What Muscles Are Worked Out When Using a Treadmill?

The treadmill is a versatile exercise machine that lets users walk, jog and run on flat or uphill surfaces. In addition to providing an effective cardiovascular workout, treadmills also help strengthen the muscles of the legs and butt. Depending on the incline, you can work the front or the rear of your legs more intensely; however, every treadmill workout strengthens both.

People who walk and jog on the treadmill with regularity gain endurance and strength in the quadriceps muscles. The quadriceps are named for the four large muscles on the front of the thighs; they are the rectus femoris, vastus lateralis, vastus medialis and vastus intermedius. These muscles help the body jump and squat in addition to walking and running. As a result, treadmill exercise applies to more than just working out; it also improves the ease with which you go about activities of daily living.

Like the quadriceps, "hamstrings" is also a collective name for a muscle group. The hamstrings, comprising the biceps femoris, the semitendinosus and the semimembranosus, lie between the buttocks and the back of the knee on the rear thigh. The muscles of the hamstrings are used for power walking and running in addition to squatting and jumping, and -- in general -- the more you exercise on the treadmill, the greater your hamstrings' endurance gains will become. However, according to the University of Wisconsin, roughly a quarter of collegiate athletes who sprint injure their hamstrings. As a result, warm up on the treadmill slowly, and increase running speeds gradually.

The calf muscles of the rear lower leg, comprising the gastrocnemius and the soleus, also work hard during treadmill exercise. According to a study from the Laboratory of Medical Physics in The Netherlands, most of the work performed by the calf muscles occurs as you push off from your toes while walking, running and jumping. You can increase the workload on your calves -- and your hamstrings -- by increasing the incline on the treadmill.

The glutes make up the muscles of the rear end and, like the leg muscles, help you walk, jump and run. "Fitness" magazine reports that people who set their treadmills to a steep incline increase the workload on their glutes significantly, which increases strength, improves endurance and burns fat and calories. Although the treadmill helps you gain leg strength, the machine is primarily known for its cardiovascular health benefits. As a result, if you exercise regularly on a treadmill you can expect health gains on the inside of your body as well as the outside.