22/06/2025
Just published 🔥
Effectiveness of Quadriceps Strength Training in Adults With Knee Osteoarthritis 🦵: A Systematic Review
👫Knee osteoarthritis (KOA) is a prevalent degenerative joint disease characterized by joint space narrowing, osteophyte formation, and cartilage degradation, leading to pain, stiffness, and reduced mobility (Heidari, 2011). With approximately 364.58 million cases globally, KOA significantly contributes to disability, particularly among older adults, with 13% of women and 10% of men over 60 years experiencing symptomatic KOA (Cui et al., 2020; Li et al., 2024). Quadriceps weakness, a modifiable risk factor, exacerbates joint loading and pain in KOA, disrupting force distribution during weight-bearing activities (Segal et al., 2010; Alshahrani & Reddy, 2023).
📘 A brand-new systematized review by Hegde et al. (2025) evaluates the effectiveness of quadriceps strengthening exercises as part of lower limb strengthening programs in reducing pain and improving function in adults with KOA, addressing conflicting literature on its efficacy. (https://pubmed.ncbi.nlm.nih.gov/40462206/)
🩺 Materials and Methods
The review utilized a systematized approach, searching the PubMed database on February 7, 2025, for free full-text randomized controlled trials (RCTs) published in English within the last five years, focusing on human subjects. The PICO framework guided the search: population (adults with KOA), intervention (lower extremity strengthening including quadriceps exercises), comparison (other physiotherapy or non-physiotherapeutic treatments), and outcome (pain reduction).
Studies were included if they involved quadriceps strengthening as part of lower limb exercises and measured pain outcomes, while those excluding quadriceps training or not reporting pain were excluded. The Joanna Briggs Institute (JBI) Critical Appraisal Tool assessed study quality, with only RCTs scoring ≥80% included.
📊 Results
From 10,314 studies identified, 258 RCTs were screened, 27 underwent full-text review, and 9 RCTs met the inclusion criteria (JBI score >80%).
Participants, aged 50–75 years, were predominantly female, reflecting KOA’s higher prevalence in women. Pain outcomes were measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC, n=4), Visual Analogue Scale (VAS, n=3), Knee Injury and Osteoarthritis Outcome Score (KOOS, n=2), and Numerical Rating Scale (NRS, n=1). Studies originated primarily from upper-middle-income countries (n=5), with comparators including pharmacological treatments (n=1), electrotherapy (n=2), exercise interventions (n=2), exercise plus electrotherapy (n=2), and others (n=2).
🔑 Key findings from the RCTs include:
▶️ Knoop et al. (2022): High-quality evidence showed resistance training reduced pain and improved function (effect size: 2.668, JBI: 12/13).
▶️ Yuenyongviwat et al. (2020): Quadriceps strengthening alone or with hip abductor exercises improved pain and function (effect size: 0.4630, JBI: 12/13).
▶️ Moezy et al. (2024): Neuromuscular electrical stimulation (NMES) combined with quadriceps strengthening outperformed NMES or exercise alone in pain reduction and muscle growth (effect size: 1.9022, JBI: 13/13).
▶️ Abed et al. (2024): Quadriceps strengthening with metformin phonophoresis (MFPH) yielded significant pain relief and range of motion (ROM) improvement (effect size: 3.0583, JBI: 12/13).
▶️ Rizvi et al. (2023): Polyvagal-based exercises with quadriceps strengthening reduced pain and stiffness in females with grade II KOA (effect size: 3.27, JBI: 11/13).
▶️ Messier et al. (2021): High- and low-intensity training reduced pain similarly, with no significant difference (effect size: 0.9581, JBI: 11/13).
▶️ Jorge et al. (2023): Strengthening exercises improved pain and function, but photobiomodulation (PBM) added no additional benefit (effect size: 1.495, JBI: 13/13).
▶️ Bennell et al. (2020): Weight-bearing and non-weight-bearing quadriceps exercises improved pain and function, with non-weight-bearing reducing joint loading in obese patients (effect size: 1.3805, JBI: 12/13).
▶️ Rafiq et al. (2021): Non-weight-bearing quadriceps strengthening reduced pain in obese patients (effect size: 0.56002, JBI: 11/13).
🏋️♀️ Effective exercises included straight leg raises, terminal knee extensions, and open/closed kinematic chain movements over 8–12 weeks. Combining quadriceps strengthening with hip abductor exercises, NMES, MFPH, or polyvagal exercises enhanced outcomes compared to standalone interventions.
✅ Discussion
The review confirms that quadriceps strengthening, as part of lower limb exercise programs, significantly reduces pain and improves function in KOA, aligning with OARSI guidelines advocating exercise as a primary non-pharmacological intervention (Lim et al., 2024; Turner et al., 2020). Quadriceps strengthening enhances neuromuscular control, joint stability, and muscle strength, mitigating compressive stresses on the knee joint (Turner et al., 2020). Non-weight-bearing exercises were particularly beneficial for obese patients, reducing joint loading (Bennell et al., 2020; Rafiq et al., 2021). Combining quadriceps training with hip abductor strengthening or adjunct therapies (e.g., NMES, MFPH) often yielded superior outcomes, suggesting synergistic effects (Moezy et al., 2024; Abed et al., 2024).
🚫 Limitations include the lack of long-term follow-up (8–24 weeks), limiting insights into sustained benefits. Variability in intervention protocols, participant characteristics (e.g., BMI, OA severity), and control groups hindered direct comparisons. The predominance of female participants may limit generalizability to males. Discrepancies in optimal exercise parameters (frequency, intensity, progression) and individual response variability highlight the need for personalized approaches (Turner et al., 2020; Thomas et al., 2022).
💡 Conclusion
Quadriceps strengthening, integrated into lower limb exercise programs, is an effective non-pharmacological strategy for reducing pain and enhancing function in KOA. Exercises such as straight leg raises, terminal knee extensions, and kinematic chain movements, performed over 8–12 weeks, are recommended for inclusion in structured protocols. Personalized interventions, considering factors like obesity and OA severity, and combining quadriceps training with adjunct therapies, optimize outcomes. Future research should focus on long-term effects, standardized protocols, and tailored exercise prescriptions to address KOA’s heterogeneity.
📒 References
Abed, M. S., et al. (2024). Effects of metformin phonophoresis and exercise therapy on pain, range of motion, and physical function in chronic knee osteoarthritis. Journal of Orthopaedic Surgery and Research, 19(1), 689.
Alshahrani, M. S., & Reddy, R. S. (2023). Quadriceps strength, postural stability, and pain mediation in bilateral knee osteoarthritis. Diagnostics, 13(19), 3110.
Bennell, K. L., et al. (2020). What type of exercise is most effective for people with knee osteoarthritis and co-morbid obesity? Osteoarthritis and Cartilage, 28(6), 755–765.
Chao, J., et al. (2021). Effect of systematic exercise rehabilitation on patients with knee osteoarthritis. Cartilage, 13(1_suppl), 1734S–1740S.
Cui, A., et al. (2020). Global, regional prevalence, incidence and risk factors of knee osteoarthritis in population-based studies. eClinicalMedicine, 29.
Heidari, B. (2011). Knee osteoarthritis prevalence, risk factors, pathogenesis and features: Part I. Caspian Journal of Internal Medicine, 2(2), 205.
Jorge, A. E. S., et al. (2023). Photobiomodulation does not provide incremental benefits to patients with knee osteoarthritis who receive a strengthening exercises program. Brazilian Journal of Physical Therapy, 27(4), 100519.
Knoop, J., et al. (2022). Stratified exercise therapy does not improve outcomes compared with usual exercise therapy in people with knee osteoarthritis. Journal of Physiotherapy, 68(3), 182–190.
Lim, A. Y., et al. (2024). The Effects of Resistance Training on Pain, Strength, and Function in Osteoarthritis: Systematic Review and Meta‐Analysis.” Journal of Personalized Medicine 14, no. 12: 1130. https://doi.org/10.3390/jpm14121130.
Moezy, A., et al. (2024). A controlled randomized trial with a 12-week follow-up investigating the effects of medium-frequency neuromuscular electrical stimulation on pain, VMO thickness, and functionality in patients with knee osteoarthritis. BMC Musculoskelet Disord 20;25(1):158
Rafiq, M. T., et al. (2023). Short-Term Effects of Strengthening Exercises of the Lower Limb Rehabilitation Protocol on Pain, Stiffness, Physical Function, and Body Mass Index among Knee Osteoarthritis Participants Who Were Overweight or Obese: A Clinical Trial. The Scientific World Journal, 2021, 6672274
Rizvi, S. A., et al. (2023). Polyvagal-based exercises combined with quadriceps strengthening in females with knee osteoarthritis. Sci Rep 3;13(1):18964..
Segal, N. A., et al. (2010). Quadriceps weakness in knee osteoarthritis: The effect on pain and disability. Arthritis Care & Research, 62(10), 1412–1419.
Thomas, E., et al. (2022). Hip abductor strengthening in knee osteoarthritis: A systematic review. Journal of Orthopaedic & Sports Physical Therapy, 52(2), 89–98.
Turner, M. N., et al. (2020). The role of resistance training dosing on pain and physical function in individuals with knee osteoarthritis: A systematic review. Sports Medicine, 50(8), 1519–1537.
Yuenyongviwat, V., et al. (2020). Effect of hip abductor strengthening exercises in knee osteoarthritis: A randomized controlled trial. BMC Musculoskeletal Disorders, 21, 561.
