Optimization of hand position on the bar for strengthening biceps brachii and latissimus dorsi during strength training.

Purpose: Pronated or supinated hand positions during strength training on the bar can affect the muscle biomechanics of the entire upper limb and shoulder girdle Understanding these relationships can help improve sports training strategies and the process of physical therapy after injuries. The aim of this study was to optimize the hand position on the bar to identify the best biomechanical movement pattern and strengthen selected muscles during strength training. Methods: A total of 31 students, 12 male and 19 female, aged 18-26 years, participated in the study. Each participant performed 4 series of bar pulls: 2 times in the pronated grip position and 2 times in the supinated grip position, at two different angles of arm opening. During the intervention, sEMG examination of the biceps brachii and latissimus dorsi was performed. Results: Significant differences were shown during strength training for the biceps brachii in the hand grip position ( p < 0.001). All the observed showed an average increase in bioelectric activity of the tested muscles in the hand grip, regardless of the angle of the arm position. Conclusions: Strength exercises of the biceps brachii in the hand grip on the bar may be analternative to milder strength training. On the other hand, training exercises in the grip require greater involvement of the biceps brachii and the latissimus dorsi. Surface electromyography precisely shows differences in the bioactivity of the upper limb muscles in the hand grip and undergrip during strength training, which confirms its diagnostic usefulness.