Abstract
The aim of this thesis was to identify and investigate athlete characteristics related to underwater undulatory swimming (UUS) performance in competitive swimming, to enhance current biomechanical understanding and better inform training prescription and practice. The aim was achieved through four research chapters.A systematic review, presented in Chapter 3 assessed the current peer-reviewed literature on the relationship between UUS performance determinants and underwater velocity in competitive swimmers. Twenty-five studies met the inclusion criteria and revealed that underwater velocity determinants vary as a function of body position, horizontal distance from the block and level of swimmer. The strongest correlates to underwater velocity overall were found to be mean foot resultant acceleration (r=0.94), kick frequency (r=0.90), vertical toe velocity (r=0.85), shoulder angle (r=0.80), body wave velocity (r=0.78), hip angular velocity (r=0.73), maximum knee flexion and extension angle (r=0.88) and maximum knee extension angle (r=0.84). Limitations in study methodologies and the literature were also identified.
The first experimental study presented in Chapter 4 established the relationship between kinanthropometric, kinematic variables, and centre of mass (COM) velocity in high-performance swimmers using three-dimensional (3D) motion capture and analysis. A secondary aim of this study was to gain insight into whether the relationships assessed in the primary aim differed between female (F) and male (M) swimmers. Twenty-one (11F, 10M) national and international level swimmers were included in the current study. There were no significant relationships identified for group data, however hip flexor strength (r=0.610) and horizontal COM displacement (r=0.665) were significantly correlated to COM velocity for female and male swimmers, respectively. COM velocity was not significantly different between female and male swimmers, despite all anthropometric measures, kick frequency, up kick (UK) time and down kick (DK) time exhibiting significant sex-related differences. Hierarchical linear regression analyses revealed that UK performance explained additional variance in COM velocity for both female and male swimmers, as well as a number of other kinanthropometric and kinematic variables.
The aim of the study presented in Chapter 5 was to investigate the impact of altering a swimmer’s preferred kick frequency on their Froude efficiency, kinematics, and velocity. 3D kinematic analyses were used to analyse UUS data of twenty (11F, 9M) national and international level swimmers. Analysis of Variance (ANOVA) and Friedman test statistics identified 10 of the 12 kinematic variables to have a significant main effect for kick frequency. COM velocity significantly decreased when kick frequency decreased and did not increase at supramaximal frequency. Froude efficiency, kick amplitude and horizontal COM displacement also decreased at supramaximal frequencies, and body wave velocity increased. The highest COM velocity was obtained at most swimmer’s self-selected frequencies, which may have been due to their extensive training history and self-organisation of their movement patterns to minimise energetic cost. As increasing velocity at kick frequencies above a swimmer’s preferred frequency would seem dependent on a swimmer’s ability to maintain kick amplitude, training programs may need to gradually expose swimmers to incremental increases in frequency with focus on additional strength and conditioning to generate greater propulsive impulses.
The final experimental study in Chapter 6 quantified the relationship between kinetic and spatiotemporal variables during tethered UUS at three external resistance loads, and underwater velocity. A secondary aim was to determine any differences in explanatory variables for velocity between sex. Participants included twenty-one national and international level swimmers (11F, 10M). Multiple Factor Analysis (MFA) were performed on variable data extracted from a robotic resistance device (1080 Sprint), and untethered peak and average UUS velocity. Twenty-four) variables were found to be highly correlated to dimension (Dim) 1 (DK kinetic variables) and Dim 2 (UK kinetic variables). Male swimmers generally produced higher DK kinetic variables compared to female swimmers and displayed greater variation in UUS performance. UK average force was the most significant explanatory variable for female and male swimmers combined, and male swimmers separately. UK average power was the most significant explanatory variable for untethered average velocity in female swimmers. Force and power generation during the UK of UUS was significantly related to untethered average velocity.
In summary, the results of this PhD thesis significantly contribute to the understanding of UUS performance and how it may be impacted by kinanthropometry, kinematics and kinetics, exhibiting key characteristics related to velocity in high-performance female and male swimmers. The findings of this thesis have the potential to inform swimming coaches, strength and conditioning practitioners, sport science staff and swimmers in their attempt to prescribe individualised training for UUS in the pool and gym. Researchers in the fields of 3D motion capture, machine learning technologies and swimming biomechanics may also use the information provided within this thesis to structure future research.
| Date of Award | 6 Jun 2024 |
|---|---|
| Original language | English |
| Sponsors | Queensland Academy of Sport & Australian Institute of Sport |
| Supervisor | Justin Keogh (Supervisor), Anna Lorimer (Supervisor) & Simon Pearson (Supervisor) |