tension production in whole muscles

the amount of tension produced by a whole muscle is determined by…

the # of individual muscle fibers contracting

motor unit

motor neuron and all the muscle fibers it controls. may contain few to thousands of muscle fibers

eyes and hands- 1 neuron innervates…

4-6 mfs

thigh and hip- 1 neuron innervates…

1000-2000 mfs

recruitment

increase in # of active motor units. produces smooth, steady increase in tension. max tension is achieved when all motor units reach complete tetanus

sustained contractions

contractions that produce less than max tension. motor units are allowed to rest in rotation

muscle tone

normal tension and firmness of a muscle at rest. elevated levels of this increases resting energy consumption

without causing movement, motor units actively…

• stabilize positions of bones and joints

• maintain balance and posture