When walking on a treadmill, the principal muscles that are engaged are your quadriceps, hamstrings, calves, and glutes. If you bump the speed up to a run, jog, or sprint, your abdominal muscles may also get a good workout. Plus, the higher the incline on your treadmill, the harder your calves and glutes will be working.
But on a rowing machine, you’re working several of the same muscle groups as you would on a treadmill, along with your upper body. During a rowing session, your deltoids, pectoralis muscles, upper back, latissimus dorsi, trapezius, biceps, and forearms are all engaged, helping you move the handles forwards and backwards with the applied tension. As for your lower body, your glutes, quadriceps, hamstrings, and calves are all working together while your abdominal muscles and mid-back keep your core strong and stable.