The influence of ramp rate on VO2peak and "excess" VO2 during arm crank ergometry

The principal aim of this study was to examine how different ramp rates influenced the attainment of peak physiological responses during incremental arm crank ergometry (ACE). Additionally, the study examined whether there was any evidence for the development of an "excess" (V)over dot O-2 during ACE due to upward curvi-linearity in the (V)over dot O-2-work rate relationship, and whether this was influenced by the ramp rate. Sixteen physically active, though non-specifically trained, men (mean +/- s age 30 +/- 8 years; height 1.79 +/- 0.07 m; body mass 84.7 +/- 13.2 kg) volunteered to participate. Having completed a familiarisation test, all subjects returned to the laboratory to complete two ramp tests on an electrically-braked ergometer in a counter-balanced order. Both ramp tests started at 60W with work rate subsequently incremented by either 6 or 12W . min(-1). Pulmonary gas exchange was measured breath-by-breath throughout the tests. Subjects achieved a greater final work rate during the 12 W . min(-1) test compared to the 6 W . min(-1) test (168 28 vs. 149 +/- 26W; p < 0.001). The (V)over dot O-2peak (3.06 +/- 0.65 vs. 2.96 +/- 0.48 L.min(-1); p=0.27), HRpeak (179 +/- 15 vs. 177 +/- 16 b.min(-1); p=0.17) and VEpeak(112 +/- 22 vs. 105 +/- 16 L.min(-1); p=0.09) were not different between the tests, but (V)over dot CO2peak (3.54 +/- 0.64 vs. 3.27 +/- 0.46 L.min(-1); p=0.01)RERpeak (1.17 +/- 0.07 vs 1.11 +/- 0.06; p < 0.001), and end-exercise blood (lactate) (11.9 +/- 2.1 vs. 10.8 +/- 2.6 mmol . L-1; p = 0.005) were all higher in the 12 W.min(-1) test. An "excess" (V)over dot O-2 was observed in 13 out of 16 tests at 12 W.min(-1) and in 15 out of 16 tests at 6 W.min(-1). Neither the magnitude of the "excess" (V)over dot O-2 (0.42 +/- 0.41 vs. 0.37 +/- 0.18 L.min(-1); p=0.66) nor the (V)over dot O-2 at which the (V)over dot O-2- work rate relationship departed from linearity (2.17 +/- 0.34 vs. 2.18 +/- 0.32 L.min(-1); p = 0.94) were significantly different between the two ramp tests. These data indicate that differences in ramp rate within the range of 6 - 12 W.min(-1) influence the peak values of work rate, (V)over dot CO2 and RER, but do not influence peak values of (V)over dot O-2 or HR during ACE. The development of an "excess" (V)over dot O-2 appears to be a common feature of ramp exercise in ACE, although the mechanistic basis for this effect is presently unclear.