25 e-Letters

  • Re: Edouard et al, 2024¬, Letter to the Editor

    Dear Editor,
    I am writing in regard Edouard et al’s recent publication in your journal to bring your attention to what I think are some errors that have perhaps slipped through the editing process.
    The paper describes the results of their protocol (Lahti et al 2020): “… to compare if there is a significant effect of the intervention on the (hamstring muscle injury) occurrence using Cox regression analysis” where the intervention was “a multifactorial and individualised HMI risk reduction programme”.
    The pre-specified outcome (hamstring injury risk) was found to be no different for those undertaking the novel programme compared to the control group at any time – i.e. the complex multifactorial individualized programme did not reduce hamstring injury incidence, risk, or burden. The authors have subsequently reported the findings of secondary analyses not outlined in the published protocol. These reported secondary analyses also found no difference in hamstring muscle injury risk/incidence, but they did report that for a sub-group of 31/90 selected participants there was a reduction in hamstring injury burden (but not others, some of whom reported an increase).
    Specifically, these apparent errors (reporting a reduction in incidence/risk for the secondary analyses where the data do not support this) are:
    1. in the abstract: “… and additional secondary analyses showed a significant association between the intervention and lower HMI burden, incidenc...

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  • A reply to Solle, Streed and Restar

    Solle et al. argue that our study “supports a conclusion for the relationship between sex and race time, as a result of the poorly constructed and likely miscategorized sex variable”. However, if this view were correct, some other explanation would be needed to explain the statistically significant correlations we found between sex and race time. Solle et al. do not provide any such explanation.

    They state that our methodology is “unreliable”. But we do not assume that our model for sex is perfectly reliable, and we emphasize throughout that we model sex probabilistically. As we explain in the appendix to our paper, and illustrate with a numerical example, if one increases the uncertainty in our model this would indicate that there is an even stronger relationship between sex and race times. Solle et al. do not consider this point in their response, and as a result they fail to explain how their theory can be reconciled with the data.

    In the absence of such an argument, we believe that their theory cannot be reconciled with the data and so must be in some way flawed. We believe that the flaw in their argument is to overstate the difficulty in ascribing a sex to a non-binary athlete. For example, Solle et al. give the impression that we modelled non-binary athletes’ sex using only their names, yet for the majority of non-binary athletes we could determine their sex from their race history.

    Solle et al. go on to argue that our use of the terminology “na...

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  • Appropriate and robust methods needed when assessing athletic performance of non-binary athletes

    Inclusion for non-binary athletes in racing events has progressed in the last three years, with five of the six Abbott Major Marathons offering non-binary running categories in 2023. Given that the “main issue for non-binary people is that they cannot compete authentically” without the non-binary category1, non-binary race divisions were created, in part, as inclusion measures for non-binary individuals. As the number of non-binary athletes participating in running is increasing2, the representation and needs of non-binary athletes should be studied using appropriate methods that are in line with current best practices3, particularly in assessing gender and sex measurement and analyses. In their paper, “Performance of non-binary athletes in mass-participation running events,” Armstrong et al. utilize several methodological approaches and analyses that do not appropriately assess the performance of non-binary athletes. As a consequence, the conclusions of the paper introduce numerous biases with results that do not accurately reflect the reality of non-binary athletes.

    In designing their study, the authors attempt to determine the sex assigned at birth (labeled natal sex in their model) of non-binary athletes based on the presumed sex assigned at birth of their names. This approach is methodologically unreliable and flawed4. Specifically, the authors fail to distinguish between sex assigned at birth, legal sex, and any sex-related medical intervention that the athle...

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  • Dr Lim Zhuang Li

    Many thanks for producing the thoroughly enjoyable article on SEM practitioners around the world. We would like to add that SEM in Malaysia has also been well established as a standalone speciality since 2002. The impetus for for kickstarting the speciality was having being appointed the host city for Commonwealth Games 1998 (Kuala Lumpur). Our training programme, was in effect a combined 4 year run-through standalone clinical training, in its inception together with Rehabilitation Medicine originally, of which very early then branched out into an independent Sports Medicine Masters training program in the early 2000s, with on average 4 to 6 trainees a year qualifying out of the program. At the moment, we have approximately nearly 60 practitioners throughout the broader Malaysia with a large number of my contemporaries working within the Ministry of Health Malaysia. Our core service focuses on optimising musculoskeletal health across all spectrum of age and health, performing diagnostic imaging and guided-pain interventional, therapeutic and regenerative procedures, sideline and team physician management, prescriptive exercise clinics and fitness/performance testing, and various collaborative work with public health in being an advocate for healthy living. The training program is indeed quite similar as to how the Australasian and British FSEM curriculum content-wise, and has been traditionally done at the University of Malaya throughout the whole clinical course. Many of...

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  • Two issues with this paper, one of which is a significant calculational error

    The systematic review by Paultre et al. supports the use of turmeric or curcumin extract for knee osteoarthritis pain.

    They did not perform a formal meta-analysis but summarize the results of individual studies by calculating effect sizes based on the data in the original papers. Unfortunately there are two problems with these, one major and the other more modest.

    The major issue is with the last study reported in table 3, Srivastava (2016). Paultre et al. report very large effect sizes for this study, such as 8.6, 9.5, and even 11 for a visual analogue scale. These effect sizes are the usual "d" value, that is the mean difference divided by the standard deviation. Effect sizes of such high magnitudes should raise a red flag that something is wrong, as they are rarely attained in clinical studies.

    The authors' impressive effect sizes for Srivastava are errors due to using a standard error of the mean (SE) as if it were a standard deviation (SD). Srivastava et al. define the statistic used in the statistical methods: "The results are presented as mean ± SE." The values shown are also impossibly small to be standard deviations, which is what caught my attention. Both at 60 days and 120 days, the "standard deviations" shown for a 10-point VAS scale are around 0.1. This suggests a range of responses of about 0.5, which is not plausible.

    The SEM is the SD divided by the square root of the sample size and represents...

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  • Available implementations

    An implementation of REDI as a dedicated R package is now available: https://grenouil.github.io/REDI/.
    A code-free web app is also provided to compute REDI directly on your datasets: https://arthurleroy.shinyapps.io/REDI/

  • Reply to editor and authors

    Dear editor/ dear authors,

    We read with interest your editorial ‘Sport and exercise medicine around the world: global challenges for a unique healthcare discipline’ [1] in BMJ Open Sport and Exercise Medicine. We would like to congratulate the authors for bringing the challenges of our speciality back into the spotlight again.

    While Sports and Exercise Medicine (SEM) may be a modern and more inclusive terminology than sports medicine, many of the challenges of our speciality have remained the same over the years. Societies such as the European College of Sports and Exercise Physicians (ECOSEP) have championed for years for the advancement of sports medicine/ SEM speciality across Europe by providing education, publishing research, organising congresses, collaborating with other organisations and serving as a source of information to the public [2–4]. ECOSEP has been promoting exercise for prevention and treatment to policy holders, creating post-graduate programmes and seminars to provide further training for physicians and bringing practitioners together, not only with biannual congress but also through promoting professional dialogue and standards [2–4]. Other societies, like the European Federation of Sports Medicine Associations (EFSMA) have been champing for a common sports medicine speciality within Europe for over 20 years, providing a detailed curriculum for sports medicine practitioners [5]. Even back then they recognised that sports medicine is a m...

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  • Response to “Important Nuances for Non-Linear Modeling”

    We thank Shrier et al. for a thoughtful expansion on the topic of non-linearity.1 The comments from the authors provide valuable insights and detail to both the handling and the interpretation of fractional polynomials and splines, and may interest readers who seek more information than the short introduction in Bache-Mathiesen, et al. 2.

    We are especially grateful for elaborating on the interpretation of restricted cubic splines, and the solution of adding a small constant (i.e. 0.1) to all values to handle the value “0” when using fractional polynomials. These topics could not be sufficiently addressed within the limited wordcount of the original article, and we encourage readers to consider these comments.

    Conflict of Interest:
    None declared.

    1. Shrier I, Wang C, Stokes T, et al. Important Nuances for Non-Linear Modeling. BMJ Open Sport & Exercise Medicine 2021
    2. Bache-Mathiesen LK, Andersen TE, Dalen-Lorentsen T, et al. Not straightforward: modelling non-linearity in training load and injury research. BMJ Open Sport & Exercise Medicine 2021;7(3):e001119. doi: 10.1136/bmjsem-2021-001119

  • Important Nuances for Non-Linear Modeling

    We would like to thank Bache-Matiesen et al.(1) for their thoughtful article on non-linear modelling in sport medicine. Our own study on the non-linear relationship between acute: chronic workload ratio (ACWR) and injury risk in children was published as a preprint (2) and recently accepted by the American Journal of Epidemiology.(3) Below, we highlight some additional underlying principles in non-linear modelling that readers should understand.

    Models are based on information, which includes both data and assumptions. Simple linear models are more prone to bias because they assume a data generating process that is likely incorrect. The flexibility of non-linear models leads to less risk of bias, but also less precision. The optimal choice between bias and uncertainty depends on the context.(4)

    Bache-Matiesen describe three non-linear modelling options: quadratic modelling, fractional polynomials (FP), and restricted cubic splines (RCS, where knots are determined by either data driven or a priori methods). These all fall under generalized additive models (GAMs), or generalized additive mixed models (GAMMs; if one uses “random effects” to adjust for repeated measures on participants).

    FP methods use a single polynomial function over the entire range of exposures to predict the outcome. Quadratic models are special cases of FP (with exponents of 0, 1 and 2) and are too restrictive to be generally recommended. RCS separate data i...

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  • Interesting study

    Thanks to the authors for providing some preliminary data on the potential effectiveness of bike-fitting to reduce pain and discomfort in cycling.
    Very interesting study, but probably some questions are worth comments from authors:
    1- Was there a proper ethics approval for this study? It seems that data was obtained retrospectively from clinical records.
    2- How transferable to training is 100W of cycling?
    3- Would authors be able to disclose the source of the 'measurement reference values'? Elaborating the criteria used for changes in bike-fit is critical to understand how and why cyclists improved their posture on the bike.

    It would have been nice to see a control group to determine how much of the perceived changes are from placebo-effect.