Knee Osteoarthritis Outcomes Improved With Both Low-Dose and High-Dose Exercise

In the setting of knee osteoarthritis, investigators found little evidence to support high-dose exercise over low-dose exercise, according to the results of their study published in Annals of Internal Medicine.

According to the study authors, “Wide variability in the exercise content prescribed and reported in the literature has made it difficult to identify an optimal exercise dose that can be agreed upon.”

To that end, they recruited 189 patients with knee osteoarthritis to participate in their study (ClinicalTrials.gov Identifier: NCT02024126), which was conducted at locations in Sweden and Norway. Patients were randomly assigned in a 1:1 ratio to receive high-dose (n=98) or low-dose (n=91) exercise therapy at a frequency of 3 times per week for 12 weeks. The therapy interventions were personalized for each participant depending on their specific needs, symptoms, and functional level and included aerobic, multisegmental, and joint-specific exercises supervised by physiotherapists. High-dose exercise consisted of 11 total exercises and lasted 70 to 90 minutes, and low-dose exercise consisted of 5 exercises and lasted 20 to 30 minutes. The primary outcome of interest was change in Knee Injury and Osteoarthritis Outcome Score (KOOS).

The mean age of the study participants was 62.1 (standard deviation [SD], 9.3) years, 56% were women, and average body mass index (BMI) was 28.0 (SD, 4.1) kg/m². Most study participants reported engaging in some form of physical activity during their spare time. Approximately three-quarters of study participants reported using medication, with one-third reporting the medication use for knee pain.

Adherence to the interventions was 98% in both groups; however, adherence to the high-dose intervention was lower than that for the low-dose intervention when all repetitions and minutes were combined (78% vs 97%, respectively).

Exercise improved KOOS among all participants, and in general, no group differences were observed. The exceptions were KOOS sport or recreation subscores at 3 (mean difference [MD], 8; 95% CI, 2-14; P =.006) and 9 (MD, 11; 95% CI, 4-17; P =.003) months and quality-of-life subscore at 9 months (MD, 8; 95% CI, 3-14; P =.004), all favoring the high-dose intervention.

In addition, more patients who engaged in high-dose exercise had a clinically important improvement in sport and recreation KOOS at 9 months compared with recipients of the low-dose exercise intervention (MD, 22; 95% CI, 5-38; P =.010).

By the 15-month follow-up visit, no significant group differences were observed.

No safety signals were reported.

A major limitation of this study was its lack of a control group.

These data indicate that although high-dose exercise is not superior to low-dose exercise for most outcomes, more intensive exercise may better improve sport and recreation and quality of life scores among patients with knee osteoarthritis.