In an effort to determine what effect the degree of muscle glycogen depletion has on the rate of resynthesis, six male cyclists completed an exercise protocol that involved both one- and two-legged cycling. One leg completed 30 min of single-leg cycling, ten one-min sprints, and 30 min cycling with both legs. This resulted in a large degree of depletion (LD). The contralateral leg completed only 30 min of double-leg cycling and experienced a small amount of depletion (SD). Following the exercise, the subjects rested quietly for 6 h and were fed a 24% carbohydrate (CHO) solution every 20 min in order to achieve a CHO intake of 0.7 g[middle dot]kg-1[middle dot]h-1. Biopsies taken from the vastus Iateralis muscle immediately after exercise revealed that the glycogen content of the LD leg decreased 93.9 (+/- 11.6) mmol[middle dot]kg-1 w.w., whereas the SD leg used 49.3 (+/- 5.7) mmol[middle dot]kg-1 w.w. (P < 0.01). Subsequent biopsies taken at 2 and 6 h of recovery demonstrated that the rate of muscle glycogen resynthesis was significantly greater in the LD leg, averaging 8.8 (+/- 2.4) mmol[middle dot]kg-1[middle dot]h-1 w.w, while the SD leg restored glycogen at a rate of 3.0 (+/- 1.0) mmol [middle dot] kg-1[middle dot]h-1 w.w. (P < 0.05). Glycogen synthase activity, expressed as its activity ratio (I/D), was also greater (P < 0.01) in the LD leg both immediately after exercise (0.45 +/- 0.05 vs 0.24 +/- 0.04) and at 2 h of recovery (0.54 +/- 0.06 vs 0.27 +/- 0.06). At 6 h of recovery, glycogen synthase activity did not differ between the legs; however, both values were significantly elevated above the pre-exercise level (P < 0.05). It is concluded that the magnitude of glycogen depletion does influence the rate of muscle glycogen resynthesis during the early hours of post-exercise recovery.
(C)1991The American College of Sports Medicine