Force Decline During Fatigue is Due to Both a Decrease in the Force Per Individual Cross-bridge and the Number of Cross-bridges

Marta Nocella, Barbara Colombini, Giulia Benelli, Giovanni Cecchi, M. Angela Bagni and Joseph Bruton

Purpose: To investigate single muscle fibers or small muscle fiber bundles isolated from flexor digitorum brevis of mice at 22–24◦ C regarding fatigue. Fatigue occurring during exercise can be defined as the inability to maintain the initial force or power output. As fatigue becomes pronounced, force and maximum velocity of shortening are greatly reduced and force relaxation is prolonged.

Conclusions: Force loss during fatigue can result from a decrease in the number of cross-bridges generating force or a decrease of the individual cross-bridge force or to both mechanisms.

IN PLAIN ENGLISH: Regardless of the science behind muscle fatigue, working hard and giving maximal effort is sound advice to assure something positive is gleaned from your exercise session..