pe 254. muscles consist of many muscle fibers (cells) connected in bundles muscle fibers are made...
TRANSCRIPT
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
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
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
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.
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+#