Systemic redox biomarkers suggest non-redox mediated processes in the prevention of bed rest-induced muscle atrophy after exercise training: The Cologne RSL study

It has been previously reported that eccentric-biased exercise training prevents the decreases in lean body mass after 60 days of head tilt down bed rest (“Cologne RSL Study”). The aim of the present study, as a part of Cologne RSL Study, was to investigate whether these anti-atrophy effects of exercise training are regulated by redox processes, as assessed indirectly via redox biomarkers in blood and urine. Twenty-four volunteers (N = 24) participated in a randomized controlled study and were randomly divided into two groups: a jump training group (JUMP, n = 12) that performed a specific eccentric-biased training protocol on a Sledge Jump System and a control group (CON, n = 11; one drop-out) that did not perform any exercise. All participants maintained a 6° head tilt down position for 24 h/day for 60 days. Redox measurements in plasma, erythrocytes and urine were performed at several time points throughout the study (i.e., baseline, intervention and recovery phases). A main effect of time was found for all dependent variables (P < .05). In particular, plasma protein carbonyls, erythrocyte catalase activity and urine F2-isoprostanes increased, while erythrocyte glutathione concentration decreased over time in both groups. In contrast, neither a main effect of group nor a significant group × time interaction was found in any of the measured variables (P > .05). In conclusion, our findings in systemic redox biomarkers indicate that the anti-atrophy effects of exercise training during a 60-day bed rest protocol are not regulated by redox processes.