The onset and magnitude of cardiovascular drift depend on exercise intensity in competitive cyclists.

Abstract

PURPOSETo examine the potential effects of cardiovascular drift (CVD) on aerobic and anaerobic metabolism.METHODCompetitive cyclists (n=11, age 40.3±10.9years, height 176±10cm, weight 70.9±11.6kg, VO2max 56.31±8.48ml▸kg−1▸min−1) performed 5 tests on a cycle ergometer 3‐5 days apart: a VO2max test (2‐min stages to exhaustion), a Maximal Lactate Steady State (MLSS), and 3 prolonged (90 min) submaximal bouts at 95%, 100%, and 105% of the MLSS (average: 190W, 199W, and 209W). HR, and VO2 were recorded continuously during the first 2 tests, the first 35 min and every 10 min thereafter for the 3 longer bouts. Blood lactate was measured at the end of each stage for the first 2 tests, and every 10 min for the 3 longer bouts.RESULTSOnly 3 cyclists completed the 105% MLSS bout, so comparisons were only made over 35 min. Onset of CVD was different for every participant at each intensity. Small changes in load (<10W) yielded differences (p < 0.05) across the 3 intensities in CVD amplitude (6 BPM, 8 BPM, and 9 BPM for the 95%, 100%, and 105% MLSS), VO2 (no change, 2 ml▸kg−1▸min−1, and 4 ml▸kg−1▸min−1), and blood lactate (0.3 mmol▸L−1, 0.5 mmol▸*;L−1, and 0.9 mmol▸L−1) between plateau and minute 30.CONCLUSIONWe successfully measured the small changes in the metabolic cost during CVD. The onset of CVD is affected by the intensity of exercise and the amplitude of CVD is greater as exercise intensity increases.Supported by the Mary Stuart Rogers Foundation and an NSF grant (DUE 0511219).