A longitudinal modelling approach for the progression of sub-elite youth swimming performance

Formal long-term athlete development programmes emerged at the turn of the century and, despite some fierce criticisms, have evolved significantly since their inception. The first generation of athletes to grow up with these systems are now coming of age. The purpose of this thesis was to track a population of adolescent school-level swimmers between the ages of 12 and 18 years over an 8-year period so as to assess their performance progression as they matured under these athlete development programmes. The first study aimed to track the performances of the sub-elite athletes at an annual international school championship and to compare their progression with those of both junior elite and elite-level swimmers. In addition to narrowing the gender gap, the records of the sub-elite swimmers have continued to improve. In contrast, both of these factors remained relatively stable for junior elite and elite-level swimmers over the same period. Swimming affords athletes the possibility of within-sport specialisation. This almost unique aspect of swimming led to the two investigations of the second study. Firstly, the paired stroke combinations preferred by swimmers were determined using Cohen’s Kappa tests in a cross-sectional design. Secondly, the stability in the event selection of each swimmer during their adolescent years was explored longitudinally. Both males (33.9±5.8%) and females (36.9±6.5%) preferred to swim the 50 and 100 m freestyle events together over any other paired stroke combination. The majority of swimmers preferred to specialise in specific stroke techniques over distance specialisms with breaststroke being the only stroke in which swimmers of both sexes chose to specialise early. Most notable was that females specialised earlier than males. Studies three (males, n = 446) and four (females, n = 514) utilised mixed linear modelling to determine the quadratic functions of the performance progressions of adolescent swimmers (between the ages of 12 and 19 y) in seven individual competition events. Males progressed at more than twice the rate of females (3.5 and 1.7% per year, respectively) in all strokes over this age range. This was likely due to the fact that females reach puberty before males. Thresholds of peak performance occurred between the ages of 18.5±0.1 y (50 m freestyle and the 200 m individual medley) and 19.8±0.1 y (100 m butterfly) for males, but between the wider range of 16.8±0.2 y (200 m individual medley) and 20.6±0.1 y (100 m butterfly) for females. Using an independent sample of Dutch Junior national swimmers (n = 13), the fifth and final study aimed to evaluate the efficacy of the models developed in studies three and four as both target setting and talent identification tools. This was achieved through a mixed-methods approach where quantitative and qualitative data confirmed the applicability of the models for adolescent swimmers of any skill level. This thesis demonstrates that sub-elite swimmers have probably benefitted from first generation athlete development models. Longitudinal modelling of their data provides a valuable platform from which all adolescent swimmers can be compared and used to inform the next generation of bespoke swimming-specific youth development programmes.