Quadriceps and knee pain: effective exercises

The quadriceps, located at the front of the thigh, help extend the knee and control the movements of the patella. The patella is the small bone at the front of the knee. Strengthening the quadriceps can reduce pain around or behind this bone, known as patellofemoral pain. A program that combines strengthening the quadriceps and the hip muscles is better supported by research than quadriceps strengthening alone for reducing pain.^{1, 2, 3}

Why is the quadriceps essential for knee health?

The quadriceps help extend the knee and control how it bends during walking, climbing stairs, and squatting. Its contraction also transmits forces between the kneecap and the thigh bone, called the femur. A strong muscle therefore does not eliminate the forces acting on the joint. Read the review on the forces between the patella and the femur. The model proposed by Dye in 2005 instead describes pain associated with stress exceeding what the tissues can withstand. This expert opinion offers an explanation for the pain without identifying a single cause applicable to everyone.⁴

Increased strain on the knee can contribute to pain if it exceeds what the person can tolerate. This explanation does not cover all possible causes.^{1, 4}

People with patellofemoral pain often have weakness in the quadriceps or hip muscles. This can guide the choice of exercises, though it does not prove that weakness alone explains their pain. The review on the quadriceps notes reduced strength in several types of contraction, without establishing a single percentage that applies to everyone.^{1, 5}

The vicious cycle of weakness

Pain may cause you to avoid certain activities. A prolonged decrease in activity can then lead to a loss of muscle strength. In one study, 24 healthy young men had one leg immobilized in a cast. Quadriceps strength decreased by an average of 9% in the group immobilized for 5 days and by 23% in the group immobilized for 14 days.⁶ These results pertain to complete immobilization, not simply a reduction in your activities. Gradually regaining strength and range of motion is part of the treatment.

After a knee injury or surgery, it may become difficult to fully contract the quadriceps. Signals from the joint then alter the muscle’s control. This phenomenon is called arthrogenic muscle inhibition.⁷ This difficulty can slow down your return to normal activities. An evaluation helps tailor the exercises to your ability to contract the muscle.

Should we specifically target the vastus medialis obliquus?

Strength training should target the entire quadriceps and the hip muscles, without attempting to isolate the vastus medialis obliquus. This portion of the quadriceps is located on the inner side of the thigh, near the kneecap. A review does not show that changing the leg’s position consistently activates this portion more than the vastus lateralis, located on the outer side of the thigh. However, the studies have limitations. Read the review on vastus medialis activation. Muscle feedback uses sensors to show you muscle activity during exercise. Some short-term results are promising: a 2024 review reports potential benefits regarding pain, functional activities, strength, and muscle activation. Programs and comparisons vary, and many combine different treatments. A trial involving 26 participants observed increased activity in the vastus medialis compared to the vastus lateralis after eight weeks, without demonstrating isolated strengthening of the vastus medialis obliquus.^{8, 9}

The vastus medialis obliquus helps control the patella, particularly by counteracting outward pulling. During certain activities, such as climbing stairs, a slight delay in the activation of the vastus medialis compared to the vastus lateralis is associated with patellofemoral pain.⁵ This association does not prove that the delay displaces the patella and then causes pain in every individual.

The 2019 guidelines do not recommend knee supports—such as braces, sleeves, or straps—for treating patellofemoral pain.^{1, 10}

The 2019 guidelines do not recommend adding a device that monitors the electrical activity of the vastus medialis to quadriceps exercises. This recommendation predates the 2024 review described above. The primary goal remains strengthening and returning to activities.¹

What exercises effectively strengthen the quadriceps?

Static contractions, squats, knee extensions, and stepping down from a step all work the quadriceps. The choice depends on what your knee can handle. A static contraction can serve as a starting point; it is not a required step before any other exercise. The examples below can be combined and adapted based on your symptoms and activities.

Exercise is the primary treatment for patellofemoral pain: it is the central component of management and should be prioritized over other approaches.^{1, 10}

Strengthening the hip muscles complements quadriceps training. It may even be advisable to focus on hip training at the beginning of the treatment plan.^{1, 2}

Contractions without movement

Static contractions, also known as isometric contractions, work the quadriceps while keeping the knee in a fixed position. They can be part of a strength-training program. Your response will guide which ones to choose; immediate relief is not guaranteed. The guidelines below are examples to be adapted in consultation with your physical therapist.

Thigh contraction, leg extended: While sitting or lying down with your back supported, gently push the back of your knee toward the bed to contract your thigh. Hold for 5 to 10 seconds, then release. A good starting point is 5 to 10 repetitions, doing fewer if needed. See the exercises recommended by Royal Berkshire.

Sitting against the wall: Lean your back against the wall with your feet extended forward. Lower yourself to a comfortable height and hold the position, then return to the starting position. Start from a lower position if your knee is tender. A researched exercise protocol recommends 30 seconds, then 45 to 60 seconds at a more advanced stage, depending on the individual’s ability. Read the researched strengthening protocol.

Exercises Involving Movement

Light squats: Stand up straight, bend your knees slightly, then slowly stand back up. Keep your knees pointing in the same direction as your feet. Increase the depth based on your comfort level. A workout routine might include three sets of 10 to 15 repetitions, but you can start with fewer. Sets are groups of repetitions separated by a rest period.

Knee extension with a resistance band: Securely attach a resistance band in front of you and loop it behind your knee. From a slightly bent position, straighten your knee against the resistance, then slowly return to the starting position. Your physical therapist can adjust the resistance and range of motion.

Exercises for Daily Activities

Stepping Down from a Step: Stand on a low, stable step; bend the supporting knee to slowly lower the other heel toward the floor. Keep the supporting knee pointing toward your toes. Hold onto the handrail if needed. Start with, for example, 5 to 10 repetitions. Then increase the height or slow down the descent depending on your comfort level. This exercise helps you develop control over your movements on stairs.

Thigh press: On the machine, push the platform with your feet to straighten your knees, then return slowly. Start with a light weight and a comfortable range of motion. A deeply bent knee increases the forces between the kneecap and the thigh. The physical therapist may reduce the range of motion or the weight if the exercise causes discomfort in the knee. Gradually increase the resistance as the movement becomes easier.

How to Adjust Exercises Based on Pain

Mild, tolerable pain during exercise may be acceptable if it subsides quickly after the session. Your knee shouldn’t be more painful the next morning. Reduce the number of repetitions, the resistance, or the range of motion if the pain increases significantly or lasts longer. Stop the exercise and seek advice if it causes new pain or persistent worsening of pain. Read the tips for adapting exercises to manage pain.

Frequency: Three strength-training sessions per week, with one rest day between sessions, is a good place to start. The frequency and number of exercises vary depending on their difficulty and how you respond to them. Light contractions can be spread out over short periods; you don’t have to do all the exercises every day. Read the guidelines for planning your strength training.

Progress takes several weeks, sometimes several months. Royal Berkshire advises allowing three to six months, with further improvement possible beyond that. This timeframe does not predict your individual outcome. If your pain still does not improve, consult a physical therapist for a personalized evaluation.

When should you seek medical advice for a knee problem?

Severe pain, a locked knee, or an inability to bear weight require urgent medical attention. These symptoms should not be attributed simply to weak quadriceps. Also seek urgent medical attention in any of the following situations:

• You can't move your knee.
• The knee is very swollen or has changed shape.
• The knee gives way or makes a painful popping sound.
• A high fever, chills, or a sensation of feeling hot or cold may accompany a red or warm knee.

A painless clicking sound is usually normal. If the pain does not improve after a few weeks, see a doctor even if there are no urgent symptoms. Read about the symptoms that warrant a doctor’s visit.

To learn more about therapeutic approaches for anterior knee pain, consult our complete guide on anterior knee pain.

References

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1. Willy RW, Hoglund LT, Barton CJ, Bolgla LA, Scalzitti DA, Logerstedt DS, et al. Patellofemoral Pain. J Orthop Sports Phys Ther. 2019;49(9):CPG1-CPG95. (Back to sections: 1, 2, 3, 4, 5, 6, 7)
2. Lack S, Barton C, Sohan O, Crossley K, Morrissey D. Proximal muscle rehabilitation is effective for patellofemoral pain: a systematic review with meta-analysis. Br J Sports Med. 2015;49(21):1365-76. (Back to sections: 1, 2)
3. Rogan S, Haehni M, Luijckx E, Dealer J, Reuteler S, Taeymans J. Effects of Hip Abductor Muscle Exercises on Pain and Function in Patients With Patellofemoral Pain: A Systematic Review and Meta-Analysis. J Strength Cond Res. 2019;33(11):3174-3187. (Back to section: 1)
4. Dye SF. The pathophysiology of patellofemoral pain: a tissue homeostasis perspective. Clin Orthop Relat Res. 2005(436):100-10. (Back to sections: 1, 2)
5. Alsaleh SA, Murphy NA, Miller SC, Morrissey D, Lack SD. Local neuromuscular characteristics associated with patellofemoral pain: A systematic review and meta-analysis. Clin Biomech (Bristol). 2021;90:105509. (Back to sections: 1, 2)
6. Wall BT, Dirks ML, Snijders T, Senden JM, Dolmans J, van Loon LJ. Substantial skeletal muscle loss occurs during just 5 days of disuse. Acta Physiol (Oxf). 2014;210(3):600-11. (Back to section: 1)
7. Rice DA, McNair PJ. Quadriceps arthrogenic muscle inhibition: neural mechanisms and treatment perspectives. Semin Arthritis Rheum. 2010;40(3):250-66. (Back to section: 1)
8. Ferlito R, De Salvo S, Managò G, Ilardo M, Sapienza M, Caldaci A, et al. The Role of Biofeedback in Conservative Treatment of Patellofemoral Pain: A Systematic Review. J Funct Morphol Kinesiol. 2024;9(1). (Back to section: 1)
9. Ng GY, Zhang AQ, Li CK. Biofeedback exercise improved the EMG activity ratio of the medial and lateral vastus muscles in subjects with patellofemoral pain syndrome. J Electromyogr Kinesiol. 2008;18(1):128-33. (Back to section: 1)
10. Wallis JA, Roddy L, Bottrell J, Parslow S, Taylor NF. A Systematic Review of Clinical Practice Guidelines for Physical Therapist Management of Patellofemoral Pain. Phys Ther. 2021;101(3). (Back to sections: 1, 2)