Cardiovascular Drift and Vo(2max) During Cycling and Walking in a Temperate Environment

Introduction: Different muscle recruitment patterns during cycling and walking may influence the magnitude of cardiovascular drift (CV drift) during these respective modes of exercise, but whether this also influences the magnitude of reduced maximal oxygen uptake (Vo(2max)) associated with CV drift is unknown. This study tested the hypothesis that cycling results in greater CV drift and a greater decrement in Vo(2max) than walking in a temperate environment. Methods: CV drift was measured in nine recreationally active women (ages=23 plus or minus 2 yr, Vo(2max)=43.0 plus or minus 5.5ml times kg(-1) times min(-1)) between 15 and 45 min of cycling or walking at 60% Vo(2max) on separate occasions in 22 degree C, 44% relative humidity. A graded exercise test to measure Vo(2max) was performed immediately after the submaximal exercise bout with no cessation of exercise. During separate trials involving each exercise mode, Vo(2max) was measured after 15 min of submaximal exercise so that changes in Vo(2max) between 15 and 45 min of exercise could be assessed between the same points in time in which CV drift occurred. Results: Across both conditions, heart rate (HR) increased 5.4% and stroke volume (SV) decreased 11% from 15 to 45 min, but Vo(2max) was not significantly affected (7% reduction; 2.70 plus or minus 0.5 L times min(-1) vs. 2.52 plus or minus 0.6 L times min(-1)). Conclusion: In a temperate environment, a small CV drift corresponds to a small, non-significant decrease in Vo(2max), regardless of whether the exercise performed is cycling or walking.