Freestyle biomechanics and shoulder injuries in competitive swimming
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Date
2018-01
Authors
Du Pisani, Louis George
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
Introduction: Epidemiologic studies have consistently noted a high incidence and
prevalence of shoulder pain and dysfunction in competitive swimmers. The reasons
for this are probably not singular but many injuries originate from faulty techniques or
mechanisms. Some specific freestyle technical flaws heavily stress the shoulders and
can lead to overuse. An assessment of an injured swimmer’s biomechanics should
be conducted to identify factors that may contribute to injury. Improving stroke
technique should be considered to prevent shoulder injuries.
Objectives: To determine the prevalence of shoulder injuries at the University of the
Free State’s swimming club (Kovsie Aquatics) during the 2014/2015 swimming
season, and to investigate if a correlation between certain freestyle biomechanical
hand and arm positions and shoulder injuries under these swimmers exist.
Methods: Sixteen competitive swimmers (6 male, 10 female) adhering to the
inclusion criteria participated in the study. Demographic data, general swimming
information, data on swim training load and shoulder injuries were collected. All
participants were subjected to laboratory testing, followed by Aquanex+Video testing
while sprinting freestyle over 10 metres. Freestyle biomechanics was analysed with
the use of an analysis template. Data captured by the Aquanex+Video hand sensors
were processed and analysed. The association between binary risk factors and the
binary variable “shoulder injury” was assessed using Fisher’s exact test, and the
relevant P-value is reported. Furthermore, the risks of injury for subjects with the risk
factor, and subjects without the risk factor are reported, together with an estimate and
an exact 95% confidence interval (CI) of the risk ratio (RR). Similarly, the association
between quantitative risk factors and shoulder injury was assessed using one-way
ANOVA.
Results: In this study 62.5% of the participants presented with a shoulder injury during
the 2014/2015 swimming season. Eighty percent of the female swimmers in this
population 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% of
the swimmers in this age category presenting with a shoulder injury. Bilateral shoulder
injuries were experienced by 70% of the injured swimmers, while 20% experienced
symptoms on the right side only, and 10% only on the left side. Sixty percent of the
injured participants experienced their symptoms only during the early pull through
phase while 10% of the swimmers experienced symptoms only during the recovery
phase. Thirty percent of the swimmers experienced symptoms during both the early
pull through and recovery phase. Although none of the risk factors investigated in this
study was statistically significant, the presence of the following freestyle
pathomechanics increased the risk of shoulder injury, and should be considered in
future 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 shoulder
Hand/Arm position where the shoulder is in hyperflexion with the fingers facing
upward 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 alarmingly
high at 62.5%. Female swimmers seem to be at a higher risk for shoulder injuries than
their male counterparts. A relationship between certain freestyle pathomechanics and
shoulder injuries in this population might exist, and some potential risk factors were
identified. Due to the relatively small sample size of this study none of the risk factors
for shoulder injury based on freestyle pathomechanics was statistically significant, thus
only indications and directions for future research can be suggested.
Description
Keywords
Freestyle biomechanics, Shoulder injuries, Competitive swimming, Dissertation (M.A. (Exercise and Sport Sciences))--University of the Free State, 2018