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Methods matter: exploring the ‘too much, too soon’ theory, part 1: causal questions in sports injury research
  1. Rasmus Oestergaard Nielsen1,2,
  2. Michael Lejbach Bertelsen1,
  3. Merete Møller3,
  4. Adam Hulme4,
  5. Mohammad Ali Mansournia5,6,
  6. Marti Casals7,8,
  7. Erik Thorlund Parner9
  1. 1 Department of Public Health, Section for Sports Science, Aarhus University, Aarhus, Denmark
  2. 2 Research Unit for General Practice, Aarhus, Denmark
  3. 3 Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
  4. 4 Centre for Human Factors and Sociotechnical Systems, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
  5. 5 Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
  6. 6 Sports Medicine Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
  7. 7 Sport and Physical Activity Studies Centre (CEEAF), University of Vic-Central University of Catalonia (UVic-UCC), Barcelona, Spain
  8. 8 Medical Department, Futbol Club Barcelona, Barça Innovation Hub, Barcelona, Spain
  9. 9 Department of Public Health, Section for Biostatistics, Aarhus University, Aarhus, Denmark
  1. Correspondence to Dr Rasmus Oestergaard Nielsen, Department of Public Health, Section for Sports Science, Aarhus University, Aarhus 8000, Denmark; roen{at}


Background It is widely accepted that athletes sustain sports injury if they train ‘too much, too soon’. However, not all athletes are built the same; some can tolerate more training than others. It is for this reason that prescribing the same training programme to all athletes to reduce injury risk is not optimal from a coaching perspective. Rather, athletes require individualised training plans. In acknowledgement of athlete diversity, it is therefore essential to ask the right causal research question in studies examining sports injury aetiology.

Purpose In this first part of a British Journal of Sports Medicine educational series, we present four different causal research questions related to the ‘too much, too soon’ theory and critically discuss their relevance to sports injury prevention.

Content If it is true that there is no ‘one size fits all’ training programme, then we need to consider by how much training can vary depending on individual athlete characteristics. To provide an evidence-base for subgroup-specific recommendations, a stronger emphasis on the following questions is needed: (1) How much training is ‘too much’ before athletes with different characteristics sustain sports-related injury? and (2) Does the risk of sports injury differ among athletes with a certain characteristic (eg, high experience) compared with athletes with other characteristics (eg, low experience) depending on how much training they perform?

Conclusion We recommend that sports injury researchers aiming to examine the ‘too much, too soon’ theory should carefully consider how they, assisted by coaches, athletes and clinicians, pose their causal research question. In the light of the limitations of population-based prevention that intends to provide all athletes with the same advice, we argue that a stronger emphasis on research questions targeting subgroups of athletes is needed. In doing so, researchers may assist athletes, clinicians and coaches to understand what training advice/programme works best, for whom and under what circumstances.

  • statistics
  • methodology
  • sport

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  • Twitter @RUNSAFE_Rasmus, @MB_Runsafe, @Merete_Moller, @system_complex, @CasalsTMarti

  • Contributors RON and MLB developed the methodological idea. RON drafted the manuscript. All authors contributed with important intellectual suggestions for improvement to the content of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.