Muscular Strength and Endurance Final Study Guide PDF

Final Study Guide **Muscular strength v muscular endurance** - Muscular strength - Ability to generate force against some resistance - Important to maintain normal levels of strength for normal healthy living - Imbalance or weakness can impair normal function - Mu...

Final Study Guide **Muscular strength v muscular endurance** - Muscular strength - Ability to generate force against some resistance - Important to maintain normal levels of strength for normal healthy living - Imbalance or weakness can impair normal function - Muscular endurance - Ability to perform repetitive muscular contractions against some resistance T**ypes of contractions and their applications/use** - Isometric contraction - Contraction that produces muscle tension but no change in muscle length - Concentric contraction - Contraction that causes muscle shortening while tension increases to overcome some resistance. - Eccentric Contraction - Resistance is greater than the muscular force being produced and muscle lengthens while producing tension - Econcentric contraction - Controlled concentric and eccentric contraction of same muscle over 2 separate joints. - Hamstring and rectus femoris of quadriceps. - Strength training must focus on functioning of muscle - Multi-planar - Various contractions -- functionally - Strength and endurance are closely related - As one improves, the tendency is for the other to do the same - For strength development - Heavier weight and low repetitions should be used - Endurance training - Lighter weight and high repetitions (10-15) are suggested - Isometric Exercise - Capable of increasing muscle strength at specific joint angles - No corresponding increase at other joint angles - May produce spikes in systolic blood pressure - Could cause life-threatening cardiovascular accident - To reduce likelihood of such an event, patient should breath - Widely used in rehabilitation - Attempt to use positional or functional exercise -- work at multiple angles throughout the range if possible **Examples of each type of contraction** - Isometric contraction- wall sits - Eccentric contraction- Lowering phase of squads - Concentric contraction- Bicep curls - Econcentric contraction- Hamstring curls **Factors that affect strength (neuromuscular efficiency, age, gender, etc.)** - Size of Muscle - Strength is proportional to cross-sectional diameter of muscle fibers - Increased cross-sectional area = increased strength and force production - *Hypertrophy* - Increase in muscle size - *Atrophy* - Decrease in muscle size - Number of Muscle Fibers - Strength is a function of the number and diameter of muscle fibers - Number of fibers is inherited characteristic - Neuromuscular Efficiency - Strength is directly related to efficiency of the neuromuscular system - Initial increases in strength during first 8-10 weeks are attributed to neuromuscular efficiency - Enhanced strength in 3 ways - **Increase motor unit recruitment** - **Increase in firing rate** - **Enhance synchronization of motor unit firing** - Age - Men and women increase strength throughout puberty and adolescence - Peaks at age 20-25 - After age 25, max strength declines 1% annually - Decline is related to physical activity - Able to retard decline in performance through activity - Biomechanical Considerations - Position of tendon attachment - Relative position of tendon attachment to fulcrum of the joint - Change in attachment will alter force generating capabilities - Length-Tension Relationship - Length of muscle determines tension that can be created - Varying lengths will produce varying tensions - Determined by overlap/interaction of actin-myosin filaments - Overtraining - Imbalance between exercise and recovery - Training exceeds physiological and psychological capacity of individual - Can have negative effect on strength training - May result in psychological or physiological breakdown - Injury, illness, and fatigue can be indicators **Fast twitch v slow twitch fibers** - Slow Twitch Fibers - Type I or slow oxidative - Resistant to fatigue - Time required to generate force is greater in slow twitch fibers, able to use more stored energy to greater extent - Primarily associated with long duration, aerobic type activities, ballistic activities - Fast Twitch Fibers - Type IIa (fast oxidative glycolytic) IIb (fast glycolytic) - Type IIx -- fatigue resistant with force capacity (a\ - Frequency of training Although there a variety of recommendations, with rehabilitation the healing process must dictate the program - Intensity is key - Variety of strengthening routines exist - *Single set* -- 1 set 8-12 reps at a slow speed - *Tri-sets* -- 3 exercises for 1 muscle group, 2-4 sets with no rest - *Multiple sets* -- 2-3 warm-up sets with progressively increasing resistance followed by several sets at the same resistance - *Superset* -- multiple exercises, 1 set of 8-10 repetitions or 1 or 2 exercises, with multiple sets of 8-10 repetitions - *Pyramid* -- multiple sets decreasing repetitions and increasing resistance - *Split routine* -- Workouts exercise different groups of muscles on different days **Open chain v closed chain** - Anatomical and functional relationships that exist in the upper and lower extremity - **Open kinetic chain** - Foot or hand not in contact with ground or some other surface - **Closed kinetic chain** - Foot or hand is weight bearing - Useful in rehabilitation - Most activities call for weight bearing of foot or hand in some capacity - May be more functional than open chain activities in some instances **Heart, blood, lungs adaptations to exercise** - Transport of oxygen relies on cardiorespiratory coordinated function - Heart - Blood vessels - Blood - Lungs - Improvements due to training - Result of increased capability of each of these four elements - Providing necessary oxygen to working tissue - Adaptations of heart - With exercise, muscle's use of oxygen increases with increased metabolism resulting in an increased need for oxygen transport - As oxygen is used by working tissue, decreased oxygen concentration triggers vasodilation - Blood flow velocity declines 🡪 increased oxygen extraction - Heart rate increases to meet demand - Stroke volume and cardiac output also change with exercise - Heart Rate (HR) - Plateaus 2-3 minutes - Heart rate increases proportionally to intensity of exercise - With increased heart rate, diastolic filling declines (less amount of time for ventricles to fill with blood) - Heart rate parameters change with age, body position, type of exercise, cardiovascular disease, heat, humidity, medication, blood volume - General prediction of maximum heart rate MHR = 220 -- age, MHR= 211- (0.64 x age) - Monitoring HR = indirect measure of oxygen consumption - Linear relationship between heart rate and oxygen consumption - Least consistent are very low and very high exercise intensities. - Stroke Volume (SV) - Volume of blood being pumped with each beat - Difference between diastolic and end systolic volume (diastolic is how much blood filled ventricles and systolic how much blood left in ventricles after contraction) - Ranges from 60 - 100mL/beat at rest and 100-120 mL/beat at maximum - Will increase up to 40-50% of HRmax - Above this point increases in volume being pumped is related to heart rate increase - Cardiac Output (Q) - Collectively determined through HR and SV (Q= SV x MHR) - Amount of blood heart is able to pump per minute - Primary determinant in maximal oxygen rate consumption - With exercise Q increases 4x-6x resting levels (normal -- endurance athlete) Factors that can impact Q - Increase in venous return - increased end diastolic volume causing increased stroke volume - Autonomic nervous system (ie, epinephrine) - Factor resisting ventricular flow (high BP, increase in afterload) can decrease Q - Conditions reducing venous return (peripheral artery disease) will decrease SV and thus Q. - Improving aerobic condition results in reducing heart rate at rest and during exercise - Result of increased stroke volume due to increased venous return and increase contractile condition of the myocardium (increase venous return allows more time to get more blood into heart) - Heart becomes more efficient 🡪 capable of pumping more blood with each stroke - Heart hypertrophy (increases in size and strength) - Adaptations in Blood Flow - Blood flow is modified during exercise - Flow to non-essential (exercise related) organs is decreased - Results in increased flow to working muscles - Blood flow to heart increases -- percentage of total cardiac output remains unchanged - Trained individuals have higher capillary density to accommodate increased supply and demand - Total peripheral resistance - Sum of all forces that resist blood flow - Decreases during exercise due to increased vessel dilation - Blood Pressure (BP) - Determined by cardiac output in relation to total peripheral resistance to blood flow - Pressure created by heart contraction - Systolic pressure - Relaxation of heart - Diastolic pressure (stays around the same during exercise) - Systolic pressure increases in proportion to oxygen consumption and Q - Failure of systolic pressure to increase with exercise is an abnormal response 🡪 exercise should be stopped - Consistent aerobic exercise will produce reduction in overall resting BP levels - Adaptations in the Blood - Training for improved cardiovascular function increases total blood volume - As a result of increased blood volume, oxygen carrying capacity increases - Total available hemoglobin increases - Overall hemoglobin concentration remains the same (may slightly decrease) with training - Adaptations of the Lungs - Pulmonary function improves with training - Volume of air that can be inspired increases - Diffusion capacity of lungs increases - Enhances exchange of oxygen and carbon dioxide - Pulmonary resistance to air flow is also decreased **Factors affecting rate of oxygen consumption** - Maximal oxygen consumption (VO~2max~) - Best indicator of cardiorespiratory endurance - Volume of oxygen consumed per body weight per unit of time - Average college male and female would average between 35 and 50 ml/min/kg - VO2max= 79.9 -- (0.39 x age)- (13.7 x gender)- (0.127 x weight)\\ - Man gender is equal to 0, women gender number is equal to 1 - Rate of oxygen consumption: - Per activity, rate of oxygen consumption is about the same for all individuals, depending on fitness level - Greater intensity = greater oxygen consumption - Ability to perform activity is oxygen consumption related - Fatigue - Insufficient oxygen supplied to muscle - Greater % of maximal oxygen consumption = less time activity can be performed - Factors affecting maximal rate - External respiration (involving ventilatory process)- lungs - Gas transport (heart, blood vessels, oxygen bring moved through the body) - Internal respiration (use of oxygen by cells)- exchange between mitochondria and cells - Most limiting factor is oxygen transport - Not ability of mitochondria to consume oxygen - High maximal aerobic capacity indicates all 3 levels are working well - Excess Post-exercise Oxygen Consumption (Oxygen Deficit) - With increased intensity, insufficient amounts of oxygen are available = oxygen deficit - Occurs initially during activity -- body adapts - Possibly result of initial lactic acid production - Deficit may be the result of: - Disturbance in mitochondrial function due to increased temperature - (Fast component) Restoration of PC depleted early in exercise and replacing store muscle and blood oxygen content - (Slow component) Providing energy for elevated respiratory rate, heart rate, catecholamines, gluconeogenesis, and conversion of lactic acid to glucose **FITT Principle and cardio** - FITT Principle - Frequency - Intensity - Type (mode) - Time (duration) - Frequency - ACSM recommends moderate intensity cardiorespiratory exercise [\] 30 min/day, [\]5 days/wk, vigorous intensity [\>] 20 min/day, [\>]3 days/wk, or a combination of both (Overall 75 minutes per week), Recommenced amount of moderate intensity cardiorespiratory exercise is 500-1000 MET/min/week - Competitive athlete should be prepared to engage in fitness activity 6 times per week, allowing 1 day for body repair and maintenance - Intensity - Should be heart rate controlled and monitored - Goal is to plateau heart rate at desired level - Workouts should be set as percentage of heart rate max (55-90%) or 40-85% of maximum oxygen uptake reserve (VO~2~R) - To appropriately set intensity prediction equations or known values for heart rate and VO~2~R should be used - Relationship between heart rate, oxygen consumption and exercise intensity makes it easy to identify pace at which heart rate will plateau - Must be mindful of fitness levels, medications, cardiovascular risk profile, patient likes/dislikes and goals - Type of Exercise - For continuous training activity must be aerobic - Whole body, large muscle movements, rhythmical in nature and uses large amounts of oxygen and elevates HR for extended period - Easy to regulate intensity (speed up or slow down) - Intermittent exercise is too variable (speed and intensity) - Time (duration) - Minimal improvements = exercise for 20 minutes - ACSM recommends 20-60 minutes with HR elevated to training levels - Intermittent exercise bouts (10 min) can also be used - Greater duration = greater improvements - Monitoring Heart Rate - Monitor pulse - Carotid pulse or radial pulse (more accurate) - Telemetry (heart rate monitor) or electrocardiography - Heart rate should be monitored before, during, and after exercise - As heart rate will plateau after reaching steady state, individual should be engaged in workout for 2-3 minutes prior to checking - Calculating heart rate - Determine MHR with maximum level workout and EKG - Appropriate estimate of MHR = 220-Age - Karvonen formula - Target HR = HR~rest~ + (0.6\[HR~max~-HR~rest~\]) - Rate of Perceived Exertion (RPE) - Scale (6-20) that can be used to rate exertion level during activity (more energy being used, often directly relates to a higher subjective rating of perceived exertion). **Interval training recommendation** - Intermittent activities involving periods of intense work and active recovery - Must occur at 60-80% of maximal heart rate - Allows for higher intensity training at short intervals over an extended period of time - Most anaerobic sports require short burst which can be mimicked through interval training - HR may reach 85-95% of maximum at peak and 35-45% during rest - Should be combined with continuous training **ACSM recommendations for caloric expenditure** - Interplay between duration, intensity and frequency creates caloric expenditure - Health benefits and training changes are related to total amount of work (caloric expenditure) - Caloric thresholds will differ based on goal - Improvements in VO~2max~ vs weight loss vs reducing risk for chronic disease - ACSM recommends energy expenditure of 150-400 calories per day - 1000 kcal per week should be initial goal - To achieve optimal fitness 300-400 kcal per day is recommended - Estimating caloric expenditure (MET x 3.5 x bodyweight in kg)/200 = kcal/min - Charts and tables exist to estimate METs for a given exercise and intensity - For weight loss - Must consider the combination of reduced caloric intake and increased use of kcal for exercise (1 pound of fat equal to 3500 to 3800 Kcal/week) **Detraining** - Physical training promotes various physiological changes - Increased size and number of mitochondria - Increased capillary bed density - Changes in resting & exercising heart rate - Changes in blood pressure - Changes in myocardial O~2~ consumption - Improved VO~2max~ - Removal of training stimulus will result in reversal of these changes - May see reversal occur in as little as 12 days **Plyometric definition** - Combination of speed and strength training - Quick powerful movement involving pre-stretching muscle and activating stretch-shortening cycle for stronger concentric contraction **Stretch reflex explanation and involved structures** - Eccentric pre-stretch 🡪 Concentric contraction - Stretch shortening cycle - Proprioceptive reflexes - Muscle spindles - Elastic properties of muscle - Energy storage - Three components - Contractile component (CC) - Muscle - Series elastic component (SEC) - Tendon - Parallel elastic component (PEC) - Concentric contraction - Force production through sliding filament theory - Force transferred externally through SEC - Eccentric contraction - SEC lengthens and contributes to overall force output - Force output = CC + SEC - Stored elastic energy 🡪 Used for force production - Proprioceptive stretch reflex - Mechanoreceptors detect stretch resulting in alterations in muscle tone, motor execution and kinesthetic awareness - Muscle spindle response is graded by the rate of stretch - Rapid loading = greater firing frequency = greater reflexive contraction - During eccentric loading, muscle tension increases, triggering Golgi tendon organ to initiate reduction in muscle excitation - Sensory impulses cause an inhibition of contracting muscle, limiting force production - With concentric contraction, muscle spindle activity is reduced with shortening muscle - As eccentric contraction occurs, muscle stretch reflex increases tension in lengthening muscle - With increase in tension, GTO fires reducing excitation of muscle - While muscle spindle and GTO oppose each other -- both contribute to increased force production - Degree of Muscle Fiber Elongation - Length is proportional to amount of stretching force applied - Absolute strength of fiber - Ability of muscle spindle to produce a neurophysiological response - Force production - Combined effects of stored elastic energy and myotatic reflex - Increased force production is dependent on transition from eccentric to concentric contraction - *Amortization phase* -- electromechanical delay between eccentric and concentric contractions **Potential reasons to avoid plyometrics** Plyometrics prerequisites - *Biomechanical Evaluation* - Should identify potential contraindications prior to initiation of program - Evaluation and functional tests - Require sound lower quarter mechanics - Stable base - Insufficiencies could result in stress failure-overload injury - Testing allows evaluation of base strength - Ensure appropriate stability with landing - Eccentric strength is critical - Closed chain stability training may be necessary prior to engagement in program - Principle holds true for upper and lower extremity - *Stability Testing* - Static stability - Ability to stabilize and control body - Postural stability - Centers on single leg strength and stability - Evaluate eccentric stabilization strength with jump test - Dynamic movement - Assess explosive, coordinated movements - Single leg hop for distance - Medicine ball chest pass - Sit-up and throw test for core and lat power - *Flexibility* - Requires general and specific flexibility - Program should begin with general warm-up and flexibility routine - Static and short dynamic stretching techniques - Plyometric Pre-Requisite Summary - Following assessment, low-intensity, in-place plyometrics can be initiated - Should progress slowly in deliberate fashion - As training and strength progresses move from moderate intensity plyometrics to ballistic-reactive plyometrics **Implementation of plyometric program** - *Direction of Body Movement* - Horizontal movement is less stressful than vertical - Dependent on weight of athlete and technical proficiency - *Weight of Athlete* - Heavier athlete = greater training demand - *Speed of Execution* - Increasing speed of particular activity increases the demands being placed on the athlete - *External Load* - Training demand is greatly increased by externally loading athlete - Should not slow speed of movement - *Intensity* - Amount of effort exerted - Altered by activity performed (double 🡪 single leg) - Progress from simple to complex - Addition of external weight or increasing height - *Volume* - Total amount of work performed - Total number of foot contacts - Varies inversely with intensity of exercise - Beginner = 75-100 (low intensity) - Advanced = 200-250 (low to moderate intensity) - *Frequency* - Number of times exercise session is performed during a training cycle - Not known for plyometrics - Recommend 48-72 hours between sessions - Intensity dependent - *Training Age* - Number of years athlete has been in formal training - Younger ages 🡪 training demand should be kept low - *Recovery* - Time between sets - Power vs. Endurance - Power 1:3 or 1:4 ratio - Endurance 1:1 or 1:2 - Emphasize eccentric loading and amortization - Implementation of Program - Instruct on proper technique - Flat footed landings - Quick landing - Success dependent on variable modification - Increased intensity generally results in decreased volume - Listen to response of athlete's body - Better to underestimate to prevent injury - Determine if plyometrics are suitable for athlete - Used in later stages of rehabilitation - Periodization - Year round progression and sequencing of strength training - Should be performed during preparatory and transitional phases - Athlete should - Be well conditioned - Exhibit athletic abilities - Exhibit coordination and proprioceptive abilities - Be free of pain from physical injury or condition - Plyometrics should not be exclusive - Part of entire training program - Will ultimately enhance the effects of training **Logical progression of plyometric exercises** - Medial to lateral (Implement in cases where injuries have occurred with medial/lateral soft tissue structures) - Progression - Bilateral 🡪 Unilateral - Lateral jumping 🡪 Lateral hopping - Lateral bounding - Acceleration and deceleration - Will also require individual to cover greater distances - Rotational Loading - Due to the need to control for rotation in the lower extremity rotational drills should also be incorporated - Spin Jumps (in-place) - Lateral hopping (dynamic distance) - Shock Absorption - Deceleration Loading - Gradually maximize the effects of gravity - Gravity minimized - Performance against gravity - Under water activities or assisted efforts through unloading - Cycle jumps and five dot drill (in place activity) - Jump downs (depth jumping) - Following assessment: - low-intensity, in-place plyometrics can be initiated - Should progress slowly in deliberate fashion - As training and strength progresses move from moderate intensity plyometrics to ballistic-reactive plyometrics