Exercise reduces musculoskeletal pain—but not because people get stronger

Exercise is widely accepted as a cornerstone of treatment for most musculoskeletal pain conditions. It is the first-line recommendation for problems such as tendinopathy, rotator cuff–related shoulder pain, low back pain, and osteoarthritis. The dominant explanation given to patients and clinicians alike is simple and intuitive: exercise works because strength increases, and pain decreases as a result. However, growing evidence suggests this explanation is largely unsupported. An article in British Journal of Sports Medicine presents alternative mechanisms based in current scientific evidence.

Across a wide range of MSK conditions, exercise consistently improves pain and function—but strength gains rarely explain why. Systematic reviews and mediation studies show no meaningful causal link between changes in muscle strength or tissue structure and improvements in pain or disability. This has been demonstrated in Achilles and patellar tendinopathy, rotator cuff–related shoulder pain, patellofemoral pain, and knee osteoarthritis. In knee OA, for example, improvements in knee extension strength explain only about 2% of the total benefit of exercise. The pattern is clear: exercise helps, but not primarily because muscles get stronger.

This mismatch between outcomes and assumed mechanisms matters. From a scientific perspective, causal explanations require more than correlation. Without identifying valid mechanisms, claims about why exercise works remain weak and unstable. Clinically, mechanistic narratives shape how therapists explain pain and how patients understand their bodies. Overemphasising strength risks reinforcing unhelpful beliefs—such as the idea that pain reflects weakness, damage, or fragility—and may demoralise patients who do not see measurable strength gains despite meaningful improvements in pain or function.

Mechanistic understanding also matters for research quality. Trials that report only whether exercise works, without examining how it works, miss opportunities to refine treatment design. Understanding mechanisms allows interventions to become more targeted, efficient, and adaptable to individual patients.

So what does the evidence suggest instead? Emerging research points to multidimensional bio-psycho-social mechanisms that better explain exercise-related pain relief. Improvements in pain self-efficacy, reductions in catastrophising, and changes in pain-related beliefs have been shown to mediate improvements in conditions such as osteoarthritis and low back pain. Reduced kinesiophobia (fear of movement) explains benefits in shoulder pain and back pain. In knee osteoarthritis, reductions in inflammatory biomarkers have also mediated pain improvement following exercise and lifestyle interventions. Trust, motivation, confidence, and the therapeutic relationship further shape outcomes by influencing engagement, adherence, and meaning.

Together, these findings suggest that exercise supports recovery by changing how people move, think, feel, and relate to pain, rather than by simply increasing force production. Exercise may recalibrate threat perception, improve confidence in movement, dampen systemic inflammation, and enhance a person’s sense of agency and capability. These effects can occur even when strength changes are small or absent.

For clinical practice, the implication is not to abandon strength training—but to update the story. Strength remains important for general health, functional independence, fall prevention, and long-term resilience. However, it should not be presented as the primary reason pain improves. A more accurate and empowering message is that exercise helps people adapt—physically, psychologically, and socially—in ways that reduce pain and restore function.

For researchers, the message is equally clear: future trials should test mechanisms, not just outcomes. Prospective mediation analyses that include psychological, inflammatory, and contextual factors are essential.

In short, exercise remains one of our most powerful tools in MSK care—but its benefits extend well beyond strength. Recognising this allows therapists to communicate more honestly, individualise treatment more effectively, and better reflect the true complexity of recovery from pain.