Relation Between Running Economy and Continuous Jumping Mechanical Power Measures

Abstract

The inter-individual variability in running economy has been explained by mechanical power with limited success; however the recovery of elastic energy is typically not included in traditional mechanical power estimates. Runners utilizing more elastic energy, which is free of metabolic cost, would be expected to be more economical (i.e., less oxygen cost for a given distance). PURPOSE: To determine if mechanical power, as measured with a continuous jumping test is inversely related to running economy. The jumping test was designed to evaluate maximal power, including the elastic potential of muscle. METHODS: Sixteen healthy, experienced, female runners (age: 25.6+6.4 yr; body mass: 59.9+5.0 kg) performed a 60-s, continuous jumping test after a sufficient warm-up. After at least 10-min of rest, they performed a 30-min treadmill run at a self-selected, submaximal speed. Indirect calorimetry was used to measure oxygen consumption with a MedGraphics metabolic cart during the final 4-min of the run. Running economy was denned as VO2 averaged over the final 30-s and normalized to running speed (ml kg−1. km−1). Mechanical power was calculated for the first 15-s, the first 30-s, and the entire 60-s of the jumping test and each measure was correlated with running economy. RESULTS: Mechanical power decreased as longer durations of jumping were analyzed (Mean+SD: 11.6+2.3, 10.8+2.0, 9.7+1.6 W.kg−1 for 15-s, 30-s, 60-s respectively). The range of running economy, when expressed as a percent of the mean (215+13 ml kg−1. km−1), was 22%. Running economy was not related to any measure of mechanical power (r-values for 15-s, 30-s, 60-s: .09, .14, .12). CONCLUSIONS: Running economy is not related to continuous jumping-based mechanical power measures. Contributions to this measure of power from the lactate and phosphogen systems may have overridden the influence of elastic energy recovery. Supported by Wacoal Sports Science Corporation