Muscle Strength, Power, and Endurance Strength: ability to generate force against resistance Power: is the relationship between strength and time Muscular endurance: repetitive muscular contractions (increase strength = increase endurance

Muscle Contractions Isometric contraction Isotonic contraction No length change occurs during contraction Pro: quick, effective, cheap, good for rehab Con: only works at one point in ROM Isotonic contraction Concentric- shortening of muscle with contraction in an effort to overcome more resistance Eccentric - lengthening of muscle with contraction because load is greater than force being produced Both are considered dynamic movements

Fast Twitch vs. Slow Twitch Fibers within a particular motor unit display distinct metabolic and contractile capability Slow twitch (Type I): Fatigue resistant Time necessary to produce force is greater Long duration, aerobic type activities Generally major constituent of postural muscles

Metabolic capabilities can change in response to training Fast twitch (Type II) Fatigue Anaerobic in nature High force in short amount of time Produce powerful movements A vs. B Individual make-up Muscles contain both types of fibers Muscle functioning impacts ratios (postural vs. powerful movement) Genetically determined Metabolic capabilities can change in response to training

Physiological and Biomechanical Factors that Determine Levels of Muscular Strength Hypertrophy vs. Atrophy Size of muscle: function of diameter and number of fibers Neuromuscular efficiency Biomechanical factors Overtraining (psychologically, physiologically) Reversibility

Explanation for Muscle Hypertrophy Three theories of muscle hypertrophy: Increase in number of fibers Infusion of blood - transient hypertrophy Increase in protein myofilament number and size PROVEN

Improved Neuromuscular Efficiency Early gains minus hypertrophy Enhanced efficiency due to enhanced neural function Other enhancements due to training Increased non-contractile tissue strength, bone mineral content, aerobic/anaerobic enzymes, enhanced oxygen uptake

Techniques of Resistance Training Progressive resistance exercise Overload principle must be applied Must work muscle at increasingly higher intensities to enhance strength over time If intensity of training does not increase, but training continues, muscle strength will be sustained

Overload Principle Activity must be increased and upgraded constantly in order to gain a higher response from the body Work at or near maximum capacity Applicable to conditioning and training

Isometric Exercises Contraction where muscle length remains unchanged Muscle contraction that lasts 10 seconds and should be perform 5-10 times/daily Pro: quick, effective, cheap, good for rehabilitation Con: only works at one point in ROM, produces spiking of blood pressure due to Valsalva maneuver

Progressive Resistance Exercises (Isotonic training) Shortening/lengthening Concentric vs. Eccentric Various types of equipment can be utilized (Free weights, machine weight) Spotter is necessary for free weight training to prevent injury, motivate partner and instruct on technique

Variations exist between free and machine weight lifting Concentric and eccentric training should be incorporated for greatest strength improvement Concentric phase of lift should last 1-2 seconds, eccentric phase 2-4 seconds Variations exist between free and machine weight lifting Motion restrictions, levels of muscular control required, amount of weight that can be lifted

Terminology associated with weight training Repetitions Repetition maximum One repetition maximum Set Intensity Recovery period Frequency

When training should be able to perform 3 sets of 6-8 repetitions Increases should occur in increments of 10% 1 RM can be utilized measure maximum amount of weight that can be lifted - must be very careful Training of a particular muscle group should occur 3-4 times per week (not on successive days)

Muscular Endurance vs. Strength Training for endurance enhances strength and vice versa Training for strength should involve lower repetitions at heavier weight Training for endurance requires lower weight at 12-15 repetitions Persons that possess greater strength also tend to exhibit greater muscular endurance

Isokinetic Training Muscle contraction at a constant velocity Maximal and constant resistance throughout the full range of motion Maximal effort = Maximal strength gains Disadvantages Cost Need for maximal effort/motivation Rehabilitation

Circuit Training Combination of exercise stations 8 - 12 stations, 3 times through Design for different training goals Flexibility Calisthenics Aerobic exercise

Calisthenic Strengthening Exercises Free exercise Isotonic training Gravity’s involvement determines level of intensity Full range of motion, may incorporate holding phase Pull-ups, push-ups, back extensions, leg extensions

Plyometric Exercise Rapid stretch, eccentric contraction followed by a rapid concentric contraction to create a forceful explosive movement Rate of stretch vs. magnitude Jumps, bounds, medicine ball throws Very technical training - skills must be learned with appropriate technique

Training for the Female Athlete Critical for female athlete Significant hypertrophy is related to testosterone present within body Remarkable gains are experienced initially due to enhanced nervous system and muscle interaction (efficiency-not muscle bulk) Following initial gains, plateau occurs, with females

Males tend to continue to increase strength with training Critical difference is the ratio of strength to body fat Females have reduced strength to body weight ratio due to higher percentage of body fat Ratio can be enhanced through weight training and decrease in body fat percentage/increased lean weight

Strength Training in Adolescents If properly supervised young athletes can improve strength, power, endurance, balance and proprioception Develop a positive body image Results in improved sports performance while preventing injuries

Strength gains can occur without significant muscle hypertrophy Close supervision and instruction is critical Progression = based on physical maturity Utilize calisthenic exercises and body weight as resistance