Muscular Strength PDF

poliquingroup.com Course Learning Outcome 7. Describe muscular strength assessment techniques and factors affecting strength, including types of muscle contraction, sexual differences, and aging. (I) (LE, IC) Learning Goal Build a foundational knowledge of the ways that muscular performance can be...

poliquingroup.com Course Learning Outcome 7. Describe muscular strength assessment techniques and factors affecting strength, including types of muscle contraction, sexual differences, and aging. (I) (LE, IC) Learning Goal Build a foundational knowledge of the ways that muscular performance can be assessed and the factors affecting strength including the benefits of training, the types of muscle contraction, sex and age. Learning Outcomes - Define muscular strength, power and endurance. - Describe the benefits of strength training - Describe the types of muscle contraction and be able to distinguish them within an activity. - List the purposes for assessing an individuals strength. - Describe the types of strength assessment techniques and provide examples of each. - Describe the factors that should be considered when assessing strength of an individual or group. - Describe the factors that affect strength including sex and age. - Describe sarcopenia, including its causes, functional impacts and prevention.  Muscular Strength A. Benefits of Strength Training B. Types of Muscular Contraction C. Purpose of Strength Assessment D. Strength Assessment Techniques E. Strength Assessment Considerations F. Effect of Various Factors on Strength  Muscular Strength Muscular strength - the greatest amount of force that muscles can produce in a single maximal effort. zimbio.com Francis Luna-Grenier  Muscular Endurance Muscular endurance - ability of a muscle group to perform repeated contractions against a submaximal load for an extended period of time. E.g. Push ups https://olympic.ca  Muscular Power Power - work per unit time - force X velocity. – Power involves strength and speed. thestar.com Derek Drouin – world and Olympic high jump champion Muscular Strength A. Benefits of Strength Training B. Types of Muscular Contraction C. Purpose of Strength Assessment D. Strength Assessment Techniques E. Strength Assessment Considerations F. Effect of Various Factors on Strength  Benefits of Strength Training Strength provides a foundation for other components of physical fitness such as: – Cardiorespiratory Capacity – Muscular Endurance bowflex.ca  Benefits of Strength Training Slow down the muscle loss that normally accompanies the aging process. Increase functional mobility so that daily activities are made both possible and easier seniorcareservicesdenver.com  Benefits of Strength Training Increase the size and strength of muscle fibers resulting in a greater physical capacity to perform Increased tendon, ligament and bone tensile strength. trainright.com  Benefits of Strength Training Stronger muscles better protect the joints that they cross. Improved physical appearance. Benefits of Strength Training Better strength in the muscles of the trunk, helps to prevent common postural problems. Stronger muscles are less likely to be strained and injured. Benefits of Strength Training Improvements in self-concept and self-esteem for both patient and athletic populations. Developing Muscular Strength & Endurance Details covered in BPK 143 Exercise : Health and Performance Types of strength training exercises – Resistance exercise Isometric (static) Isotonic (dynamic) Choosing equipment (Whole body exercises) Choosing exercises (Functional fitness) Frequency Intensity and time Key Points to Remember Quality training and quality recovery Continually change up your routine Use free weights and machines Use whole body exercises Focus on functional fitness training Complete a warm-up and cool down Try different exercise routines Make it enjoyable!!! Muscular Strength A. Benefits of Strength Training B. Types of Muscular Contraction C. Purpose of Strength Assessment D. Strength Assessment Techniques E. Strength Assessment Considerations F. Effect of Various Factors on Strength A. Types of Muscular Contraction 1. Dynamic (isotonic) contraction 2. Isometric contraction 3. Isokinetic contraction A. Types of Muscular Contraction 1. Dynamic (isotonic) contraction - the bony levers move through a range of motion when the appropriate muscles perform work. - Machines or free weights seniorcareservicesdenver.com  A. Types of Muscular Contraction Dynamic Nautilus Machines – – accommodating resistance devices – leverage characteristics change as the joint goes through a range of motion – muscle is stressed more at more optimally at all joint angles.  A. Types of Muscular Contraction Dynamic contractions can be either concentric or eccentric: Concentric contraction - the muscle shortens with varying tension as it lifts a constant load. Eccentric contraction - the external resistance exceeds the muscle force and the muscle lengthens while developing force. Eccentric contractions are usually used in resisting gravity. A. Types of Muscular Contraction 2. Isometric contraction - static contraction. Tension is developed but there is no change in the angle of the joint or the length of the muscle.  A. Types of Muscular Contraction 3. Isokinetic contraction - the muscle is shortened at a constant velocity determined by instrumentation which allows a person to exert maximal force throughout the full range of motion. Muscular Strength A. Types of Muscular Contraction B. Purpose of Strength Assessment C. Strength Assessment Techniques D. Strength Assessment Considerations E. Effect of Various Factors on Strength Muscular Strength A. Benefits of Strength Training B. Types of Muscular Contraction C. Purpose of Strength Assessment D. Strength Assessment Techniques E. Strength Assessment Considerations F. Effect of Various Factors on Strength  B. Purpose of Strength Assessment Assess muscular fitness Identify specific areas of weakness Monitor progress in a rehabilitation program Measure effectiveness of a resistance training program Motivation for training Muscular Strength A. Benefits of Strength Training B. Types of Muscular Contraction C. Purpose of Strength Assessment D. Strength Assessment Techniques E. Strength Assessment Considerations F. Effect of Various Factors on Strength C. Strength Assessment Techniques 1. One Repetition Maximum - Estimated from Variable Repetition Maximum 2. Dynamometer Techniques 3. Computer-Assisted, Isokinetic Methods C. Strength Assessment Techniques 1. One Repetition Maximum Maximum amount of weight lifted once. Use free weights or machines that allow dynamic muscle contractions - Universal Gym, etc. Only appropriate for very experienced C. Strength Assessment Techniques 1. Estimated One Repetition Maximum (1 RM) Estimated from repetitions to failure on machines Variable-repetition maximum tests. 1 RM = (weight lifted) / [1.0278 - (n X 0.0278)] n = repetitions to failure (not to exceed 10) Safer than using 1-RM, especially with beginners C. Strength Assessment Techniques 2. Dynamometer Techniques a strength testing dynamometer usually consists of a spring of some type which is deformed a certain amount when a specific force is applied to it. (eg) - hand grip dynamometer - measures isometric strength - relatively inexpensive, high reliability if body position is carefully standardized for each trial of the test C. Strength Assessment Techniques 3. Computer-Assisted, Isokinetic Methods equipment such as Biodex, KIN/COM, etc. isokinetic machine, but many of these machines can also test strength in isometric, concentric, and eccentric modes C. Strength Assessment Techniques 3. Computer-Assisted, Isokinetic Methods has a computer which can be programmed at any initial and final force, angle, velocity, or number of repetitions. measure peak torque using a force transducer and joint angle using an electrogoniometer. extensive manipulations can be performed on collected data using computer software accurate and reliable, but expensive used for research and elite athlete assessment Muscular Strength A. Benefits of Strength Training B. Types of Muscular Contraction C. Purpose of Strength Assessment D. Strength Assessment Techniques E. Strength Assessment Considerations F. Effect of Various Factors on Strength D. Strength Assessment Considerations In addition to validity, reliability, etc., 1. Standardized instructions should be given prior to testing. 2. If a warm-up is given, it should be of uniform duration and intensity 3. Ensure that the angle of measurement on the limb or test device is consistent among subjects D. Strength Testing Considerations 4. Consider individual differences in body size and proportion when evaluating strength scores between individuals and groups. **Subject A - Bert **Subject B - Ernie *Weight = 79.5 Kg *Weight = 79.5 Kg *Height = 185 cm *Height = 165 cm *Body fat = 10% *Body fat = 10% Bert Ernie Who do you think could lift more weight? A. Bert B. Ernie Bert Ernie D. Strength Assessment Considerations 5. Test and training mode specificity are important for optimal expression of true strength gains. Training using one mode of muscle activity (concentric, eccentric, isometric, isokinetic) should be assessed within an identical type of muscle activity within a strength test D. Strength Assessment Considerations 6. Safety is an important consideration when performing strength evaluations. Ensure that all equipment is in proper working order and that standard weight room safety procedures are being followed.  D. Strength Assessment Considerations 7. Test administrators should be well trained and have a thorough understanding of all testing procedures and protocols. Muscular Strength A. Benefits of Strength Training B. Types of Muscular Contraction C. Purpose of Strength Assessment D. Strength Assessment Techniques E. Strength Assessment Considerations F. Effect of Various Factors on Strength E. Effect Of Various Factors On Strength 1. Muscle Cross Sectional Area 2. Body Size 3. Muscle Fiber Composition 4. Mechanical Factors 5. Sex and Age E. Effect Of Various Factors On Strength 1. Muscle Cross Sectional Area there is a strong positive relationship between muscle CSA and strength. Muscles increase in strength by increasing their size and by enhancing the recruitment and firing rates of their motor units. Tissue / Cell Growth Hypertrophy - an increase in size of a cell such as a muscle fiber Hyperplasia - an increase in number of cells such as adipose cells  1. Muscle Cross Sectional Area Current research indicates that muscle fiber hypertrophy accounts for most, if not all, of the increase in muscle cross- sectional area due to an overload training program. There is evidence that muscle fiber hyperplasia occurs in animals, but there is presently no direct evidence that it occurs in humans. Note : ratio of nuclei to fiber volume ratio stays consistent E. Effect Of Various Factors On Strength 2. Body Size there is a positive correlation between body size or mass and absolute strength. There is a negative correlation between body mass and the strength/mass ratio. The strength to mass ratio directly reflects an athlete’s ability to accelerate his or her body. All else being equal, smaller athletes are stronger kilogram for kilogram than larger athletes.  2. Body Size Relationship Between Body Size and Strength Olympic Champion A Olympic Champion B Height = 4 feet, 10 inches Height = 6 feet, 2 inches Mass = 132 lbs Mass = 290 lbs Clean and Jerk = 410 lbs Clean and Jerk = 560 lbs = 3.2 X body mass = 1.9 X body mass 2. Body Size Large athletes dominate sport events which require a high level of absolute strength (e.g., throwing events in track and field) while smaller athletes dominate sport events which require a high strength/body mass ratio (e.g., gymnastics). E. Effect Of Various Factors On Strength 3. Muscle Fiber Composition for a given size of muscle, there is a positive correlation between percentage of fast twitch fibers and strength. E. Effect Of Various Factors On Strength 4. Mechanical Factors the force exerted by a muscle is affected by: A. the initial length of the muscle fibers B. the angle of pull of the muscle on the bony skeleton C. the speed of shortening E. Effect Of Various Factors On Strength 5. Sex after age 16, the average female is about 2/3 as strong as the average male when the measure of strength is the absolute amount of force exerted or weight lifted. Prior to puberty the strength of boys is only slightly greater than the strength of girls. 5. Sex Sex differences in strength in adults are greater in the arms and shoulders than in the legs. On average, the female's upper body is 50% to 60% as strong as the male's upper body and the female's lower body is 70% to 80% as strong as the male's lower body. individuals are not average and the differences between two individuals of the same sex are often greater than differences between statistical averages of each of the sexes. Valerie Adams – New Zealand Four-time world champion, two-time Olympic Champion and three-time Commonwealth champion  5. Sex The reasons why on average males are stronger are as follows: – The average male is physically larger (height and weight) than the average female. – Differences in body composition - the average male has more muscle and less fat due to the male sex hormone, testosterone, which stimulates muscle growth. – Because most human muscles can produce approximately 16 to 30 newtons of force per square centimeter cross-sectional area, larger muscles are stronger muscles.  5. Sex The reasons why on average males are stronger are as follows: – Body proportion differences - during adolescence, the skeletal proportions change: boy's shoulders broaden relative to their hips, and girl's hips broaden relative to their waists and shoulders. – The broader shoulders of the adult male allow more muscle to be packed onto the skeletal frame and create a mechanical advantage for muscles acting on the shoulder.  5. Sex The reasons why males are stronger are as follows: – Cultural factors - less emphasis on strength activities for females, – weight training has become much more popular and socially acceptable for females. 5. Sex Females are equally as strong as males when strength is expressed per unit cross sectional area of muscle. There is no qualitative difference between male and female muscle.  5. Sex You cannot distinguish male muscle from female muscle under a microscope. Female muscle tissue does not differ, unit for unit, in potential force output from male muscle tissue. This indicates that the training potential and methods of training for men and women should be similar. 5. Sex After strength training on the same routine, men have greater absolute increases in both strength and muscle hypertrophy than women. However women achieve similar percentage increases in strength as men. Women display less muscle hypertrophy since they have less testosterone. 5. Sex Research has revealed that men and women of all ages can increase their muscle size and strength as a result of progressive strength training. There is a great deal of variability in the responsiveness of muscles to strength training within sexes and age groups - individual differences.  6. Age Muscle strength in children: – Muscle strength progressively improves as children age and mature, principally as a result of increasing muscle size. – Hormonal influences at puberty (testosterone) are responsible for the dramatic increase in muscle bulk and strength in males. During this time period the increase in muscle mass in both sexes is due to hypertrophy of individual muscle fibers and not hyperplasia. 6. Age Resistance training before puberty safe and effective if children: – Have good motor skills – Have an ability to follow qualified instructor – Balance push / pull with functional exercises – Do not work to failure Muscle strength can be improved without significant increases in muscle size – Neuromuscular adaptation 6. Age Muscle strength in children: – Consider chronological age versus biological age when designing individualized weight training programs for children – During the time period surrounding peak height velocity (age 11.5 in girls and age 13.5 in boys), young athletes may be at increased risk for injury.  6. Age Maximum strength of men and women is generally achieved between the ages of 20 and 30 years, at the time when muscle cross sectional area is usually the greatest. Thereafter, there is a progressive decrease in strength for most muscle groups due primarily to a reduced muscle mass which is brought about by a decrease in the total number of muscle fibers in a given muscle and a decrease in individual fiber size. These changes are more pronounced in the fast-twitch fibers. These changes in muscle volume are due to a combination of decreased physical activity patterns and aging. 6. Age Indirect evidence (cross sectional studies) indicates that habitual physical activity slows down the strength decrements with aging. Weakest 20 year olds similar to average 70 year olds Dodds PLOS ONE December 4, 2014  6. Age Muscle rehabilitation programs for well, older populations have shown significant increases in muscle strength, muscle volume, and other parameters of muscle structure and function. Studies have documented that, given an adequate training stimulus, older men and women show similar or greater percentage strength gains compared to young individuals after a properly designed strength training program.  6. Age For the older person (age 65-85 years), muscle strength is a major component of successful performance in almost every activity of daily living. It is vital to the maintenance of upright posture, walking, going up and down stairs, and the accomplishment of simple tasks such as eating and dressing. fitnessvigil.com 6. Age Summary of Adaptations to Aging and Resistance Training* Aging Resistance Training Muscle strength Decreases Increases Muscle endurance Decreases Increases Muscle mass Decreases Increases Muscle fiber size Decreases Increases Muscle metabolic Decreases Increases capacity Resting metabolic Decreases Increases rate Body fat Increases Decreases Bone mineral Decreases Increases density Physical function Decreases Increases *This table was taken from page 182 in “Essentials of Strength Training and Conditioning” by Thomas Baechle and Roger Earle, Human Kinetics Publishers, 2000. Sarcopenia Sarcopenia - defined as the age-related loss of skeletal muscle mass, strength, and function Aging is a process of growing old – From maturity to senescence Physical characteristics of old age – A significant decline in skeletal muscle mass and strength – Decreased Physical Activity – Decreased Food Intake Sarcopenia is caused by various factors – Neural Apoptosis (cell death) – Imbalance of muscle protein synthesis/degradation – Physical inactivity – Hormonal imbalance – Food intake (insufficient protein) Physical Function and Sarcopenia Sarcopenia markedly enhances – loss of physical functioning – the risk of disability – more dependency towards other people – more medical-care costs http://joefriel.typepad.com/.a/6a0120a92f5af5970b019aff7b6976970c-600wi The age associated decline in muscle mass, strength and power can be delayed or reversed by training  Prevention Strength Training Hormonal Therapy Dietary Intervention Reduction in Sedentary time