skeletal structure and function

Fast- twitch fibers (type II) exhibit 4 characteristics

-Exhibit four characteristics 1. High capability for electrochemical transmission of action potentials 2. High myosin ATPase activity 3. Rapid Ca2 release and uptake by efficient sarcoplasmic reticulum 4. High rate of crossbridge turnover -These factors contribute to this fibers rapid energy generation for quick, powerful muscle actions

Slow-twitch fibers (type I) continue 2 things both slow twitch and fast twitch

-Highly fatigue resistant and ideally suited for prolonged aerobic exercise -slow-oxidative fibers with slow shortening speed: and rely on oxidative metabolism -both slow- and fast-twitch muscle fiber types contribute during near-maximum aerobic and anerobic exercise

Fast-twitch fibers (type II) continue 4 things

-Intrinsic speed of shortening and tension development ranges from 3 to 5 times faster than slow-twitch fibers -rely on well-developed, short term glycolytic system from energy transfer -Activation predominates in anaerobic-type sprint activities and other forceful muscle actions that rely entirely on anaerobic energy transfer -activation plays an important role in stop and go or change of pace sports such as basketball, soccer, lacrosse, or field hockey

Fiber type differences among athletic groups 4 things

-Men, women and children on average possess 45 to 55% slow-twitch fibers in arm and leg muscles -fast-twitch fibers distribute equally between type IIa and type IIx subdivisions -although no gender differences exist in fiber distribution, large inter individual variation occurs -trend in ones muscle fiber type distribution remains fairly consistent among the bodys major muscle groups

Slow-twitch fibers (Type I) -four distinguishing characteristics

-generate energy for ATP resynthesis through aerobic system of energy transfer (aerobic) -four distinguishing characteristics 1. low myosin ATPase activity 2. slow calcium handling ability and shortening speed 3. less well developed glycolytic capacity than fast-twitch fibers 4. large and numerous mitochondria

Muscle fiber type differ in 3 different characteristics

-skeletal muscle contains two main types of fibers that differ in three characteristics --primary mechanisms used to produce ATP --type of motor neuron innervation --type of myosin heavy chain expressed -The proportions of each type of muscle fiber vary from muscle to muscle and from person to person

Fiber type differences among athletic groups endurance elite success depends on

...Endurance athletes possess predominantly slow-twitch fibers; fast-twitch fibers predominate for elite sprint athletes -performance success depends not only on muscle fiber composition, but on a blending of many physiologic, bichemical, neurologic, and biomechanical "support systems" -larger muscle fibers in male athletes along with a larger total muscle mass are principal gender differences in muscle morphology.

Fast twitch ( type II) Type II fibers distribute in three primary subtypes:

1. type IIa: (hybrid) represents fast-oxidative-glycolytic fibers (long term anaerobic) <30 min (good at a lot of things) -easier to transfer to a different fiber type 2. Type IIx (previously referred as type IIb): midway between a and b types in physiologic and metabolic characteristics (short term anaerobic) <5 min 3. "New" types IIb: possesses greatest anaerobic potential and most rapid shortening velocity : represents "true" fast-glycolytic fiber (really fast, really strong) -sprinters, NFL <1 min

Polymyocitis

autoimmune disease cause weakness and fatigue -body attacks your own muscle because it thinks there is an invader (attacks own muscle and WBC)