Walking and Running Economy: Inverse Association with Peak Oxygen Uptake
PURPOSE:: To test the hypothesis that V02peak is positively correlated with the regression coefficients of the curve-linear relationship between VO2 and speed during a protocol consisting of submaximal walking and running. METHODS:: 19 healthy males (age 26.4 +/- 6.4 yr.; height 179.9 +/- 7.2 cm; weight 77.7 +/- 8.7 kg; % fat 16.3 +/- 7.3) and 21 healthy females (age 25.6 +/- 4.9 yr.; height 167.2 +/- 5.4 cm; weight 61.6 +/- 7.7 kg; % fat 24.0 +/- 6.8) underwent an incremental treadmill test to determine VO2peak, and on two separate days performed an exercise protocol consisting of treadmill walking on a level grade at 2.0 mph (54 m.min), 3.0 mph (80 m.min), and 4.0 mph (107 m.min), and running at 6.0 mph (161 m.min). Subjects exercised for 5 min at each velocity, with 3 min rest in between each exercise bout. Pulmonary ventilation (VE) and gas exchange were measured breath-by-breath each min. The average of VO2 values obtained during the last two min of exercise for both exercise sessions was used in polynomial random coefficient regression (PRCR) analysis. RESULTS:: In the PRCR analysis for walking speeds only, both linear (r = 0.31; p = 0.053) and quadratic (r = 0.35; p = 0.029) were modestly correlated with VO2peak.Steady-state VO2 during walking at 3.0 and 4.0 mph, and running at 6.0 mph, was also modestly correlated with VO2peak (r = 0.30 - 0.48). CONCLUSION:: The results confirm our hypothesis and suggest that, as walking speed increases, the increase in VO2 is positively correlated with the VO2peak. Our findings are consistent with the notion that cardiorespiratory fitness and exercise economy are inversely related.