Comparison among three different intensities of eccentric contractions of the elbow flexors resulting in the same strength loss at one day post-exercise for changes in indirect muscle damage markers.

Abstract

The present study compared three different intensity elbow flexor eccentric exercises resulting in the same magnitude of maximal voluntary isomeric contraction torque (MVC) decrease at 1day post-exercise for changes in several indirect markers of muscle damage and proprioception. Sedentary young men performed eccentric contractions of the elbow flexors using a dumbbell corresponding to either 10%, 50% or 100% of MVC to induce ~ 20% decrease in MVC at 1day post-exercise (n = 12/group). MVC, range of motion (ROM), upper arm circumference (CIR), muscle soreness, plasma creatine kinase (CK) activity, and proprioception measures (force match, joint position sense) were taken before to 5days after exercise, and the changes were compared among the groups. MVC and ROM recovered faster (P < 0.05) in the order of 10% (e.g., 3days post-exercise: -3 ± 4%, 0 ± 1%), 50% (-12 ± 3%, -3 ± 2%) and 100% group (-16 ± 4%, -5 ± 1%). Peak CIR, muscle soreness and CK activity were smaller for 10% (Δ3 ± 1mm, 26 ± 10mm, 1049 ± 316IU/L) than 50% (Δ6 ± 2mm, 36 ± 14mm, 1473 ± 429IU/L) and 100% groups (Δ8 ± 2mm, 47 ± 15mm, 2104 ± 929IU/L). The proprioception measures recovered faster (P < 0.05) for 10% followed by 50% then 100% group. The recovery rate of MVC from immediately to 1day post-exercise was correlated (P < 0.05) with the changes in the muscle damage and proprioception markers. These results suggest that the MVC at 1day post-exercise does not necessarily predict the changes in muscle damage markers in the following days, but the MVC recovery rate in the first 24h reflects the magnitude of muscle damage better.