Exercise-intensity dependent alterations in plasma redox status do not reflect skeletal muscle redox-sensitive protein signaling

Abstract

Objectives

Redox homeostasis and redox-sensitive protein signaling play a role in exercise-induced adaptation. The effects of sprint-interval exercise (SIE), high-intensity interval exercise (HIIE) and continuous moderate-intensity exercise (CMIE), on post-exercise plasma redox status are unclear. Furthermore, whether post-exercise plasma redox status reflects skeletal muscle redox-sensitive protein signaling is unknown.

Design

In a randomized crossover design, eight healthy adults performed a cycling session of HIIE (5 × 4 min at 75% W_max), SIE (4 × 30 s Wingate’s), and CMIE work-matched to HIIE (30 min at 50% of W_max).

Methods

Plasma hydrogen peroxide (H₂O₂), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) activity, and catalase activity were measured immediately post, 1 h, 2 h and 3 h post-exercise. Plasma redox status biomarkers were correlated with phosphorylation of skeletal muscle p38-MAPK, JNK, NF-κB, and IκBα protein content immediately and 3 h post-exercise.

Results

Plasma catalase activity was greater with SIE (56.6 ± 3.8 U ml⁻¹) compared to CMIE (42.7 ± 3.2, p < 0.01) and HIIE (49.0 ± 5.5, p = 0.07). Peak plasma H₂O₂ was significantly (p < 0.05) greater after SIE (4.6 ± 0.6 nmol/ml) and HIIE (4.1 ± 0.4) compared to CMIE (3.3 ± 0.5). Post-exercise plasma TBARS and SOD activity significantly (p < 0.05) decreased irrespective of exercise protocol. A significant positive correlation was detected between plasma catalase activity and skeletal muscle p38-MAPK phosphorylation 3 h post-exercise (r = 0.40, p = 0.04). No other correlations were detected (all p > 0.05).

Conclusions

Low-volume SIE elicited greater post-exercise plasma catalase activity compared to HIIE and CMIE, and greater H₂O₂ compared to CMIE. Plasma redox status did not, however, adequately reflect skeletal muscle redox-sensitive protein signaling.