By Jordana Bieze Foster
Adding exercise to a dietary program does not significantly increase weight loss or reduce loading in overweight patients with knee osteoarthritis (OA) compared to diet alone, but the addition of exercise is associated with significant improvements in pain and function, according to preliminary results of a large 18-month trial presented in April at the 2013 World Congress on Osteoarthritis.
In the Intensive Diet and Exercise for Arthritis (IDEA) trial, conducted at Wake Forest University in Winston-Salem, NC, 454 overweight and obese patients (mean body mass index of 33.6) with tibiofemoral knee OA were randomized to one of three interventions: diet only, exercise only, or diet plus exercise. The dietary intervention involved initial energy-intake deficits of 800-1000 kcals/day, with a weight loss goal of at least 10% of baseline weight. Exercise was done three times a week; each 60-minute session included 20 minutes of strength training and 30 minutes of aerobic exercise, primarily walking.
Mean weight loss after 18 months was significant in the diet-only group (9.5% of body weight lost) and the diet-plus-exercise group (11.4%), and both groups also demonstrated significant decreases in knee compressive force compared to baseline. Between-group differences in weight loss and loading were not statistically significant.
But there were significant differences between the two groups with regard to pain and function. Pain levels decreased by 51% in the diet-plus-exercise group, compared to a 21% decrease in the diet-only group. Similarly, function improved by 47% in the diet-plus-exercise group, compared to 29% in the diet-only group. Adding exercise to diet was also associated with significantly greater walking velocity and six-minute walk distance than diet alone.
“Exercise should be recommended in addition to diet as part of standard care for obese and overweight patients with knee osteoarthritis,” said Stephen P. Messier, PhD, professor and director of the J.B. Snow Biomechanics Laboratory at Wake Forest University, who presented the findings at the congress as part of a plenary lecture. The study protocol was published in July 2009 by BMC Musculoskeletal Disorders.
The researchers were surprised to find, however, that none of the interventions had any effect on disease progression, and that adding exercise to diet did not significantly affect the percentage of lean mass lost along with fat.
“The intensity of our exercise intervention in this population was insufficient to change lean mass,” Messier said. “In most studies you’ll find that the exercise is not intense enough. We’re doing a study now on high-intensity strength training specifically to maintain lean mass.”
Messier SP, Legault C, Mihalko S, et al. The intensive diet and exercise for arthritis (IDEA) trial: Design and rationale. BMC Musculoskelet Disord 2009;10:93.