Publicação
Kinematical constrictions during Breaststroke swimming with a portable gas analyzer snorkel
| Resumo: | OBJECTIVE: To determine the kinematical constrictions in maximal breaststroke swimming bouts with the AquaTrainer snorkel (Cosmed, Rome, Italy). METHODS: Seven national level breaststrokers performed two maximal bouts of 100-m swims (separated by 48 hours): (i) one bout connected to the AquaTrainer snorkel (constricted swim); (ii) one bout without the snorkel (free swim). The swims were videotaped in sagittal plane with a pair of cameras providing a dual projection from both above and underwater. The study comprised kinematical analysis of stroke cycles using APAS and a VCR (f = 50 Hz). To create a single dual projection image, the independent digitalization from both cameras was reconstructed with the help of a calibration volume and a 0.01). The 2D-DLT algorithm. Digitalization reliability was high (ICC=0.97 following measures were assessed: (i) swimming performance (T100); (ii) stroke parameters (stroke cycle period, stroke rate, stroke length and mean swimming velocity); (iii) estimated swimming efficiency by the swimming index; (iv) speed fluctuation (dv) and the mathematical characterization of dv. Mean dv curves normalized to time were computed with MATLAB. The polynomial regression (7th power) between dv and normalized duration of the full stroke cycle was calculated. Wilcoxon tests were performed to compare significant differences in the dependent variables (performance, stroke mechanics and efficiency variables) according to the independent variable (free versus constricted swim) (P 0.05). RESULTS: T100 was significantly higher for constricted swimming than in free condition (6.26%; Z=-2.366; P=0.02). The remaining variables showed no significant differences between the two swimming conditions. In both exercise conditions, dv was characterized by a bi-modal profile. The determination coefficients for the dv mathematical model were significant (P<0,01) and 0,47. DISCUSSION & CONCLUSION: None of the stroke mechanics and efficiency variables evaluated presented significant differences between both swimming conditions. The AquaTrainer constrictions might be related mainly to the start and turn phases. (Supported by FCT grant: POCI/DES/58362/2004) |
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| Autores principais: | Reis, V. |
| Outros Autores: | Silva, A.; Barbosa, T.; Brito, J.; Reis, A.; Louro, Hugo; Conceição, A. |
| Assunto: | Kinematical constrictions Swimming performance Stroke parameters AquaTrainer snorkel Breakstroke |
| Ano: | 2009 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Instituto Politécnico de Santarém |
| Idioma: | inglês |
| Origem: | Repositório Científico do Instituto Politécnico de Santarém |
| Resumo: | OBJECTIVE: To determine the kinematical constrictions in maximal breaststroke swimming bouts with the AquaTrainer snorkel (Cosmed, Rome, Italy). METHODS: Seven national level breaststrokers performed two maximal bouts of 100-m swims (separated by 48 hours): (i) one bout connected to the AquaTrainer snorkel (constricted swim); (ii) one bout without the snorkel (free swim). The swims were videotaped in sagittal plane with a pair of cameras providing a dual projection from both above and underwater. The study comprised kinematical analysis of stroke cycles using APAS and a VCR (f = 50 Hz). To create a single dual projection image, the independent digitalization from both cameras was reconstructed with the help of a calibration volume and a 0.01). The 2D-DLT algorithm. Digitalization reliability was high (ICC=0.97 following measures were assessed: (i) swimming performance (T100); (ii) stroke parameters (stroke cycle period, stroke rate, stroke length and mean swimming velocity); (iii) estimated swimming efficiency by the swimming index; (iv) speed fluctuation (dv) and the mathematical characterization of dv. Mean dv curves normalized to time were computed with MATLAB. The polynomial regression (7th power) between dv and normalized duration of the full stroke cycle was calculated. Wilcoxon tests were performed to compare significant differences in the dependent variables (performance, stroke mechanics and efficiency variables) according to the independent variable (free versus constricted swim) (P 0.05). RESULTS: T100 was significantly higher for constricted swimming than in free condition (6.26%; Z=-2.366; P=0.02). The remaining variables showed no significant differences between the two swimming conditions. In both exercise conditions, dv was characterized by a bi-modal profile. The determination coefficients for the dv mathematical model were significant (P<0,01) and 0,47. DISCUSSION & CONCLUSION: None of the stroke mechanics and efficiency variables evaluated presented significant differences between both swimming conditions. The AquaTrainer constrictions might be related mainly to the start and turn phases. (Supported by FCT grant: POCI/DES/58362/2004) |
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