Introduction: Running is a popular physical activity but associated with high rates of musculoskeletal injury. Running is perceived by some to be detrimental to joint health, yet it does not seem to increase the risk of knee or hip osteoarthritis (OA) or accelerate OA progression. Cartilage loss is the hallmark feature of OA and the impact of running on cartilage is not well understood. This study summarises the immediate impact of running on cartilage in healthy adults and those with, or at risk of OA, using magnetic resonance imaging (MRI) measures. Secondarily we explored the delayed impact of running on hip and knee cartilage, regional differences within each joint and associations with sex, run duration and age.
Methods: This study was a systematic review of six databases, with random-effects meta-analyses of studies that used MRI and a within-subject study design to measure change in hip or knee cartilage within 48 hours pre- and post-running. Risk of bias was assessed with the Newcastle-Ottawa Scale and certainty of evidence evaluated using the GRADE assessment.
Results: Twenty-four studies were included, evaluating 389 healthy knees and 57 knees with/at risk of OA (and no hips) in 378 participants (41% female). Participants were generally healthy, young adults (mean age 32 years, BMI 23kg/m2). Thirty-three percent of studies were assessed low risk of bias. Decreases in knee cartilage morphology (thickness/volume) and composition (quality) occurred immediately after running and were greatest in the patellofemoral compartment. Morphology changes ranged from a loss of patellar cartilage volume of 5.5% (95%CI 4.4-5.7%) to a loss of weight-bearing femoral cartilage thickness of 2.8% (1.9-3.7%). Tibiofemoral composition measures (T2 relaxation times) recovered to baseline levels within 90 minutes, and existing cartilage defects were not altered within 48 hours after run completion.
Discussion: There is very low certainty evidence that running immediately decreases the thickness, volume and composition of patellofemoral and tibiofemoral cartilage. These findings support the biphasic model of a hydrostatic cartilage response to loading with redistribution and exudation of small amounts of water. Immediately after running, T2 relaxation times reduced, consistent with expected water loss and matrix consolidation in healthy cartilage. Cartilage composition changes returned to baseline within 60-90 minutes of run completion and morphology (volume/thickness) was reported to recover from 15 minutes-12 hours after running. There are no relationships between cartilage changes after running and age or sex although a trend was noted that indicated increased relaxation time reductions with increased run duration.
- •A single bout of running causes small, transient changes in cartilage and is not bad for the knees of healthy, young adults.
- •Running can be promoted as a public health physical activity endeavour knowing that it doesn’t appear to immediately alter joint structure detrimentally.
My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract.