Straight Leg Raising Exercise Progression After Knee Surgery

If you have had knee surgery like an anterior cruciate ligament (ACL) repair or a patellar lateral release, then you may require a physical therapist to help you with your rehabilitation. Your physical therapist will work closely with you to help improve your knee range of motion and strength and decrease your knee pain and swelling.

The main goal after knee surgery is to help you return to your normal activity and function. After surgery, the muscles in your leg will likely be weak, and your physical therapist will prescribe exercises to help you improve the strength in your hips, quadricepshamstrings, and calf muscles.

Straight leg raises are a great way to help improve the strength of your quadriceps and muscles in your hips. A typical ACL rehabilitation protocol will likely include performing straight leg raises on your back, your side, and your stomach to help target those muscles that support your knee and help with normal walking.

After your knee surgery, you must protect your knee from external forces that may place high levels of stress through your knee joint. Shear forces, like ones that abnormally pull your shin forward or sideways, can disrupt your knee ligaments while they are healing after surgery. This disruption may cause re-injury of your ligaments and delay your recovery. In a worst-case scenario, re-injury to your knee ligaments may require you to have your knee surgery again to repair the damage.

So how do you protect against unwanted forces going through your knee joint while performing straight leg raising exercises? Is there a way to increase the amount of weight you are using during straight leg raises while still guarding against shear forces that may injure your healing knee ligaments?

In this step-by-step article, you will learn about the proper way to increase resistance to your straight leg raising exercises while still protecting your healing ligaments against unwanted stress that may re-injure your knee.

Before starting this exercise progression, please check in with your healthcare provider or physical therapist to make sure that exercising is safe for your specific condition.


Straight Leg Raising with a Brace On

Before starting to progress your straight leg raising, you should be able to perform the exercise while wearing a brace on your leg. After surgery, your healthcare provider may have you wear a brace to protect your healing knee.

The straight leg raise immediately after surgery can be made safer with the use of your knee brace. Many times after ACL or lateral release surgery, your surgeon will require you to wear a brace on your knee to protect it against excessive bending or straightening. Your brace also helps to protect your knee from sideways forces through your knee joint.

To perform this initial straight leg raise, keep your brace on, lie on the floor, bend your unaffected knee, and keep your surgical knee straight. Try to contract your quadriceps by straightening your knee all the way, and slowly lift your leg up off the floor.

You should lift your leg up about 12 inches, hold it in this position for one or two seconds, and then slowly lower your leg down. Repeat this exercise 10 to 15 times.

To strengthen your hip muscles, you can perform this straight leg raise on your side or on your stomach. Just be sure to keep your brace on to protect your knee, keep your quadriceps muscle contracted, and slowly lift and lower your leg 10 to 15 repetitions.


Straight Leg Raises With No Brace

Ben Goldstein

Once you can perform a few sets of 10 to 15 repetitions of straight leg raises with your brace on, you can challenge your knee muscles more by performing the straight leg raise with no brace on. You must check with your healthcare provider or physical therapist before doing the exercise without your brace, as a significant force through your knee joint may disrupt the ligaments as they heal.

The straight leg raises without your brace are done just like the ones with your brace. Lie on your back, bend one knee, tighten your quadriceps, and lift your leg up 12 inches. Repeat 10 to 15 times.

To perform the straight leg raises on your side, thus strengthening your gluteus medius muscles of your hip, lie on your side with your surgical leg on top. Bend your bottom knee for stability. Tighten your quadriceps muscles, and lift your leg about 12 inches up. Be sure to keep your knee straight and in line with your hips and body. Perform 10 to 15 repetitions.

A common mistake during the straight leg raises on your side is to allow your leg to glide forward while raising it up. Be sure to keep it in line with your body while lifting and lowering your leg.

When performing straight leg raises on your stomach, simply lie face down, tighten your quadriceps, and lift your leg up 5 to 10 inches without arching your back too much. Be sure not to roll or twist your back to one side. Lift and lower your leg slowly for 10 to 15 repetitions.

When you are able to perform two to three sets of straight leg raises with no weight and no knee brace, it is time to challenge your leg muscles more by adding weight.


Add Resistance to Your SLR While Protecting Your Knee

Ben Goldstein

Adding cuff weights to your straight leg raises can help to challenge your leg muscles more and can help progress your strengthening program after your knee surgery. Adding resistance must be done safely to prevent shear forces from over-stressing your knee ligaments while they are healing.

To safely add weight to your straight leg raises, first use a one-pound cuff weight and wrap it around your thigh just above your kneecap. This helps to add some resistance without placing too much stress on your knee joint.

The amount of resistance will feel light and may not be too challenging since the torque (remember physics) on your leg will be minimized by the placement of the weight, and thus a short lever arm.

With the weight above your kneecap, perform your straight leg raising exercises just as before. Perform 10 to 15 repetitions, and build up to two to three sets.

You can increase the amount of weight you use in two ways: use a heavier cuff weight above your knee to perform the exercise, or start sliding your cuff weight to an area below your kneecap.

When you use a cuff weight below your kneecap, you will be placing some stress through your shin bone, and this could put stress on your healing ACL or other ligaments, so be sure to speak with your physical therapist before sliding the cuff weight down your leg.

When you can perform two to three sets of 10 to 15 repetitions of the exercises, you are ready to move onto the final progression of straight leg raises.


Straight Leg Raise With Full Resistance

Ben Goldstein

To perform SLR exercises with full resistance, place your one pound cuff weight around your ankle. This can place significant stress on your knee joint, so be sure to check with your healthcare provider or physical therapist before starting this.

Perform your SLR exercises for 10 to 15 repetitions on your back, your side, and your stomach. To increase the resistance, simply use a heavier cuff weight around your ankle when doing the exercises.

A Word From Verywell

After knee surgery, straight leg raises can be a great way for you to work on strengthening your hip and leg muscles. The exercises could possibly place a significant amount of stress on your healing knee ligaments and tendons. By starting out using your knee brace, and then progressing the amount of resistance by altering​ the placement of a cuff weight, you can be sure that you are challenging your leg muscles while still keeping your knee ligaments safe from harm.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Academy of Orthopaedic Surgeons. Knee Arthroscopy Exercise Guide.

  2. Webster KE, Feller JA. Exploring the high reinjury rate in younger patients undergoing anterior cruciate ligament reconstruction. Am J Sports Med. 2016;44(11):2827-2832. doi: 10.1177/0363546516651845

  3. Ishii Y, Noguchi H, Sato J, et al. Clinical relevance of active straight leg raising, standing up, and walking after total knee arthroplasty in a cross-sectional study. Eur J Orthop Surg Traumatol. 2018;28(5):947-953. doi: 10.1007/s00590-017-2100-z.

  4. Rocchi, J.E., Labanca, L., Luongo, V. et al. Innovative rehabilitative bracing with applied resistance improves walking pattern recovery in the early stages of rehabilitation after ACL reconstruction: a preliminary investigation. BMC Musculoskelet Disord 21, 644 (2020).

  5. Bieler T, Aue Sobol N, Andersen LL, et al. The effects of high-intensity versus low-intensity resistance training on leg extensor power and recovery of knee function after acl-reconstruction. BioMed Research International. 2014;2014:e278512.

By Brett Sears, PT
Brett Sears, PT, MDT, is a physical therapist with over 20 years of experience in orthopedic and hospital-based therapy.