Weighing above normal weight ranges and wishing to try running or Zumba? Not many recommend doing these as they fear applying increased stress on the knee might disturb it contributing towards joint pain and more. Overweight/obese people are generally recommended to pursue walking as the primary exercise form to reduce a certain amount of weight before moving on to other more intense ones such as jogging, running, playing a sport and likewise. But there are many controversies surrounding the fact whether running is harmful to the knee, especially if it would induce osteoarthritis.
Osteoarthritis (OA) is the common form of arthritis that exists as a leading cause of disability, especially in the elderly population and those participating in sports activity. Knee osteoarthritis (KOA) is one of the primary causes of long-term disability in the world that can result in chronic pain, limit activity level and decrease quality of life of the affected individual. Age, obesity and genetic factors are the primary risk factors for KOA which can be greatly eliminated by performing regular physical activity. But sadly, not even a quarter of the world population meet the recommended guidelines of performing 150 minutes of moderate-intensity activity per week. Not many individuals take up exercise as a serious means to fight knee osteoarthritis and it becomes the physician’s burden to deliver the required exercise performance from the patient. Walking is the best preferred option by physicians but running exists as one of the popular activity forms among individuals as it bestows numerous psychological and physical benefits on the individual. But running has always remained as an activity form that has been negatively associated with knee joint health (since the knee exists as one of the frequently used body parts in runners).
Chronic mechanical overloading can damage structures within the knee. But there are also opinions that runners generally have a lower body mass index compared to non-runners that could protect them against knee osteoarthritis. We have data supporting and opposing the effect of running as an exercise: AlentornGeli et al. related recreational running with lower rates of KOA while competitive running was linked to higher rates. Though research on this topic is growing day by day the absence of precise knowledge on the understanding between KOA and running is absent until now. We also have data showing that long-distance running might be linked to progression of knee OA in the absence of knee injury, obesity or poor muscle tone. OA results in higher disability rates leading to increased rates of hip and knee replacements.
Running, an exercise form, that exists as the favourite among millions of individuals is now at the junction of also existing as one of the causes of knee osteoarthritis. Even an elevation in BMI causes a raise in the risk of OA.
Studies that Support or Reject Running as a Risk Factor for OA
A longitudinal study on long-distance runners and controls suggest that disability levels in runners increase with age at 25% of the rate of more sedentary controls. When the study was designed in 1984 there were serious concerns that running could accelerate OA due to repetitive trauma to the joints. The study is a long-term one conducted for a period of 18 years with a hypothesis that long-distance runners were prone to more severe OA than aged populations. The study included long-distance runners aged ≥50 years who had been into running for more than a decade. The control group was selected from a random sample thereby assembling a cohort of 538 runners and 423 controls who met the eligibility criteria. Weight-bearing radiographs of the knee was taken in 1984, 86, 89, 93, 96 and 2002. During the 18 years of study, radiographs of the knee was taken for both runners and the control group. After a series of eliminations and due to unfavourable reasons only 113 participants remained in the radiographic study and of them, 98 (45 runners and 53 controls) had at least two sets of radiographs.
All participants provided information on demographics, medical history, BMI, exercise routines, injuries and functional status. The total time spent on performing vigorous-intensity exercises such as running, swimming, brisk walking and aerobic dance was noted down. Participants in the intervention group were slightly younger, had a lower BMI and reported a greater prevalence of knee injury than the controls. They had also decreased their running time by 55% at the end of the follow-up period but maintained overall time spent in vigorous-intensity exercise (almost 300 minutes/week). In the control group, a small proportion of them were involved in running as an exercise form and all the controls increased their overall time spent in vigorous activities by 100 minutes/week and this was mostly brisk walking. There was a significant difference in the time spent in running between the intervention and control group throughout the study.
Most of the participants showed little OA at the start and end of final radiographs. Though total knee scores were worse in runners at baseline compared to controls the scores of both the groups at the end of the study remained the same. Joint space width (JSW) of the worst knee was worse among runners than controls at the initial radiograph but was nearly identical at the final assessment. While two participants in the control group had undergone knee replacement there were none in the runner group with such need for replacements. Three controls had a JSW of 0, one participant in the runners group had a JSW of 0 and only 10 participants (6 controls and 4 runners) had JSW in the worst knee ≤1 mm. Total knee score (TKS) remained low for all participants at the final radiographs. The mean TKS was 3.6 for runners and 4.2 for controls while the possible scores can be between 0 and 36.
The study result is consistent with some other long-distance running study results that show that running may not be an independent risk factor for knee OA. But we also have a number of studies that show that participation in specific sports at the elite level does increase the risk of knee OA. This study is an example for the fact that long-distance running should not be discouraged among healthy older adults fearing progression of knee OA.
Osteoarthritis Initiative (OAI)
In the OAI there were more than 2000 participants who completed a survey of exposure to leisure-time physical activities and the study dealing with the effect of running on KOA is a cross-sectional study nested within the OAI in men and women aged between 45 and 79 years who showed no symptoms of OA nor had high risks for the same; or were at a high risk for developing OA or already had knee OA. All the participants were asked to complete a questionnaire which probed into 37 leisure-time physical activities that included jogging or running. All the participants were asked to identify activities that they performed for at least 20 minutes in a day at least 10 times in their lives during the age periods of: 12-18, 19-34, 35-49 and ≥50 years old. 3 most frequently performed activities by each of the participants were identified during those age periods and information regarding them were recorded. Those individuals who mentioned running or jogging among the top 3 activity list were defined as runners in that specific age period.
At the 48-month visit the participants were asked to report on any knee-specific pain or stiffness. BMI, height, weight and reports on any knee injuries were reported at baseline and during annual visits. After database search, elimination and selection the study included 2,637 participants of which 55.8% were females, 634 of them were from the progression cohort (had symptomatic OA at baseline), 1,899 were from the incidence cohort (did not have symptomatic OA but had high risk of developing the same during follow-up) and 104 were from the nonexposed control group. 778 of the participants had been engaged with running at some point in life but only 2-5% ran competitively. Results showed that any history of running was associated with less frequent knee pain, had lower odds of radiographic and symptomatic OA compared to those who never ran in the unadjusted model but when adjusted for BMI, height, weight, sex and leisure-time physical activity that significantly correlated with running during the relevant time frame there was no significant difference found. There was no link found between running and either injury or BMI in any of the 3 outcomes. Studies show that injuries can occur in 7-50% of runners and because of this, runners are expected to be at a high risk for knee OA but there was no such risk found in the present study. The researchers attribute this to the lower BMI seen in runners compared to non-runners. This study shows that running does not cause harm to the knee in any way and those with lowest BMIs were involved in running as a major activity form in their lives.
Perception of Individuals & Physicians about Running and Knee Health in Canada
A cross-sectional survey was conducted in the Canadian population and once individuals agreed to participate, the respondents placed themselves in one of the five subgroups based on their profiles: non-runners without KOA (NRUN), non-runners who have received a diagnosis of KOA (NRUN-OA), runners without KOA (RUN), runners who have received a diagnosis of KOA (RUN-OA) and healthcare professionals (HCP) from different backgrounds. All the participants were asked to fill questionnaires that contained a series of questions pertaining to the study. A total of 114 non-runners, 388 runners and 329 HCP completed the survey. Results showed that 13.1% of public respondents perceived running as an activity that hurt the knee and 25.9% of them were uncertain of the effect. A great number of participants belonging to the NRUN and NRUN-OA group had a negative perception compared to the RUN group, 8.2% of the HCP felt that regular running was bad for knee joint health but 78.1% of them disagreed on this point. There was a negative perception felt by 3.9% of HCP who ran and 15.2% of HCP who did not run. Only 7.6% of the public felt running to be an activity that leads to KOA but 33.9% of them were unsure about it. Only 2.7% of the RUN population felt running to be detrimental to knee health compared to 23.1% of NRUN and 24.2% of NRUN-OA population.
15.5% of the public felt that running marathons or long-distances would end up in KOA while 43.6% of them were uncertain of the results. But 47.9% of the RUN, 15.4% in NRUN and 19.4% in NRUN-OA disagreed with this result. On the whole, 17.9% of the public felt that running with KOA would lead to profound knee damage, 48.4% were uncertain and 32.7% of the NRUN population and 46.8% of the NRUN-OA population agreed with this statement than the run subgroup. 41.9% public felt that running with KOA was ok on days when there were no symptoms felt but 39.5% were uncertain about it. But it was 12.4% of the general public who felt that running with KOA was a means to accelerate the need for a total knee arthroplasty but more than 50% of the public were confused regarding their stand in this. 30.8% of NRUN and 37.1% of the NRUN-OA population agreed compared to 5.4% of the run population. The study shows the clear confusion existing among individuals with regards to running and its effect on KOA.
All these studies show that evidences are still inconclusive and the risk of developing OA has to be identified individually presently. There is no way in which we can conclude on the role of running in knee OA with these results.
Long-distance Running & Knee Osteoarthritis A Prospective Study: /https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2556152/
Is There an Association between a History of Running and Symptomatic Knee Osteoarthritis? https://onlinelibrary.wiley.com/doi/full/10.1002/acr.22939
What are the Perceptions about Running and Knee Joint Health among the Public & Healthcare Practitioners in Canada? https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0204872
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