The effect of different work rate increasing rates on cardiopulmonary exercise testing in arm ergometer

Cycle ergometer is commonly used for cardiopulmonary exercise testing (CPET), which is the objective and quantitative golden standard for functional evaluation and training, while arm CPET is less commonly used to clinically assess a patient's overall functioning. To determine optimal CPET protocols, we studied the effect of different work rate increasing rates of arm ergometer on CPET key variables.

We recruited fourteen non-symptomatic participants without any clinical diagnosis, and first performed maximal leg CPET for functional evaluation, followed by four maximal arm ergometer CPETs using different work rate increasing rates (5, 20, 35, and 50 W/min) in random order on various days in one week (7 days). The key variables are oxygen uptake ( $\dot{V}C{O}_2$ ), heart rate (HR), minute ventilation ( $\dot{V}E$ ), tidal volume (VT), breathing frequency (Bf), anaerobic threshold (AT), work rate, incremental exercise time (Tlim), respiratory exchange ratio (RER). One-way analysis of variance (ANOVA) with Tukey's post-hoc test compared outcomes across the four increasing rate protocols, and a paired t-test assessed arm vs. leg differences.

All participants safely finished maximal CPET using leg and arm ergometers, and they had normal leg CPET peak $\dot{V}{O}_2$ [92.89±18.37 (73.34-143.63) %predicted]. Each arm ergometer protocol elicited similar $\dot{V}{O}_2$ (1.37±0.31, 1.35±0.32, 1.34±0.31 and 1.33±0.30 L/min, P=0.99), HR (P=0.96), $\dot{V}E$ (P=0.98), VT (P=0.98) and Bf (P=0.81) at peak and AT (P=0.96). However, there were significantly different peak work rate (58±11, 80±18, 95±22 and 110±22 W, P<0.001), peak RER (1.08±0.07, 1.17±0.12, 1.20±0.12 and 1.21±0.14, P=0.03) and maximal RER during recovery (1.36±0.13, 1.45±0.18, 1.49±0.13 and 1.53±0.20, P=0.04), which were positively correlated with work rate increasing rate (R2=0.985, 0.823, 0.939, respectively). There were significantly different Tlim with negative relationship (11.61±2.29, 4.02±0.91, 2.71±0.64 and 2.19±0.44 min, P<0.001, R²=0.383).

The study indicates that same as leg ergometer CPET, the arm ergometer CPET also needs optimized increasing rate of incremental exercise for each subject. We preliminarily recommend a work rate increasing rate of about 10-20 W/min in arm ergometer CPET for healthy individuals, which needs further investigation for functional evaluation and training.