Heavy reliance on carbohydrate across a wide range of exercise intensities during voluntary arm ergometry in persons with paraplegia

Abstract

Context/objective

To describe and compare substrate oxidation and partitioning during voluntary arm ergometry in individuals with paraplegia and non-disabled individuals over a wide range of exercise intensities.

Design

Cross-sectional study.

Setting

Clinical research facility.

Participants

Ten apparently healthy, sedentary men with paraplegia and seven healthy, non-disabled subjects.

Interventions

Rest and continuous progressive voluntary arm ergometry between 30 and 80% of peak aerobic capacity (VO_2peak).

Outcome measures

Total energy expenditure and whole body rates of fat and carbohydrate oxidation.

Results

A maximal whole body fat oxidation (WBFO) rate of 0.13 ± 0.07 g/minute was reached at 41 ± 9% VO_2peak for subjects with paraplegia, although carbohydrate became the predominant fuel source during exercise exceeding an intensity of 30–40% VO_2peak. Both the maximal WBFO rate (0.06 ± 0.04 g/minute) and the intensity at which it occurred (13 ± 3% VO_2peak) were significantly lower for the non-disabled subjects than those with paraplegia.

Conclusion

Sedentary individuals with paraplegia are more capable of oxidizing fat during voluntary arm ergometry than non-disabled individuals perhaps due to local adaptations of upper body skeletal muscle used for daily locomotion. However, carbohydrate is the predominant fuel source oxidized across a wide range of intensities during voluntary arm ergometry in those with paraplegia, while WBFO is limited and maximally achieved at low exercise intensities compared to that achieved by able-bodied individuals during leg ergometry. These findings may partially explain the diminished rates of fat loss imposed by acute bouts of physical activity in those with paraplegia.

Keywords:

• Spinal cord injuries
• Paraplegia
• Ergometry
• Energy metabolism
• Physical exertion
• Carbohydrates
• Fats

Acknowledgements

The authors wish to thank the participants for their time and efforts. Additionally, we would like to thank Jennifer Raeburn and Elizabeth Edwards for their assistance in the preparation of this manuscript.