Freestyle biomechanics and shoulder injuries in competitive swimming

[摘要] Introduction: Epidemiologic studies have consistently noted a high incidence andprevalence of shoulder pain and dysfunction in competitive swimmers. The reasonsfor this are probably not singular but many injuries originate from faulty techniques ormechanisms. Some specific freestyle technical flaws heavily stress the shoulders andcan lead to overuse. An assessment of an injured swimmer's biomechanics shouldbe conducted to identify factors that may contribute to injury. Improving stroketechnique should be considered to prevent shoulder injuries.Objectives: To determine the prevalence of shoulder injuries at the University of theFree State's swimming club (Kovsie Aquatics) during the 2014/2015 swimmingseason, and to investigate if a correlation between certain freestyle biomechanicalhand and arm positions and shoulder injuries under these swimmers exist.Methods: Sixteen competitive swimmers (6 male, 10 female) adhering to theinclusion criteria participated in the study. Demographic data, general swimminginformation, data on swim training load and shoulder injuries were collected. Allparticipants were subjected to laboratory testing, followed by Aquanex+Video testingwhile sprinting freestyle over 10 metres. Freestyle biomechanics was analysed withthe use of an analysis template. Data captured by the Aquanex+Video hand sensorswere processed and analysed. The association between binary risk factors and thebinary variable 'shoulder injury was assessed using Fisher's exact test, and therelevant P-value is reported. Furthermore, the risks of injury for subjects with the riskfactor, and subjects without the risk factor are reported, together with an estimate andan exact 95% confidence interval (CI) of the risk ratio (RR). Similarly, the associationbetween quantitative risk factors and shoulder injury was assessed using one-wayANOVA.Results: In this study 62.5% of the participants presented with a shoulder injury duringthe 2014/2015 swimming season. Eighty percent of the female swimmers in thispopulation presented with a shoulder injury, compared to 30% of the male swimmers.The 17 to 18 years age category seemed to be most susceptible to injury, with 75% ofthe swimmers in this age category presenting with a shoulder injury. Bilateral shoulderinjuries were experienced by 70% of the injured swimmers, while 20% experiencedsymptoms on the right side only, and 10% only on the left side. Sixty percent of theinjured participants experienced their symptoms only during the early pull throughphase while 10% of the swimmers experienced symptoms only during the recoveryphase. Thirty percent of the swimmers experienced symptoms during both the earlypull through and recovery phase. Although none of the risk factors investigated in thisstudy was statistically significant, the presence of the following freestylepathomechanics increased the risk of shoulder injury, and should be considered infuture research of this problem:1. A right hand that crosses the midline upon hand entry;2. Thumb first hand entry;3. A left hand entering between the midline of the body and the shoulderHand/Arm position where the shoulder is in hyperflexion with the fingers facingupward at the end of the entry phase;4. Hand position outside the elbow during the early pull through phase;5. Swimming 'catch-up' stroke.Conclusion: In the current study the prevalence of shoulder injuries is alarminglyhigh at 62.5%. Female swimmers seem to be at a higher risk for shoulder injuries thantheir male counterparts. A relationship between certain freestyle pathomechanics andshoulder injuries in this population might exist, and some potential risk factors wereidentified. Due to the relatively small sample size of this study none of the risk factorsfor shoulder injury based on freestyle pathomechanics was statistically significant, thusonly indications and directions for future research can be suggested.

[发布机构] University of the Free State