Evidence for muscle damage following variation in resistive force during concentric high intensity cycle ergometry exercise: body mass or composition?

The purpose of this study was to compare power outputs, and concentrations of creatine kinase (S-CK), myoglobin (S-Mb) and blood lactate ([La-]b) following 30 s of maximal cycle ergometry exercise when resistive forces were dependent on total-body mass (TBM) and fat-free mass (FFM). Cardiac troponin concentrations (S-cTnl) were also determined to exclude protein leakage from the myocardium. Significant differences (P<0.05) in peak power output (PPO) were found between the TBM and FFM protocols (1020±134 vs. 953±114 Watts respectively). Differences were also found between pedal velocities and resistive forces (134±8 vs. 141±7 rev/min; 6±1 vs. 5±1 kg respectively). Significant differences were also noted for S-CK from rest to immediately post exercise during both the TBM and FFM protocols. Data for La-]b were also significantly different recorded from rest, to immediately post and 24 h post exercise for both the TBM and FFM protocols. Differences were observed immediately post exercise between the TBM and FFM protocols for S-Mb concentrations (P<0.05). The results of the study suggest that greater power outputs are obtainable with significantly less muscle damage when resistive forces reflect FFM mass during loading procedures.