Glycogen depletion patterns during continuous and intermittent ice skating

The glycogen depletion patterns in the vastus lateralis muscle were studied during ice skating using eight hockey players. For each subject, exercise consisted of either repeated bouts (10) of high intensity work (120% Vo2 max) or continuous work (60 min) of low intensity (55% Vo2 max). During continuous skating, glycogen showed a 29% decline (p less than 0.05) over the 60 min. In the intermittent condition, there was a two fold greater depletion (p less than 0.05) with the most rapid loss occurring during the first five, one min work bouts. Histochemical analysis by fiber type indicated that the most pronounced glycogen loss was from the Type I fibers during continuous skating whereas during the intermittent condition, a preferential loss occurred in the Type II fibers, most notably the Type IIB fibers. Measurements of muscle metabolites during continuous skating indicated no change for ATP from the rest condition at 30 or 60 min, a reduction (p less than 0.05) in CP (4.1 mmoles.kg-1) at 60 min and an elevation (p less than 0.05) in lactate (0.85 mmoles.kg-1) at 60 min. In the intermittent condition, reductions (p less than 0.05) in ATP (0.47 mmoles.kg-1) and CP (8.7 mmoles.kg-1) and elevations (p less than 0.05) in lactate (21.7 mmoles.kg-1) were found following 5 work bouts. Thereafter, no significant changes were observed. It is concluded that the glycogen depletion patterns and alteration in muscle metabolites are similar to those seen during cycling at similar percentages of Vo2 max.