Background The main treatment for diastasis recti abdominis (DRA) is physical therapy. Most existing research focuses on the types of intervention to take, the effects of exercise, and the evaluation methods of these effects. So far, there are no recognized exercise programs. Perhaps researchers have overlooked the changes in trunk mechanics caused by pregnancy, as well as the relationship between biomechanics and exercises for DRA. This study aims to explore the mechanisms of rehabilitation exercise for DRA from a biomechanical perspective.
Methods PubMed, EMBASE, CNKI, and Web of Science databases were consulted using the terms 'Diastasis rectus abdominis, Abdominis Muscle,' 'Biomechanics,' 'Linea alba,' 'Physical therapy,' 'transversus abdominis,' and 'trunk stabilization.' All English and Chinese-written published articles were included until Oct, 2023.
Results The transverse abdominis muscle (TrA) is located deep within the abdominal wall and is attached to the fascia (aponeurosis) at both the front and back ends. During the Abdominal Drawing-In Maneuver, the muscles contract centrally. They shorten and thicken, resulting in reduced abdominal volume, increased abdominal pressure, and improved trunk stability. It also causes the displacement of the aponeurosis on both sides, resulting in centripetal force. The transverse fiber constitutes the main structure of the dorsal rectus sheath and the posterior layer of the linea alba. According to measurements obtained through shear wave elastic ultrasonic imaging and other equipment, the transverse stress is high and the compliance is low. Its biomechanical characteristics facilitate the transverse transfer of force generated by the TrA to the linea alba, and the force on both sides ends in the linae alba, which increases the tension. In patients with DRA, the linea alba undergoes significant deformation, and its stiffness decreases.
Conclusions The deformation of the linea alba is the main feature of DRA. TrA is the only muscle in the abdominal region that can increase the tension of the linea alba and improve the stability of the trunk by increasing internal abdominal pressure. Therefore, exercising TrA is the best treatment for the rehabilitation of DRA from mechanisms.