The primary muscles involved in power walking are the muscles of the lower body. Hip flexors (iliopsoas, sartorius), hip adductors, and knee extensors (quadriceps in the front of your thigh) swing your leg forward. The tibialis anterior (shin) flexes your foot so you land on your heel. Glutes, hamstrings (back of the thigh) and the gastrocnemius and soleus in your calf extend your leg behind you and power the push-off with your back foot. Abdominal and back muscles work as stabilizers to keep you standing tall as you walk. Upper body muscles such as your deltoids (shoulders), pectoralis major (chest), and biceps brachii (front of upper arm) are activated when you swing your arms.