Muscular Strength & Endurance Fitness Concepts PEAC 1621 Kirk Evanson

Muscle Physiology Muscle Composition and Organization Muscle fiber (muscle cell)- composed of myofibrils Myofibrils → muscle fibers → fascicles → muscles Muscle fiber types Slow-twitch (aerobic)- relatively fatigue resistant, but they don’t contract as rapidly or strongly as fast-twitch fibers. Fast-twitch (aerobic or anaerobic)- contracts more rapidly and forcefully than slow-twitch fibers but fatigue more quickly.

Muscle Physiology Muscle Most muscles contain a mixture of slow-twitch and fast-twitch fibers Endurance activities (e.g. jogging, swimming) primarily utilize slow-twitch while power activities (e.g. weight lifting) utilize fast-twitch Motor unit- the motor nerve and the muscle fibers that are innervated by that nerve The body recruits only the minimum number of motor units needed to produce the required amount of force. The greater the force, the greater the recruitment of motor units.

Benefits of Muscular Strength and Endurance Injury Prevention Good muscle strength in areas such as the abdomen, hips, lower back, and legs can support the back in proper alignment and help prevent low-back pain Training also improves the strength of tendons, ligament, and cartilage cells, which decreases the risk for injury

Benefits of Muscular Strength and Endurance Improved Body Composition Strength training improves body composition by increasing muscle mass Increases in muscle mass increase basal metabolic rate. BMR can increase up to 15% The body requires more calories, therefore there is less fat deposition

Benefits of Muscular Strength and Endurance Improved Muscle and Bone Health with Aging Strength training prevents muscle and nerve degeneration commonly associated with aging Also decreases the risk of hip fracture and other life-threatening injuries Decreases the progressive loss of muscle tone with age (sarcopenia) By age 75, 25% of men and 75% of women will be unable to lift 10 lbs. Weight training can mitigate these changes

Benefits of Muscular Strength and Endurance Prevention and Management of Chronic Disease Strength training improves glucose metabolism Modifies the risk factors for cardiovascular disease Decreases diastolic blood pressure Positive alterations in cholesterol Increases in HDL, decreases in LDL Strength training improves bone mineral density Beneficial in the prevention of osteoporosis and associated bone fractures Aberrations in glucose metabolism are associated with type 2 diabetes

Types of Exercise Static (isometric) Exercise Involves a muscle contraction without a change in the length of the muscle or the angle in the joit on which the muscle acts. Common for early physical therapy Do not build muscle throughout the range of motion Dynamic (isotonic) Exercise Involves a muscle contraction with a change in the length of the muscle

Types of Exercise Dynamic Exercise (cont.) Constant resistance exercise Fixed weight- easier at certain joint angles due to mechanical advantages based on muscle insertion points and length Variable resistance- resistance is varied throughout the movement to maintain intensity throughout all joint angles

Types of Exercise Dynamic Exercise (cont.) Eccentric- involves placing a load on a muscle as it lengthens Plyometrics- the sudden eccentric loading and stretching of muscles followed by a forceful concentric contraction (video)

Types of Exercise Dynamic Exercise (cont.) Isokinetic- the resistance can be moved at a fixed speed. Measurements can be made for multiple muscle groups in addition to group comparisons (quadriceps/hamstring ratio) (video)

Exercise Equipment Free vs. Machine weights Free weights Pros Cons More muscles needed for the movement Improvements made in multiple areas Requires more calories than machine weights Cons Movements are more complex and require more strength- the risk of injury increases Spotters may be needed

Exercise Equipment Free vs. Machine weights Machine weights Pros Cons Reasonably easy to perform Many safety mechanisms in place to decrease (but not eliminate) the risk of injury Cons The intensity of the movement has a limit- can only recruit so many muscles to do a controlled movement It can be difficult to find the ‘perfect’ machine to work the desired target area

FITT Principle Exercise frequency Exercise intensity and volume 2-3 days/week 48 hours of rest needed to allow for adequate recovery Exercise intensity and volume Repetitions and Sets Low repetitions- maximal effort- increase in strength High repetitions- medium effort- increase in muscular endurance

FITT Principle Exercise intensity and volume (cont.) Repetitions and Sets 3-5 sets Sets can be determined based off of the intensity of the set Type or mode of exercise Variety is the spice of life- work multiple muscle groups

Exercise Training Specificity The body will adapt to stress A leg press will not appreciably improve lower body muscle endurance, however jogging will Exercises should be selected based off of individual exercise goals