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Sex differences in injury during top-level international athletics championships: surveillance data from 14 championships between 2007 and 2014
  1. Pascal Edouard1,2,3,
  2. Nina Feddermann-Demont4,5,
  3. Juan Manuel Alonso6,7,
  4. Pedro Branco6,8,
  5. Astrid Junge4,9,10
  1. 1Department of Clinical and Exercise Physiology, Sports Medicine Unity, University Hospital of Saint-Etienne, Saint-Etienne, France
  2. 2Laboratory of Exercise Physiology (LPE EA 4338), University of Lyon, Saint Etienne, France
  3. 3Medical Commission, French Athletics Federation (FFA), Paris, France
  4. 4FIFA Medical Assessment and Research Centre (F-MARC), Zurich, Switzerland
  5. 5Department of Neurology, University Hospital Zurich, Zurich, Switzerland
  6. 6Medical & Anti Doping Commission, International Association of Athletics Federations (IAAF), Monaco, Monaco
  7. 7Department of Sports Medicine, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
  8. 8European Athletics Medical & Anti Doping Commission, European Athletics Association (EAA), Lausanne, Switzerland
  9. 9Medical School Hamburg, Hamburg, Germany
  10. 10Schulthess Clinic Zürich, Zurich, Switzerland
  1. Correspondence to Dr Pascal Edouard, Department of Clinical and Exercise Physiology, Sports Medicine Unity, Bellevue Hospital, University Hospital of Saint-Etienne, Saint-Etienne Cedex 2 42 055, France; Pascal.Edouard42{at}gmail.com

Abstract

Background Injury incidence has been reported for international athletics championships from 2007 to 2012. However, it is unclear whether male or female athletes differ in risk and/or characteristics of injuries.

Objective To compare the incidences and characteristics of injuries that occurred during international athletics championships between female and male athletes.

Methods The national medical team and the local organising committee physicians reported all injuries daily on a standardised injury report form during 14 international championships from 2007 to 2014. Relative risks (RR) of injury, 95% CI and magnitude thresholds were calculated.

Results The rate of injuries per 1000 registered athletes was significantly higher in male (110.3±6.8) than in female (88.5±6.7) athletes (RR=1.25; 95% CI 1.13 to 1.37, small effect size). Male athletes incurred significantly more injuries in the thigh (RR=1.64; 95% CI 1.32 to 2.05, small), lower leg (RR=1.36; 95% CI 1.05 to 1.75, small) and hip/groin injuries (RR=2.26; 95% CI 1.31 to 3.88, moderate), more muscle strains (RR=1.64; 95% CI 1.33 to 2.04, small), cramps (RR=1.81; 95% CI 1.35 to 2.43, small), and especially more thigh strains (RR=1.66; 95% CI 1.25 to 2.19, small), but fewer stress fractures (RR=0.32; 95% CI 0.12 to 0.81, moderate) than female athletes. A higher injury risk of male than of female athletes was observed in sprints (RR=1.32; 95% CI 1.06 to 1.66, small), middle distance runs (RR=1.48; 95% CI 1.06 to 2.06, small), race walks (RR=2.55; 95% CI 1.27 to 5.10, moderate) and jumps (RR=2.13; 95% CI 1.53 to 2.97, moderate). No sex difference was found for cause and severity of injury.

Conclusions Injury risk during international athletics championships differed between female and male athletes for location, type and event groups. Injury prevention strategies should be sex-specific, regarding the differences in injury location and type.

  • Epidemiology
  • Injury
  • Athletics
  • Prevention
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Introduction

During top-level international athletics championships, injury risk was about 100 injuries per 1000 athletes for outdoor championships, and about 63 injuries per 1000 athletes for indoors championships.1 Around half of these injuries lead to time loss in sport.1 Knowledge of such epidemiological data is the first step in the injury prevention sequence.2 The second step is to determine risk factors to identify predisposed athletes and develop injury prevention strategies with the goal of protecting the athlete's health.2–4

Sex is a risk factor for injury during athletics championships. It has been reported that male athletes suffered more injuries than female athletes during previous World and European outdoor championships.5–7 Sex-specific differences in injury location and type have been reported from some championships.5–9 However, these studies include data from just one championship per study, and have contradictory results. A recent summary of publication on injuries during 13 international athletics championships1 did not report sex-specific results.

The aim of the present study was to compare the incidences and characteristics of injuries during 14 top-level international athletics championships from 2007 to 2014 between male and female athletes to further evaluate the role of sex as an injury risk factor and provide the information necessary to develop sex-specific recommendations for injury prevention.

Methods

The study design, injury definition and data collection procedure was identical for all championships and have been previously described in detail.1 ,5–11

Newly incurred injuries during the respective athletics championships were reported daily by the national medical teams (physicians and/or physiotherapists) and/or by the local organising committee physicians (LOC). An injury was defined as ‘all musculoskeletal injuries (traumatic and overuse) newly incurred during competition or training regardless of the consequences with respect to the athlete's absence from competition or training’.8 ,10

Injuries were recorded during 14 top-level international athletics championships from 2007 to 2014, and included in the present analysis: World Outdoor Championships (WOC) 2007,8 2009,5 2011,6 2013; Olympic Games (OG) 2008,12 2012;13 European Outdoor Championships (EOC) 2010, 2012;7 World Indoor Championships (WIC) 2008, 2010, 2014; European Indoor Championships (EIC) 2009, 2011,9 2013.11 All except WOC 2013, WIC 2014 and EIC 2013 were part of the overall analysis by Feddermann-Demont et al.1

Definitions and calculation of indices used in the present study have been described by Feddermann-Demont et al1 and by Timpka et al14 In cases where a single injury incident resulted in more than one injured body part and/or type of injury, each body part and/or type, injury was counted as a separated injury. Thus, numbers of athletes and injuries, and incidences could differ slightly from previous publications where injury incidents were treated as one injury.1 ,5–9 ,11–13 Event groups were in accordance with the consensus statement.14 Incidences of all (time-loss) injuries, training injuries and in-competition (time-loss) injuries were calculated as number of injuries per 1000 registered athletes using a list of athletes provided by the International Association of Athletics Federations (IAAF) or the European Athletics Association (EAA).

Data of male and female athletes were compared for individual championships as well as pooled for outdoor, indoor and all championships. Data were analysed and presented using frequencies, percentages, cross-tabulations, incidences, relative risks (RR) with 95% CI, and χ2 test. RR were also analysed for practical significance using magnitude-based inferences. Magnitude thresholds for relative risks have been reported as trivial, small, moderate, large and very large for relative risks values of <1.2, <1.9, <3.0, <5.7 and <19 and the inverse for reductions in proportions >0.9, >0.7, >0.5, >0.3 and >0.1, respectively.15 All data were processed using Excel. Significance was accepted at p<0.05.

Results

Medical teams participation, response rate and coverage

On average 27.5% of all registered countries participated in the injury surveillance project, covering on average 75% of registered athletes; the national medical staff returned on average 87.6% of the expected injury report forms (information is missing for OG 2008, OG 2012 and WIC 2010). The completeness of injury data from LOC and medical teams averaged 95.6%. No athlete refused to allow his/her data to be used for scientific research.

Incidences and characteristics of injuries

A total of 961 injuries were reported in male athletes and 632 in female athletes, of these 450 (46.8%) injuries of male and 308 (48.9%) of female athletes were reported to result in time loss from sport. The overall incidence of injuries was significantly higher in male than female athletes (110.3±6.8 vs 88.5±6.7 injuries per 1000 registered athletes, respectively; RR=1.25; 95% CI 1.13 to 1.37, small); excluding injury data from EOC 2010, WIC 2008 and WIC 2010 because those competition studies had missing data for sex (table 1). No significant differences were reported in the proportion of injured male and female athletes between age-groups (<20, 21–25, 26–30 and >31 years).

Table 1

Number of registered athletes and of injuries, incidences of injuries per 1000 registered athletes and relative risks with lower and upper limits of ±95% CI and probabilistic inferences about the true standardised magnitude in relative risks, in male and female athletes during 14 international athletics championships 2007–2014

Male athletes suffered significantly more injuries, in-competition injuries, time-loss injuries and in-competition time-loss injuries than female athletes for outdoor and all championships, while the injury incidence in indoor championships and of training injury were similar for both sex (table 2). Overall, the injury incidences were significantly higher in male than female athletes for sprints, middle distance runs, race walks and jumps (for details see table 2). In outdoor events, male athletes had a significantly higher injury incidence than female athletes in sprints, race walks and jumps while in indoor events the difference was only significant for combined events.

Table 2

Incidences per 1000 registered athletes and relative risks (RR) of injury with lower and upper limits of ±95% CI and probabilistic inferences about the true standardised magnitude in relative risks, in male and female athletes during outdoor (WOC 2007, 2009, 2011, 2013, OG 2012, EOC 2012) and indoor (WIC 2014, EIC 2009, 2011, 2013) championships

The injury frequency differed significantly between male and female athletes for location (for all injuries: χ2=19.6, p=0.05) and type (for all injuries: χ2=36.1, p<0.001; table 3), but not for cause and severity. Overall, higher incidences were reported in male than female athletes for thigh, lower leg, hip/groin injuries as well as for muscle strain and muscle cramps (table 3). The incidence of stress fractures was higher in female than male athletes (table 3). Out of the eight most frequent diagnoses, significantly higher injury risks in male than in female athletes were observed for thigh strains, thigh cramps and lower leg cramps (table 3).

Table 3

Incidences of injury per 1000 registered athletes and relative risk of injury with lower and upper limits of ±95% CI and probabilistic inferences about the true standardised magnitude in relative risks, in male and female athletes for location, type and specific diagnoses (WOC 2007, 2009, 2011, 2013, OG 2012, EOC 2012, WIC 2014, EIC 2009, 2011, 2013)

Discussion

The main findings of the present study were that male athletes had 25% higher risk of injury than female athletes during top-level international athletics championships, and that injury risk of male and female athletes differed with regard to location, type and event groups.

Sex-related differences in injury risk

The higher injury risk in male athletes extends previous studies reporting data during single athletics championships.5–7 The present study combined results from 14 international championships, therefore strongly supports these results. Male athletes had about 25% higher risk of sustaining an injury during international championships than female athletes. Male athletes had 24% and 35% higher injury risk during international outdoor and indoor championships than female athletes, respectively, while insignificant for indoors. It is unknown whether the sex differences in injury risk are related to anatomical and physiological differences between female and male athletes, or reflect the different athletics event groups and patterns (technique, power, strategy, training/competition loads) and/or risk-taking behaviours.

Epidemiological studies during the whole-season report conflicting results: higher risk in male athletes,16 or in female athletes17 ,18 or no sex-related differences.17–20 The study design, injury surveillance methods, injury definition and classifications varied in those studies. Prospective studies on large cohort of athletes during whole-season and using a same validated method14 should help to better determine/understand the risk factor of sex.14 ,21

Sex-related differences in injury risk have also been reported in other sports. The injury risk of male athletes is higher in FIFA World Cups football players,22 taekwondo fighters during the Olympic Games 201213 and elite skiers,23 while a higher injury risk in female athletes is reported in aquatics sports during the FINA World Championships 2009,24 in alpine and snowboarding during the Winter Olympic Games 201025 and in football during the Olympic Games 2012.13 Thus, the sex-specific difference should be regarded in epidemiological studies in the presentation of results. For clinical practice, the knowledge of the sex-specific injury risk of each sport is important in the risk factors screening.

Sex-related differences in injury characteristics

In top-level international athletics championships, injury characteristics, such as location and type, varied between sexes. Thigh injuries were more frequent in male than female athletes, which is consistent with previous reporting data during single athletics championships.5 ,7 As previously shown for the athletics championships in Daegu 2011, male athletes suffered more muscle strains and muscle cramps than female athletes.6 Interestingly, male athletes had about twice the risk of thigh strains than female athletes (table 3), although thigh strains were the most frequent injury diagnosis in female and male athletes.

Further studies should distinguish between hamstring and quadriceps strains and the level of severity to determine whether sex-related difference apply to all or just to specific types of thigh strains. Determining the origin of this sex-related difference in thigh strains incidence can help to develop specific/adapted prevention measures. Sex-differences in (1) the morphological and physiological characteristics (muscle mass,26 strength,26 power,27 activity,28 ,29 fatigue,30 stiffness31 or sacropelvic morphology32…), (2) the sprint/running biomechanics,30 ,33 or (3) the athletics event groups (technique, pattern, exposure (number of events in combined events or distance of runs in race walking)) have been reported which should be further analysed for the thigh strains.

The higher risk of stress fractures in female athletes has been reported previously for athletics34 and for sports in general.35 Although stress fractures represented low percentage of all injuries (in the present study 2.9% of all injuries and 4.9% of in-competition time-loss injuries of female athletes), it should not be neglected, because it could be one symptom of the female athlete triad (now called the Relative Energy Deficiency in Sport (RED-S)).36 RED-S affects many aspects of physiological function, and should, therefore, be diagnosed and treated early to prevent further health and performance consequences.36 Stress fractures may be a related warning signal.

Sex-related differences in event groups

Sex difference in the injury incidences were observed in specific events. A higher injury risk in male than in female athletes has been observed in sprints, middle distance runs, race walks and jumps. The difference in race walks can be explained by different distances for men (20 and 50 km) and women (20 km). For sprints, middle distance runs and jumps, the exposure is similar to both female and male athletes, however, other parameters (anatomical, physiological, biomechanical or psychological factors) should be studied to explain the observed differences.

Methodological considerations

This is the first study on sex-specific injury risk including a large number of international athletics championships, which strengthens the presented results. However, some championships could not be included in the analysis due to missing data. Although the coverage of athletes and the response rate of medical teams were high, some injuries could be missing as during previous studies.5–9 ,11 However, since LOC participated in injury collection in addition to medical teams, we can expect that all injured athletes have been recorded. Also, it is unlikely that the missing data resulted in any bias of the sex-related analysis. As outlined above, differences between female and male athletes in injury risk and characteristics could have been influenced by differences in exposure, especially in race walks and combined events. Since univariate analyses where the only variable of sex was performed, the observed sex differences are due to an uneven distribution of risk factors that were unaccounted for. Finally, since the event groups contains events which are of different biomechanical and biometric components, further study should analyse the injury incidence in the separate events.

Practical implications

These present results highlight the interest of presenting/analysing separately epidemiological data from male and female athletes. This is of interest for injury surveillance during championships, but also for prospective studies on large cohort of athletes during whole-season, which represent a fundamental perspective in athletics injury prevention research.14 ,21

The knowledge of the sex-specific injury risk is also important in risk factor screening. Indeed, injury risk, injury rate and injury characteristic, are different between male and female athletes, therefore clinical examination and prevention measures could be adapted with sex. The next step is now to determine the origin of these sex-related differences by future biomechanical and/or physiological studies.

Summary and conclusions

During 14 top-level international athletics championships, male athletes had higher risk of injuries than female athletes. Moreover, injury incidences differed between sexes for location, type and event groups. Males suffered more thigh strains than female athletes. Our data add weight to the call that for injury prevention, ‘one size does not fit all’.37 Specifically from this analysis, prevention strategies will likely need to take sex into account and where appropriate, be adapted to the differences in injury characteristics between female and male athletes.

What are the new findings?

  • Male athletes had a significant higher risk to be injured compared to females during the international athletic championships.

  • Injury risk differed between female and male athletes in location, type and event groups.

  • Male athletes suffered more thigh strains (RR=1.66, 95% CI 1.25 to 2.19) but fewer stress fractures (RR=0.32, 95% CI 0.12 to 0.81) than female athletes.

How might it impact on clinical practice in the near future?

  • Injury prevention strategies should be sex-specific, adapted to the differences in injury characteristics between female and male athletes.

Acknowledgments

The authors highly appreciate the cooperation of the team of physicians and the medical staff of the different championships (WOC, EOC, OG, WIC, EIC) who volunteered their time to collect the data for this project. The authors would also like to thank Mathieu Oriol (Lucien Neuwirth Cancer Institute, Saint Etienne, France) for his contribution for the statistical analyses.

References

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Footnotes

  • Contributors PE made substantial contributions to conception and design of the project, prepared data files for championships, analysis and interpretation of data of all championships, drafting, writing and revising of the manuscript and final approval of the version to be published. NF-D made substantial contributions to prepare data files for some championships, revision of the manuscript and final approval of the version to be published. JMA made substantial contributions to development of the project and data collection, revision of the manuscript and final approval of the version to be published. PB made substantial contributions to the data collection, revision of the manuscript and final approval of the version to be published. AJ made substantial contributions to conception and design of the project, development of methods for injury surveillance and analysis, prepared data files for some championships, analysis and interpretation of data of all championships, revision of the manuscript, final approval of the version to be published.

  • Competing interests None.

  • Ethics approval The study was reviewed and approved by the Oslo University School of Medicine Ethical Committee (for athletics championships from 2007 to 2011 and for Olympic Games) and the Saint-Etienne University Hospital Ethical Committee (for athletics championships from 2012 to 2014).

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

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