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Publications

Estimation of mechanical power and energy cost in elite wheelchair racing by analytical procedures and numerical simulations

Publication . Forte, Pedro; Marinho, D.A.; Morais, J.E.; Morouço, Pedro; Barbosa, Tiago M.

The aim was to compare the mechanical power and energy cost of an elite wheelchair sprinter in the key-moments of the stroke cycle. The wheelchair-athlete system was 3D scanned and then computational fluid dynamics was used to estimate the drag force. Mechanical power and energy cost were derived from a set of formulae. The effective area in the catch, release and recovery phases were 0.41m(2), 0.33m(2) and 0.24m(2), respectively. Drag increased with speed and varied across the key-moments. The catch required the highest total power (range: 62.76-423.46W), followed-up by the release (61.50-407.85W) and the recovery (60.09-363.89W).

2018Journal article

Open access

The use of physical activity trackers in Portuguese adolescents and adults

Publication . Lopes, Vitor P.; Sá, Carla

The pandemic of physical inactivity is associated with a range of chronic diseases and early deaths (Ding et al., 2016). Estimates from 2012 indicated that not meeting physical activity recommendations is responsible for more than 5 million deaths globally each year (Lee et al., 2012). Nowadays, sedentary behaviours are highly prevalent, and data from adults in high-income countries suggest the majority of time awake is spent being sedentary (Matthews et al., 2008). This study aimed to investigate the use of physical activity trackers in Portugal, in particular how often people use it and how they use it to monitor exercise/physical activity.

2018Conference paper

Open access

Determinant factors of long-term performance development in young swimmers

Publication . Morais, J.E.; Silva, A.J.; Marinho, D.A.; Lopes, Vitor P.; Barbosa, Tiago M.

To develop a performance predictor model based on swimmers’ biomechanical profile, relate the partial contribution of the main predictors with the training program, and analyze the time effect, sex effect, and time × sex interaction. 91 swimmers (44 boys, 12.04 ± 0.81 y; 47 girls, 11.22 ± 0.98 y) evaluated during a 3-y period. The decimal age and anthropometric, kinematic, and efficiency features were collected 10 different times over 3 seasons (ie, longitudinal research). Hierarchical linear modeling was the procedure used to estimate the performance predictors. Performance improved between season 1 early and season 3 late for both sexes (boys 26.9% [20.88;32.96], girls 16.1% [10.34;22.54]). Decimal age (estimate [EST] –2.05, P < .001), arm span (EST –0.59, P < .001), stroke length (EST 3.82; P = .002), and propelling efficiency (EST –0.17, P = .001) were entered in the final model. Over 3 consecutive seasons young swimmers’ performance improved. Performance is a multifactorial phenomenon where anthropometrics, kinematics, and efficiency were the main determinants. The change of these factors over time was coupled with the training plans of this talent identification and development program.

2017Journal article

Open access

Stability of pace and turn parameters of elite long-distance swimmers

Publication . Morais, J.E.; Barbosa, Tiago M.; Neiva, Henrique P.; Marinho, D.A.

This study aimed to assess the stability of the performance, pace and turn parameters of elite long-distance male swimmers during an 800 m freestyle race. The sample was composed by 38 male swimmers, participating in the 800 m event at the 2016 LEN European Aquatic Championships (long course meter). The performance, and a set of pace and turn parameters were analyzed. A customized software was used to perform each race analysis. Swimmers spent 64.05 ± 0.50% and 35.95 ± 0.49% of the final race time in the clean swim and turns, respectively. In the pace parameters, the clean swim was the only one that did not differ between the first and second half of the race (1.63 ± 0.05 vs 1.62 ± 0.05 m·s−1), and in the turn parameters, the water break distance was also similar (5.13 ± 1.17 vs 5.06 ± 0.98 m). A significant and moderate-strong variation was verified for the performance (total race lap effect: p < 0.001, η2 = 0.62), and a significant and moderate variation for the pace parameters (total race: p < 0.001, 0.15 ≤ η2 ≤ 0.33), and for the turn parameters (total race: p < 0.01, 0.15 ≤ η2 ≤ 0.33). Present data (pace and turn variation) shows that elite long-distance male swimmers do not maintain a similar pattern during an 800 m freestyle race. Future research is need to understand if this lack of pace and turn stability is the best way to enhance the performance, or if swimmers should be advised to control their pace and turn. Nevertheless, coaches are advised to help swimmers with feedback about their pace (i.e., controlling the intermediate 30 m) and turn performances (i.e., controlling the 5 m in and 15 m out), leading to a positive effect in their final race time.

2019Journal article

Open access

Start and turn performances of elite sprinters at the 2016 European Championships in swimming

Publication . Morais, J.E.; Marinho, D.A.; Arellano, Raúl; Barbosa, Tiago M.

The aim of this study was to examine the performance characteristics of male and female finalists in the 100-m distance at the 2016 European Championships in swimming (long-course-metre). The performances of all 64 (32-males and 32-females) were analysed (8 swimmers per event; Freestyle, Backstroke, Breaststroke and Butterfly). A set of start and turn parameters were analysed. In the start main outcome, male swimmers were faster in Butterfly (5.71 ± 0.14s) and females in Freestyle (6.68 ± 0.28s). In the turn main outcome, male and female swimmers were faster in Freestyle (males: 9.55 ± 0.13s; females: 10.78 ± 0.28s). A significant and strong stroke effect was noted in the start and turn main outcome, in both sexes. In the start plus the turn combined, males and females were faster in Freestyle (males: 15.40 ± 0.20s; females: 17.45 ± 0.54s). The start and the turn combined accounted almost one-third of the total race time in all events, and non-significant differences (p > 0.05) were noted across the four swim strokes. Once this research made evident the high relevance of start and turns, it is suggested that coaches and swimmers should dedicate an expressive portion of the training perfecting these actions

2019Journal article

Open access