Chapter 5 Physiology of Training

1. PE 254 Chapter 5 Physiology of Training

2. Muscle Physiology • Muscles consist of many muscle fibers (cells) connected in bundles • Muscle fibers are made up of myofibrils • Strength training increases the number of myofibrils and the size of muscle fibers = hypertrophy • Inactivity reverses the process = atrophy

3. Skeletal Muscle Tissue

4. Muscle Fibers • Slow-twitch fibers (Type I) • Fatigue resistant • Don’t contract as rapidly and forcefully as fast-twitch fibers • Rely primarily on oxidative energy system • Fast-twitch fibers ( Type II) • Contract rapidly and forcefully • Fatigue more quickly than slow-twitch fibers • Rely more on nonoxidative energy system

5. Motor Units • Motor units (nerves connected to muscle fibers) are recruited to exert force

6. Motor Unit Recruitment

7. Specificity—Adapting to Type of Training • The body adapts to the particular type and amount of stress placed on it • To develop a particular fitness component, perform exercises specifically designed for that component

8. Progressive Overload—Adapting to Amount of Training • Placing increasing amounts of stress on the body causes adaptations that improve fitness; progression is critical • FITT principle for overload: • Frequency—How often • Intensity—How hard • Time—How long (duration) • Type—Mode of activity

9. Reversibility—Adapting to a Reduction in Training • Fitness improvements are lost when demands on the body are lowered • If you stop exercising, up to 50% of fitness improvements are lost within 2 months

10. General Adaptation Syndrome(G.A.S.) • Alarm • Resistance • Exhaustion

11. Flexibility • The range of motion in a joint or group of joints • Important for general fitness and wellness • Static versus dynamic flexibility

12. What Determines Flexibility? • Joint structure—joints vary in direction and range of movement • Joint capsules = semielastic structures that give joints strength and stability but limit movement • Muscle elasticity and length • Collagen = white fibers that provide structure and support • Elastin = yellow fibers that are elastic and flexible • Titin = muscle filament with elastic properties; contributes to flexibility.

13. Muscle Elasticity and Length

14. Nervous System Activity • Proprioceptors send information about the muscle and skeletal systems to the nervous system • Stretch receptors (muscle spindles) • Golgi tendon organs (GTO) • If a muscle is stretched, signals between the stretch receptors and nervous system control muscle length and movement and protect muscles from injury

15. Nervous System Activity • Proprioceptive neuromuscular facilitation (PNF) = a technique for stretching muscles that relies on neuromuscular reflexes to stimulate training effects • Regular stretching trains all of the proprioceptors • Proprioceptors adapt very quickly to stretching and lack of stretching

16. Benefits of Flexibility and Stretching Exercises • Joint health • Prevention of low-back pain and injuries • Other potential benefits: • Relief of aches and pains • Relief of muscle cramps • Improved body position and strength for sports • Maintenance of good posture and balance • Relaxation • Lifetime wellness benefits

17. Frequency of Exercise • The American College of Sports Medicine (ACSM) recommends that stretching exercises be performed a minimum of 2–3 days per week; ideally 5-7 days per week • Stretch when muscles are warm, either after a workout or after the active part of a warm-up • Do not stretch before a high-performance activity

18. Intensity and Time (Duration) of Exercise • Stretch to the point of slight tension or mild discomfort • Hold each stretch for 15–30 seconds • Do 2–4 repetitions of each exercise • Rest for 30–60 seconds between stretches

19. Types of Stretching Techniques • Static stretching = slowly stretching a muscle and holding the stretched position • Ballistic stretching = suddenly stretching a muscle through a bouncing or swinging movement • Dynamic stretching = stretching by moving joints slowly through their range of motions in a controlled manner • Proprioceptive neuromuscular facilitation = obtaining a greater training effect by using neuromuscular reflexes; for example, contracting a muscle before it is stretched

20. http://www.youtube.com/watch?v=4GWlJMSAlu4 The athlete and partner assume the position for the stretch, and then the partner extends the body limb until the muscle is stretched and tension is felt. The athlete then contracts the stretched muscle for 5 - 6 seconds and the partner must inhibit all movement. (The force of the contraction should be relevant to the condition of the muscle. For example, if the muscle has been injured, do not apply a maximum contraction). The muscle group is relaxed, then immediately and cautiously pushed past its normal range of movement for about 30 seconds. Allow 30 seconds recovery before repeating the procedure 2 - 4 times.

21. Types of Stretching Techniques • Passive stretching = muscles are stretched by force applied by an outside source • Active stretching = muscles are stretched by a contraction of the opposing muscles • Safest technique is active static stretching, with an occasional passive assist http://video.google.com/videosearch?q=flexibility+training+exercises&hl=en&emb=0&aq=5&oq=flexibility+#