Abstract
Recreational running is a type of physical activity with proven health benefits, including improvements in aerobic fitness and cardiovascular function. Recreational running is reported as one of the most popular physical activities among Australians, with 7.4% of the population participating. As with any physical activity, there are health-related risks, with musculoskeletal injuries the most commonly observed injury in runners, specifically, Achilles tendon injuries and bone stress injuries. Running-related injuries are complex conditions,and their development depends on the interaction of multiple factors. These include extrinsic factors, such as training, lifestyle habits, and intrinsic factors, such as sex, age and genetic predisposition. Musculoskeletal injuries are recurrent in nature, preventing runners from their regular physical activity and therefore affect their health. An increased understanding of factors that contribute to the development of the injuries may, therefore, assist with injury prevention strategies, reduce injury rates and potentially encourage more people to exercise regularly. This study aimed to investigate the health, training and lifestyle habits of Australian recreational runners, identifying the most common running-related injuries and associated risk factors, and explore genetic variants associated with Achilles tendon injuries and bone stress injuries using a genome-wide association study (GWAS) approach.The project utilised an online survey platform and versatile promotional approaches in order to recruit recreational runners across Australia. A 25-month recruitment campaign resulted in a dataset of 4,720 completed survey responses. This study demonstrated that our cohort of recruited Australian recreational runners met recommended physical activity guidelines;and health risk factors such as smoking, overweight and hypertension were not typical.Moreover, the commencement of a running program was associated with significant weight loss. In addition, this study identified significant differences in running habits of male and female runners, with men were more likely to run more than six sessions per week and at a faster race pace than female recreational runners. In relation to injuries, an Achilles tendon injury was the most commonly reported injury, with its occurrence associated with being male, older in age, and faster race pace and stretching. The second most commonly reported injury was a bone stress injury, and its occurrence was associated with younger age, obesity, and longer weekly running distance and stretching.
Whilst a large-scale survey (4,720 participants) was achieved (Chapters 2 and 3), and despite numerous adjustments and targeted recruitment strategies, our recruitment into the IIGWAS were smaller than expected. The data and findings presented in Chapters 4 and 5 are from this initial explorative study of genetic association with Achilles tendon injuries and bone stress injuries. Challenges of recruitment for large-scale genetic studies are also discussed throughout this thesis.
The GWAS component of the presented study comprises 1,099 analysed samples achieving only 23.1% and 95.8% of our case-control recruitment targets, respectively. The genetic data analyses were of an explorative nature as the sample size was not sufficient for reaching the significance levels required for the GWAS. The case-control analysis of the genetic variants associated with Achilles tendon injuries identified several putative genes(TCF7L1, DOCK4 and TLE1), which were linked to the Wnt signalling pathway. The study failed to replicate the results of previously reported genetic associations with Achilles tendon injuries, except two results of polymorphisms which were a putative replication (rs1110495in the intragenic region (6:51914974) and rs12722 in COL5A1 gene). These results should be interpreted with caution due to the imputed nature of the data. The second case-control analysis of genetic association with bone stress injuries identified only one genetic variant in the gene TMEM135, whose protein function may contribute to the development of these injuries. Attempts to replicate previously shown genetic associations did not confirm those findings, except one putative replication for rs2051748 in CALCR gene. However, identified associations have to be taken with caution due to the small sample size of the study and risk of false-positive results.
In conclusion, this study demonstrated that Australian recreational runners had a body mass index within the healthy weight range, seemed to be meeting the recommended physical activity guidelines and were non-smokers. The identified sex differences in training habits may contribute to the promotion of recreational running depending on biological sex. The described factors associated with running-related injuries, specifically Achilles tendon injuries and bone stress injuries contributed to the body of knowledge about the development of running-related injuries and potentially would advance injury preventive strategies. The analyses of the genetic data provided new information about potentially important genetic markers and pathways, which may contribute to the development of running-related injuries and further our understanding of the pathophysiology behind these injuries. The collected phenotypic and genomic data may also contribute to the future research of these injuries, data meta-analysis and a better understanding of the genetics of multifactorial conditions.
| Date of Award | 12 Oct 2019 |
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| Original language | English |
| Supervisor | Kevin John Ashton (Supervisor), Nuala Byrne (Supervisor), David Hughes (Supervisor), Nicole Vlahovich (Supervisor) & Paul Leo (Supervisor) |