Experts bust common sports medicine myths
Does running cause knee OA?
During another talk at the meeting, William O. Roberts, MD, characterized the notion that running causes knee osteoarthritis as largely a myth for recreational runners. However, elite runners and athletes who participate in other sports may face an increased risk of developing the condition.
Well-established risk factors for knee OA include post–joint injury proteases and cytokines and injury load stress on articular cartilage. “Other risk factors include overweight and obesity, a family history of OA, exercise, heavy work that involved squatting and kneeling, and being female,” said Dr. Roberts, professor of family medicine and community health at the University of Minnesota, Minneapolis.
He discussed three articles on the topic drawn from medical literature. One was a retrospective cross-sectional analysis of 2,637 Osteoarthritis Initiative participants, 45-79 years of age, who had knee-specific pain or knee x-ray data 4 years into the 10-year–long study (Arthritis Care Res. 2017 Feb;69[2]:183-91).
More than half of the participants (56%) were female, their mean body mass index was 28.5 kg/m2, only 20% reported more than 2,000 bouts of running during their lifetime, and about 5% had run competitively.
Adjusted odds ratios of pain, radiographic OA, and symptomatic OA for those prior runners and current runners, compared with those who never ran, were 0.82 and 0.76 (P for trend = .02), 0.98 and 0.91 (P for trend = .05), and 0.88 and 0.71 (P for trend = .03), respectively.
The authors concluded that running does not appear to be detrimental to the knees, and the strength of recommendation taxonomy was rated as 2B.
In a separate analysis, researchers performed a systematic review and meta-analysis of 11 cohort (6 retrospective) and 4 case-control studies related to running and knee arthritis (Am J Sports Med. 2016 May;45[6]:1447-57). The mean ages of subjects at outcome assessment ranged from 27 years to 69 years, and the sample size ranged from 15 to 1,279 participants. The four case control studies assessed exposure by mailed questionnaire or by personal interview.
The meta-analysis suggests that runners have a 50% reduced odds of requiring a total knee replacement because of OA.
“It contradicts some previous studies, and there were confounders,” Dr. Roberts said of the analysis. “The one that I noticed is that people would delay surgery to keep running. That’s what I find in my practice.”
The researchers were unable to link running to knee OA development. Moderate- to low-quality evidence suggests a positive association with OA diagnosis but a negative association with requirement for a total knee replacement.
Based on published evidence, they concluded there is no clear advice to give regarding the potential effect of running on musculoskeletal health and rated the strength of evidence as 1A.
A third study Dr. Roberts discussed investigated the association between specific sports participation and knee OA (J Athl Train. 2015 Jan. 9. doi: 10.4085/1062-6050-50.2.08). After locating nearly 18,000 articles on the topic, the researchers limited their meta-analysis to 17 published studies.
They found that the overall risk of knee OA prevalence in sports participants was 7.7%, compared with 7.3% among nonexposed controls (odds ratio, 0.9). However, risks for knee OA were elevated among those who participated in the following sports: soccer (OR, 3.5), elite long-distance running (OR, 3.3), competitive weightlifting (OR, 6.9), and wrestling (OR, 3.8). The researchers concluded that athletes who participate in those sports “should be targeted for risk-reduction strategies.”
“So, does running cause knee OA? It depends,” said Dr. Roberts, who is also medical director of Twin Cities in Motion. “There is a potential risk to high-volume, high-intensity, and long-distance runners, but there does not appear to be a risk in fitness or recreational runners. Of course, you can’t erase your genetics.”
He called for more research on the topic, including prospective longitudinal outcomes studies, those that study the role of genetics/epigenetics in runners and nonrunners who develop knee OA and those focused on the knee joint “chemical environment,” referring to recent work that suggests that running appears to decrease knee intra-articular proinflammatory cytokine concentration (Eur J Appl Physiol. 2016 Dec;116[11-12]:2305-14).
“It’s okay to run for fitness, because the health benefits far outweigh the risk of knee OA,” Dr. Roberts said. “If you run hard and long, it could be a problem. We probably should be screening for neuromuscular control to reduce anterior cruciate ligament disruption.”
Does it help to stretch before exercise?
Stretching before engaging in exercise is a common practice often recommended by coaches and clinicians – but it appears to have no role in preventing injuries during exercise itself.
