Effects of Running and Walking on Osteoarthritis and Hip Replacement Risk

Paul T. Williams

Disclosures

Med Sci Sports Exerc. 2013;45(7):1292-1297. 

In This Article

Abstract and Introduction

Abstract

Purpose: Running and other strenuous sports activities are purported to increase osteoarthritis (OA) risk, more so than walking and less-strenuous activities. Analyses were therefore performed to test whether running, walking, and other exercise affect OA and hip replacement risk and to assess the role of body mass index (BMI) in mediating these relationships.

Methods: In this article, we studied the proportional hazards analyses of patients' report of having physician-diagnosed OA and hip replacement versus exercise energy expenditure (METs).

Results: Of the 74,752 runners, 2004 reported OA and 259 reported hip replacements during the 7.1-yr follow-up; whereas of the 14,625 walkers, 696 reported OA and 114 reported hip replacements during the 5.7-yr follow-up. Compared with running <1.8 MET·h·d−1, the risks for OA and hip replacement decreased as follows: 1) 18.1% (P = 0.01) and 35.1% (P = 0.03) for the 1.8- and 3.6-MET·h·d−1 run, respectively; 2) 16.1% (P = 0.03) and 50.4% (P = 0.002) for the 3.6- and 5.4-MET·h·d−1 run, respectively; and 3) 15.6% (P = 0.02) and 38.5% (P = 0.01) for the ≥5.4-MET·h·d−1 run, suggesting that the risk reduction mostly occurred by 1.8 MET·h·d−1. Baseline BMI was strongly associated with both OA (5.0% increase per kilogram per square meter, P = 2 × 10−8) and hip replacement risks (9.8% increase per kilogram per square meter, P = 4.8 × 10−5), and adjustment for BMI substantially diminished the risk reduction from running ≥1.8 MET·h·d−1 for OA (from 16.5%, P = 0.01, to 8.6%, P = 0.21) and hip replacement (from 40.4%, P = 0.005, to 28.5%, P = 0.07). The reductions in OA and hip replacement risk by exceeding 1.8 MET·h·d−1 did not differ significantly between runners and walkers. Other (nonrunning) exercise increased the risk of OA by 2.4% (P = 0.009) and hip replacement by 5.0% per MET·h·d−1 (P = 0.02), independent of BMI.

Conclusions: Running significantly reduced OA and hip replacement risk due to, in part, running's association with lower BMI, whereas other exercise increased OA and hip replacement risk.

Introduction

Osteoarthritis (OA) is the leading cause of disability in the aged, affecting between 7% and 25% of Caucasians >55 yr old, and is projected to become the fourth most common medical condition in women.[11] There is a common perception that, over the long run, running is injurious to joints.[11] Running and vigorous sports activity do, in fact, increase the risk of knee trauma and injuries, which in turn are known risk factors for knee OA.[11] Alternatively, running reduces body weight,[38,39] a known risk factor for OA,[3] which may offset in part its pro-OA effects, resulting in diminished OA risk or even OA protection. Exercise may also promote cartilage thickening[12,13] and prevent the loss cartilage proteoglycans,[30,34] which provide cartilage's viscoelastic properties.[22] These effects are important because cartilage thinning[11] and focal loss of proteoglycans[5] are prominent features of OA.

Case–control studies suggest a positive relationship between OA and physical sporting activities in general, and running in particular, with an odds ratio of approximately 2 for both.[20] There are prospective studies in humans that claim that exercise increases,[2,3,6,16,23,31,32,37] has no significant effect,[1,5,9,10,17,27] or decreases the risks for hip replacement or OA.[18,24] There are also animal studies suggesting that exercise increases[14] or decreases OA risk.[7,29]

With nearly 90,000 participants, the National Runners' and Walkers' Health Studies are the largest prospective cohorts specifically recruited for the study of health benefits and risk of physical activity. Their data provide a unique opportunity to test whether OA and hip replacement risk are 1) increased by running, walking, and other exercise in relation to amount and intensity; 2) increased more for running than walking; and 3) reduced because of the leanness of higher mileage runners and walkers.

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