Metabolic implications of resistive force selection for oxidative stress and markers of muscle damage during 30 s of high-intensity exercise.

The purpose of this study was to compare power outputs, and blood concentrations of lipid hydroperoxides (LH), malondialdehyde (MDA), creatine kinase (CK), myoglobin (Mb) and lactate ([La-]B) following 30 s of maximal cycle ergometry when resistive forces were derived from total-body mass (TBM) or fat-free mass (FFM). Alpha-tocopherol (AT), retinol (R) and uric acid (UA) concentrations were also measured to qualify the activity of antioxidants. Cardiac troponin levels were determined to exclude myocardial damage and to verify that any CK was predominantly derived from skeletal muscle. Differences (P<0.05) in peak power output, pedal velocity and resistive forces were observed when the TBM and FFM protocols were compared [953 (114) W vs 1,020 (134) W; 134 (8) rpm vs 141 (7) rpm; 6 (1) kg vs 5 (1) kg respectively). LH and MDA concentrations increased immediately post-exercise during the TBM protocol only (P<0.05) and were greater when compared to FFM (P<0.05). LH and MDA values decreased 24 h post-exercise. Increases in CK concentrations were recorded immediately post-exercise for both the TBM and FFM protocols with greater concentrations recorded for TBM (P<0.05). Decreases were observed 24 h post-exercise. Mb concentrations were greater immediately post-exercise for the TBM protocol and were greater than those recorded for FFM (P<0.05). Values decreased 24 h later (P<0.05). AT and UA concentrations decreased immediately post-exercise for both protocols (P<0.05) and increased 24 h later (P<0.05). There were no changes observed in R concentrations at any of the blood sampling stages. [La-]B increased (P<0.05) immediately post-exercise for both protocols, and decreased 24 h later (P<0.05). The results of the study suggest that greater power outputs are obtainable with significantly less oxidative stress and muscle disruption when resistive forces reflect FFM mass as opposed to TBM.