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.

Differences in Acute Metabolic Responses to Bionic and Nonbionic Ambulation in Spinal Cord Injured Humans and Controls

“…Substrate partitioning was not altered across conditions in either group; however, this is not surprising given that the intensity of walking was below the threshold beyond which a shift in fuel source from fat to carbohydrate is commonly observed. 24 Nonetheless, absolute rates of carbohydrate and fat oxidation during walking were elevated significantly above seated and standing trials in both groups.…”

Hemodynamic and cardiorespiratory responses to various arm cycling regimens in men with spinal cord injury

“…Results from the graded exercise test are depicted in Table 2. VO 2 peak was equal to 1.5 ± 0.8 L/min which represents typical values in SCI [27][28][29][30].…”

Effects of Circuit Resistance Training and P Timely Protein Supplementation on Exercise-Induced Fat Oxidation in Tetraplegic Adults

“…Limited data examining conditioning effects on substrate utilization 43 indicate no changes for fat utilization in 10 persons with paraplegia following 6 weeks of CRT. In the current investigation, fat oxidation during exercise almost doubled after 6 months in participants with tetraplegia, but only if they consumed a PS immediately prior to and after exercise.…”

“…For example, nondisabled individuals have been reported to only reach peak fat oxidation rates of 0.06 ± 0.04 g/min when performing arm ergometry at intensities similar to those attained during the GXT. 43 In addition, persons with paraplegia (T3-L1) have been reported to achieve similar or higher rates of fat oxidation as equally fit nondisabled subjects during 60 minutes of arm ergometry. 12 Future investigations will be needed to determine whether the low levels of fat oxidation observed during arm ergometry can be overcome by using different modes of exercise that incorporate a larger muscle mass, such as FES.…”