Strength training improves the evolution of knee osteoarthritis

Although the WHO recommends that the general population engage in regular physical activity, only about 30% of patients in the United States achieve recommended levels of strength training. In the context of knee osteoarthritis (OA), one of the possible explanations for this fact is that patients with the disease may consider that mechanical overload can generate pain or worsen OA, leading to hesitation and kinesiophobia.

With the hypothesis that strength training may be useful for patients with osteoarthritis, without presenting significant risks of worsening the natural history of the disease, Lo et al. conducted a study to evaluate the relationship between history of this type of physical activity and symptom outcomes and radiographic progression of knee OA.

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Strength training improves the evolution of knee osteoarthritis

Methods

This study was conducted as part of the Osteoarthritis Initiative (OAI), a multicenter prospective observational study. The present analysis was carried out cross-sectionally. Patients with complete data on strength training, knee pain, and radiographic evidence of osteoarthritis were included.

Questionnaires were administered (Historical Physical Activity Survey Instrument) in the OAI’s 96-month visit regarding the performance of strength exercises at 4 different moments in the participants’ lives: 12-18, 19-34, 35-49 ≥50 years. The outcome variables analyzed were radiographic changes in OA (Kellgren-Lawrence ≥2), symptomatic OA and frequent knee pain, all assessed at month 48.

Results

2607 patients with complete data were included, of the 4796 followed in the OAI. Of these, 44% were male, with a mean age of 63.4±8.9 years and an average BMI of 28.5±4.9 kg/mtwo. 39% had frequent knee pain, 58% signs of OA on radiography, 28% symptomatic OA; 4% underwent total knee arthroplasty and 49% had a history of injury prior to the 48-month visit.

Regarding physical activity, 1789 (68.6%) were not exposed to strength training, while 818 (31.4%) were. Of those who performed strength exercises, the majority did so after the age of 50.

The adjusted OR for frequent knee pain was 0.82 (95%CI 0.68-0.97); that for radiographic OA was 0.83 (95%CI 0.70-0.99) and that for symptomatic OA was 0.77 (95%CI 0.63-0.94). The findings were similar in the different age strata analyzed.

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Comments

This study is important because it documents that the practice of strength training has benefits in improving OA. Therefore, it is the role of the doctor who cares for patients with OA to guide physical exercise, without the old concept that this can worsen the patient’s condition.