Mechanics Of Running Grade Ability

Abstract

Variation exists between runners in their ability to run uphill versus downhill. The determination of what leads to one runner being more economical at one grade versus another may be due to biomechanical, physiological, neuromechanical, or perhaps other factors. PURPOSE: In this study, we focused on determining whether certain running mechanics would predict a runner’s ability to perform uphill versus downhill running. METHODS: Twenty-one experienced runners ran uphill, level, and downhill while having oxygen uptake measured. Conditions were performed in random order and repeated on a second day. Speeds of uphill, level, and downhill running were selected with the intent to have similar efforts on average for each grade. Runners used the Saucony TypeA shoe for all conditions. Oxygen measures were averaged over the final three minutes of each five minutes run at each condition. A best-fitting line was generated through oxygen uptake versus grade to classify uphill/downhill running ability. The steepness of this slope indicated whether runners were more economical at uphill or downhill running. Various running mechanics were measured using Vicon Nexus and a Bertec treadmill. A linear regression determined any correlations between peak vertical force, stride rate, plantar velocity, and ground time against uphill/downhill running ability. RESULTS: Peak force was the only factor associated with uphill/downhill running ability (t = 3.05, R2 = 0.53, p < 0.01). The slope of oxygen uptake versus grade averaged 0.076 ± 0.278 ((ml/kg/min)/%grade) with slopes ranging from -0.39 to 0.57 ((ml/kg/min)/%grade). CONCLUSIONS: Runners that prefer a greater vertical ground reaction force while running on level ground were more economical during downhill running than uphill.