Effect of Forefoot–Rearfoot and Pelvic–Scapular Weight Shifts on Lower-Limb and Lumbar Muscle Activity during Static Wall-Squat Exercises

Abstract

(1) Background: The static body-weight wall-squat (SBWS) exercise is often included in the early rehabilitation stages of the lower limb. To establish its effectiveness and optimise its application, it is important to precisely quantify the muscle contribution to different versions of this exercise. (2) Methods: We analysed the electromyographic activity of lower limb and lumbar muscles during the SBWS with knees flexed at 45° by manipulating three different variables: horizontal distance of the ankles from the wall; scapular or pelvic location of the centre of pressure Cwall of the force exerted by the wall on the back; rearfoot or forefoot location of the centre of pressure CGR of the ground reaction force. (3) Results: The forefoot-to-rearfoot CGR shift significantly increased the vastus medialis, vastus lateralis, and tibialis anterior activity up to 23%, 26%, and 44% of the maximum voluntary isometric contraction (MVIC). The lumbar muscle activity was maximised (23% MVIC) shifting CGR at the forefoot, Cwall at the scapular zone, and placing the feet far from the wall. (4) Conclusions: These SBWS methods might be effective for quadriceps, tibialis anterior, and lumbar muscles strengthening in the early phase of rehabilitation intervention as soon as the patient can tolerate partial weight-bearing. The exercise appears suitable for patients with low back pain and limited lumbar muscle endurance, or quadriceps weakness and inhibition secondary to a knee injury.