Blood Lactate Response To Maximal Exercise In Master Cross-country Skiers

Abstract

PURPOSE To examine the blood lactate responses to maximal exercise in the laboratory and on the snow across a competitive racing season in masters level male and female cross-country skiers. METHODS Twelve competitive cross-country skiers, six women (45.3 ± 3.6 yrs) and six men (50.8 ± 1.6 yrs) were studied at the start of their competitive season (December) and at the end of the racing season (March and April). Diet was controlled the morning of testing and activity levels were kept to a minimum the day prior to testing. Blood lactate, heart rate (HR) and oxygen consumption (VO2) responses to maximal graded exercise testing were examined using a treadmill protocol in the laboratory. Within 2 weeks of each laboratory test, blood lactate and heart rate responses were determined during skate skiing at different paces on the snow. Summary of RESULTS While there were gender differences in height, weight and body composition, these variables did not change significantly during the season. However, there were significant differences in heart rates at 2, 3 and 4 mMol/L of lactate between tests in the laboratory compared to tests on the snow during the early part of the season. The HR on the snow was lower at the same level of lactate on the snow in the early part of the season compared to both laboratory tests and to the test on the snow late in the season. At the end of the competitive season there were no changes in the lactate-heart rate profiles between the 2 laboratory tests, but there were significant changes between the 2 field tests. As the season progressed, the values on the snow became closer to the values in the laboratory. Women had lower heart rates at each level of lactate in all the tests, but had a similar change to the men over the racing season. There were significant improvements in VO2peak in the women only (53.6 ± 0.26 ml/kg/min vs. 55.9 ± 0.92 ml/kg/min) over the 4-month racing season. CONCLUSIONS 1) Testing in the laboratory at the start of the competitive season had a different lactate vs. HR response than testing on the snow 2) as the season progressed the lactate vs. HR response on the snow more closely matched the response in the laboratory. 3) Women had different lactate vs. heart rate responses compared to men.