Why do muscles ‘shudder’ when lifting weights?
In: Biology
Muscle fiber recruitment (activation) is not equally precise throughout a muscle’s range of force output. When we perform fine manipulation, the motor units recruited fall within a range of high resolution but low force. These motor units each have relatively few muscle fibers. When we lift near our max force output, the motor units recruited are larger and less precise. These have relatively many muscle fibers per unit. Look up Henneman’s size principle for more info.
Shaking near max force output is due to the on-off switching of big motor units as your body tries to do things related to load balancing and fatigue management.
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