Browsing by Author "Nevill, Alan M."
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- Analysis of the physiological response in junior tennis players during short-term recovery: understanding the magnitude of recovery until and after the 25 seconds rulePublication . Morais, J.E.; Bragada, José A.; Silva, Rui; Nevill, Alan M.; Nakamura, Fabio Y.; Marinho, D.A.Literature lacks evidence about the physiological recovery of tennis players between points. This study aimed to: (i) verify the heart rate (HR) and oxygen uptake (V̇O2) recovery variance in young tennis players from the end of a tennis drill until the 25-s mark and onwards (65-s limit), performed at several intensities, and (ii) test the curve fitting that better characterizes the players’ HR and V̇O2 recovery, from the end of the drill until the 65-s mark. The sample was composed of 13 male tennis players (age: 16.80 ± 1.61 years) recruited from a National Tennis Association. Players were instructed to perform a drill test (“two-line drill wide mode”) based on an intensity increment protocol. Three levels of intensity were used based on the reserve HR and V̇O2. A significance level effect was observed on the HRreserve and V̇O2reserve (P <.001). At all three levels of intensity, the first 25 s were enough to significantly (P <.001) recover the HRreserve and V̇O2reserve. The same significance trend (P <.001) was maintained until the 65 s but with a lower magnitude over time. Overall, the HR and V̇O2 curve fitting indicated a cubic relationship at the three levels of intensity (except the V̇O2 at the first level). Considering the specific test performed, players significantly elicited their physiological profile for every additional 10 s (after the 25-s rule) in the three levels of intensity performed. Despite this being a drill test and not a competitive point, coaches, players, and tennis organizations should be aware of these findings
- Identification of key somatic features that are common and the ones that differ between swim strokes through allometric modelingPublication . Rejman, Marek; Nevill, Alan M.; Garrido, Nuno D.; Rudnik, Daria; Morais, J.E.The aim of this study was to explore which key somatic features are common to four swim strokes and medley, and specifically to identify which characteristics benefit only specific strokes. Methods: The sample was composed of 130 swimmers (95 males aged 19.5 ± 2.9 years and 35 females aged 18.4 ± 2.8 years). A set of anthropometric variables was used to predict swimming speed in the four swimming strokes and medley. Results: A multiplicative model with allometric body size components was used to identify the demographic and anthropometric predictors of swimming speed. Trunk height and waist circumference were the only variables significantly different among swimming strokes (p < 0.05). Associations between swimming speed and arm length were similar in breaststroke and medley, and in freestyle, backstroke and butterfly (R2 = 60.9%). The model retained as swimming speed predictors the age2, upper body circumference, hand breadth, waist circumference, and subscapular skinfold thickness (these last two had negative associations). Conclusion: All these predictors were common to all four swim strokes and medley. Arm length was also retained as a significant predictor, but this one varied significantly between the four different swim strokes and medley. These findings highlight the importance of having a “V-shape” trunk, longer upper limbs, and large hands as predictors of swimming performance
- Race Analysis and Determination of Stroke Frequency: Stroke Length Combinations during the 50-M Freestyle EventPublication . Morais, J.E.; Barbosa, Tiago M.; Bragada, José A.; Nevill, Alan M.; Marinho, D.A.The aims of this study were to: (1) analyze and compare the stroke kinematics between junior and senior elite male swimmers in every section of the race during the 50-m freestyle event, and; (2) identify stroke frequency (SF)–stroke length (SL) combinations on swim speed independently for junior and senior swimmers in each section of the 50-m freestyle event. Eighty-six junior swim- mers (2019) and 95 seniors (2021) competing in the 50-m long course meter LEN Championships were analyzed. The t-test in- dependent samples (p ≤ 0.05) were used to compare juniors and seniors. The SF and SL combinations on swim speed were ex- plored using three-way ANOVAs. Senior swimmers were signif- icantly faster in the 50-m race than juniors (p < 0.001). Speed presented the largest significant difference (p < 0.001) in section S0-15 m (start until the 15th meter mark) being seniors fastest. Both junior and senior swimmers revealed a significant categori- zation (p < 0.001) by stroke length and stroke frequency in each race section. It was possible to model several SF–SL combina- tions for seniors and juniors in each section. The fastest swim speed in each section, for seniors and juniors independently, was achieved by a SF–SL combination that may not be the fastest SF or the longest SL. Coaches and swimmers must be aware that de- spite the 50-m event being an all-out bout, several SF–SL combi- nations were observed (independently for juniors and seniors), and they differ between race sections.
- Understanding the role of propulsion in the prediction of front-crawl swimming velocity and in the relationship between stroke frequency and stroke lengthPublication . Morais, J.E.; Barbosa, Tiago M.; Nevill, Alan M.; Cobley, Stephen; Marinho, D.A.Introduction: This study aimed to: 1) determine swimming velocity based on a set of anthropometric, kinematic, and kinetic variables, and; 2) understand the stroke frequency (SF)-stroke length (SL) combinations associated with swimming velocity and propulsion in young sprint swimmers.Methods: 38 swimmers (22 males: 15.92 +/- 0.75 years; 16 females: 14.99 +/- 1.06 years) participated and underwent anthropometric, kinematic, and kinetic variables assessment. Exploratory associations between SL and SF on swimming velocity were explored using two two-way ANOVA (independent for males and females). Swimming velocity was determined using multilevel modeling.Results: The prediction of swimming velocity revealed a significant sex effect. Height, underwater stroke time, and mean propulsion of the dominant limb were predictors of swimming velocity. For both sexes, swimming velocity suggested that SL presented a significant variation (males: F = 8.20, p < 0.001, eta(2) = 0.40; females: F = 18.23, p < 0.001, eta(2) = 0.39), as well as SF (males: F = 38.20, p < 0.001, eta(2) = 0.47; females: F = 83.04, p < 0.001, eta(2) = 0.51). The interaction between SL and SF was significant for females (F = 8.00, p = 0.001, eta(2) = 0.05), but not for males (F = 1.60, p = 0.172, eta(2) = 0.04). The optimal SF-SL combination suggested a SF of 0.80 Hz and a SL of 2.20 m (swimming velocity: 1.75 m s(-1)), and a SF of 0.80 Hz and a SL of 1.90 m (swimming velocity: 1.56 m s(-1)) for males and females, respectively. The propulsion in both sexes showed the same trend in SL, but not in SF (i.e., non-significant variation). Also, a non-significant interaction between SL and SF was observed (males: F = 0.77, p = 0.601, eta(2) = 0.05; females: F = 1.48, p = 0.242, eta(2) = 0.05).Conclusion: Swimming velocity was predicted by an interaction of anthropometrics, kinematics, and kinetics. Faster velocities in young sprinters of both sexes were achieved by an optimal combination of SF-SL. The same trend was shown by the propulsion data. The highest propulsion was not necessarily associated with higher velocity achievement
- Upper-limb kinematics and kinetics imbalances in the determinants of front-crawl swimming at maximal speed in young international level swimmersPublication . Morais, J.E.; Forte, Pedro; Nevill, Alan M.; Barbosa, Tiago M.; Marinho, D.A.Short-distance swimmers may exhibit imbalances in their upper-limbs' thrust (differences between the thrust produced by each upper-limb). At maximal speed, higher imbalances are related to poorer performances. Additionally, little is known about the relationship between thrust and swim speed, and whether hypothetical imbalances exist in the speed achieved while performing each upper-limb arm-pull. This could be a major issue at least while swimming at maximal speed. This study aimed to: (1) verify a hypothetical inter-upper limb difference in the determinants related to front-crawl at maximal swim speed, and; (2) identify the main predictors responsible for the swim speed achieved during each upper-limb arm-pull. Twenty-two male swimmers of a national junior swim team (15.92 +/- 0.75 years) were recruited. A set of anthropometric, dry-land strength, thrust and speed variables were assessed. Anthropometrics identified a significant difference between dominant and non-dominant upper-limbs (except for the hand surface area). Dry-land strength presented non-significant difference (p<0.05) between the dominant and non-dominant upper-limbs. Overall, thrust and speed variables revealed a significant difference (p<0.05) between dominant and non-dominant upper-limbs over a 25 m time-trial in a short-course pool. Swimmers were not prone to maintaining the thrust and speed along the trial where a significant variation was noted (p<0.05). Using multilevel regression, the speed achieved by each upper-limb identified a set of variables, with the peak speed being the strongest predictor (dominant: estimate=0.522, p<0.001; non-dominant: estimate=0.756, p<0.001). Overall, swimmers exhibit significant differences between upper-limbs determinants. The upper-limb noting a higher dry-land strength also presented a higher thrust, and consequently higher speed. Coaches should be aware that sprint swimmers produce significant differences in the speed achieved by each one of their upper-limbs arm-pull.
- A visual scan analysis protocol for postural assessment at school in young studentsPublication . Alves, Maria E.; Marinho, D.A.; Carneiro, Duarte N.; Alves, Jorge; Forte, Pedro; Nevill, Alan M.; Morais, J.E.The aim of this study was to compare the X-ray diagnosis with a non-invasive method for spine alignment assessment adopting a visual scan analysis with a plumb line and simetograph in middle-school students. The sample of this study was composed of 31 males and 50 females with an average age of 14.23 (± 3.11) years. The visual scan analysis was assessed at a school; whereas, the X-ray was performed in a hospital. The Wilcoxon signed-rank test was used to assess the differences between methods and scoliosis classifications (non-accentuated <10º and scoliosis >10º), and the Kappa was used to assess the agreement between methods. The comparisons between the methods revealed non-significant differences (z = −0.577; p = 0.564), with almost perfect agreement between tests (K = 0.821; p < 0.001). Moreover, no statistical significance was observed between methods by the scoliosis classification (z = −1.000; p = 0.317), with almost perfect agreement between tests (K = 0.888; p < 0.001). This research supports the conclusion that there are no significant differences between the two methods. Therefore, it should be highlighted that this field test should be used by physical education teachers in their classes, or in a school context, in order to determine misalignments or scoliosis prevalence among middle-school students