When using an elliptical, you never take your feet off the pedals.
Invented in the 1990s, elliptical trainers are designed to simulate a running gait but eliminate the impact on your joints. The movement on an elliptical actually resembles a combination of stair-climbing and cross-country skiing in which your legs travel along a smooth elliptical path. While both running and an elliptical trainer provide a cardio workout, an elliptical trainer with levers and an adjustable stride length strengthens your upper body in addition to your legs.
Many Muscles on an Elliptical
Both running and the elliptical workout use your glutes, quads, hamstrings, gastrocnemius and tibialis anterior. However, an elliptical workout recruits muscles that you don't use when you run, so runners often use ellipticals for cross-training, according to June Kahn and Lawrence Biscontini's book вЂњMorning Cardio Workouts.вЂќ By pumping on the elliptical's arm levers, you can strengthen your deltoids, lats, biceps and triceps. In a 2002 study published in вЂњMedicine & Science in Sports & Exercise,вЂќ researchers at the University of Idaho found that you can recruit more and different muscle fibers by adjusting your stride length on the elliptical. Adjusting your stride length on a run may increase the risk of injury. Because running is a high-impact workout, how your legs absorb and transfer ground force depends on an efficient stride length, according to RunnersConnect. If you overstride, the force may be distributed throughout your lower body in such a way that it damages your joints.
Running and Muscular Imbalances
The main muscles used for running are the hamstrings, hip flexors and the two large calf muscles -- the gastrocnemius and soleus. Your quads, anterior tibialis and hip abductors work to stabilize your body. Because of the repetitive motion of running, runners typically suffer from tight overdeveloped hamstrings and calves and weak stabilizing muscles, which increases the risk of injury, according to the вЂњRunner World Guide to Cross-TrainingвЂќ by Matt Fitzgerald. In contrast to running, you can adjust your stride length on an elliptical to maintain muscular balance. While a short stride resembles stair climbing and works your quads and calves, a longer stride puts more stress on your hamstrings and glutes. Because running is an impact activity, adjusting stride length in the middle of a workout in the way that you do on an elliptical may be jarring for your joints.
Zero vs. Much Impact
The primary advantage of using an elliptical trainer with adjustable stride is that you can achieve a rigorous cardio and weight-bearing workout with zero impact on your joints. When you run, you exert a force of up to eight times your body weight on your joints, according to вЂњDr. Scott's Knee Book: Symptoms, Diagnosis, and Treatment of Knee ProblemsвЂќ by W. Norman Scott and Robert Gotlin. Even if you slow down to a walk on the treadmill, your joints are still absorbing the impact of twice your body weight.
The Bigger Burn
In comparison to an elliptical trainer, running demands more mechanical work -- such as absorbing impact and resisting rotation -- and burns more calories. If a 180-pound man performs a moderate 45-minute workout on a treadmill, he can expect to burn 675 calories, according to вЂњA Man's Guide to Muscle and StrengthвЂќ by Stephen Cabral. If that same man performs a 45-minute workout on an elliptical trainer, he'll burn 441 calories. However, in the University of Idaho study, researchers found that you can burn more calories by increasing the length of your stride on an elliptical trainer with an adjustable stride and not feel as if you're expending more effort.