During the underwater phase of the swimming start drag forces are constantly acting to slow the swimmer down. The current study aimed to quantify total drag force as well as the specific contribution of wave drag during the underwater phase of the swimming start. Swimmers were towed at three different depths (surface, 0.5 m, 1.0 m) and four speeds (1.6, 1.9, 2.0, 2.5 m·s–1), totaling 12 conditions. Wave drag and total drag were measured for each trial. Mixed modeling and plots were then used to determine the relationships between each towing condition and the amount of drag acting on the swimmer. The results of this study show large decreases in total drag as depth increases, regardless of speed (–19.7% at 0.5 m and –23.8% at 1.0 m). This is largely due to the significant reduction in wave drag as the swimmers traveled at greater depth. It is recommended that swimmers travel at least 0.5 m below the surface to avoid excessive drag forces. Swimmers should also perform efficient breakouts when transitioning into free swimming to reduce the duration spent just below the surface where drag values are reported at their highest.
Elaine Tor, David L. Pease, and Kevin A. Ball
Elaine Tor, David L. Pease, and Kevin A. Ball
The swimming start is highly influential to overall competition performance. Therefore, it is paramount to develop reliable methods to perform accurate biomechanical analysis of start performance for training and research. The Wetplate Analysis System is a custom-made force plate system developed by the Australian Institute of Sport—Aquatic Testing, Training and Research Unit (AIS ATTRU). This sophisticated system combines both force data and 2D digitization to measure a number of kinetic and kinematic parameter values in an attempt to evaluate start performance. Fourteen elite swimmers performed two maximal effort dives (performance was defined as time from start signal to 15 m) over two separate testing sessions. Intraclass correlation coefficients (ICC) were used to determine each parameter’s reliability. The kinetic parameters all had ICC greater than 0.9 except the time of peak vertical force (0.742). This may have been due to variations in movement initiation after the starting signal between trials. The kinematic and time parameters also had ICC greater than 0.9 apart from for the time of maximum depth (0.719). This parameter was lower due to the swimmers varying their depth between trials. Based on the high ICC scores for all parameters, the Wetplate Analysis System is suitable for biomechanical analysis of swimming starts.
Emily Nicol, Simon Pearson, David Saxby, Clare Minahan, and Elaine Tor
Purpose: The ability of elite breaststroke swimmers to maximize average velocity maintained throughout a race is reportedly mediated by a number of range-of-motion, dryland strength–power, and anthropometric characteristics. The present study aimed to develop a physical profile and evaluate the relationship between dryland strength–power and stroke kinematic variables in elite breaststroke swimmers. Methods: A series of range-of-motion, dryland strength–power, and anthropometric measures were assessed in 11 elite-level breaststroke specialists and used to establish group-based averages and expected variance within an elite breaststroke population. Results: Analysis of the relationships between dryland strength–power parameters and breaststroke kinematics revealed strong associations (r > .7, minimum 95% confidence range of g > 0.80 or < −0.80) most frequently at 100-m and maximal paces. From further analysis of these associations, a series of second-order models of best fit were calculated to describe the relationship between dryland strength–power parameters and propulsive velocity. Five models strongly described the relationship between countermovement jump height, mean pull-up velocity, and average propulsive velocity. Conclusions: These models can be used to assess propulsion effectiveness and act as a catalyst for technique evaluation. It is also recommended that strength and conditioning coaches consider the inclusion of explosive movements, such as countermovement jumps and maximal velocity pull-ups, in dryland training programs designed for sprint breaststroke swimmers.
Elaine Tor, David L. Pease, Kevin A. Ball, and Will G. Hopkins
Time trials are commonly used in the lead-up to competition. A method that evaluates the relationship between time trial and competition performance in swimming would be useful for developing performance-enhancement strategies.
To use linear mixed modeling to identify key parameters that can be used to relate time-trial and competition performance.
Ten swimmers participated in the study. Each swimmer was analyzed during 3 time trials and 1 competition. Race video footage was analyzed to determine several key parameters. Pooling of strokes and distances was achieved by modeling changes in parameters between time trials and competition within each subject as linear predictors of percent change in performance using mixed modeling of log-transformed race times.
When parameters were evaluated as the effect of 2 SD on performance time, there were very large effects of start time (2.6%, 90% confidence interval 1.8–3.3%) and average velocity (–2.3%, –2.8% to –1.8%). There was also a small effect for stroke rate (–0.6%, –1.3% to 0.2%). Further analysis revealed an improvement in performance time of 2.4% between time trials and competition, of which 1.8% (large; 1.4–2.1%) was due to a change in average velocity and 0.9% (moderate; 0.6–1.1%) was due to a change in start time; changes in remaining parameters had trivial effects on performance.
This study illustrates effective analytical strategies for identifying key parameters that can be the focus of training to improve performance in small squads of elite swimmers and other athletes.