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To the Editor,
We read the recent publication by Nathan, Davies & Swaine (2018) with great interest due to a mutual interest in the subject of Generalised Joint Hypermobility (GJH) and its influence on injuries within elite sport. The authors of this paper should be commended for undertaking a study with such good participant numbers over a range of sports. We believe that the findings of this study suggesting that GJH may be protective of joint ligament damage may be a very important initial paper leading to valuable further exploration within specific sports and specific joints. However despite this good work we would like to take the opportunity to raise a concern over one of their conclusions and how this may confuse readers of the article.
In the discussion section of this paper Nathan et al. (2018) suggest that the findings of this study may suggest that “regular stretching may increase flexibility, and this could subsequently reduce rates of injury in those that are less flexible.” We believe that this statement may lead to misunderstanding as the terms “flexibility” and “joint hypermobility” are two completely different entities.
GJH is a hereditary physiological entity whereby most synovial joints move beyond their normal limits (Pacey et al., 2010) and may, or may not be symptomatic. This entity is commonly classified by the use of the Beighton Scale, as in the Nathan et al. (2018) paper, whereby adult participants are deemed positive i...
GJH is a hereditary physiological entity whereby most synovial joints move beyond their normal limits (Pacey et al., 2010) and may, or may not be symptomatic. This entity is commonly classified by the use of the Beighton Scale, as in the Nathan et al. (2018) paper, whereby adult participants are deemed positive if they score five or more out of nine on the scale (Juul-Kristensen et al., 2017). The term flexibility however would commonly be recognised as the length of the muscle crossing the joint. It is suggested that within the paper the term “flexible joint” is overused, and the correct terminology should be “lax joint” as this would more closely match the fact that the authors are looking to further understand the influence of joint hypermobility.
We would suggest concluding that greater flexibility would decrease injury risk means the authors are misleading readers. It would be hypothesised that the decreased risk of injury within the ankle for example, may come from the ability of the athlete to enter ranges of inversion without stressing the passive ligamentous structures of the ankle which is thought to be in part due to the abnormal ratio of mobile type III collagen in hypermobile participants (Child, 1986). Flexibility of the muscles around the ankle joint is unlikely to provide a protective effect in this position. It is also worth noting that the terminology in the paper suggests that rates of joint sprains are lower in hypermobile participants highlights the fact that the authors were looking at ligamentous injury, and not muscular pathologies. It is unlikely that a stretching protocol would be able to influence the mobility of the passive ligamentous structures to such a degree that they would subsequently be classed as hypermobile, and therefore potentially at decreased risk of injury.
We would again like to highlight that this piece of work by Nathan et al. (2018) is a very important piece in the early stages are trying to better understand the influence of GJH upon injury risk. It is hoped that greater utilisation of the Lower Limb Assessment Score in sports where lower limb pathologies are most common may be able to assist in addressing the impact on practice suggestions from the authors.
Child, A.H. (1986). Joint hypermobility syndrome: Inherited disorder of collagen synthesis. The Journal of Rheumatology, 13(2), 239-243.
Juul-Kristensen, B., Schmedling, K., Rombaut, L., Lund, H. & Engelbert, R.H.H. (2017). Measurement properties of clinical assessment methods for classifying generalized joint hypermobility- A systematic review. American Journal of Medical Genetics Part C (Seminars in Medical Genetics), 175C, 116-147.
Nathan, J.A., Davies, K. & Swaine, I. (2018). Hypermobility and sports injury. BMJ Open Sport & Exercise Medicine, 4.
Pacey, V., Nicholson, L.L., Adams, R.D., Munn, J. & Munns, C.F. (2010). Generalized Joint Hypermobility and Risk of Lower Limb Joint Injury During Sport: A Systematic Review with Meta-Analysis. The American Journal of Sports Medicine, 38(7), 1487-1497.