Influence Of Running Direction On Metabolic Costs May Be Attenuated By Body Weight Support

Abstract

During running on land, backward running produces greater metabolic and muscular demands than when running forward at the same speed. This type of research is important to identify the similarities and differences of forward and backward running, in order to best prescribe backward running as a cross-training stimulus for forward running. PURPOSE: The purpose of this study was to investigate the influence of running direction on metabolic, biomechanical, and perceptual demands during running at different levels of body weight support (BWS). METHODS: Thirteen participants ran forward and backward on a lower body positive pressure treadmill at 0%BWS, 20%BWS, and 50%BWS conditions at the same speed. We measured oxygen uptake (VO2), heart rate (HR), muscle activity (rectus femoris, biceps femoris, tibialis anterior, gastrocnemius), and stride frequency during the tests. Additionally, we calculated metabolic cost of transport (CoT). Furthermore, we used rating of perceived exertion (RPE) and feeling scale to investigate participants’ perceptual demands during the tests. VO2, HR, CoT, RPE, feeling scale, muscle activity, and stride frequency were analyzed using a 2 (directions) x 3 (BWS) repeated measures analysis of variance (α = 0.05). RESULTS: VO2, HR, and CoT were influenced by the interaction of BWS and running direction (P < 0.01). For example, CoT during backward running were greater than when running forward only when running at 0%BWS (4.5 ± 1.1 and 5.8 ± 1.4 J/kg/m in CoT for forward and backward running, respectively: P < 0.001). However, muscle activity from the rectus femoris, stride frequency, and RPE during backward running were averages of 113.5%, 11.3%, and 2.8 rankings greater than when running forward, respectively, regardless of BWS (P < 0.001). CONCLUSIONS: Backward running may require greater biomechanical and perceptual demands compared to forward running at the same speed, regardless of BWS. However, the influence of a change in running direction on metabolic demands may be attenuated by BWS. Supported by JSPS Grant Number 16 K01663.