The Oxygen required for horizontal and grade walking on a motor-driven treadmill

Abstract

Oxygen uptake (.ovrhdot.VO2)was measured in males age 10-59 while they walked at 3 mph at various grades on a motor-driven treadmill. The number of subjects in each age group was as follows: age 10-11, N = 24; age 12-13, N = 46; age 14-15, N = 55; age 16-17, N = 53; age 18-19, N = 30; age 20-24, N = 56; age 25-29, N = 35; aged 30-34, N = 32; age 35-39, N = 99; age 40-44, N = 106; age 45-49, N = 78; age 50-54, N = 42; and age 55-59, N = 11. Subjects walked a 3 mph a 0% grade for 3 min; thereafter, the treadmill was raised 3% every third minute with speed maintained. Oxygen uptake was measured continously but only the values during the last minute at each grade were used in the present analysis. The subjects were in a "steary state", insofar as .ovrhdot.VO2 was concerned, by the second minute. These data were used to validate formulas for estimating .ovrhdot.VO2 in horizontal and grade walking published in Guidelines for Graded Exercise Testing and Exercise Prescipition (1). The formulas are accurate for estimating the mean oxygen requirement in grade walking from 6-18% in adult males. In horizontal walking and walking at 3% grade, the formulas underestimate .ovrhdot.VO2 in all age groups. In boys under age 18, the fomulas underestimate the energy requirement in walking at all grade levels. The error is about 0.5 ml .cntdot. kg-1. min-1 for each year under 18 years of age. It was concluded that when applied to adult populations, the formulas provide reasonable estimates of the actual oxygen requirement for treadmill walking provided the subjects are in a .ovrhdot.VO2 steady-state.