You’ve heard of lower body exercise like squats or leg presses. But there's a pair of machines that will help you work specific muscles that other leg exercises can miss: the leg extension and hamstring curl machines.  

These machines provide isolation exercises for your legs. This type of exercise works only one muscle or group of muscles, which means you can build up that part of your body quickly. If you want your thigh muscles to really stand out in those shorts you just bought, the leg extension machine is for you!  


Leg Extensions 


Leg extensions using this exercise machine work your thighs. In fact, that’s basically the only thing that they work. That’s great if you want to build strength and mass quickly. To get started, slide into a sitting position on the machine from the open side. 

Adjust the back pad using the release handle directly behind it so that the position is comfortable for you. Proper placement of the back pad lets you stabilize yourself with your core as you work out your legs. Pick a position that brings the back of your knees even with the front of the seat.  

Next, choose the right weight from the stack with the pin. It can be tempting to start too high – your thigh muscles are powerful after all. But this is a machine that you should use for reps and full range of movement, not weight. It’s better to start light – around 80 pounds is good for beginners.   

Now, adjust the shin pad so that it is just above your ankles. Be careful when you’re adjusting the machine at this point. You want to make sure that your knees bend at no more than 90 degrees in the starting position. If your knees are bent too much, you risk putting strain on your knee joints. The same goes for locking your knees when your legs are fully extended. Avoid that.  

Now you’re ready to get going. To use the machine, lift your ankles from the starting position. Push with your thighs. A common mistake is going too fast and lifting with a kicking motion. Instead, move your legs slowly and deliberately. The more time you spend moving your legs, the more time you’re spending with your muscles engaged. Engaged muscles mean a better workout. 

Hamstring Curls 

Hamstring curls are a great way to balance the muscles that you work when you’re doing leg extensions. This exercise is also good for people with sedentary jobs who don’t get a lot of walking in. Even pro cyclists can benefit from using this machine, since biking works the quads so heavily and doesn’t do as much for the hamstrings. 

With hamstring curls, you’re essentially doing the opposite motion to leg extensions. You’re exerting force by bending and pulling with your legs instead of pushing with them. Choose the weight in the same way as you did with your leg extensions. Start low, and you might want to consider going even lower. Your hamstrings aren’t as powerful as your quads. 


After you’ve selected a weight, adjust the calf pad based on your height. Lower numbers for shorter people, higher numbers for taller. You want the pad to rest at the point where your calves meet the tendon. 

Next lie face down on the machine. Hook your legs under the resistance pads. Your legs should be fully extended, but remember not to lock your knees.  

Bend your legs at the knees to bring your heels toward your glutes. You want to get a full range of motion when you use this machine. Bend your knees as much as you can. Then slowly release to all the way back to the initial position. Repeat. 

This machine is a great way to get a feel for what it’s like to work your hamstrings. Other exercises involve the hamstrings, but people aren’t always aware that they are working those muscles. 

A Good Total Workout 

Remember that since these are isolation machines, they only work one group of muscles at a time. That means you have to pair them with compound exercises to get the most out of your routine. Compound exercises work a lot of different muscles or muscle groups at once. Try making these exercises a part of your workout: 

20 reps leg extensions 

Keep the weight low and your reps slow! The point is to feel the burn at the end of the set, not to work as hard as you can at first. 

10 dumbbell squats 

Squats with a full barbell can be intimidating! Luckily, there’s an easier way to get in a compound leg and core workout. Grab a couple dumbbells and do squats while you’re holding them.

20 reps hamstring curls 

Same deal as the leg extensions! Low and slow. You’re really isolating your hamstrings here, so don’t try to get too ambitious. Try and feel how your hamstrings work with the rest of your legs. 

10 dumbbell lunges 

Lunges are a great way to work your thighs. Take a hold of the same dumbbells you used for the squats. Take a big step forward with one leg, bend your knees, and lower yourself toward the ground. Next use the opposite leg and repeat.

Pick weights that fit your skill level, and repeat this circuit about three to five times. Rest for a minute or two in between sets. 

The leg extension and hamstring curl machines can be found next to each other on the fourth floor of the fitness center at our Upper East Side campus and near the dumbbell weight racks in the fitness center in Battery Park City.