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Open access

Jorge Morais, Mário Costa, Erik Mejias, Daniel Marinho, António Silva and Tiago Barbosa

Morphometric Study for Estimation and Validation of Trunk Transverse Surface Area To Assess Human Drag Force on Water

The aim of this study was to compute and validate estimation equations for the trunk transverse surface area (TTSA) to be used in assessing the swimmer's drag force in both genders. One group of 133 swimmers (56 females, 77 males) was used to compute the estimation equations and another group of 131 swimmers (56 females, 75 males) was 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. Also measured was 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. For males TTSA=6.662*CP+17.019*CSD-210.708 (R2=0.32; Ra 2=0.30; P<0.01) and for females TTSA=7.002*CP+15.382*CSD-255.70 (R2=0.34; Ra 2=0.31; P<0.01). For both genders 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 R2=0.39 for males and R2=0.55 for females. More than 80% of the plots were within the 95% interval confidence for the Bland-Altman analysis in both genders.

Open access

Paulo Simões, José Vasconcelos-Raposo, António Silva and Helder Fernandes

Effects of a Process-Oriented Goal Setting Model on Swimmer's Performance

The aim of this work was to study the impact of the implementation of a mental training program on swimmers' chronometric performance, with national and international Portuguese swimmers, based on the goal setting model proposed by Vasconcelos-Raposo (2001). This longitudinal study comprised a sample of nine swimmers (four male and five female) aged between fourteen and twenty, with five to eleven years of competitive experience. All swimmers were submitted to an evaluation system during two years. The first season involved the implementation of the goal setting model, and the second season was only evaluation, totaling seven assessments over the two years. The main results showed a significant improvement in chronometric performance during psychological intervention, followed by a reduction in swimmers' performance in the second season, when there was no interference from the investigators (follow-up).

Open access

Ana Conceição, António J. Silva, José Boaventura, Daniel A. Marinho and Hugo Louro

Abstract

The purpose of this paper was to examine the characteristics of waves generated when swimming with and without the use of Aquatrainer® snorkels. Eight male swimmers performed two maximal bouts of 25 m breaststroke, first without the use of a snorkel (normal condition) and then using a snorkel (snorkel condition). The body landmarks, centre of the mass velocity, stroke rate, stroke length, stroke index, and Strouhal number (St) were quantified. Fourier analysis was conducted to determine the frequency, amplitude, and phase characteristics of the vertical undulations. We also determined the undulation period, the first and second harmonic wave percentage, and the contribution of these components to the power of each of the wave signals. The first wave harmonics had a frequency of 0.76 Hz (normal condition) and 0.78 Hz (snorkel condition), and the second wave harmonics had a frequency of 1.52 Hz (normal condition) and 1.56 Hz (snorkel condition). Under the normal conditions, the wave amplitude was higher on the vertex (0.72 m) and cervical (0.32 m) than that produced under snorkel conditions (0.71 m and 0.28 m, respectively). The lowest values were found in the hip (0.03 m in normal conditions, and 0.02 m in snorkel conditions) and in the trunk (0.06 m in normal conditions, and 0.04 m in snorkel conditions). It can be concluded that snorkel use seems to lead to slight changes in the biomechanical pattern in swimming velocity, as well as several stroke mechanical variables.

Open access

Irena Pusica, Ivan Srejovic, Jovana Bradic, Jelena Smigic, Stefani Bolevich, Sergey Bolevich, Vladimir Jakovljević and Dusica Djordjevic

Abstract

Energy drinks (EDs) contain caffeine and other active ingredients which affect cardiovascular system. The aims of this study were to examine direct effects of Red Bull (RB) on cardiodynamics and oxidative stress in isolated hearts of rats. The rats were divided into four groups: untrained rats who never consumed ED (dED-UT); untrained rats who consumed ED 5 days a week during 4 weeks (ch+dED-UT); rats trained 5 times a week for 4 weeks, but did not consume ED (dED-T); rats trained and consumed ED 5 times a week for 4 weeks (ch+dED-T). After sacrificing, hearts were isolated and perfused according to Langendorff technique. Through the isolated heart of all rats in each group, RB was administered. The parameters of cardiac function were recorded, and the levels of prooxidants were measured in the coronary effluent during coronary autoregulation. Rats in ch+dED-UT group had significantly lower rates of myocardial contraction and relaxation compared to rats in dED-UT group. The same effect was recorded in the dED-T group compared to dED-UT group. The levels of hydrogen peroxide were significantly higher in trained rats. Rats in ch+dED-T group also had significantly higher levels of superoxide anion radical and index of lipid peroxidation, as well as lower levels of nitrites when compared to ch+dED-UT group, while opposite effect was recorded in rats in dED-T group compared to dED-UT group. The RB could have a potentially negative inotropic effect in chronic consumers. Prooxidative effect of RB was most pronounced in trained chronic consumers.

Open access

Jairo Silva, Amandio Geraldes, Antônio Natali, João Pereira, Rodrigo Vale and Estélio Dantas

Acute Effects of Swimming on the Arterial Pressure of Hypertensive Adults

Aim. The purpose of this work was to verify the acute effects of a regular swimming programme on the arterial pressure of hypertensive adults.

Material and methods. The sample was composed of 26 individuals who presented mild to moderate hypertension. The subjects were divided into two groups: the Experimental Group (EG) comprising 13 subjects (four men and nine women) and the Control Group (CG) comprising 13 subjects (seven men and six women), with average ages of 38.40 ± 8.24 and 38.36 ± 8.96 years, respectively. GE individuals took part in a regular swimming programme consisting of three weekly fifty-minute sessions of training (ST) for 10 weeks, whereas GC individuals were instructed not to alter their physical activity and nutritional habits. The Kruskal-Wallis test was used to determine statistical significance (p < 0.05).

Results. At the end of the ten weeks, an increase of 4.8% in Systolic Blood Pressure at rest (from 133.67 ±2.26 to 138.56 ± 3.23) and an increase of 7.8% in Diastolic Blood Pressure (from 83.15 ± 1.50 to 89.67 ± 7.19) were observed.

Conclusion. The results allow us to conclude that a regular swimming programme, consisting of training sessions three times a week for 10 weeks, was not sufficient to significantly alter the acute pressure levels of hypertensive adults.

Open access

Nuno Amaro, Daniel A. Marinho, Nuno Batalha, Mário C. Marques and Pedro Morouço

Abstract

The aim of the present study was to examine the reliability of tethered swimming in the evaluation of age group swimmers. The sample was composed of 8 male national level swimmers with at least 4 years of experience in competitive swimming. Each swimmer performed two 30 second maximal intensity tethered swimming tests, on separate days. Individual force-time curves were registered to assess maximum force, mean force and the mean impulse of force. Both consistency and reliability were very strong, with Cronbach's Alpha values ranging from 0.970 to 0.995. All the applied metrics presented a very high agreement between tests, with the mean impulse of force presenting the highest. These results indicate that tethered swimming can be used to evaluate age group swimmers. Furthermore, better comprehension of the swimmers ability to effectively exert force in the water can be obtained using the impulse of force.

Open access

K. Wolska, P. Szweda, K. Lada, E. Rytel, K. Gucwa, B. Kot and M. Piechota

Abstract

The molecular-typing strategy, ERIC-PCR was used in an attempt to determine the genomic relationship of 28 P. aeruginosa strains isolated from faeces of healthy bovine, bovine mastitis and from faeces of hospital patients as well as from environment. ERIC-PCR fingerprinting revealed large molecular differentiation within this group of isolates. Twenty two out of 28 strains tested generated unique patterns of DNA bands and only three genotypes consisted of two isolates each were identified. We also tested the P. aeruginosa isolates for their ability to form a biofilm on abiotic surfaces including polyvinylchloride and polystyrene. Different biofilm-forming abilities were demonstrated among strains; however, most of them (64.3%) showed moderate-biofilm forming ability. The strains with increased swimming and twitching motility displayed elevated biofilm formation. However, a negative correlation was found between slime and initial biofilm production. On the basis of the results obtained, we suggest that there are no major differences in phenotypic properties between P. aeruginosa strains isolated from different sources

Open access

Krystyna Zatoń, Izabela Cześniewicz and Stefan Szczepan

Abstract

Introduction. The aim of the study was to ascertain the physiological effects of verbal feedback on changes in the movement efficiency of a dry-land swimming ergometry task (butterfly stroke). Material and methods. The study involved 100 healthy and physically active males (1st year university students majoring in physical education) that were untrained in swimming (19.56 ± 1.32 years of age, 181.23 ± 4.35 cm in height, and 70.54 ± 8.6 kg in weight). The sample was randomised into two groups (control and experimental). In the first trial, both groups executed the butterfly stroke on a Weba Sport swim ergometer with no augmented feedback. In a second trial, the experimental group was provided with verbal cues relating kinesthetic information on task execution. Trial duration was 10 min, with the first 5 min devoted to the swimming task and the remaining 5 min serving as a cool-down. Variables under consideration included physiological cost, rate of recovery, heart rate recovery, estimated recovery time, and work output. Results. No improvement in the variables related to the physiological cost was observed in the verbal feedback condition although a significant increase in work output was observed in the experimental group (p < 0.05). Conclusions. An improvement in work output without modulating the physiological cost of work suggests that appropriately prepared verbal cues may enhance performance in a swimming ergometry task.

Open access

Maria Teresa da Silva Pinto Marques-Dahi, Flavio Henrique Bastos, Ulysses Okada de Araujo, Cinthya Walter and Andrea Michele Freudenheim

Abstract

Purpose. In Front-Crawl swimming stroke, the interaction between two of its components, i.e. arm stroke and breathing, affects the performance of the motor skill as a whole and therefore can be considered a critical aspect of the skill. The purpose of our study was to investigate if a verbal instruction emphasizing this interaction could lead to learning gains when provided along with video demonstrations.

Methods. Participants (children) were randomly assigned to three experimental groups according to the type of verbal instruction provided. Component and Interaction groups received their specific instructions along with video demonstrations of a model execution of the Front-Crawl. The Control group watched the same video, but received no further instruction concerning the movement pattern. In the Acquisition phase (AQ) all groups performed 160 trials (organized in 4 sessions) of the task that consisted in swimming 8 meters the Front-Crawl at a comfortable velocity. To assess learning gains, a retention test (RT) and a transfer test (TR) were carried out one week after the end of the AQ.

Results. Regarding RT and TR, the one-way ANOVA on the movement pattern score showed a significant difference between groups, with post-hoc tests revealing that the Interaction group achieved higher score than the Control group.

Conclusions. The results reveal that enhancing aspects of a video demonstration with verbal instruction improves learning gains of the Front-Crawl in children. Additionally, the results suggest that providing verbal instructions about the interaction between stroke and breathing might promote learning gains, compared to providing instructions about the stroke component individually.

Open access

Wojciech Seidel, Andrzej Klarowicz, Marek Rejman and Stefan Szczepan

Abstract

Introduction. When evaluating the swimming technique of people with disabilities, a particularly important factor, besides physiological aspects, is the efficiency of the effort expended. This suggests that assessing and monitoring the effectiveness of swimming should be a regular part of training for swimmers with disabilities. Therefore, it seems important to distinguish how changes occur in the parameters that determine the effectiveness of swimming. This is especially true of anaerobic lactic exercise as the lactic acid concentration in the blood increases significantly. The aim of this study was to evaluate the usefulness of calculating velocity and the stroke index in the swimming training of people with disabilities, along with the progressive fatigue of a high-intensity interval training workout. Material and methods. The sample comprised 12 elite competitors with a disability. The experiment consisted in swimming sequential distances of 48 m, 50 m, 52 m, and 54 m at maximum intensity. Competitors performed four sets of four repetitions with a 75-second interval between repetitions and 15 minutes of active resting between sets. All sets were recorded using five digital cameras with a frequency of 50 frames per second. The recorded material was analysed with the use of motion analysis software, and the stroke index was calculated. Results. There was found to be no significant change in the average swimming velocity during each set and corresponding repetition, which means that the participants were able to tolerate the training intensity. Also, the stroke index did not change to a statistically significant degree in either of the subsequent sets or the subsequent repetitions (p < 0.05). Conclusions. We conclude that analysing the value of the swimming stroke index for people with disabilities can be a diagnostic method for assessing the effectiveness of high-intensity interval training.