Myofascial force transmission between latissimus dorsi and contralateral gluteus maximus in runners: a cross-sectional study

The anatomical connection between latissimus dorsi (LD), thoracolumbar fascia, and contralateral gluteus maximus (GM) enables myofascial force transmission (MFT) between the shoulder, trunk, and hip. This study investigates whether regular sports practice, specifically running, influences this MFT pathway. Given the potential changes in tissue stiffness from sports practice and the importance of this property for MFT, we hypothesize that runners may exhibit greater MFT between the LD and GM, resulting in altered passive properties of the lumbar and hip regions during LD contraction. This study aimed to investigate whether runners present a higher modification in lumbar stiffness and passive properties of the contralateral hip due to LD contraction than sedentary individuals. The lumbar stiffness, hip resting position, passive hip torque, and stiffness of fifty-four individuals were assessed using an indentometer and an isokinetic dynamometer, respectively, in two conditions: LD relaxed, and LD contracted. The main and interaction effects were assessed using a two-way ANOVA. The LD contraction increased lumbar stiffness (p < 0.001; η_p² = 0.50), externally rotated the hip resting position and increased the passive hip torque and stiffness (p < 0.05; η_p² > 0.1) in both groups. In addition, runners presented higher lumbar stiffness compared to sedentary in the LD contracted condition (p = 0.017, ES_d = 0.54). Although runners exhibited increased lumbar stiffness during LD contraction, the MFT from the shoulder to the hip joint occurred similarly in both groups.