Metabolic and Cardiorespiratory Differences in Incremental Upper and Lower-Body Exercise in Healthy Adults-A...

Upper-body exercise is increasingly applied in athletic and exercise settings; however, acute physiological and perceptual differences compared to lower-body exercise remain insufficiently characterized. This study compared maximal performance parameters during incremental upper- and lower-body exercise in healthy adults.

Seventeen moderately trained participants (eight females, nine males) completed randomized incremental tests on a hand crank ergometer (HCE) and a cycle ergometer (CE). Maximal fat oxidation (MFO), intensity at maximal fat oxidation (FAT_max), peak oxygen uptake (VO₂^peak), maximal heart rate (HR_peak), peak power output (PPO), immediate post-exercise lactate (LA_post), and differentiated ratings of perceived exertion (RPE_breathing and RPE_muscles) were assessed.

MFO was significantly lower during HCE compared with CE (0.26 vs. 0.55 g·min^-1, p < 0.001), occurring at a lower FAT_max (42.6% vs. 51.6% of VO₂^peak_,p = 0.016). Furthermore, relative VO₂^peak (34.1 vs. 48.9 mL·kg^-1·min^-1, p < 0.001), HR_peak (178 vs. 189 beats·min^-1, p < 0.001), and relative PPO (1.8 vs. 4.1 W·kg^-1, p < 0.001) were substantially reduced during HCE. While RPE_breathing was higher during CE (19.1 vs. 17.6, p < 0.001), RPE_muscles (19.4 vs. 19.8, p = 0.111) and LA_post (9.8 vs. 8.6 mmol·L^-1, p = 0.060) did not differ significantly between modalities. No significant modality-by-sex interactions were observed for any outcome.

These findings demonstrate pronounced modality-specific differences in metabolic, cardiorespiratory, and perceptual responses. Exercise modality should therefore be carefully considered when interpreting maximal exercise tests and prescribing training or rehabilitation programs.