Straight Leg Raises
Physical Therapy Knee Exercise

Physical Therapists often use straight leg raises to help people strengthen their knees after certain knee injuries.

Before I talk more about this exercise, I want to say that if you have knee pain you should seek counsel from a licensed health care professional to find the appropriate exercises for your condition.

Okay, back to leg raises...

When there is any injury that causes swelling inside the knee joint, the muscles around the knee don't work as well. The quadriceps are very susceptible to weakness when the knee is swollen.

One of the first goals of rehab programs is to decrease swelling, because it is nearly impossible to improve strength significantly when a joint is swollen.

Once the swelling is gone, strength does not automatically return to the pre-injury level, so you often have to focus on strengthening muscles after an injury.

Straight leg raises are a great way to strengthen the quads and hip flexors, and the pictures are below.

Quad and Knee Strengthening Exercise

Starting Position: Simply lie on your back, and bend one knee so that your foot is flat on the floor.

Form: Begin by contracting and tensing up your quad muscle (the front of your thigh).

While keeping your thigh contracted and your knee straight, lift your leg off the floor until your thighs are parallel with each other.

Pause for a brief moment at the top and then slowly return to the starting position.

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Personal Trainer Tips: There are 2 major keys to performing this exercise correctly.

First, you must make sure that you contract your quad muscle before you lift your leg and you must keep your thigh tensed throughout the entire range of motion.

The second key is to make sure that your knee is completely straight through the entire range of motion. When you get fatigued or when the quad is not strong, there will be a tendency for the knee to bend slightly.

Focus on keeping your thigh tensed and move in a slow and controlled motion. Perform 10-15 repetitions on each leg for 1-3 sets.

Once you master this exercise, you can progress it by using ankle weights.


Strong quadriceps are so important for knee stability, and working the quads with leg raises can help to strengthen the knees.

In addition to leg raises, quad sets (tensing the thighs), and short arc quads (end range knee extension) are also used as knee rehabilitation exercises.

These exercises can be good for many people suffering from slightly achy knees, but remember that you should see a professional if you are experiencing knee pain.

Yours in Health,
Dr. Charles PT/ PT

Return to the Main Knee Strengthening Exercises Page from Straight Leg Raises.