The influence of ramp rate on V̇O_2peak and "excess" V̇O₂ 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" V̇O₂ during ACE due to upward curvi-linearity in the V̇O₂-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 60 W with work rate subsequently incremented by either 6 or 12 W·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 ± 26 W; p < 0.001). The V̇O _2peak (3.06 ± 0.65 vs. 2.96 ± 0.48 L·min ^-1; p = 0.27), HR_peak (179 ± 15 vs. 177 ± 16 b·min^-1; p = 0.17) and V̇E_peak (112 ± 22 vs. 105 ± 16 L·min^-1; p = 0.09) were not different between the tests, but V̇CO_2peak (3.54 ± 0.64 vs. 3.27 ± 0.46 L·min^-1; p = 0.01) RER_peak (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" V̇O₂ 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·O ₂ (0.42 ± 0.41 vs. 0.37 ± 0.18 L̇min^-1; p = 0.66) nor the V̇O₂ at which the V̇O₂-work rate relationship departed from linearity (2.17 ± 0.34 vs. 2.18 ± 0.32 L̇min^-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 Ẇmin^-1 influence the peak values of work rate, V̇CO₂ and RER, but do not influence peak values of V̇O ₂ or HR during ACE. The development of an "excess" V̇O₂ appears to be a common feature of ramp exercise in ACE, although the mechanistic basis for this effect is presently unclear.