Force-velocity relationship profile of elbow flexors in male gymnasts

The theoretical maximum force (F₀), velocity (V₀), and power (P_max) of athletes calculated from the relationship between force and velocity (F-V relationship) and the slope of the F-V relationship, reflect their competitive and training activity profiles. Evaluating the F-V relationship of athletes facilitates categorizing the profiles of dynamic muscle functions in relation to long-term sport-specific training. For gymnastics, however, no studies have tried to examine the profiles of F-V relation and power output for upper limb muscles in relation to the muscularity, while the use of the upper extremities in this sport is very unique as described earlier.

It was hypothesized that the F-V relationship of the elbow flexion in gymnasts might be characterized by low capacity for generating explosive force, notably in terms of the force normalized to muscle size.

The F₀, V₀, and P_max derived from the force-velocity relationship during explosive elbow flexion against six different loads (unloaded condition, 15, 30, 45, 60, and 75% of maximal voluntary isometric elbow flexion force (MVF_EF)) for 16 gymnasts (GYM) and 22 judo athletes (JD). F₀ and P_max were expressed as values relative to the cross-sectional area index (CSA_index) of elbow flexors (F₀/CSA_index and P_max/CSA_index, respectively), which was calculated from muscle thickness in the anterior upper arm. The electromyogram (EMG) activities of the biceps brachii (BB) during the maximal isometric and dynamic tasks were also determined.

There were no significant differences in CSA_index of elbow flexors between GYM and JD. MVF_EF/CSA_index for GYM was significantly lower than that for JD. Force was linearly associated with velocity in the dynamic elbow flexion for all the participants (r =  - 0.997 to -0.905 for GYM, r =  - 0.998 to -0.840 for JD). F₀, F₀/ CSA_index, V₀, P_max, P_max/CSA_index, and MVF_EF were significantly lower in GYM than in JD. The activity levels of BB during the dynamic tasks tended to be lower in GYM than in JD at load of <45%MVC.

Gymnasts cannot generate explosive elbow flexion force corresponding to their muscle size. This may be due to low neuromuscular activities during the maximal dynamic tasks against relatively low loads.