Effects Of A Single Bout Or Chronic High-intensity Exercise On Inflammation In Individuals With Paraplegia

Individuals living with a spinal cord injury (SCI) have chronic low-grade inflammation, which may partly explain their increased risk of cardiovascular disease. In non-SCI populations, a single bout of whole-body high-intensity exercise stimulates a potent anti-inflammatory response, whilst chronic exercise training reduces low-grade inflammation. PURPOSE: To determine the effect of a single bout and chronic upper-body high-intensity interval exercise (HIIE) on inflammatory cytokines in individuals with chronic (>1-year post-injury) paraplegia. METHODS: In study 1, ten individuals with paraplegia (eight males, two females; age: 49 ± 10 yr) completed three conditions in a randomised order under fasted conditions: HIIE (8 x 60-s intervals at 70% peak power output), moderate-intensity continuous exercise (MICE; 25 min at 45% peak power output), and a resting control condition. Venous blood samples were taken prior to exercise, and at 30-min and 60-min post-exercise. In study 2, twenty-two individuals with paraplegia (12 males, 10 females, 45 ± 8 yr) were randomised to an HIIT intervention or control group. Participants in the HIIT group (n = 12) performed four sessions per week of arm-crank based HIIE (10 x 60-s intervals at 80-90% peak heart rate) for six weeks. Participants in the control group (n = 10) were instructed to continue their habitual physical activity and diet patterns. A venous blood sample was taken in the fasted state at baseline and follow-up. Inflammatory cytokine (IL-6, TNF-α, IFN-γ) concentrations were measured in duplicate from serum blood samples using electrochemiluminescence assays. Two-way ANOVAs were used to identify any time, group/condition, or interaction effects. RESULTS: Baseline concentrations were 1.09 ± 1.53 pg/mL, 3.34 ± 2.36 pg/mL, and 2.16 ± 2.51 pg/mL for IL-6, TNF-α, and IFN-γ respectively. In Study 1, there was no differences in IL-6 (p = 0.16), TNF-α (p = 0.65), and IFN-γ (p = 0.25) concentrations between HIIE, MICE, and the resting control condition. In Study 2, there was no differences in IL-6 (p = 0.61), TNF-α (p = 0.63), and IFN-γ (p = 0.62) concentrations between the HIIT and control group. CONCLUSION: Upper-body HIIE has no acute or chronic effect on inflammatory status in individuals with chronic paraplegia. Supported by the University of Bath Alumni Fund.