Chapter 5 Physiology of Training

PE 254

Muscle PhysiologyMuscles consist of many muscle

fibers (cells) connected in bundles Muscle fibers are made up of

myofibrilsStrength training increases the

number of myofibrils and the size of muscle fibers = hypertrophy

Inactivity reverses the process = atrophy

Skeletal Muscle Tissue

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

Motor Units Motor units (nerves connected to

muscle fibers) are recruited to exert force

Motor Unit Recruitment

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

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

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

General Adaptation Syndrome(G.A.S.)

AlarmResistanceExhaustion

10

Flexibility

The range of motion in a joint or group of joints

Important for general fitness and wellness

Static versus dynamic flexibility

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.

Muscle Elasticity and Length

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

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

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

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

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

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

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.

http://www.youtube.com/watch?v=4GWlJMSAlu4

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+#