18. Motor Units, Recruitment & Length-Tension

What is a motor unit?

Motor neuron and all the muscle fibers it stimulates

What fiber composition characterizes small motor units?

Fewer muscle fibers

What functional capability is provided by small motor units?

Precise control

What fiber composition characterizes large motor units?

More muscle fibers

What functional capability is provided by large motor units?

Powerful contractions

What is recruitment?

Activating more motor units

What effect does recruitment have on muscle tension?

Increase in tension

What functional benefit is allowed by recruitment?

More forceful contraction

What factor influences the tension a muscle can generate?

Actin and myosin overlap

When is actin-myosin overlap measured for the length-tension curve?

Prior to contraction

At what resting length condition does muscle produce less tension?

Overly shortened or stretched

What percentage of maximal tension is produced at optimal length?

100% of maximal tension