Acute changes in antioxidants and oxidative stress to vigorous arm exercise: an intervention trial in persons with spinal cord injury and healthy controls

STUDY DESIGN: Intervention trial. BACKGROUND: Literature remains unclear on possible health benefits and risks assosciated with high intensity exercise for persons with SCI. Elevated oxidative stress levels might influence their ability to exercise at high intensity. We investigated several biomarkers of oxidative stress and antioxidant defense at rest, during and after vigorous exercise among persons with chronic SCI. SETTING: Sunnaas Rehabilitation Hospital, Norway. METHODS: Six participants (five males) with chronic SCI (AIS A, injury level thoracic 2–8, >1 year postinjury) and six matched able-bodied controls performed two maximal arm-cranking tests, with one-three days in between. During the second exercise test, participants performed three bouts with four minutes arm cranking at high intensity (85–95% of peak heart rate (HR(peak))), before they reached maximal effort. Blood and urine biomarkers for oxidative stress and antioxidant levels were collected at six time points at the day of the second exercise test; baseline, at high intensity exercise, at maximal effort, at five, 30 and 60 min post-exercise, and 24 h post exercise. RESULTS: Participants with SCI had significant lower levels of creatinine (∆16 µmol/L, p = 0.03), α-carotene (∆0.14 nmol/L, p < 0.001) and β-carotene (∆0.51 nmol/L, p = 0.001) at baseline compared to controls. Urine and blood biomarkers of oxidative stress and antioxidant levels showed similar response to vigorous exercise in the SCI and control group. CONCLUSIONS: SCI participants showed similar changes in redox status during high intensity exercise compared to matched able-bodied. SCI participants had lower levels of exogen antioxidants both before, during and after vigorous exercise.