Are Calf Raise Exercises Concentric or Eccentric?

Function

Calf raises, like most exercises, have both a concentric and eccentric phase. During the concentric phase of a calf raise, your calf muscles contract, pushing you upward. As you begin the return movement, your calf muscles lengthen while maintaining enough contracting force to counter the pull of gravity. That’s called the eccentric phase of the exercise.

Length of Phases

Using a slow, controlled movement for each phase is vital for ensuring that your calf raises are effective. As a general rule, the concentric phase of any exercise should be slow, and the eccentric movement should be twice as slow as that. For example, if the concentric phase takes three seconds, the eccentric phase should take six seconds. A certified fitness instructor should help you determine the optimal length of time for each phase of your calf raise and help you design a calf-exercise program designed for your fitness goals.

Muscles

Your calves have two muscles: the gastrocnemius and the soleus. You can see the gastrocnemius muscle when you flex your calf. The soleus muscle lies deep beneath the gastrocnemius. Doing different types of calf raises ensures that both the gastrocnemius and the soleus receive some attention.

Types

Standing calf raises challenge the gastrocnemius because your knees are locked straight. In contrast, bent-knee calf raises challenge the soleus, but they require a special machine that allows you to push your bent knees upward against a padded bar. A donkey calf raise is another variety that challenges the gastrocnemius muscles. It’s an advanced -- and silly-looking -- exercise that requires a partner to sit on your bent back while you lower and raise yourself with your calf muscles. Your partner’s weight is centered over your hips rather than your shoulders, making donkey calf raises the most effective exercise for developing large calves, according to the book “Natural Bodybuilding,” by John Hansen.

Resistance

If you hold a barbell or use a calf-raise resistance machine, you can increase the resistance of the exercise. But don’t attempt any weighted calf raise -- especially donkey calf raises -- without first working with a certified fitness instructor to ensure that your form is correct. An instructor also might recommend using heavy weights in combination with long eccentric phases to maximize muscle development.