Decline leg curls help define the hamstring muscles.
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Decline leg curls, also called hamstring curls, are an isolation exercise. This means they only target one muscle group at a time, which are the hamstrings located on the backs of your upper thighs. Positioning the bench at a decline enables you to move your legs in a better range of motion, recruits the hamstrings more efficiently and works your muscles harder.
Decline Curl Basics
Place a dumbbell on the floor at the end of a decline bench. Lie face down on the bench so that your chest is higher than your feet. Pick up a dumbbell with your feet and secure it vertically between the arches of both your feet. Grab onto the top of the bench and bend your knees. Curl the dumbbell upward toward your buttocks until your knees form a 90-degree angle. Squeeze your thighs as you lift the weight up. Slowly lower the weight back to the starting position. Aim for a total of 12 repetitions. The work should come from your hamstrings.
Mix It Up
If you find the decline leg curl too difficult, do it without the dumbbell. If it is still too difficult, perform the exercise on a flat bench or from the floor. To target your hamstring muscles a little differently, do the decline leg curl from your back. Lie on the bench so that your head is lower than your feet. Bend your knees and lift your hips up until your knees form 90-degree angles. Reverse the motion and return to the starting position. You can also do this version with your calves on an exercise ball.
Form Fixes and Tricks
For best results, concentrate on curling your legs up through full range of motion. In other words, curl them as far as you can comfortably. Using full range of motion helps you to better target your hamstrings and improves flexibility. Have an exercise partner place the dumbbell between your feet if you find it difficult to lift it up from the floor yourself. Always work at your own pace and fitness level.
Start out with a light weight -- 5 to 10 pounds -- and gradually increase the dumbbell weight as your strength improves. Using too heavy of a dumbbell can cause you to swing or jerk your body, which can cause injury. Ensure that you have a very secure grip on the dumbbell with your feet before you attempt to curl up. For best results, keep your upper legs and upper body as still as possible as you perform decline leg curls. Warm up your muscles before your workout with five to 10 minutes of light cardio, like walking or riding a stationary bike.