When lifting a heavy object, the strength of leg muscle contractions is determined by the
A) number of thick and thin filaments involved in each sarcomere during contraction.
B) amount of ATP used by each active sarcomere during muscle contraction.
C) number of calcium ions released by the sarcoplasmic reticulum.
D) frequency of action potentials and number of muscle fibers stimulated.

Question

Quizplus · Accepted Answer

The strength of leg muscle contractions when lifting a heavy object is primarily determined by the frequency of action potentials and the number of muscle fibers stimulated. This is because the force of a muscle contraction increases with the frequency of stimulation (which can lead to tetanus at high frequencies) and with the recruitment of more muscle fibers to contract.

When Lifting a Heavy Object, the Strength of Leg Muscle