Relationship Of Stride Characteristics To Trunk Acceleration And Metabolic Cost In Collegiate Runners

Abstract

There has been recent interest regarding the importance of gait characteristics as determinants of running performance. Within homogenous groups of elite distance runners, factors other than VO2max contribute to the variation in running performance. Running economy is one such factor and clarifying the gait characteristics that influence running economy is important to understand running performance. PURPOSE: This study quantified stride characteristics, trunk acceleration, metabolic cost of running, and their interaction in collegiate runners. METHODS: Subjects consented to procedures approved by EMU CHHS Human Subjects Committee. High-resolution accelerometer (HRA, G-Link ADXL 210, Microstrain Inc., VT), full-body optical motion-capture (Vicon MX, Vicon,, CO), and indirect calorimetry (Oxycon Mobile, CareFusion, CA) measurements were collected from seven male NCAA DI collegiate distance runners during treadmill running at speeds of 3.33, 3.89, and 4.44 m·s-1. Root mean square (RMS) accelerations were calculated for the mediolateral (ML), anterior-posterior (AP), vertical (VT) axis and resultant Euclidian scalar (RES). Ratio of axial accelerations (Xra= Xrms/RES) were also determined for VTra, MLra and APra. The kinematic stride characteristics of stance time, stance time (percent gait cycle), stride length, and stride rate were determined from optical motion capture. RESULTS: Stride rate, stance time, and stride length were different across speeds (p < 0.05). Linear stepwise regressions showed that VO2, AP acceleration, and RES acceleration were influenced by stride length (R2 = 0.86, 0.28, and 0.22, respectively, p < 0.05). VT acceleration was related to stance time percent (R2 = 0.243, p < 0.05) and VTra was related to stride length and stance time (R2 = 0.65, p < 0.05), while APra was related to stride rate (R2 = 0.21, p < 0.05). CONCLUSION: We have previously shown that trained runners exhibit higher VT and VTra than untrained and that VTra and APra influence metabolic cost of running. Therefore, these differences may partially be explained by differences in stride length, stance time percent, and stride rate. Of these, stride length and stance time percent appear to be most important.