Loading...
58 results
Search Results
Now showing 1 - 10 of 58
- Changes of the energetic profile in masters' swimmers over a seasonPublication . Ferreira, M I; Barbosa, Tiago M.; Neiva, Henrique; Alves, J Vilaça; Costa, M J; Marinho, DanielThe aim of this study was to track and compare the changes of performance and energetic profile of male and female masters swimmers during a season. Eleven female (age: 34.7±7.3-y) and fourteen male (age: 35.6±7.4-y) with 4.2±3.7-y and 3.9±1.6-y of experience in masters, respectively, performed an all-out 200 m freestyle to evaluate total energy expenditure (Etot), aerobic (Aer), anaerobic lactic (AnL) and alactic (AnAl) contributions. The oxygen uptake (VO2) was measured immediately after the 200 m trial and the VO2 reached during the trial was estimated through the backward extrapolation of the O2 recovery curve. Fingertip capillary blood samples were collected before the 200 m trial and 3, 5, and 7 minutes after its end. Significant differences were observed between male (TP1:177.50±30.96s; TP2:174.79±29.08s; TP3:171.21±22.38s) and female (TP1:205.18±24.47s; TP2: 197.45±20.97s; TP3: 193.45±18.12s) for 200 m freestyle performance at the three time periods (TPs). Male presented higher Etot in all TPs (TP1:230.40±48.40kJ; TP2:242.49±37.91kJ; TP3:257.94±46.32kJ) compared with that found for female swimmers (TP1:188.51±35.13kJ; TP2:193.18±20.98kJ; TP3:199.77±25.94kJ). Male presented higher AnL (TP1:33.42±6.82kJ; TP2:30.97±8.73kJ; TP3:30.66±8.27kJ) and AnAl (TP1:30.61±3.48kJ; TP2:30.61±3.48kJ; TP3:30.60±3.48kJ) than female (TP1:18.83±8.45kJ; TP2:14.98±4.17kJ; TP3:18.33±8.66kJ) and (TP1:24.32±2.22kJ; TP2:24.31±2.23kJ; TP3: 24.31±2.23kJ). Aerobic metabolism is the major contributor for Etot both in male (TP1:71.63±4.99%; TP2:74.05±5.03%; TP3:76.14±4.46%) and female swimmers (TP1:76.87±3.86%; TP2:79.40±3.63%; TP3:78.40±5.54%). The better performance obtained by male compared to female swimmers may be due to the different contributions of the energetic pathways. Aerobic metabolism was the major contributor to Etot in a 200 m race, in both genders. Partial aerobic contribution was higher in female, while partial anaerobic contribution was greater in male.
- Physical Fitness Differences Between Prepubescent Boys and GirlsPublication . Marta, Carlos C.; Marinho, Daniel; Barbosa, Tiago M.; Izquierdo, Mikel; Marques, MCThe purpose of this study was to analyze in which physical capabilities boys and girls are closer or distant. An additional objective was to find which of the body fat, physical activity, and somatotype factors have a greater effect on prepubescent children's physical fitness. This was a cross-sectional study involving 312 children (10.8 ± 0.4 years). The physical fitness assessment employed sets of aerobic fitness, strength, flexibility, speed, agility, and balance. The boys presented higher values in all selected tests, except tests of balance and flexibility, in which girls scored better. Gender differences in the physical fitness were greatest in the explosive strength of upper (p ≤ 0.01, η(p)(2) = 0.09) and lower limbs (p ≤ 0.01, η(p)(2) = 0.08), although with a medium-size effect of gender, and smaller in the abdominal (p > 0.05, η(p)(2) = 0.007) and upper limbs (p > 0.05, η(p)(2) = 0.003) muscular endurance, and trunk extensor strength and flexibility (p > 0.05, η(p)(2) = 0.001). The endomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the girls, and the ectomorphic (p ≤ 0.01, η(p)(2) = 0.31) and mesomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the boys, had the high-sized effect on the physical fitness. The physical activity in the girls, and the endomorphic and body fat in the boys, did not have a significant effect. These findings can help in the planning of activities that take into account the success and motivation of both boys and girls and thus increase levels of physical activity and physical fitness at school. However, in prepubescent children, one cannot neglect the influence of genetic determinism, observed from the morphoconstitutional point of view.
- Energetics, Biomechanics, and Performance in Masters' Swimmers: A Systematic ReviewPublication . Ferreira, Maria I; Barbosa, Tiago M.; Costa, Mário Jorge; Neiva, Henrique; Marinho, DanielThis study aimed to summarize evidence on masters' swimmers energetics, biomechanics, and performance gathered in selected studies. An expanded search was conducted on 6 databases, conference proceedings, and department files. Fifteen studies were selected for further analysis. A qualitative evaluation of the studies based on the Quality Index (QI) was performed by 2 independent reviewers. The studies were thereafter classified into 3 domains according to the reported data: performance (10 studies), energetics (4 studies), and biomechanics (6 studies). The selected 15 articles included in this review presented low QI scores (mean score, 10.47 points). The biomechanics domain obtained higher QI (11.5 points), followed by energetics and performance (10.6 and 9.9 points, respectively). Stroke frequency (SF) and stroke length (SL) were both influenced by aging, although SF is more affected than SL. Propelling efficiency (ηp) decreased with age. Swimming performance declined with age. The performance declines with age having male swimmers deliver better performances than female counterparts, although this difference tends to be narrow in long-distance events. One single longitudinal study is found in the literature reporting the changes in performance over time. The remaining studies are cross-sectional designs focusing on the energetics and biomechanics. Overall, biomechanics parameters, such as SF, SL, and ηp, tend to decrease with age. This review shows the lack of a solid body of knowledge (reflected in the amount and quality of the articles published) on the changes in biomechanics, energetics, and performance of master swimmers over time. The training programs for this age-group should aim to preserve the energetics as much as possible and, concurrently, improve the technique. Training sessions should feature a higher percentage of technical drills with the goal of enhancing the swim technique. Another goal should be the association of technique enhancement with aerobic and anaerobic sets, enabling the swimmer to improve the swimming efficiency.
- The Hydrodynamic Study of the Swimming Gliding: a Two-Dimensional Computational Fluid Dynamics (CFD) AnalysisPublication . Marinho, Daniel; Barbosa, Tiago M.; Rouboa, Abel I; Silva, AntónioNowadays the underwater gliding after the starts and the turns plays a major role in the overall swimming performance. Hence, minimizing hydrodynamic drag during the underwater phases should be a main aim during swimming. Indeed, there are several postures that swimmers can assume during the underwater gliding, although experimental results were not conclusive concerning the best body position to accomplish this aim. Therefore, the purpose of this study was to analyse the effect in hydrodynamic drag forces of using different body positions during gliding through computational fluid dynamics (CFD) methodology. For this purpose, two-dimensional models of the human body in steady flow conditions were studied. Two-dimensional virtual models had been created: (i) a prone position with the arms extended at the front of the body; (ii) a prone position with the arms placed alongside the trunk; (iii) a lateral position with the arms extended at the front and; (iv) a dorsal position with the arms extended at the front. The drag forces were computed between speeds of 1.6 m/s and 2 m/s in a two-dimensional Fluent(®) analysis. The positions with the arms extended at the front presented lower drag values than the position with the arms aside the trunk. The lateral position was the one in which the drag was lower and seems to be the one that should be adopted during the gliding after starts and turns.
- Young Swimmers’ Classification Based on Kinematics, Hydrodynamics, and AnthropometricsPublication . Barbosa, Tiago M.; Morais, Jorge; Costa, Mário Jorge; Goncalves, José; Marinho, Daniel; Silva, AntónioThe aim of this article has been to classify swimmers based on kinematics, hydrodynamics, and anthropometrics. Sixty-seven young swimmers made a maximal 25 m front-crawl to measure with a speedometer the swimming velocity (v), speed-fluctuation (dv) and dv normalized to v (dv/v). Another two 25 m bouts with and without carrying a perturbation device were made to estimate active drag coefficient (CDa). Trunk transverse surface area (S) was measured with photogrammetric technique on land and in the hydrodynamic position. Cluster 1 was related to swimmers with a high speed fluctuation (ie, dv and dv/v), cluster 2 with anthropometrics (ie, S) and cluster 3 with a high hydrodynamic profile (ie, CDa). The variable that seems to discriminate better the clusters was the dv/v (F=53.680; P<.001), followed by the dv (F=28.506; P<.001), CDa (F=21.025; P<.001), S (F=6.297; P<.01) and v (F=5.375; P=.01). Stepwise discriminant analysis extracted 2 functions: Function 1 was mainly defined by dv/v and S (74.3% of variance), whereas function 2 was mainly defined by CDa (25.7% of variance). It can be concluded that kinematics, hydrodynamics and anthropometrics are determinant domains in which to classify and characterize young swimmers' profiles.
- Longitudinal interventions in elite swimming: a systematic review based on energetics, biomechanics, and performancePublication . Costa, Mário Jorge; Bragada, José; Marinho, Daniel; Silva, António; Barbosa, Tiago M.Longitudinal information requires the notion of repeated measurements throughout time. Such data is important because it allows the determination of the effectiveness of an intervention program. Research in competitive swimming has given special emphasis to energetics and biomechanics as determinant domains to improve performance. The purpose of this systematic review was to summarize longitudinal evidences on the energetic, biomechanical, and performance status of elite swimmers. A computerized search was made in 6 databases, conference proceedings, and department files. The 28 studies that satisfied the inclusion criteria were selected for analysis. Studies' qualitative evaluation was made by 2 independent reviewers using the Quality Index. These studies were then gathered into 3 main categories according to their reported data: energetics (n = 18), biomechanics (n = 9), and performance (n = 8). The conclusions were as follows: (a) elite swimmers are able to demonstrate from slight to substantial changes in their performance and energetic and biomechanical profiles within and between seasons; (b) the magnitude of change is dependent on the characteristics of the training programs, the duration of the intervention, and subject's gender; and (c) future research should emphasize the use of more complex procedures to improve the quality of the interventions.
- Characterization of speed fluctuation and drag force in young swimmers: A gender comparisonPublication . Barbosa, Tiago M.; Costa, Mário Jorge; Morais, Jorge; Morouço, Pedro; Moreira, Marc; Garrido, Nuno; Marinho, Daniel; Silva, AntónioThe aim of this study was to compare the speed fluctuation and the drag force in young swimmers between genders. Twenty-three young pubertal swimmers (12 boys and 11 girls) volunteered as subjects. Speed fluctuation was measured using a kinematical mechanical method (i.e., speedo-meter) during a maximal 25-m front crawl bout. Active drag, active drag coefficient and power needed to overcome drag were measured with the velocity perturbation method for another two maximal 25m front crawl bouts with and without the perturbation device. Passive drag and the passive drag coefficient were estimated using the gliding decay velocity method after a maximal push-off from the wall while being fully immersed. The technique drag index was also assessed as a ratio between active and passive drag. Boys presented meaningfully higher speed fluctuation, active drag, power needed to overcome drag and technique drag index than the girls. There were no significant gender differences for active drag coefficient, passive drag and passive drag coefficient. There were positive and moderate-strong associations between active drag and speed fluctuation when controlling the effects of swim velocity. So, increasing speed fluctuation leads to higher drag force values and those are even higher for boys than for girls.
- Estimating the Trunk Transverse Surface Area to Assess Swimmer's Drag Force Based on their Competitive LevelPublication . Barbosa, Tiago M.; Morais, Jorge; Costa, Mário Jorge; Mejias, Jean Erik Gonçalves; Marinho, Daniel; Silva, AntónioThe aim of this study was to compute and validate trunk transverse surface area (TTSA) estimation equations to be used assessing the swimmer's drag force according to competitive level by gender. One group of 130 swimmers (54 females and 76 males) was used to compute the TTSA estimation equations and another group of 132 swimmers (56 females and 76 males) were used for its validations. Swimmers were photographed in the transverse plane from above, on land, in the upright and hydrodynamic position. The TTSA was measured from the swimmer's photo with specific software. It was also measured the height, body mass, biacromial diameter, chest sagital diameter (CSD) and the chest perimeter (CP). With the first group of swimmers it was computed the TTSA estimation equations based on stepwise multiple regression models from the selected anthropometrical variables. The TTSA prediction equations were significant and with a prediction level qualitatively considered as moderate. All equations included only the CP and the CSD in the final models. In all prediction models there were no significant differences between assessed and estimated mean TTSA. Coefficients of determination for the linear regression models between assessed and estimated TTSA were moderate and significant. More than 80% of the plots were within the 95% interval confidence for the Bland-Altman analysis in both genders. So, TTSA estimation equations that are easy to be computed by coached and researchers were developed. All equations accomplished the validation criteria adopted.
- Association Between Force-Time Curve Characteristics and Vertical Jump Performance in Trained AthletesPublication . Marques, MC; Izquierdo, Mikel; Marinho, Daniel; Barbosa, Tiago M.; Ferraz, Ricardo; González-Badillo, Juan JoséCountermovement jump (CMJ) has been extensively used in training; yet, limited and contradictory kinematic data are available for trained subjects. To our best knowledge, no other studies have evaluated the associations between force-time curve characteristics and CMJ in a large sample of trained athletes using a linear transducer. Thus, the aim of this study was to determine the association between force-time measures and CMJ performance collected with a linear transducer. Thirty-five trained athletes were asked to perform 3 maximal weighted CMJ using a linear transducer attached to a barbell (17 kg). The data indicated that the maximal rate of force development (RFD(max)) was strongly related to CMJ displacement (r = 0.809/0.807, p < 0.001) and also to the percentage of peak force (r = -0.823/-0.809, p < 0.001) at RFD(max). Velocity and displacement at RFD(max) were not correlated to CMJ height. It was therefore concluded that the percentage of PF applied at RFD(max) and RFD(max) were the best predictive variables for CMJ performance in this study.
- Does Warm-Up Have a Beneficial Effect on 100-m Freestyle?Publication . Neiva, Henrique; Marques, MC; Fernandes, Ricardo J.; Viana, João L.; Barbosa, Tiago M.; Marinho, DanielTo investigate the effect of warm-up on 100-m swimming performance. Twenty competitive swimmers (with a training frequency of 8.0 ± 1.0 sessions/wk) performed 2 maximal 100-m freestyle trials on separate days, with and without prior warm-up, in a counterbalanced and randomized design. The warm-up distance totaled 1000 m and replicated the swimmers' usual precompetition warm-up strategy. Performance (time), physiological (capillary blood lactate concentrations), psychophysiological (perceived exertion), and biomechanical variables (distance per stroke, stroke frequency, and stroke index) were assessed on both trials. Performance in the 100-m was fastest in the warm-up condition (67.15 ± 5.60 vs 68.10 ± 5.14 s; P = .01), although 3 swimmers swam faster without warm-up. Critical to this was the 1st 50-m lap (32.10 ± 2.59 vs 32.78 ± 2.33 s; P < .01), where the swimmers presented higher distance per stroke (2.06 ± 0.19 vs. 1.98 ± 0.16 m; P = .04) and swimming efficiency compared with the no-warm-up condition (stroke index 3.46 ± 0.53 vs 3.14 ± 0.44 m2 · c1 · s1; P < .01). Notwithstanding this better stroke-kinematic pattern, blood lactate concentrations and perceived exertion were similar between trials. These results suggest that swimmers' usual warm-up routines lead to faster 100-m freestyle swimming performance, a factor that appears to be related to better swimming efficiency in the 1st lap of the race. This study highlights the importance of performing swimming drills (for higher distance per stroke) before a maximal 100-m freestyle effort in similar groups of swimmers.