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Effective Quadriceps Training in Patellofemoral Pain

Original Editor - Stacy Schiurring based on the course by Claire Robertson

Top Contributors - Stacy Schiurring, Jess Bell and Kim Jackson

Page Summary

  • Pain and swelling inhibit the quadriceps, particularly the vastus medialis, which may alter patellar kinematics and contribute to patellofemoral joint dysfunction.
  • Quadriceps strengthening for patellofemoral pain should target the whole quadriceps rather than isolating the vastus medialis obliquus (VMO), working to fatigue on alternate days.
  • Closed chain exercise between 0° and 45° and open chain exercise between 90° and 45° keep patellofemoral joint stress relatively low, particularly in early rehabilitation.
  • Exercise pain should stay at or below 3/10, and blood flow restriction training may help patients who cannot work to fatigue by using low loads.

Introduction

Patellofemoral pain likely results from a combination of factors rather than a single cause.[1] These include biomechanical factors, such as altered patellar tracking, gluteal and quadriceps weakness and reduced flexibility of muscles such as the quadriceps, hamstrings and calf, as well as psychological factors such as kinesiophobia.[1][2][3][4][5] The contribution of each factor varies between patients. This page focuses specifically on the role of quadriceps strengthening in patellofemoral pain.

Patellofemoral Joint Biomechanics

Please review this article for an overview of the patellofemoral joint.

Joint Kinematics

The patella has several mechanical functions.[6] It connects the muscles of knee extension to the tibia and contributes to knee extension by transferring the force of the quadriceps to the tibia via the patellar tendon, like a mechanical pulley.[7][6] It also alters the direction of the quadriceps’ force throughout knee range of motion (ROM).[6]

At full knee extension, the patella sits above the trochlear groove of the femur, slightly laterally, with some of its articular surface in contact at the distal lateral facets. In this position, the patella provides approximately 30% of the total knee extension torque.[6] As the knee flexes, the patellar tendon pulls the patella into the trochlear groove, causing a slight medial translation.[7]

At around 30° of knee flexion, the medial facets engage in the trochlear groove, and from this point the patella translates and tilts increasingly laterally.[7] After 45° of knee flexion, the patella slowly moves into medial rotation.[7] Beyond 90° of flexion, contact occurs on the proximal half of the medial and lateral facets,[7] and the patella provides approximately 13% of total knee extension torque between 90° and 120°.[6] This lateral-medial-lateral path is described as a “C-curve pattern”, with approximately 3 mm of displacement in each direction.[6] During knee extension from 45° to 0°, the patella also tilts medially.[6]

In open kinetic chain movements, the patella follows the path of the tibia because the patellar tendon inserts at the tibial tubercle. It glides inferiorly during knee flexion and superiorly during knee extension, and with a quadriceps set, it should move approximately 10 mm superiorly. As the knee flexes, the patellar contact area increases and distributes joint forces over a larger surface area. This reduces the likelihood of injury from repetitive high compressive forces.[6]

In closed kinetic chain movements, the patella remains relatively in one place within the quadriceps tendon, and the femur moves on the patella.[6]

Quadriceps and Patellar Control

If you would like to read more about the quadriceps muscle, see the linked articles: (1) Rectus femoris, (2) Vastus lateralis (VL), (3) Vastus medialis (VM), and (4) Vastus intermedius.

Vastus Medialis Muscle Architecture

The vastus medialis (VM) muscle divides into two parts: proximal vastus medialis longus (VML) and distal vastus medialis obliquus (VMO).

The vastus medialis (VM) has two parts, the proximal vastus medialis longus (VML) and the distal vastus medialis obliquus (VMO), which differ in fibre orientation.[8][9] VMO anatomy varies considerably between people, with fibre angles ranging from around 40° to 70° to the femoral axis. The extent of the VMO attachment along the medial border of the patella also varies. In some people, it covers around 95% of the border, while in others it covers only about a third.[10]

Vastus Medialis Inhibition

Pain and swelling can both inhibit the vastus medialis, including the VMO, and this inhibition may alter patellar kinematics and contribute to joint dysfunction.[10]

Pain: Hodges et al.[11] demonstrated that pain can alter knee muscle activity even when it is of non-muscle origin. They injected hypertonic saline into the infrapatellar fat pad of pain-free volunteers to induce pain and found that this altered the activity of the quadriceps, including the VMO.[11] These effects are not limited to acute injury. Persistent knee pain can lead to delayed or reduced VMO activation and poorer muscle performance, and over time, atrophy can change the muscle’s architecture.[10]

Swelling: inhibits the quadriceps, and the vastus medialis is affected at lower volumes than the vastus lateralis and rectus femoris. Spencer et al.[12] found that 20 to 30 mL of fluid in the knee joint was enough to inhibit the vastus medialis, whereas 50 to 60 mL was needed to inhibit the rectus femoris and vastus lateralis. Even a small effusion can therefore be clinically relevant.

VMO Architecture and Exercise

A number of ultrasound studies have explored how VMO architecture can be changed with exercise. Key findings:

  • Athletic people tend to have a larger VMO fibre angle than sedentary people.[13]
  • A six-week quadriceps strengthening programme increased VMO fibre angle and insertion length in healthy participants.[14]
  • Open and closed chain exercise can both produce significant changes in VMO architecture; a study by Elniel et al. found no significant differences between exercise type (open vs closed).[15]
  • Adding NMES enhances the effect of targeted exercises on VMO fibre angle.[16]
  • Ongoing exercise (i.e. two sessions per week) is necessary to maintain gains achieved in an initial exercise regime; gains are "partly reversed" when exercise ceases.[17]

Exercise-related changes in VMO architecture are thought to reflect muscle hypertrophy. Exercise-induced hypertrophy mainly increases the diameter of muscle fibres rather than their number. As the muscle fibre diameter increases, their orientation within the muscle changes as the fibres push against the surrounding fibres. This changes the angle of pennation.[10][18]

The following video provides a simple overview of how muscular damage and repair result in muscular hypertrophy and growth.

[19]

Quadriceps Exercise Theory

Exercises should target the quadriceps as a whole rather than attempting to isolate the VMO, as working the quadriceps also works the VMO. Ideally, patients should not exercise if they have swelling or significant pain. During exercise, aiming for no more than 3 out of 10 is a reasonable guide.[10]

If pain limits exercise, it can help to schedule sessions at a less painful time of day or to time them with pain medication. Icing before exercise may also be considered, particularly for post-surgical patients, as it can improve quadriceps muscle fibre recruitment.[20] A practical approach to building strength is to work the quadriceps to fatigue on alternate days, allowing recovery between sessions.[10] If a patient cannot exercise effectively to fatigue, blood flow restriction training may be an option,[21][22] as it allows the muscle to be fatigued using low loads,[10] and may help reduce pain during functional tasks and modestly improve quadriceps strength in the short term.[23] Quadriceps exercises should work synergistically with the gluteal muscles to encourage quality limb control, and should include movements and activities that are meaningful to the patient and support their long-term goals.[10]

Closed-chain Exercises

Steinkamp et al.[24] compared patellofemoral joint stress during leg press and leg extension exercises in 20 healthy adults at 0°, 30°, 60° and 90° of knee flexion. Stress was significantly greater during leg extension at 0° and 30°, and significantly greater during the leg press at 60° and 90°, with the two crossing over at approximately 50°.[24] This supports using closed chain exercises in the range of 0° to 45° and open chain exercises in the range of 90° to 45°, particularly in the early stages of rehabilitation.[10]

Progression of closed-chain exercises such as squats, lunges, or the leg press does not necessarily mean moving into deeper flexion, which is more likely to cause irritation. Progression can involve modifying the activity by changing the load, the support surface, the length of the isometric hold, etc. Once the patient has improved their strength and endurance, it becomes appropriate to increase the depth of movement. Building exercise tolerance slowly will decrease the likelihood of exercise induced muscle soreness.[10]

An early progression might begin by limiting range to between 0° and 45° while increasing the load. A double leg wall squat to 45° is a good starting point. This can be progressed to isometric holds with most of the weight on one leg and the other foot off-loaded on a step or ball, and then to longer holds. The patient can then come away from the wall and perform a double leg squat with added weight, such as a barbell or dumbbells, before progressing to a double leg squat on an unstable surface such as foam or a BOSU.[10]

Closed chain exercises between 0° and 45° can be combined with open chain exercises between 90° and 45°, so that the quadriceps work across 0° to 90° of knee flexion while patellofemoral joint stress stays relatively low.[10] Vary the exercises and modify as appropriate to ensure the patient is achieving muscle fatigue, and allow enough recovery between sessions for hypertrophy to occur.[10]

Example of exercise prescription:[10]

  • 4 sets of 8 repetitions to fatigue on alternate days
  • Once strength has improved, the emphasis can shift towards endurance, for example three or four sets of 20 repetitions.

Open-chain Exercises

Open chain exercises can be used in the earlier stages of rehabilitation, with range limited to between 90° and 45°, where patellofemoral joint stress is relatively low. Options include seated knee extension with or without a resistance band, or a leg extension machine.[10]

Resources

Optional Additional Reading:


Optional Video:

[25]


References

  1. ↑ 1.0 1.1 Gragnani BC, Hart HF, Forsyth A, Barton CJ, De Oliveira Silva D. Patellofemoral pain is a multifactorial complex condition; Are we missing a multidisciplinary approach to its management? Time for a paradigm shift. Open Access J Sports Med. 2026 Feb 5;16:517971.
  2. ↑ Callahan EA, Chin KE, Chu SK. Current evidence of evaluation and management of the athlete with patellofemoral pain syndrome. Curr Phys Med Rehabil Rep. 2025;13(30).
  3. ↑ Garza-Borjón A, González-González M, de la Garza-Salazar JF, Simental-Mendía M, Acosta-Olivo C. Understanding the patho-anatomy of patellofemoral pain: A crucial foundation for comprehensive management. Orthop Rev (Pavia). 2024 Nov 23;16:125840.
  4. ↑ Willy RW, Hoglund LT, Barton CJ, Bolgla LA, Scalzitti DA, Logerstedt DS, et al. Patellofemoral pain. J Orthop Sports Phys Ther. 2019 Sep;49(9):CPG1-CPG95.
  5. ↑ Zhu G, Jia Y, Hao Y, Miao X, Zhang E. Pain-related function, muscle stiffness, and muscle activation in adults with patellofemoral pain. BMC Musculoskelet Disord. 2026 Mar 18;27(1):299.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Loudon JK. Biomechanics and pathomechanics of the patellofemoral joint. International journal of sports physical therapy. 2016 Dec;11(6):820.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Wheatley MG, Rainbow MJ, Clouthier AL. Patellofemoral mechanics: a review of pathomechanics and research approaches. Current Reviews in Musculoskeletal Medicine. 2020 Jun;13(3):326-37.
  8. ↑ Peeler J, Cooper J, Porter MM, Thliveris JA, Anderson JE. Structural parameters of the vastus medialis muscle. Clinical Anatomy: The Official Journal of the American Association of Clinical Anatomists and the British Association of Clinical Anatomists. 2005 May;18(4):281-9.
  9. ↑ Ono T, Riegger-Krugh C, Bookstein NA, Shimizu ME, Kanai S, Otsuka A. The boundary of the vastus medialis oblique and the vastus medialis longus. Journal of Physical Therapy Science. 2005;17(1):1-4.
  10. ↑ 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 10.10 10.11 10.12 10.13 10.14 Robertson, C. Patellofemoral Joint Programme. Effective Quadriceps Training in Patellofemoral Pain. Plus. 2022.
  11. ↑ 11.0 11.1 Hodges PW, Mellor R, Crossley K, Bennell K. Pain induced by injection of hypertonic saline into the infrapatellar fat pad and effect on coordination of the quadriceps muscles. Arthritis Care & Research. 2009 Jan 15;61(1):70-7.
  12. ↑ Spencer JD, Hayes KC, Alexander IJ. Knee joint effusion and quadriceps reflex inhibition in man. Arch Phys Med Rehabil. 1984 Apr;65(4):171-7.
  13. ↑ Benjafield AJ, Killingback A, Robertson CJ, Adds PJ. An investigation into the architecture of the vastus medialis oblique muscle in athletic and sedentary individuals: an in vivo ultrasound study. Clinical Anatomy. 2015 Mar;28(2):262-8.
  14. ↑ Khoshkhoo M, Killingback A, Robertson CJ, Adds PJ. The effect of exercise on vastus medialis oblique muscle architecture: an ultrasound investigation. Clinical Anatomy. 2016 Sep;29(6):752-8.
  15. ↑ Elniel AR, Robertson C, Killingback A, Adds PJ. Open-chain and closed-chain exercise regimes: an ultrasound investigation into the effects of exercise on the architecture of the vastus medialis oblique. Phys Ther Rehabil. 2017;4:3.
  16. ↑ Hilal Z, Robertson CJ, Killingback A, Adds PJ. The effect of exercise and electrical muscle stimulation on the architecture of the vastus medialis oblique - the ‘Empi’ electrotherapy system. J Ortho & Sport Med. 2018. (1)1-5.
  17. ↑ Arnantha, Harry, C. Robertson, A. Killingback and Philip J. Adds. “Maintenance of exercise-induced changes in the architecture of the VMO: how much is enough? An in-vivo ultrasound study.” 2018;1(1).
  18. ↑ Torrente QM, Killingback A, Robertson C, Adds PJ. The effect of self-myofascial release on the pennation angle of the vastus medialis oblique and the vastus lateralis in athletic male individuals: an ultrasound investigation. International Journal of Sports Physical Therapy. 2022;17(4):636.
  19. ↑ YouTube. What makes muscles grow? - Jeffrey Siegel| TED Ed. Available from: https://www.youtube.com/watch?v=2tM1LFFxeKg [last accessed 16/08/2022]
  20. ↑ Loro WA, Thelen MD, Rosenthal MD, Stoneman PD, Ross MD. The effects of cryotherapy on quadriceps electromyographic activity and isometric strength in patient in the early phases following knee surgery. Journal of Orthopaedic Surgery. 2019 Feb 25;27(1):2309499019831454.
  21. ↑ Kong W, Wang Z, Zhou Q, Yan X, Li J, Zhao Y, et al. Comparing the impact of intermittent blood flow restriction training and high-load resistance training in individuals with patellofemoral pain: a randomized controlled trial. Arch Phys Med Rehabil. 2025 Dec;106(12):1789-1797.
  22. ↑ Lee J, Kwon H, Lee Y. Low-intensity blood flow-restricted multi-joint exercise improves muscle function in patients with patellofemoral pain syndrome: a randomized trial. Med Sci Monit. 2026 Jan 29;32:e950516.
  23. ↑ Hou C, Liu Z, Wang C, Wang J, Zhou H, Ma X, et al. Effects of blood flow restriction exercise interventions on patellofemoral pain syndrome: a systematic review and meta-analysis. Front Physiol. 2026 Jun 18;17:1859305.
  24. ↑ 24.0 24.1 Steinkamp LA, Dillingham MF, Markel MD, Hill JA, Kaufman KR. Biomechanical considerations in patellofemoral joint rehabilitation. The American journal of sports medicine. 1993 May;21(3):438-44.
  25. ↑ YouTube. CLOSED VS OPEN KINETIC CHAIN MOVEMENTS. WHAT'S THE DIFFERENCE ? CKC Vs OKC !!! Available from: https://www.youtube.com/watch?v=3wwEyV5CdBM [last accessed 16/08/2022]
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