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Bottom line
Pooled evidence from 27 randomized trials indicates resistance training moderately improves pain, strength, and function in knee and hip osteoarthritis, though benefits are moderate rather than dramatic and hip evidence is thin.
Moderate evidencePublished
Evidence hierarchy
Study participants
Adults with knee or hip osteoarthritis (Kellgren-Lawrence grades 1-4); 25 knee-OA trials, 2 hip-OA trials
Study Summary
This systematic review and meta-analysis pooled 27 randomized controlled trials (1712 participants) to assess whether resistance training improves pain, muscle strength, and physical function in people with knee or hip osteoarthritis (OA). Across all studies, resistance training produced moderate, statistically significant improvements in pain (SMD -0.48), strength (SMD 0.40), and function (SMD -0.56) compared with control groups. Benefits for pain and strength appeared at every intervention duration, while functional improvement was not seen at durations under 4 weeks; both knee and hip OA improved. The authors caution that effect sizes were generally moderate, only 2 of 27 trials studied hip OA, publication bias was detected for pain and function, and many trials had methodological weaknesses, so resistance training is best viewed as one effective component of OA management rather than a standalone cure.
Key Findings
| Finding | Detail | Impact |
|---|---|---|
| Resistance training moderately reduced OA pain | Across 24 studies, pain improved with a standardized mean difference of -0.48 (95% CI -0.58 to -0.37, I2 45%), interpreted by the authors as a moderate effect. | High |
| Resistance training moderately increased muscle strength with no heterogeneity | Across 11 studies, strength improved (SMD 0.40, 95% CI 0.32 to 0.47, I2 0%) despite the inclusion of varied resistance methods (aquatic, concentric/eccentric, fast/slow contractions). However, the gain was not significant versus usual care (SMD 0.39, 95% CI -0.01 to 0.79). | High |
| Resistance training moderately improved physical function | Across 17 studies, function improved (SMD -0.56, 95% CI -0.65 to -0.47, I2 30%), with the largest effect versus no-intervention controls (SMD -0.74). | High |
| Functional benefit required more than 4 weeks of training | Subgroup analysis showed no significant functional effect at durations of 4 weeks or less (SMD -0.26, 95% CI -0.55 to 0.03), whereas pain and strength improved at all durations. Between-subgroup differences by duration were not statistically significant. | Medium |
| Both knee and hip OA benefited | Pain, strength, and function improved for both joints, but only 2 of 27 studies focused on hip OA, so the authors advise caution interpreting the hip results. | Medium |
| Publication bias was detected and adjusted for | Egger's regression flagged bias for pain (p=0.03) and function (p=0.03). After trim-and-fill adjustment, effects remained significant but smaller (pain SMD -0.31; function SMD -0.43). | Medium |
Across 24 studies, pain improved with a standardized mean difference of -0.48 (95% CI -0.58 to -0.37, I2 45%), interpreted by the authors as a moderate effect.
Across 11 studies, strength improved (SMD 0.40, 95% CI 0.32 to 0.47, I2 0%) despite the inclusion of varied resistance methods (aquatic, concentric/eccentric, fast/slow contractions). However, the gain was not significant versus usual care (SMD 0.39, 95% CI -0.01 to 0.79).
Across 17 studies, function improved (SMD -0.56, 95% CI -0.65 to -0.47, I2 30%), with the largest effect versus no-intervention controls (SMD -0.74).
Subgroup analysis showed no significant functional effect at durations of 4 weeks or less (SMD -0.26, 95% CI -0.55 to 0.03), whereas pain and strength improved at all durations. Between-subgroup differences by duration were not statistically significant.
Pain, strength, and function improved for both joints, but only 2 of 27 studies focused on hip OA, so the authors advise caution interpreting the hip results.
Egger's regression flagged bias for pain (p=0.03) and function (p=0.03). After trim-and-fill adjustment, effects remained significant but smaller (pain SMD -0.31; function SMD -0.43).
Strengths
- Prospectively registered (PROSPERO) and conducted per PRISMA 2020 guidelines
- Large pooled sample (27 RCTs, 1712 participants) drawn from four databases
- First meta-analysis in this line of work to specifically report effects on muscle strength, with very low heterogeneity for the strength outcome (I2 0%)
- Subgroup analyses by intervention duration and by joint add clinical nuance
- Formal publication-bias assessment (funnel plot, Egger's regression, trim-and-fill) with effects remaining significant after adjustment
- Study quality formally rated with the PEDro scale (20 of 27 studies rated good)
Limitations
- Only 2 of 27 included studies focused on hip OA, so hip findings should be interpreted with caution
- Publication bias was detected for pain and function outcomes (Egger's p=0.03); adjusted effects were smaller
- Effect sizes were generally moderate, not large
- Most pain and function measures were patient-reported, so a placebo/contextual effect cannot be ruled out
- Surgical and more severe patients were excluded, which may have produced more favorable results
- Many trials lacked patient/therapist blinding, and more than half lacked random allocation and intention-to-treat analysis, risking bias and overestimation
- Few trials assessed durations of 4 weeks or less, limiting conclusions about very short programs
- No analysis of how outcomes relate to factors such as age, sex, BMI, or disease severity
Key Takeaways for Patients
What This Means for You
- 01Strengthening exercises for the muscles around an arthritic knee or hip may moderately ease pain, build strength, and make everyday activities easier.
- 02Give it time: pain and strength may improve fairly early, but improvements in day-to-day function tended to need more than about 4 weeks of consistent training.
- 03Many different styles of resistance training (in water, with bands or weights, slow or fast) appeared to help build strength, so you can pick an approach that fits your preferences and budget.
- 04Resistance training is one helpful piece of osteoarthritis care; guidelines suggest combining several exercise types, so discuss a tailored plan with your clinician or physical therapist.
- 05These were moderate-sized benefits, not a cure, and stronger evidence exists for knee OA than hip OA.
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