Coherence in muscle activity of the biceps brachii at middle, proximal and distal tendon region among the arm wrestling contestants

The aim of this study was to analyze the electromyographic (EMG) activity of biceps brachii (BB) muscle under the same muscle contraction in three different locations. For this reason, arm wrestling contest was conducted to record the EMG signal from ten male subjects. Electrodes were placed on the three locations of upper arm BB; i.e. middle (belly) of BB (M), lower part (L) and upper part (U) of the BB belly. Average EMG (EMGAVG), root mean square (EMGRMS) and highest peak of the signal [EMGHigh(pk)] were calculated from the sum of EMG activity. The analysis of the effect of electrode placement location using ANOVA (analysis of variance) tests yielded a number of statistically significant differences. The results indicated, 1) majority of the EMG results confirmed the muscle activity was higher in the order of L, M and U, 2) among the 16 comparisons among the muscles (from winners and losers), there was main interaction found between the entire BB of winners and losers, also another 7 results displayed same interaction (p<0.05), but remaining 8 locations did not significant (p>0.05), 3) in the loser, the BB was forced to perform eccentric contraction as the forearm is being pronated and elbow was gradually being extended, on the other hand, contraction of the BB was concentric in the winner, and 4) winners (during concentric contraction) did not always produce highest EMG peak and some of the results (muscle activity) of loser’s (during eccentric contraction) revealed higher than the winners. The findings of the study contain a precious contribution to rehabilitation, biomedical and sports medicine by describing an experimental set up to measure muscle electrophysiology during physical activity in the case of arm activities.