Authors Laura M. Horga, Johann Henckel, Anna Di Laura, Martin A. Belzunce, Harry Hothi, Alister J. Hart, of the Royal National Orthopaedic Hospital, discuss the results of their Exercise for Science multidisciplinary medical research project.
Long distance running (>21 km) including marathons (42 km) and ultramarathons (>42 km), has significantly increased in popularity over the last decade [1-2]. Despite its various cardio-respiratory benefits, long-distance running has been anecdotally associated with a risk of injury, varying widely between 19-80% [3]. However, there is no reliable scientific evidence to support these numbers and clarify whether there is any cause for concern.
Exercise for Science [4] is a multidisciplinary medical research project aiming to answer the question: Is long-distance running bad for the hip joints?
The project is led by Professor Alister Hart and is based in London. It’s unusual in bringing together specialists from diverse fields to focus on the medical effects of exercise. Key is the collaboration with Consultant Radiologists Dr Anastasia Fotiadou at the Royal National Orthopaedic Hospital and Dr Anna Hirschmann at the University Hospital of Basel, together with engineers and scientists.
The research team has applied high-resolution magnetic resonance imaging (3 Tesla MRI), which enables anatomical visualisation of internal musculoskeletal joint structures including early signs of lesions, to study the hip joints and muscles of first-time marathon runners and high-dose runners.
What have we discovered?
Baseline study [5]
The research team recruited 52 asymptomatic volunteers who were falling into 3 different categories, based on their activity level: 1) 8 inactive non-runners; 2) 28 moderately active runners (average half a marathon (21 km)/week) and 3) 16 highly active runners (≥ marathon (42 km)/week).
The aim was to compare the hip condition of these 3 groups on 3.0 T MRI scans.
Two musculoskeletal radiologists reported the hip MRI results using validated semi-quantitative scoring systems. The participants completed a Hip disability and Osteoarthritis Outcome Score (HOOS) questionnaires to indicate their perceived hip function.
Results showed that the number of hip abnormalities on 3.0 T MRI was not significantly different among inactive non-runners, moderately active runners and highly active runners in most hip joint structures. This includes the labrum, articular cartilage, ligaments and tendons.
Interestingly, there were no chondral defects or bone marrow oedema in highly active runners.
Only minor non-specific bone marrow abnormalities were more common in runners than in non-runners, which was not deemed to be significant.
No significant changes in hip symptoms or joint functionality were observed.
Take home message: Regular long-distance running does not add damage to your hips!