Fat Oxidation during Exercise in People with Spinal Cord Injury, and Protocols Used: A Systematic Review

Background: The aim of this study was to summarize evidence on energy metabolism through peak fat oxidation (PFO) and maximum fat oxidation (Fat(max)), as well as to analyze the protocols used in people with spinal cord injury (SCI) and to examine the main factors related to fat oxidation ability (i.e., age, sex, level of physical activity, and level and degree of injury). Methods: Studies to determine PFO and Fat(max) using indirect calorimetry with an arm exercise protocol for SCI patients were included after a systematic search. Other endpoints included study design, sample size, control group, demographic data, level of injury, physical condition, protocol, outcomes measured, and statistical findings. Results: Eight studies (n = 560) were included. The mean value of VO(2peak) was 1.86 L∙min(−1) (range 0.75–2.60 L∙min(−1)) (lowest value in the tetraplegic subjects). The PFO ranged between 0.06 and 0.30 g∙min(−1) (lowest rates: the non-trained subjects with cervical SCI; highest: the tetraplegic subjects). Two types of exercise protocol were found: arm cycle ergometer, and wheelchair propulsion with a computerized ergometer. Five studies used an incremental protocol (2–3 min/stage, different load increments); the rest performed tests of 20 min/stage at three intensities. Conclusion: There are few existing studies measuring fat oxidation in SCI, many of which used small and heterogeneous samples. PFO was lower in SCI subjects when compared with non-injured people performing lower-limb exercise; however, comparing upper-limb exercise, people with SCI showed higher values.