Depletion and resynthesis of glycogen in arm and leg muscles after a classical 15-K cross-country ski race

• Introduction: Bicycle exercise or running has been most frequently used in studies of glycogen usage during exercise and the replenishment in the recovery afterwards. In cross-country skiing muscle glycogen is probably a dominant factor for maintaining speed and can be crucial in the finish. In this sport the arms may be more critical than the legs both for speed and finish, especially in the classical technique. Thus, in the present study we examined muscle glycogen content in arm and leg muscle in connection with a race and the first 24 hrs after the race with two specific aims. 1) Evaluate whether arm muscles use more glycogen than the leg muscles and whether there is a muscle fibre type specific glycogen depletion pattern for the type 2 fibres, 2) Evaluate whether water intake instead for carbohydrates during the first 4 hrs after the race affect the resynthesis of glycogen acutely and next morning. Methods: Ten elite male competitive cross-country skiers (Age:22; Body height:182 cm; Body mass:80.8 kg; VO2max:72 ml kg-1 min-1) performed a 15K classical race in varying terrain. The subjects were placed into two groups; a H2O-group and a CHO-group. Directly after the race the H20-group was only allowed to drink water whereas the CHO-group used a normal post-race strategy to refill CHO with sport drink and gel and thereafter a meal. After 4 hrs both groups had the same carbohydrate enriched food intake. Muscle biopsies were obtained from an arm (triceps brachii) and a leg (v. lateralis) muscle before, directly after, as well as 4 and 20 hrs after the race. Muscles samples were analyzed for fibre types and glycogen as well as glycogen depletion pattern. Results: Muscle glycogen measured directly after the race was reduced by 32 % (484.7 to 331.3 mmol kg-1dw) in the legs and 69 % (from 540.2 to 167.1 mmol kg-1dw) in the arms. Type 1 muscle fibre type depletion was the dominant finding for both arms and legs, with some type 2A fibres being partly depleted in the arms. After 4 hrs with water no elevation in neither arm nor leg muscle glycogen content was observed but with CHO the legs did increase with 80 and the arms with 110 mmol kg-1dw and significantly more in the legs compared to the arms(P<0.05). Next morning regardless of being in H20- or the CHO group all subjects had returned to close to their pre-race muscle glycogen content in both arms and legs. Conclusion: The main findings were 1) in classical/diagonal skiing is the recruitment pattern of muscle fibre types the typical for prolonged exercise with primarily type 1 fibres being glycogen depleted but equally clear is that the arms are more used than the leg muscle as muscle glycogen stores were more markedly utilized in the arm as compared to the leg muscles.2) Restoration of the muscle glycogen stores are dependant of a carbohydrate intake but of note is that in only 20 hrs of recovery was the pre exercise glycogen level reached regardless of no carbohydrate intake for 4 hrs immediately after the race.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Idrottsvetenskap (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Sport and Fitness Sciences (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

Nyckelord

endurance

energy

glycogen

muscle

skiing

Sports

Idrott

Physiology

Fysiologi

Publikations- och innehållstyp

ref (ämneskategori)

kon (ämneskategori)