Background The purpose of the study was to assess energy expenditure and substrate oxidation to treadmill running (TR) and cycle ergometer (CE) exercise in normal-weight (NW) and obese (OB) men. Methods 27 NW (BMI: 21.2 ± 1.2 kg/m2) and 25 OB (BMI: 27.2 ± 1.3 kg/m2) men were recruited in this study. Each participant completed resting metabolic rate and energy expenditure tests during the fixed absolute workloads (TR at 7 and 8 km/h and CE at 50 and 100 W) by indirect calorimetry. Results Gross VO2 (L/min) was higher for OB during CE at 100 W (p < 0.05), and TR at 7 and 8 km/h (both p < 0.01), no difference was found when the values were adjusted for FFM, but lower gross (all p < 0.01) and net VO2 (all p < 0.05) when the values were adjusted for body mass. While net energy expenditure (kcal/min) was greater for OB group during TR at 7 and 8 km/h (both p < 0.01), but similar in both groups during CE at 50 and 100 W. For CE, gross efficiency was significantly lower in OB during CE at 50 and 100 W (both p < 0.01), but no difference was found in net efficiency. A higher fat oxidation rate was found during CE at 50 and 100 W (both p < 0.05) for OB than NW. For both NW and OB subjects, fat contribution was greater during CE at 50 W than CE at 100 W (both p < 0.01). Obesity significantly affected gross and net VO₂ and fat oxidation but showed no significant main effect on CHO oxidation, however, a significant obesity × type interaction was found in CHO oxidation (F = 10.325, p = 0.002, partial η² = 0.171). While exercise type and intensity appear to have a significant effect on CHO oxidation (with type × intensity interaction), only exercise type appears to have a significant effect on fat oxidation (without interaction with intensity). Conclusions These findings suggested that OB showed the higher energy cost than NW during CE at higher intensity and TR. CE without weight burden resulted in a greater fat oxidation rate and higher fat oxidation contribution in OB than NW. For cycling, net efficiency does not differ between NW and OB subjects. Exercise type and intensity are both factors influencing substrate oxidation during exercise. It is concluded that the exercise type and intensity have to be taken into account when prescribing for obese subjects. Future studies should apply equal relative physiological intensities to interpret the energy expenditure and substrate oxidation differences between normal and obese subjects.

The energy expenditure and substrate oxidation of treadmill running and cycle ergometer exercise in normal-weight and obese men

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2026年7月20日

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Jingjing Xue,
Shuo Li,
Tingting Sun,
Kongjun Zhang,
Ping Hong

摘要

Background

The purpose of the study was to assess energy expenditure and substrate oxidation to treadmill running (TR) and cycle ergometer (CE) exercise in normal-weight (NW) and obese (OB) men.

Methods

27 NW (BMI: 21.2 ± 1.2 kg/m²) and 25 OB (BMI: 27.2 ± 1.3 kg/m²) men were recruited in this study. Each participant completed resting metabolic rate and energy expenditure tests during the fixed absolute workloads (TR at 7 and 8 km/h and CE at 50 and 100 W) by indirect calorimetry.

Results

Gross VO₂ (L/min) was higher for OB during CE at 100 W (p < 0.05), and TR at 7 and 8 km/h (both p < 0.01), no difference was found when the values were adjusted for FFM, but lower gross (all p < 0.01) and net VO₂ (all p < 0.05) when the values were adjusted for body mass. While net energy expenditure (kcal/min) was greater for OB group during TR at 7 and 8 km/h (both p < 0.01), but similar in both groups during CE at 50 and 100 W. For CE, gross efficiency was significantly lower in OB during CE at 50 and 100 W (both p < 0.01), but no difference was found in net efficiency. A higher fat oxidation rate was found during CE at 50 and 100 W (both p < 0.05) for OB than NW. For both NW and OB subjects, fat contribution was greater during CE at 50 W than CE at 100 W (both p < 0.01). Obesity significantly affected gross and net VO₂ and fat oxidation but showed no significant main effect on CHO oxidation, however, a significant obesity × type interaction was found in CHO oxidation (F = 10.325, p = 0.002, partial η² = 0.171). While exercise type and intensity appear to have a significant effect on CHO oxidation (with type × intensity interaction), only exercise type appears to have a significant effect on fat oxidation (without interaction with intensity).

Conclusions

These findings suggested that OB showed the higher energy cost than NW during CE at higher intensity and TR. CE without weight burden resulted in a greater fat oxidation rate and higher fat oxidation contribution in OB than NW. For cycling, net efficiency does not differ between NW and OB subjects. Exercise type and intensity are both factors influencing substrate oxidation during exercise. It is concluded that the exercise type and intensity have to be taken into account when prescribing for obese subjects. Future studies should apply equal relative physiological intensities to interpret the energy expenditure and substrate oxidation differences between normal and obese subjects.