Pulmonary O2 uptake on-kinetics in rowing and cycle ergometer exercise

The purpose of this study was to characterise, for the first time, the pulmonary O-2 uptake ((V) over dot O-2) on-kinetic responses to step transitions to moderate and heavy intensity rowing ergometer exercise, and to compare the responses to those observed during upright cycle ergometer exercise. We hypothesised that the recruitment of a greater muscle mass in rowing ergometer exercise (Row) might limit muscle perfusion and result in slower Phase II (V) over dot O-2 kinetics compared to cycle exercise (Cyc). Eight healthy males (aged 28 +/- 5 years) performed a series of step transitions to moderate (90% of the mode-specific gas exchange threshold, GET) and heavy (50% of the difference between the mode-specific GET and (V) over dot O-2 max) work rates, for both Row and Cyc exercise. Pulmonary (V) over dot O-2 was measured breath-by-breath and the (V) over dot O-2 on-kinetics were described using standard non-linear regression techniques. With the exception of Delta (V) over dot O-2/Delta WR which was similar to 12% greater for Row, the (V) over dot O-2 kinetic responses were similar between the exercise modes. There was no significant difference in the time constant describing the Phase II (V) over dot O-2 kinetics between the exercise modes for either moderate (rowing: 25.9 +/- 6.8 s versus cycling: 25.7 +/- 8.6 s) or heavy (rowing: 26.5 +/- 3.0 s versus cycling: 27.8 +/- 5.1 s) exercise. Furthermore, there was no significant difference in the amplitude of the (V) over dot O-2 slow component between the exercise modes (rowing: 0.34 +/- 0.13 L min(-1) versus cycling: 0.35 +/- 0.12 L min(-1)). These data suggest that muscle (V) over dot O-2 increases towards the anticipated steady-state requirement at essentially the same rate following a step increase in ATP turnover in the myocytes, irrespective of the mode of exercise, at least in subjects with no particular sport specialism. The recruitment of a greater muscle mass in rowing compared to cycling apparently did not compromise muscle perfusion sufficiently to result either in slower Phase II (V) over dot O-2 kinetics or a greater (V) over dot O-2 slow component amplitude during heavy exercise. (c) 2004 Elsevier B.V. All rights reserved.