The Influence of Latissimus Dorsi Contraction During Bridge Exercises on Core and Lower Limb Muscle Activity

To investigate the influence of latissimus dorsi contraction during bridge exercises on core and lower limb muscle activity.To investigate the influence of latissimus dorsi contraction during bridge exercises on core and lower limb muscle activity.

The subjects were ten healthy adult males (age 27.1 ± 2.3 years). The measurement position was supine with the hip joint in a neutral position and the knee joint flexed at 90°, with both feet firmly on the ground. The upper arms were in contact with the bed, and the hands were placed on the chest. The bridge exercise involved lifting and holding the hips until the hip joint was at 0° flexion, ensuring that compensatory movements did not occur. Surface electromyography (ULTIUM, NORAXON) was used to measure the activity of four muscles: the gluteus maximus (GM), semitendinosus (ST), erector spinae (ES), and rectus abdominis (RA). Latissimus dorsi contraction was achieved by pushing against the bed with the arms. Three conditions for upper limb contraction were set: same side as the dominant leg, opposite side, and both sides. The measurement order was randomized, and each condition was measured twice to calculate the average over five seconds, normalizing to the maximum voluntary contraction (MVC) to express results as %MVC. MVC was measured as isometric maximal contraction for 5 seconds in the measurement limb at Daniels' MMT5 level. Statistical analysis was performed using the Friedman test and multiple comparison methods to compare %MVC among the three conditions for each muscle. The significance level was set at 5%.

The %MVC for GM was 7.0 (5-25) % for the same side, 14.7 (5-37) % for the opposite side, and 8.7 (4-32) % for both sides, with significant differences observed between the opposite and both sides, and between the opposite and same sides (p 0.05). No significant differences were found between the same and both sides. ST, ES, and RA showed no significant differences among the conditions.

The results indicate that contracting the latissimus dorsi by pushing against the bed with the opposite upper limb increases GM muscle activity, while ST, ES, and RA showed no changes in muscle activity among the conditions. It is reported that GM connects with the opposite latissimus dorsi through the thoracolumbar fascia, which may explain the significant increase observed in the opposite side. Conversely, there is no connection between the latissimus dorsi and ST, ES, and RA, which may account for the lack of change in muscle activity.

When performing bridge exercises aimed at strengthening the GM, pushing against the bed with the opposite upper limb may allow for more efficient exercise therapy.