Figure 1. Comparison of the physiological parameters between incremental and constant work rate exercise tests.

At 100% exercise, Oxygen consumption (VO₂), heart rate (HR), minute ventilation (V_E) and respiratory exchange ratio (RER) were similar between incremental and endurance tests. However, slopes for these parameters rose steadily over the entire duration of the incremental cardiopulmonary exercise test (CPET) and the incremental shuttle walk test (ISWT), whereas their slopes rose sharply from baseline to 25% of maximum exercise at which point they appeared far less steep until test end for the cycle endurance test (CET) and the endurance shuttle walk test (ESWT). Mean (SE) values of physiological parameters are expressed at the same relative time (e.g. 0%, 25%, 50%, 75% and 100%) from the maximal exercise duration. The shaded zone represents the initial warm-up period of the CPET, the CET and the ESWT. *p<0.05; **p<0.01; ***p<0.001 for the comparison of the slopes of each parameter from baseline to 25% of exercise duration, and from 25% to 100% (test end).