RESTRICTED MUSCLE BLOOD FLOW DURING SKATING 1614

Abstract

We have previously hypothesized restricted muscle blood flow during speed skating secondary to high intramuscular forces and the prolonged duty cycle of the skating stroke. To test this hypothesis we studied speed skaters (n=10) during submaximal and maximal cycling and in-line skating, in both low (knee angle=107°) and high (knee angle=112°) skating positions (CE vs SkL vs SkH). Consistent with the hypothesis were reductions during skating in VO2max (54.6 vs 51.4 vs 52.3 ml/kg), the VO2 @ 4 mmol/L blood lactate (44.9 vs 37.3 vs 41.8 ml/kg), and cardiac output at maximal exercise(acetylene rebreathing) 33.2 vs 25.9 vs 25.6 L/min). The reduction in maximal cardiac output was not attributable to differences in HRmax (196 vs 191 vs 193 b/min), but to a reduction in SVmax (172 vs 134 vs 128 ml/beat). The reduction in SV appeared to be related to an increased calculated systemic vascular resistance (297 vs 381 vs 360 dynes/s/cm). During maximal skating there was also a greater% O2desaturation of the vastus lateralis, based on near infrared spectrophotometry (50 vs 74 vs 65% of maximal desaturation during cuff ischemia). The results of this study support the hypothesis that physiological responses during speed skating are dominated by restriction in blood flow, attributable either to high intramuscular forces, the long duty cycle of the skating stroke or both.