Journal of Applied Physiology, Vol 61, Issue 2 477-481, Copyright © 1986 by American Physiological Society
Skeletal muscle lactate dehydrogenase isozyme alterations in men and women marathon runners
F. S. Apple and M. A. Rogers
Total lactate dehydrogenase (LD) and LD isozyme activities in gastrocnemius
muscle from trained men and women runners were measured in response to the
chronic stress of training for a marathon race (42.2 km). Following 9 wk of
training, total LD activity in skeletal muscle from men and women runners
significantly (P less than 0.02) decreased 2.26 and 2.25 U/mg protein,
respectively. However, men's total LD activities were significantly (P less
than 0.001) less than the women's both before and after training.
Significant (P less than 0.05) increases in LD1 activities in skeletal
muscle in men and women runners were also observed after training. No
significant correlations were detected between percent fiber type
composition in men or women vs. the changes in total LD activity, changes
in LD1 activity, maximal O2 consumption or training distance averaged per
week after the training period. The biochemical adaptations in skeletal
muscle that occurred in the LD isozyme composition in both men and women
runners make the runners skeletal muscle appear similar to heart muscle in
LD1 and LD2 activities.
