Abstract
BACKGROUND: Oxidative stress contributes to the activation of muscle protein synthesis after high-intensity resistance exercise (HIRE) or low-intensity resistance exercise combined with blood flow restriction (LIBFR), but it is unclear if this oxidative stress response post-exercise is monophasic or multiphasic. We aimed to answer this question using albumin Cys34 oxidation as an oxidative stress marker. METHODS: Seven untrained individuals completed HIRE and LIBFR on separate days. Albumin Cys34 oxidation (total and reversibly and irreversibly oxidized fractions), muscle oxygenation, oxygen consumption (V˙O2), lactate, and heart rate (HR) were measured before and up to 5 h post-exercise. RESULTS: Both HIRE and LIBFR induced a biphasic increase in total oxidized albumin Cys34, with a transient peak in irreversibly oxidized albumin Cys34 immediately post-exercise (p < 0.001) before a delayed sustained increase in reversibly oxidized albumin Cys34, which peaked at 90-120 min and lasted ≥5 h post-exercise (p < 0.05). Muscle oxygenation decreased immediately post-exercise (p < 0.001) before rising above baseline (p < 0.05). V˙O2, HR, and blood lactate peaked post-exercise (p < 0.001) and returned to baseline within 15-90 min. Irreversibly oxidized albumin Cys34 was positively correlated with lactate and V˙O2 post-exercise (p < 0.001). CONCLUSION: Here, we show that resistance exercise, with or without blood flow restriction, results in an early biphasic oxidative stress response after exercise.