How does the body increase force during muscle contractions?

The body increases force during muscle contractions primarily by recruiting additional motor units and increasing the frequency of stimulation. This process is known as motor unit recruitment. When more muscle fibers are activated, there is an increase in the overall force produced by the muscle. Additionally, varying the stimulation frequency of those motor units enables the muscle fibers to generate stronger and quicker contractions through a mechanism called temporal summation.

When the stimulation frequency is increased, subsequent signals arriving before the muscle has completely relaxed can lead to stronger contractions, sometimes termed tetanic contractions, which maximizes force output. This is crucial during activities requiring strength or power, as leveraging both the number of active motor units and their firing rate allows the body to adapt to different demands effectively.

In contrast, reducing stimulation frequency would lead to weaker muscle contractions, and relying solely on fast-twitch fibers ignores the benefits of slow-twitch fibers, which contribute to endurance and stabilization. Moreover, decreasing muscle temperature is not a method employed by the body to increase force; in fact, lower temperatures can inhibit muscle performance.