Changes in Cost of Locomotion Are Higher after Endurance Cycling Than Running When Matched for Intensity and Duration

IntroductionCost of locomotion (C-L) has been shown to increase after endurance running and cycling bouts. The main purpose of this study was to compare, in the same participants, the effect of both modalities on C-L when matched for relative intensity and duration.MethodsSeventeen recreational athletes performed two incremental tests in running and cycling to determine the first ventilatory threshold then two 3-h bouts of exercise at 105% of threshold, with gas exchange measurements taken for 10 min at the start, middle and end of the 3 h to calculate C-L. Neuromuscular fatigue during isometric knee extensor contractions and force-velocity profile on a cycle ergometer were assessed before and immediately after the 3-h trials.ResultsC(L) significantly increased at mid (+3.7%, P = 0.006) and end (+7.4%, P < 0.001) of exercise for cycling compared with start, whereas it did not change with time for running. Cardio-respiratory and metabolic variables changed similarly for cycling and running, therefore not explaining the time-course differences in C-L between modalities. Changes in C-L during cycling correlated significantly with loss of maximal force extrapolated from the force-velocity profile (r = 0.637, P = 0.006) and changes in cadence (r = 0.784, P < 0.001).ConclusionsThe type of locomotion influences the effects of exercise on energy cost because 3 h of exercise at the same relative intensity caused a significant increase of cycling C-L, and no changes in running C-L. The changes in C-L in cycling are likely due, at least in part, to fatigue in the locomotor muscles.