, hemoglobin, stroke volume and maximal cardiac output all increase in adolescents who train ○ Being physically active will help in aerobic fitness even if not specifically training ○ A sedentary lifestyle is associated with poor aerobic fitness while active lifestyle contributes modestly to aerobic fitness Endurance training greatly improves it Aerobic Development and Training in Adulthood ○ Average maximal oxygen uptake per kilogram of body weight peaks in the 20s then decreases throughout adult years ○ Loss is approximately 1% per year of life ○ Athletic ad active adults maintain a higher peak VO2 than sedentary adults ○ Most common activities to assess aerobic performance are Cycling on ergometer or walking or running on treadmill VO2 is measured Maximal working capacity Cardiovascular Structure and Function ○ Related to the structure of heart and blood vessels Major structural changes in a non diseased heart with aging include a progressive loss of cardiac muscle, loss of elasticity in cardiac muscle fibers, a thickening of the left ventricular wall, and  fibrotic changes in the valves ○ Effects of structural changes on cardiovascular function Maximum heart rate Maximum achievable heart rate with physical exertion gradually declines with aging Stroke Volume Stroke volume of older adults may or maynot decline Cardiac Output At rest or with submaximal work is unchanged with aging Healthy older adults experience a decline in cardiac output during heavy activity with a decline in peak VO2 Blood Pressure Older adults reach peak cardiac output at lower intensity of work than younger adults Older adults' more rigid arteries resist the volume of blood the heart pumps into them esp. If having atherosclerosis Lifestyle induced physical activity or associated with lower systolic blood pressure Blood Flow and Hemoglobin content For activity to be sustained, oxygen must be delivered to the working muscles by the blood Peripheral flow is maintained in older adulthood ○ Peak O2 declines throughout adulthood, a trend that is related to a decrease in maximum heart rate and in muscle mass. Active older adults maintain an edge in peak O2 over those who are sedentary. Respiratory Structure and Function ○ Elasticity of the lung tissue and chest walls declines with aging Therefore, older adults expend more effort in breathing than young adults ○ Lung volume Forced vital capacity Reflects a large inspiratory capacity of the lungs and results in better alveolar ventilation Because greatest part of oxygen diffusions to capillaries takes place in alveoli, better alveolar ventilation contributed to increased amounts of oxygen circulating the blood and reaching working muscles ○ Forced vital capacity is the maximum volume of air the lungs can't expel after maximal inspiration. ○ Decreased vital capacity with aging is established 4-5 percent per decade ○ Oxygen and carbon dioxide exchange in the lungs loses some efficiency with aging Changes in Muscle Mass ○ Decline in peak VO2 is probably related to loss of muscle mass and the ability of muscles to use oxygen as well as to cardiovascular and respiratory changes  ○ The more muscle mass, the greater the peak VO2 ○ Maintenance of muscle mass is a factor in minimizing the loss of endurance performance ○ Addition of adipose tissue with aging works against VO2 ○ Recovery period after vigorous activity lengthens ○ Various systems can constrain the potential for vigorous, sustained activity Training Programs in Adulthood ○ Adults who maintain an active lifestyle Declines are not as dramatic in older adults Keep VO2 steady for a time in older adults Sharply reduce the decline of peak VO2 Only 5 percent decline in men Significantly increase peak VO2 Even low intensity training can be very effective for older adults early in their exercise programs ○ Inactive older adults taking up aerobic training also improve in other strength and mobility tasks ○ Adults benefit from aerobic training because it minimizes the decline in performance that would otherwise accompany aging. ○ Older adults with cardiovascular disease should participate in programs designed specifically for this population Long-Term Training Effects ○ Lifelong endurance athletes had a significantly higher aerobic capacity and higher final workload ○ Lifelong endurance exercise has a positive influence on endurance levels in older adulthood Possibly through maintenance of the plasticity of physiological systems, benefiting overall health while reducing risk of disability and mortality ○ Regular activity in youth has positive lifelong benefits ○ Factor for endurance is individuals current activity level Test Your Knowledge 1. How do anaerobic endurance and aerobic endurance change with growth in childhood? How do they change with aging? 2. Can prepubescent children improve anaerobic endurance with training? Aerobic endurance? Explain your answers. 3. What are the sex differences in anaerobic and aerobic endurance over the life span? To what factors might these differences be attributed? 4. At what points in the life span can individuals improve aerobic endurance with training? Do those who build higher endurance in youth realize a lifelong benefit? What types of studies best answer this question? Why? 5. How is anaerobic endurance measured? Aerobic endurance? What is the difference between power and capacity in the measurement of anaerobic and aerobic endurance? 6. Do we know whether being active as a child or teen makes a difference in fitness levels in adulthood? On what do you base your answer? 7. How does maturity affect anaerobic and aerobic endurance in youth? 8. If you wanted to predict a youth’s endurance level, would you base your prediction on age, size, maturity, or some combination of these? Why? 9. What factors tend to limit the aerobic endurance of older adults? The Anaerobic endurance? Chapter 11: Development of Strength and Flexibility Pg. 394-430 Introduction ○ Strength and flexibility are constraints to skilled performance ○ Skills can be performed only if one has sufficient strength ○ Flexibility is necessary for many activities ○ Training that promotes increased muscle mass at the expense of flexibility puts athletes at risk of injury Muscle Mass and Strength ○ Muscle mass follows a sigmoid growth pattern Largely the result of an increase in muscle fiber diameter Sex differences are minimal until puberty ○ Loss of muscle is small from young adulthood until age of 50 ○ Strength is the ability to exert force ○ Activities of daily living can become difficult without sufficient strength Older adults who have lost much of their strength have difficult with every day tasks and have a greater risk of falling ○ The amount of force a muscle group exerts depends on the fibers that are neurologically activated and on leverage (mechanical advantage muscle fibers gain based on where force is applied in relation to the axis of rotation) In turn, fivers activated depend on cross sectional area of the muscle and on the degree of coordination activating the fibers ○ Cross sectional area of muscle increase with growth in youth ○ Strength increase as muscles grow, but muscle mass is not the only factor in strength ○ Neurological factors are also involved and changed over life to influence strength Development of Strength ○ One of the individual constraints that change with growth and aging Development of strength in Youth ○ Strength steadily increase as children grow older ○ Boys and girls similar strength levels until around 13 years old ○ Although boys are very slightly stronger than girls during childhood  ○ Boys continue to steadily improve through adolescence whereas girls start plateau ○ Largest contributor to strength in childhood was the cross sectional area of the elbow flexor muscles. ○ In children strength is greatly related to muscle mass. ○ Isotonic strength is the exertion of force against constant resistance through the range of motion at a joint. I.e 1 rep max ○ Isokinetic strength is the exertion of force at a constant limb velocity through the range of motion at a joint. I.e Cybex machine ○ Isometric strength is the exertion of force without a change in muscle length (i.e., without movement of a limb). I.e flexed arm hang ○ Other factors involved in strength levels: Peak gain indicates the point of fastest increase Peak strength increase follow peak muscle increase Endocrine system plays a role Neural influences that change with maturation can influence strength Myelination of nerve fibers Improved muscle coordination Improved of motor unit activation There is support that older children can activate a greater proportion of motor units to exert force ○ Functional strength tasks have a strength component and a skill component. ○ Two skills that involved functional muscle strength are vertical jumping and springing Practice and experience as well as leg strength influence children's performance on both tasks Functional muscle strength, just as isometric strength, increased at a faster rate than one would anticipate from muscle growth alone ○ Strength increases gradually throughout childhood; boys experience a spurt of increased strength in adolescence, whereas strength increases steadily in girls. ○ Boys gain more muscle mass in adolescence than girls do, as a result of androgen secretion Strength Training in Youth ○ Often a constraints in performance of motor task ○ Strength level interacts with task and environment to afford certain movement or how movement is performed ○ Training can change the point which strength becomes a rate limiter for a given task or skill  ○ Boys and girls as young as 6 or 7 can increase their strength with a variety of resistance training methods ○ Prepubertal individuals gain more strength expressed as a percentage change from their starting strength ○ Postpubertal individuals gain more absolute strength with training ○ Muscle strength increases with training. Compared with their nontraining counterparts, prepubescent boys achieved larger relative increases in the strength of four muscle groups at two speeds of movement. ○ Children who participated in PE for 200 minutes per week showed improvement in strength and bone strength after 7 years compared to children who only received 60 minutes of PE per week. Gains in muscle endurance and flexibility Training for certain performance worked I.e strength training for strength and power training for power ○ Strength was lose when boys stopped training ○ Prepubescent children can increase strength with training, even without an accompanying increase in muscle size. ○ Negative side effects? Children bones are still growing and could be susceptible to injury at traction and pressure epiphysis (growth plates) Weight training is risk for chronic injury or traumatic injury Loss of flexibility depending on training No differences in height or bone injuries have been found ○ Beneficial effects prePubescent and postponement boys improved strength with training Isometric training, plyometric training Adolescents showed higher recovery capacity between sets Greater gains in explosive power Adolescents need to be supervised closely when weight training for improved strength ○ After puberty, muscle hypertrophy can accompany regular strength training ○ Men and women on a weight training program gained strength at identical levels in terms of percentage increase, but men gained more strength in terms of absolute increase for two of four tests. Using absolute terms Such as women and men both gain 5 %, but men had more to start with so they gained more ○ Coordination and recursion of muscle units appeared to be similar in males and females. ○ Muscle hypertrophy is more noticeable in adolescence tboys and men in that a percentage increase of a larger muscle mass yields greater absolute dimensions Development of Strength In Adulthood ○ The average adult man is stronger than the average adult woman ○ Women can produce only 60% to 80% of the force men can exert  Most of these differences can be attributed to differences in arm and shoulder strength rather