how to build strong, defined thighs

Personal Trainer Mill Valley CA

Want firmer thighs and a lifted booty? The Leg Curl is an exercise you don’t want to skip. If you’ve been training with us, you know our 20-minute workouts target the entire body including one of the biggest muscles- the hamstrings. If having a strong, firm thighs and a lifted backside is something you’re striving for… keep reading.

The Muscles Used

The hamstrings are large muscles that make up the back of your thighs and are the primary movers worked in the Leg Curl. In addition to the hamstrings, this power exercise also targets the calves. These main muscles targeted by the Leg Curl are largely responsible for the appearance of your thighs and lower legs and train the muscles that are responsible for running speed. To learn how to target the hamstrings along with your buttocks, read our article on the Leg Press.

How it Works

The hamstrings contract to provide knee flexion, which is the technical name for the movement performed during the Leg Curl.

Each hamstring is a group of four muscles that start on your pelvis (around the bottom of your buttocks), cover the backs of your thighs and attach to the lower leg, just below your knee.

The hamstrings have two major functions: to flex your knee, and pull your thigh backward (hip extension). Performing the exercise looks like this:

  1. The Leg Curl (seated in particular) begins with you seated and legs stretched out in front of you in between two pads.
  2. Your feet are flexed with toes pointing straight up to engage the muscles in the back of the leg and upper body is upright and relaxed.
  3. As you begin to move the weight, you’re trying to pull your heels close to your buttocks, keeping your toes pointed up throughout the entire range of motion.
  4. Once you have reached your full range of motion- you’ve brought your heels back as far as they can go, you want to squeeze your hamstrings in the contracted position for approximately 3 seconds and slowly resist the weight back to the beginning position.

Like all exercises, you avoid resting in between repetitions and slowly push yourself to reach Muscle Success.

Why Do It?

Building the muscle fibers in the hamstrings can provide a firm appearance to the backs of the thighs, and can also create an ovular shape. This can be seen if you look at the back of someone’s thighs from a side view.

The Leg Curl is a very efficient exercise, in that the calves (gastrocnemius) assist the hamstrings in flexing the knees. Many women wear high-heeled shoes because the elevated heels force the calves to contract, making the leg look more defined and shapely. Using the Leg Curl can create that same muscularity in the lower legs without needing the shoes.

Hamstrings in Day-to-Day Function

The hamstrings are a major muscle group responsible for pulling the leg down after the knee rises.

The foot drives into the ground and propels you forward. The acceleration comes from the leg and foot being pulled down as fast as possible. The faster the foot can move downward, the greater the acceleration.

For any athlete who sprints, such as those playing baseball, softball, and football, the Leg Curl trains a muscle that is critical to maximizing acceleration. You don’t need to be an athlete or play competitive sports to benefit from this exercise. Performing the Leg Curl regularly will help to improve leg strength and overall mobility for anyone.

Maximizing Your Leg Curl in 2 Minutes or Less

In order to get the most out of your 1-2 minutes on the Leg Curl, your coach will help you achieve these three things:

  1. Full Range of Motion: A full range of motion helps to give a thorough workout to the targeted muscles. Think “heels to butt” and give those hammies a big squeeze as you strive for each repetition.
  2. Flex Your Feet: A fuller range of motion can be accomplished when the ankles are dorsi flexed, meaning the tops of your feet are pulled towards your shins. If your toes are pointed down as you flex your knees, your calves will be multitasking with two responsibilities, and they will do poorly in each. Keep your toes up to make sure your calves can do their best in flexing your knees.
  3. Muscle Success: You knew it was coming! Achieving muscle success by fully fatiguing the hamstrings will help you build the strength you’re looking for.


Whether you desire firm, rounded thighs or to run faster during your favorite sport, the Leg Curl is a quick & efficient way to achieving strong and sexy stems. Strengthen your legs and define your entire body with a 20-minute workout.