Does ultra-marathon running damage your hips?
Published May 2021 in BMJ Open Sport & Exercise Medicine
Our first hip study was a collaboration between UCL, Royal National Orthopaedic Hospital NHS Trust, The London Clinic and Richmond Runfest. The aim was to analyse the hip joints of inactive non-runners, moderately active runners and highly active runners. Our findings suggest that regular distance running does not cause additional damage to runners’ hip joints.
Marathons (42 km) and ultramarathons (>42 km), have steadily grown in popularity over the past three decades. Despite its multiple cardiorespiratory benefits, long-distance running has been linked with risks of lower extremity injuries — but the scientific evidence remains very limited.
While the knee has received more research attention in the past, as a presumably common site of running-related injuries, little is known about the health status of runners’ hips.
This was the first study of its kind, looking at hip joints in inactive people, moderate runners and highly active runners. Key areas of interest were the labrum, articular cartilage, ligaments and tendons. The study helps address popular misconceptions that long distance running damages the hip joints.
Coronal Dixon MR images showing intra-articular abnormalities in four volunteers, in ‘in-phase’ MRI sequences: (A) Moderately active runner 1 with labrocartilage separation (small arrow) and full thickness cartilage defect (big arrow); (B) moderately active runner 2 with simple labral tear (small arrow) and subcortical cyst (circle); (C) highly active runner 1 with complex labral tear (small arrow); (D) moderately active runner 3 with subchondral bone marrow oedema (square); SHOMRI grading system was used in the assessment of labrum, cartilage and bone marrow; SHOMRI, scoring hip osteoarthritis with MRI.
Axial Dixon MR images showing tendinosis, in ‘water phase’ sequences in two volunteers, respectively; (A) moderately active runner 1 with psoas tendinosis (arrow); (B) highly active runner with hamstring tendinosis (arrow). Arrows indicated the specific MRI findings. Grading systems developed by Chi et al were used in the assessment of tendons. Tendinosis is low-grade abnormality.
In short…
The study
Our objective was to assess hip health in non-runners, moderate runners and long-distance runners.
The study was a collaboration with organisers of Richmond Runfest, which helped us source participants, while non-runners were recruited via communications at University College London.
52 participants met the requirements: to be aged 18+, have no health or hip problems, and no pain in or injury to the hips.
The final cohort included 8 inactive non-runners, 28 moderately active runners (c. 21km per week) and 16 highly active runners (over 42km per week).
All participants underwent MRI scans of both hips.
What we found
There were no significant differences in demographics among inactive non-runners, moderately active runners and highly active runners.
Abnormalities in the labrum (cartilage in the hip socket) were found in 6% of non-runners’ hips, 21% of moderately active runners’ hips, and 16% of highly active runners’ hips.
Abnormalities of the acetabular cartilage were identified in 5% of moderately active runners’ hips, while no lesions were found in highly active runners and inactive non-runners.
Bone marrow oedema was only detected in 13% of moderately active runners’ hips.
Moderately active runners showed small abnormalities to tendons in 16% of hips. Highly active runners had tendinosis in 28% of hips. No tendon issues were detected in inactive non-runners; however, differences between groups were not statistically significant.
Abnormalities in ligaments were found in 11% of hips among moderately active runners and in 6% of those in highly active runners. No abnormalityties were found in non-runners’ hips. Differences between groups were not statistically significant.
Generally, significant differences were not found among inactive non-runners, moderately active runners and highly active runners.
Only bone marrow oedema was significantly more common in moderately active runners than the other groups, while subchondral cysts were significantly more common in runners than non-runners — however, these were minor/small in size and presented no symptoms.
No cartilage defects or bone marrow oedema were detected in highly active runners.
What it means
The results suggest that long distance running has no negative impact on the hip joint.
Only minor, non-specific abnormalities were more common in runners than non-runners.
Our findings could help reassure people that long-distance running is not detrimental to their hips.
Further studies are needed to clarify how much exercise is optimal in the long term.
