Speed Training With Leg Curls & Extensions

The key to increasing your running and sprinting speed is strengthening your leg muscles and making sure your front leg muscles and back leg muscles are not imbalanced in strength. Leg curls will work the backs of your thighs, which are your hamstrings, and leg extensions will work the fronts of your thighs, which are your quadriceps. Doing these weight-training exercises for your legs will help you run and sprint faster. Be sure to consult with your doctor before starting any new weight-training regimen.

Muscles for Speed

When working on increasing your speed, you want to avoid focusing more on the quads than the hamstrings and causing an imbalance that slows you down when you run. Building both your quads and hamstrings will help you gain speed over time. Make sure you work out both muscle groups whenever you work one of them at the gym.

Seated Leg Curl

To do the seated leg curl, use the hamstring curl machine at the gym. Sit down on the machine with the backs of your lower legs on the padded lever. Place the lap pad on top of your thighs. Adjust for your height if needed. Holding the machine's side handles, use your hamstring muscles to push the padded lever downward so that your feet curl under your thighs. Tighten your abs to keep your body still from the hips up. Hold the leg curl for about one second, then slowly release.

Standing Leg Curl

The standing leg curl works both your hamstrings and your abs. You'll need a resistance band and something to anchor it to. Tie one end of the resistance band to your right ankle and the other end to the anchor directly. Your resistance band should be parallel to the floor; stand at a distance so that it doesn't sag or pull tight against your ankle. Standing tall with your feet hip-width apart, tighten your abs to help you keep your torso still. Keeping your thighs, torso and upper body motionless, slowly bend your right knee to lift your foot to your buttocks. Keep your arms by your sides. If you're having trouble balancing, hold onto a stable surface or a chair. Slowly lower your right leg. Remember to do the left leg, too.

Leg Extensions

To do leg extensions, you'll need to sit in the leg extension machine at the gym. Instead of pushing your feet down and back like in the leg curl, to do the leg extension you push upward against the roller pad to work the fronts of your thighs. The fronts of your ankles should be behind the lower roller pads so you can push the roller pads upward, in effect extending and straightening your legs as the stack of weight rises. Slowly lower your feet.

Safety and Other Considerations

When using weight machines, if you're unsure what amount of weight to use as resistance, start with the lowest amount of weight and increase the weight until your targeted muscles feel worked but the rest of your body isn't strained by the weight. The amount of weight you use should allow you to do between 10 and 20 repetitions of each exercise without straining your body. Rest for 30 seconds between sets, and do three sets of each exercise. Allow your muscles to recover for at least two days after each workout so you don't overexert them. Stretch and massage your muscles if they get sore to promote faster healing.