Exercise induced increases in muscle fiber number.
The effect of weight-lifting, which induced muscular enlargement, on fiber number was tested in the flexor carpi radialis muscle by operantly conditioning 6 cats to flex their right wrist against increasing resistance for an average of 101 weeks. The left was used as a control. At the end of training, the cats were performing "one-arm" lifts with an average of 57% of their body weight. There was an 11% greater muscle weight (P less than 0.01) and 9% (P less than 0.02) more fibers in the exercised muscles from the right limb than in the left. This study using a different method, supports our earlier observations that prolonged weight-lifting exercise significantly increases the total number of muscle fibers.
Gonyea
W J
WJ
Sale
D G
DG
Gonyea
F B
FB
Mikesky
A
A
D000818:Animals; D002415:Cats; D005260:Female; D008297:Male; D009132:Muscles / Q000033:anatomy & histology*; D009929:Organ Size; D005082:Physical Exertion