The accuracy of the American College of Sports Medicine metabolic equation for walking at altitude and higher-grade conditions

The purpose of this study was to examine the accuracy of the American College of Sports Medicine (ACSM) walking equation at low walking speeds, altitude (1,550 m), and higher grades. Twenty men and women (mean [+ or -] SD, age, 28 [+ or -] 6 years; height, 171 [+ or -] 13 cm; weight, 67.8 [+ or -] 18.1 kg) completed 2 randomized testing sessions under altitude (AL) ([P.sub.1][O.sub.2] = 123.1 mm Hg [20.93%]) and sea level control (SLC) ([P.sub.1][O.sub.2] 147.3 mm Hg [25.00%]) conditions. Steady-state oxygen uptake ([Vo.sub.2]) was measured while subjects walked at 50 m*[min.sup.-1] at 8 separate grades (0, 5, 10, 15, 18, 21, 24, and 27%). Steady-state [Vo.sub.2] measurements from the last 2 minutes of each grade in AL and SLC were compared to the predicted [Vo.sub.2]. of each grade according to the ACSM walking equation. Mean [Vo.sub.2] differences between predicted and AL values ranged from -0.5 to 1.4 ml*[kg.sup.-1]*[min.sup.-1], averaged 0.1 ml*[kg.sup.-1]*[min.sup.-1] across all grades, and were significant (p < 0.051 at 0 percent grade. Mean [Vo.sub.2] differences between predicted and SLC values ranged from 0.6 to 3.0 ml*[kg.sup.-1]*[min.sup.-1], averaged 1.4 ml*[kg.sup.-1]*[min.sup.-1] across all grades, and were statistically significant (p < 0.05) at 0 and 5 percent. The standard error of the estimate (SEE) for the prediction of [Vo.sub.2] under AL and SLC were 2.2 and 2.0 ml*[kg.sup.-1]*[min.sup.-1], respectively. Total errors for the prediction of [Vo.sub.2]max under AL and SLC were 2.3 and 2.6 ml*[kg.sup.-1]*[min.sup.-1], respectively. Overall, the findings indicate that the current ACSM prediction equation for walking is appropriate for application at low speeds, moderate altitude, and higher grades. Key Words. oxygen consumption, prediction of [Vo.sub.2], sea level