Effects of Velocity and Weight Support on Ground Reaction Forces and Metabolic Power during Running

Abstract

The authors are with the Department of Integrative Physiology, University of Colorado, Boulder, CO.The biomechanical and metabolic demands of human running are distinctly affected by velocity and body weight. As runners increase velocity, ground reaction forces (GRF) increase, which may increase the risk of an overuse injury, and more metabolic power is required to produce greater rates of muscular force generation. Running with weight support attenuates GRFs, but demands less metabolic power than normal weight running. We used a recently developed device (G-trainer) that uses positive air pressure around the lower body to support body weight during treadmill running. Our scientific goal was to quantify the separate and combined effects of running velocity and weight support on GRFs and metabolic power. After obtaining this basic data set, we identified velocity and weight support combinations that resulted in different peak GRFs, yet demanded the same metabolic power. Ideal combinations of velocity and weight could potentially reduce biomechanical risks by attenuating peak GRFs while maintaining aerobic and neuromuscular benefits. Indeed, we found many combinations that decreased peak vertical GRFs yet demanded the same metabolic power as running slower at normal weight. This approach of manipulating velocity and weight during running may prove effective as a training and/or rehabilitation strategy.

Short Term Technology-Assisted-Aerobic Exercise (AlterGR, GlideTrakTM, Vasper) in a Community Fitness Center for Patients with Mild to Moderate Parkinson’s Disease: Subjective Perceptions and Motor Effects

“…The faster the speed, the greater the un-weighting needed to keep the ground reaction forces low [31]. The air distributed system allows more comfortable un-weighting than a harness system [35].…”

“…The air distributed system allows more comfortable un-weighting than a harness system [35]. With greater un-weighting, individuals may achieve faster running speeds compared to over ground running [31]. For this study, the objective was to un-weight participants by 40-50% and jog with the treadmill speed 3.5 to 7 mph.…”

“…To facilitate improvement in walking speed, endurance and balance while minimizing the ground reaction forces on the lower limbs [31,35], the therapist could select either the AlterG R or the GlideTrakTM. A more complete history on urological problems was added to the medical history to minimize urinary complaints specifically on the AlterG R. All patients are asked to stop by the rest room before training on the AlterG R and each therapist discussed the potential feelings of urgency with each patient before training on the AlterGR, particularly when planning to unweight up to 50% of body weight.…”

“…While a treadmill can be used to force individuals with PD to move more rapidly, increased ground reaction forces can lead to increased joint and spine pain. Thus, harness systems have been created to protect from falling as well as un-weight individuals to minimize ground reaction forces and facilitate spinal pattern generators for walking/running (body weight supported treadmill training BWSTT) [31][32][33][34].…”

Return to sport following hip injury

“…Ground reaction forces are reduced for running and walking at all levels of un-weighting using the LBPP treadmill versus full body weight [8,12,[14][15][16]. Running mechanics are not significantly affected with un-weighting with respect to stride length and knee and ankle sagittal plane ROM [8,17,18].…”