Browsing by Author "Costa, Aldo M."
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- Estimating time-to-contact with temporal occlusion in relay swimming: a pilot studyPublication . Ribeiro, Lilian; Costa, Aldo M.; Louro, Hugo; Sobreiro, Pedro; Esteves, Pedro; Conceição, AnaThe purpose of this study was to analyse swimmers' perceptual judgements of a simulated time-to-contact task in freestyle swimming relays. The study sample consisted of 31 national-level swimmers of both genders (n = 18 males, 17.22 ± 1.95 yrs.; n = 13 females, 14.61 ± .76 yrs.). Participants were asked to watch two videos corresponding to the last course of a given swimmer during a competition of 4 × 100 m and 4 × 200 m freestyle events. These videos were presented with temporal occlusion correspondent to predetermined approaching distances (7.5, 5.0, and 2.5 m). Participants were required to simulate a typical position in standby for exiting the block and estimate the time-to-contact of the incoming swimmer by pressing a switch. A Wilcoxon test was performed to determine differences between time-to-contact and real contact time. The results showed that estimation of time-to-contact was generally lower than real contact time at all approaching distances (with occlusion) and for both genders (p < .05), except at a 7.5-m distance in the men's 4 × 200 m (p = .744; r = .09) and at 5.0 m in both the 4 × 100 m and 4 × 200 m for the female group (p = .279, r = .22 for 4 × 100 m; p = .2453, r = .17 for 4 × 200 m). The larger variation (Δ) between estimation and real contact time was found at a 7.5 m occlusion distance in the female 4 × 100 m (p < .001; r = .82). Swimmers tend to underestimate the time-to-contact of the incoming swimmer, in the context of a simulated relay race. Taken together, these results highlight the importance of perceptual abilities development in swimmers to optimize their technique and effectiveness during relay starts.
- The relative age effect among elite youth competitive swimmersPublication . Costa, Aldo M.; Marques, Mário C.; Louro, Hugo; Ferreira, Sandra S.; Marinho, Daniel A.The aim of this study was to analyse the relative age effect (RAE) in competitive swimming. The best 50 Portuguese swimmers (12- to 18-year-olds) for the main individual swimming pool events of both genders were considered. Analysis was conducted on 7813 swimming event participants, taking account of respective swimmer birth dates and the Fédération Internationale de Natation points gained. Differences in the distribution of birth dates by quarter year were determined using the Chi-square. A one-way analysis of variance ANOVA was used to test for differences measured in points between individuals by quarterly birth year intervals. A two-way analysis of variance ANOVA was also conducted to test the interaction between gender and seasonal birth date with regard to performance. The results show an inequitable distribution (p<0.01) of birth dates by quarter for almost all age groups and both genders. However, the distribution of birth dates by quarter for each considered swim event shows that RAE seems to exist only for 12-year-old females and 12- to 15-year-old males. Analysing mean swimming performance, post-hoc results (p<0.01) show no consistency in RAE. Higher performance occurs among older swimmers only in 100 m butterfly (female 1998, 1st≠2nd quarter, p=0.003). The results also show no interaction between gender and seasonal birth date (p<0.01). Findings of this study show that a higher number of swimmers, particular males, are born in the first two quarters of the year, although there is mostly no effect of seasonal birth date on performance differences within the top 50 swimmers.