Variability in energy cost of running during one training season in high level runners

The purpose of this study was to investigate the effect of training specificity on a possible change in the energy cost of running over a period of one training season in high level competition runners. Four middle distance and four long distance runners participated in treadmill tests on three sessions after a specific training period. In each session, every subject participated in two tests to determine, in the first test the maximal oxygen consumption and in the second test the energy cost of running. The second test was performed at 60% and 80% of Vmax (maximal speed reached during the first test, respectively 12 and 16 km.h-1), and at 0% grade. The maximal oxygen uptake (VO2max, ml.kg-1.min-1) increased significantly between the first and the last session (p < 0.05). For all the tests, long distance runners showed higher values of VO2max than middle distance runners (p < 0.001). During the year, there were no significant changes in energy cost (C, ml/kg-1.km-1) between the first and the last session (respectively at 60% and 80% vmax: 165 +/- 5.8 vs 164 +/- 4.9 and 167.5 +/- 3.5 vs 166.8 +/- 3.3), and no differences were found between middle and long distance runners. An addition, no changes were found in lactate concentration or in respiratory exchange ratio during all the training season. Discussion set out the difficulty to conclude to a stability in energy cost of running. First by the fact that the energy cost reflects both positive and negative effects of training.(ABSTRACT TRUNCATED AT 250 WORDS)