Muscular Strength & Endurance

1. Muscular Strength & Endurance Fitness Concepts PEAC 1621 Kirk Evanson

2. 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.

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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 http://www.atitudejiujitsu.com.br/images/ply.jpg

11. 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) http://2.bp.blogspot.com/_K6GPv8xcGQE/Rcp66D8BFQI/AAAAAAAAAGQ/uuFjyHFfgLg/s320/JustinIsokineticMach1.JPG

12. Exercise Equipment • Free vs. Machine weights • Free weights • Pros • 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

13. Exercise Equipment • Free vs. Machine weights • Machine weights • Pros • 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

14. FITT Principle • Exercise frequency • 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

15. 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

16. 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