Moderate Activity May Be Key to Saving Knees
CHICAGO – Too much exercise led to early degenerative cartilage changes in the knee in healthy people and in those at risk for osteoarthritis, according to an MRI-based study.
Over a 4-year period, 205 individuals who exercised at various intensity levels underwent MR imaging that showed significant T2 progression, suggestive of accelerated cartilage matrix biochemical degeneration (P<0.05), said Wilson Lin, a research fellow at the University of California San Francisco, during a presentation at the Radiological Society of North America meeting.
"This study seems to suggest that people should do things in moderation," Lin said during an RSNA press briefing. "You want to exercise the knee, but you don't want to stress the knee in such a way that would be detrimental. If [people] wanted to run marathons and work out several times a week, I would present them with the evidence that this could be harmful."
The relationship between physical activity and the evolution of osteoarthritis is unclear, but cross-sectional studies have shown that very low and high levels of exercise may be associated with higher cartilage T2 relaxation times compared with mild levels of exercise.
Lin's group enrolled people from two cohorts -- incidence and normal -- of the Osteoarthritis Initiative Incidence. Participants' ages ranged from 45 to 60 and the body mass indices ranged from 19 kg/m2 to 27 kg/m2.
None of the participants had knee pain at baseline (zero score on the Western Ontario and McMaster Universities Arthritis Index), and a Kellgren-Lawrence score of less than 2 in the right knee at baseline.
Physical activity was scored using the Physical Activity Scale for the Elderly (PASE) questionnaire, which was averaged over a 4-year time period and categorized into tertiles. The rigorous activity tertile generally consisted of 1 hour of vigorous physical activity, three times or more per week.
T2 values of articular cartilage were measured at the patella, medial/lateral femur and medial/lateral tibia of the right knee in multi-echo spin-echo sequences at baseline, 2 years, and 4 years.
All compartments in the knee showed significant T2 progression over the study period, Lin said.
The authors also reported that T2 progression was higher in the highest tertile on PASE than in the midtertile at the medial tibia (2.8 versus 2.0, P=0.04) and the patella (4.1 versus 3.1, P=0.02). The average T2 of all knee compartments combined was 2.5 versus 2.0 (P=0.03) for highest PASE tertile compared with midtertile.
T2 progression was also higher in the lowest tertile than in the midtertile in all compartments, but results were not significant. "We did observe a trend to higher T2 relaxation times in the most sedentary individuals (about 2.4) but that did not reach statistical significance (P<0.10)," co-author Thomas Link, MD, PhD, told MedPage Today.
Link also told MedPage Today that according to previous studies, people who exceed 10,000 steps a day based on a pedometer appeared to be at risk of acceleration progression of cartilage damage. However, he said there was no science to determine the number of steps that would be considered sedentary.
Link noted that study did involve individuals who were at high risk for knee osteoarthritis because of family history, obesity, or a history of knee injury or replacement surgery.
He suggested that people should use correct footwear and attend classes that emphasize exercise safety.
"This shows that titrating physical activity may be important, not just being physically active," said Candice Johnstone, MD, who moderated the RSNA press briefing. "Being super-aggressive in exercise may be worse than moderate exercise such as walking."
"I was not surprised by these results. This is more like common sense," added Johnstone, who is from the Medical College of Wisconsin in Milwaukee. "This adds to information people have to use to design their own exercise program."
The Osteoarthritis Initiative Incidence is sponsored by NIH.
Lin reported no conflicts of interest. Link disclosed commercial relationships with GE Healthcare.
Johnstone reported no conflicts of interest.
Lin reported no conflicts of interest. Link disclosed commercial relationships with GE Healthcare.
Johnstone reported no conflicts of interest.
Primary source: Radiological Society of North America
Source reference:
Lin W, et al "High levels of physical activity are associated with greater cartilage degeneration over a period of 4 years as assessed with T2 relaxation time measurements – 3T MRI data from the Osteoarthritis Initiative" RSNA 2012; Abstract LL-MKS-SU1B.
No comments:
Post a Comment