The influence of elbow joint angle on different phases of force development during maximal voluntary contraction

The first aim of the study was to find an elbow joint angle at which muscle can produce maximum voluntary force (Lo(MVC)) and to compare that angle with an angle at which the fastest rates of force development occur (Lo). The second aim of the study was to find if changes in MVC and force development speed at an angle smaller (Ls) and larger (Ll) than the optimal angle depend on whether Ls and Ll were compared to Lo or Ls and Ll to Lo(MVC). Twenty-four male physical education students were tested four times using the BIODYNA dynamometer to measure torque versus time at an optimal length, as well as at lengths that were shorter (Ls = optimal -30 degrees) and longer (Ll = optimal +50 degrees). The average values of optimal angles for force development indices (Lo) were similar to the angle at which maximum force was produced (Lo(MVC)); however, there was a small (5-10 degrees) difference between Lo and Lo(MVC) in the majority of subjects. The results showed that during elbow flexion with the forearm in the midrange position, the difference between Lo and Lo(MVC) was small and did not affect MVC; however, it had a significant effect on the relation between joint angle and force development speed.