BLOOD VOLUME CHANGE DURING ROLLER SKIING AND ITS RELATIONSHIP TO ANAEROBIC THRESHOLD

Abstract

During incremental exercise, there appears to be a linear relationship between changes in BV (ΔBV) and exercise intensity to a certain point, at which the rate of increase in ΔBV is minimal. This point at which there is no more increase in ΔBV (IP of ΔBV) maybe due to the greater intramuscular pressure impairing blood flow, at higher intensity exercise, which will limit O2 supply to the working muscle and shift the energy pathway to anaerobic glycolysis. PURPOSE: To examine the relationship between the IP of ΔBV and anaerobic threshold (AT). METHODS: Eight male cross-country skiers (22.4 ± 3.2 yrs old) performed incremental roller skiing where treadmill speed remained constant while elevation increased by 1% each minute to exhaustion. A portable dual wavelength Near Infrared Spectrophotometer was used to measure ΔBV and oxygen desaturation in the capillary bed of the vastus lateralis during exercise. RESULTS: A positive relationship (r = 0.78) was observed between time to IP of ΔBV to the time at which AT occurred. IP of ΔBV occurred about ∼35 seconds earlier than AT determined from ventilation and gas exchange. In addition, moderate correlation (r = 0.67) was observed between the rate of deoxygenation at the onset of exercise and %VO2 at AT. CONCLUSION: The results of this study suggest that the IP of ΔBV observed using NIRS may indicate the point at which AT starts to occur. The IP of ΔBV may be the point at which there is an inadequate blood supply to the muscle, resulting in a mismatch between oxygen supply and demand. As a result, this mismatch will promote anaerobic glycolysis for energy production. Sponsored by United States Olympic Committee and NIH HL 44125