A stairmill, or stepmill, is similar to a treadmill, but it has moving steps instead of a flat surface. You вЂњclimbвЂќ the steps as they move, so it's like walking up a continuous flight of stairs. A stepmill primarily works your gluteus maximus, iliopsoas, hamstrings, quadriceps, calf muscles and spine.
Gluteus Maximus and Iliopsoas
The gluteus maximus is the fleshy muscle that forms your buttocks. It attaches the sacrum, or base of the spine, and the hip bone, and it runs down to attach to the top and back part of the thigh bone. It straightens your leg when you step on a stair. The iliacus attaches to the inner portions of the pelvic bone and sacrum, and the psoas major attaches to the spinal bones of the lower back. They merge to form the iliopsoas that attaches to the front and top part of the femur. Ilipsoas bends your hip when you lift your leg.
Hamstrings and Quadriceps
Semitendinosis, semimembranosis and the long and short heads of the biceps femoris make up the hamstring muscles. They run from the back and bottom of your hip bone down to your knee. They straighten your hip when you step on a stair and bend your knee as you lift your leg. Rectus femoris, vastus lateralis, vastus medialis and vastus intermedius are the quadriceps muscles. They run from the front of your hip down to the tendon that attaches to your kneecap. Quadriceps muscles straighten your knee when you step on a stair.
The gastrocnemius runs from the upper portions of your lower leg bones down to the achilles tendon that attaches to the ankle bone. It forms the fleshy part of your calf. The soleus muscle runs underneath the gastrocnemius and also runs to the back of the ankle bone. The calf muscles plantarflex your ankle when you push the ball of your foot down onto the stair. You plantarflex your ankle when you point your toes downward and raise your heel up.
The spinal muscles help keep your trunk and shoulders level as your hips move. Spinal muscles include the deep intrinsic muscles that run between the vertebrae, or spine bones, and the erector spinae muscles that lie over them.
According to Jessica Mathews, M.S., E-RYT, of the American Council on Exercise, stairmills and step climbers can provide cardiovascular exercise and strength training for your lower body. She says that posture is important and that you should maintain an upright posture and not lean heavily on the side bars. Poor posture will decrease the effectiveness of the workout. Matthews also suggests that you gradually increasing the length of your stairmill workouts to build endurance.