Effect of body weight-support on the relationship between velocity and oxygen consumption during running

Devices that provide body weight-support (BWS) during treadmill running have been evaluated for their effect on the metabolic cost of running. While much has been said of the proportionality between the amount of BWS provided, and the amount that metabolic cost is reduced, less has been said of the effect of BWS on the relationship between velocity and oxygen consumption rate (VO 2) across a wide range of velocities. This study's goals were three-fold: 1) to determine the most accurate degrees of BWS provided by a device that uses lower-body positive-pressure, 2) to determine whether a period of accommodation to running on a BWS treadmill using LBPP was necessary to ascertain stable VO2 measures, and 3) to determine whether a significant difference in the rate of change in VO2 with increments in velocity (deltaVO 2/deltaV) occurred at different levels of BWS. The LBPP device used in this study demonstrated the most accuracy at levels of BWS between 10-30 %, with the actual amount of BWS becoming progressively less than that stated by the device-calibrated values. Stable VO2 measurements were achieved after approximately 45 minutes of accommodation to LBPP treadmill running, and the time to accommodation tended to increase with increasing degrees of BWS. Finally, BWS significantly decreased the cost of running across a range of equivalent velocities, and deltaVO2/deltaV decreased significantly with increasing degrees of BWS. Understanding the effect of BWS on the cost of running across a range of velocities may allow better predictions of the change in velocity and BWS necessary to achieve equivalent cardiovascular stress.