Variability in energy cost and walking gait during race walking in competitive race walkers

Purpose: The aim of this study was to examine the variability of energy cost (Cw) and race walking gait after a 3-h walk at the competition pace in race walkers of the same performance level. Methods: Nine competitive race walkers were studied. In the same week, after a first test of (V) over dot O-2max determination, each subject completed two submaximal treadmill walks (6 min length, 0% grade, 12 km.h(-1) speed) before and after a 3-h overground test completed at the individual competition speed of the race walker. During the two submaximal tests, subjects were filmed between the 2nd and the 4th min, and physiological parameters were recorded between the 4th and the 6th min. Results: Results showed two trends. On the one hand, we observed a significant and systematic increase in energy cost of walking (mean Delta Cw = 8.4%), whereas no variation in the gait kinematics prescribed by the rules of race walking was recorded. On the other hand, this increase in metabolic energy demand was accompanied by variations of different magnitude and direction of stride length, of the excursion of the heel and of the maximal ankle flexion at toe-off among the race walkers. Conclusion: These results indicated that competitive race walkers are able to maintain their walking gait with exercise duration apart from a systematic increase in energy cost. Moreover, in this form of locomotion the effect of fatigue on the gait variability seems to be an individual function of the race walk constraints and the constraints of the performer.