Effect of High-Intensity Strength Training on Knee Pain and Knee Joint Compressive Forces Among Adults With Knee Osteoarthritis: The START Randomized Clinical Trial

Abstract

Importance: Thigh muscle weakness is associated with knee discomfort and osteoarthritis disease progression. Little is known about the efficacy of high-intensity strength training in patients with knee osteoarthritis or whether it may worsen knee symptoms.

Objective: To determine whether high-intensity strength training reduces knee pain and knee joint compressive forces more than low-intensity strength training and more than attention control in patients with knee osteoarthritis.

Design, setting, and participants: Assessor-blinded randomized clinical trial conducted at a university research center in North Carolina that included 377 community-dwelling adults (≥50 years) with body mass index (BMI) ranging from 20 to 45 and with knee pain and radiographic knee osteoarthritis. Enrollment occurred between July 2012 and February 2016, and follow-up was completed September 2017.

Interventions: Participants were randomized to high-intensity strength training (n = 127), low-intensity strength training (n = 126), or attention control (n = 124).

Main outcomes and measures: Primary outcomes at the 18-month follow-up were Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) knee pain (0 best-20 worst; minimally clinically important difference [MCID, 2]) and knee joint compressive force, defined as the maximal tibiofemoral contact force exerted along the long axis of the tibia during walking (MCID, unknown).

Results: Among 377 randomized participants (mean age, 65 years; 151 women [40%]), 320 (85%) completed the trial. Mean adjusted (sex, baseline BMI, baseline outcome values) WOMAC pain scores at the 18-month follow-up were not statistically significantly different between the high-intensity group and the control group (5.1 vs 4.9; adjusted difference, 0.2; 95% CI, -0.6 to 1.1; P = .61) or between the high-intensity and low-intensity groups (5.1 vs 4.4; adjusted difference, 0.7; 95% CI, -0.1 to 1.6; P = .08). Mean knee joint compressive forces were not statistically significantly different between the high-intensity group and the control group (2453 N vs 2512 N; adjusted difference, -58; 95% CI, -282 to 165 N; P = .61), or between the high-intensity and low-intensity groups (2453 N vs 2475 N; adjusted difference, -21; 95% CI, -235 to 193 N; P = .85). There were 87 nonserious adverse events (high-intensity, 53; low-intensity, 30; control, 4) and 13 serious adverse events unrelated to the study (high-intensity, 5; low-intensity, 3; control, 5).

Conclusions and relevance: Among patients with knee osteoarthritis, high-intensity strength training compared with low-intensity strength training or an attention control did not significantly reduce knee pain or knee joint compressive forces at 18 months. The findings do not support the use of high-intensity strength training over low-intensity strength training or an attention control in adults with knee osteoarthritis.

Trial registration: ClinicalTrials.gov Identifier: NCT01489462.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Messier reported receiving grants from the National Institute of Arthritis Musculoskeletal and Skin Diseases. Dr Mihalko reported receiving grants from the National Institutes on Health (NIH). Dr Beavers reported receiving grants from the NIH. Dr Nicklas reported grants from Wake Forest School of Medicine. Dr Hunter reported receiving personal fees from Pfizer, Lilly, Merck Serono, and TLCBio. Dr Guermazi reported receiving personal fees from MerckSerono, Pfizer, TissueGene, Galapagos, Roche, AstraZeneca, Boston Imaging Core Lab (BICL) LLC and is the president and founder of BICL. Dr Bennell reported receiving grants from the NIH, the National Health and Medical Research Council, and Medibank Private and personal fees from UpToDate. Dr Loeser reported receiving grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and Bioventus and personal fees from Unity Biotechnology. No other disclosures were reported.

Figures

Figure 1.. Participant Flow Through the Study of the Effect of High-intensity Strength Training on Knee Pain and Knee Joint Compressive Forces

aParticipant may have been ineligible for more than 1 reason. bPersons excluded due to x-ray for multiple reasons. cStaff considered participation a danger to themselves or others. dA stratified block randomization method, stratified by body mass index (BMI) and sex, was used to assign all eligible persons to 1 of 3 intervention groups.

Figure 2.. Unadjusted Pain Score and Knee Joint Compressive Force Across the 18-Month Study

The middle line in the plot boxes represents the median values; the X, the mean values; and the boxes, the interquartile range. The whiskers extend to the most extreme observed values within 1.5 × the interquartile range of the nearer quartile, and the dots represent observed values outside the range. WOMAC indicates Western Ontario and McMaster Universities Osteoarthritic Index. B, A knee compressive force of 872 N was equivalent to mean body weight. One pound (0.45 kg) of force is equivalent to 4.45 N of force.