The onset and magnitude of cardiovascular drift depend on exercise intensity in recreational runners.

Abstract

PURPOSETo examine the potential effects of cardiovascular drift (CVD) on aerobic and anaerobic metabolism.METHODRecreational runners (n=10, age 40.3±8.3years, height 176±7cm, weight 71.29±10.76kg, VO2max 57.29±5.96ml▸kg−1▸min−1) participated and each performed 5 running tests 2‐4 days apart: a VO2max test (2‐min stages to exhaustion), a Maximal Lactate Steady State test (MLSS), and 3 prolonged (45 min) submaximal bouts at intensities corresponding to 95%, 100%, and 105% of the MLSS velocity (1% grade). HR and VO2 were recorded continuously; blood lactate was measured after each stage during the first 2 tests, and every 10 minutes for the 3 prolonged bouts.RESULTSOnset of CVD was different for every participant, often with no HR plateau in the 105% MLSS bout. Small differences in exercise intensity (0.22 m▸sec−1) yielded significant differences (p < 0.05) across the 3 intensities in the amplitude of CVD (increases of 7 BPM, 14 BPM, and 18 BPM for the 95%, 100%, and 105%), VO2 (1.42 ml▸kg−1▸min−1, 1.8 ml▸kg−1▸min−1, and 1.39 ml▸kg−1▸min−1), and blood lactate (0.25 mmol▸L−1, 0.88 mmol▸L−1, and 1.08 mmol▸L−1) between steady state and minute 40.CONCLUSIONWe successfully measured changes associated with the metabolic cost of exercise 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).