By James Walker CCS, STM, BioSig, Master Trainer
Training principles of exercise science con’t…
7. Muscle Balance – each muscle action or group has an opposite muscle action or group (agonist vs. antagonist).
· e.g. triceps vs. biceps, must maintain a mutual balance in strength and flexibility to function properly.
· In performance activity the antagonist muscles may act as a brake to slow down acceleration e.g. the elbow flexors act as a brake to the elbow extensors in a punch, so they need to be strong to perform this task.
· Demonstrate-a throw or punch or sprint.
8. Muscle Fiber Type and Energy System – there are two basic muscle fiber types, slow twitch (IA) and fast twitch (IIAo, IIA & IIB). Each muscle fiber type has a corresponding energy system that supplies it and determines its action and performance parameters.
· Slow twitch (IA) utilizes oxygen (aerobic) as its primary energy source, 3 minutes or longer duration and has an intensity threshold of 25% or less of the persons strength capacity and is used during postural and endurance activities.
· Fast twitch oxidative glycolytic IIAo utilizes glycogen (anaerobic) and oxygen (aerobic) as its energy sources and is strength endurance oriented, 2 to 3 minutes in duration and has an intensity of 25% to 60% of a person’s maximal strength capacity.
· Fast twitch glycolytic IIA utilizes glycogen (anaerobic) as its primary energy source and is strength oriented, 13 to 30 seconds in duration and has an intensity of 60% to 85% of a person’s maximal strength capacity.
· Fast twitch phosphogenic IIB utilizes creatine phosphate (CP) and adenosine triphosphate (ATP) (anaerobic) as its primary energy sources and is explosive-power oriented, 1 to 12 seconds in duration and has an intensity threshold of 85% to 100% of a person’s maximal strength capacity.
· Examples: 25-50 mile race vs.800-1500 meters vs. 200-400 meters vs. 50-100 meters sprint.
9. Muscle Receptors and Sensors – within the muscles there are various receptors and sensors (proprioceptors) that perform specific tasks e.g.,
· vestibular receptors- measure balance and equilibrium;
· muscle spindle- measures change in muscle fiber length and change in muscle fiber speed;
· Golgi tendon organ- measures the range of motion (rom) or stretch in muscle tendons;
· Ruffini receptors- measures the position of the muscle and joint in relation to space;
· Pacinian corpuscle- measures the tension and pressure within the muscle fiber and tendon.
· All of these sensors relay information from the muscles to the spinal cord and/or to the brain or central nervous system. In turn the appropriate muscle response occurs.
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