Glycogen depletion pattern and lactate accumulation in leg muscles during recreational downhill skiing

SummaryTwenty-eight adult female and male subjects performed recreational skiing, which took place in terrain with short and long slopes. Muscle biopsies were obtained before and after the skiing from the lateral portion of the quadriceps femoris for histochemical evaluation of glycogen depletion in individual fibres and biochemical analysis of glycogen and lactate content. Blood lactate was also determined. After a day of skiing the decline in muscle glycogen averaged 33 mM/kg in both short and long slope terrain. Technically advanced skiers had a reduction of 38 mM/kg and less advanced skiers had a reduction of 28 mM/kg (p<0.05). In most subjects there was a predominant loss of glycogen from the slow-twitch fibres (ST). In the most talented skiers glycogen depletion was also observed in the fast-twitch a fibres (FTa). In contrast a pronounced depletion of the fast-twitch b fibres (FTb) was observed in the technically unskilled skier.Muscle lactate concentrations ranged 2–8 mM/kg, the higher values observed in the technically better skiers. Blood lactate values reflected muscle lactate at a 1–2 mM/l lower level.The obtained results suggest that recreational downhill skiing performed by experienced skiers can be characterized as dynamic exercise and that glycogen depleted muscle fibres may contribute to the fatigue experienced after a day of skiing.