The last little bit of a chin-up is usually the most difficult to perform because
A) of the lever properties of the muscle-joint interaction.
B) stretched sarcomeres have less overlap where cross-linking can occur.
C) of psychological fatigue that is a metabolic by-product of the exertion.
D) the necessary switch from fast- to slow-twitch fibers.
E) Both a and b

Question

Quizplus · Accepted Answer

The last little bit of a chin-up requires a greater force output because of the lever properties of the muscle-joint interaction. This is combined with the fact that the muscle fibers are at their maximum stretch, with sarcomeres having less overlap where cross-linking can occur, making it physically more difficult to generate force. Therefore, both a and b are correct. Psychological fatigue or the switch from fast- to slow-twitch fibers may also play a role, but they are not the primary reasons why the last little bit of a chin-up is more challenging.

The Last Little Bit of a Chin-Up Is Usually the Most