Exercise Running

The aim of this study was to compare the spatio-temporal parameters of trained runners and untrained participants with the same foot strike pattern (rearfoot) during running at controlled speeds. Twenty-one participants were classified in two groups according to their training experience: Trained (n=10, amateur runners with long distance training experience) and Untrained (n=11, healthy non-trained participants). Anthropometric variables were recorded, and the participants performed both a submaximal (between 9 and 15 km·h) and a graded exercise running test (from 6 km·h until exhaustion) on a treadmill. Physiological (VO2max, heart rate, running economy, peak speed…) and biomechanical variables (contact and flight times, step rate and length) were simultaneously registered. Trained runners showed higher step rate and shorter step length than the Untrained group at the same running speeds (between 4-7%, p<0.05) and at the same physiological intensities (between 7-11%, p<0.05). However, there were no differences in contact and flight times between groups. Significant differences (p<0.05) and large effect sizes (Cohen's d) between groups were found for body mass, sum of 6 skinfolds, VO2max, peak speed, ventilatory threshold and respiratory compensation threshold speeds. The Trained group also showed a∼7% better running economy (ml·kg·km) than the Untrained group. In conclusion, adopting higher step rate and shorter step length may be an adaptive mechanism of the Trained group to reduce injury risk and possibly improve running economy. However, contact and flight times were consistent regardless of training level.