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  • Author: João Paulo Vilas-Boas x
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Pedro Morouço, Kari L. Keskinen, João Paulo Vilas-Boas and Ricardo Jorge Fernandes

The purpose of the current study was to identify the relationships between competitive performance and tether forces according to distance swam, in the four strokes, and to analyze if relative values of force production are better determinants of swimming performance than absolute values. The subjects (n = 32) performed a 30 s tethered swimming all-out effort. The competitive swimming velocities were obtained in the distances 50, 100 and 200 m using official chronometric values of competitions within 25 days after testing protocol. Mean force and velocity (50 m event) show significant correlations for front crawl (r = .92, p < .01), backstroke (r = .81, p < .05), breaststroke (r = .94, p < .01) and butterfly (r = .92, p < .01). The data suggests that absolute values of force production are more associated to competitive performance than relative values (normalized to body mass). Tethered swimming test seems to be a reliable protocol to evaluate the swimmer stroking force production and a helpful estimator of competitive performance in short distance competitive events.

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Pedro Figueiredo, Ana Silva, António Sampaio, João Paulo Vilas-Boas and Ricardo J. Fernandes

The aim of this study was to evaluate the determinants of front crawl sprint performance of young swimmers using a cluster analysis. 103 swimmers, aged 11- to 13-years old, performed 25-m front crawl swimming at 50-m pace, recorded by two underwater cameras. Swimmers analysis included biomechanics, energetics, coordinative, and anthropometric characteristics. The organization of subjects in meaningful clusters, originated three groups (1.52 ± 0.16, 1.47 ± 0.17 and 1.40 ± 0.15 m/s, for Clusters 1, 2 and 3, respectively) with differences in velocity between Cluster 1 and 2 compared with Cluster 3 (p = .003). Anthropometric variables were the most determinants for clusters solution. Stroke length and stroke index were also considered relevant. In addition, differences between Cluster 1 and the others were also found for critical velocity, stroke rate and intracycle velocity variation (p < .05). It can be concluded that anthropometrics, technique and energetics (swimming efficiency) are determinant domains to young swimmers sprint performance.

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Raquel Carvalho, Olga Vasconcelos, Pedro Gonçalves, Filipe Conceição and João Paulo Vilas-Boas

Exercise seems to attenuate the postural control system and anticipatory postural adjustments (APAs) decline, but no conclusive findings are available. This study analyses, in elderly people, the exercise effect in APAs during the raising of a load with both arms in the sagittal plane. Twenty eight males over the age of 60 (65,8 ± 4,07 yr old)—9 veterans in exercising, 9 who exercise recently, and 10 sedentary—were asked to raise a load with both arms simultaneously to shoulder level, in standing position, as fast as possible. It was studied the electromyography (EMG) pattern of the main muscles. The APAs were quantified through the time integral of EMG records (iEMG). Anticipatory changes in the postural muscles were seen in all groups. We observed, in the tibialis anterior activity, a higher significant activation in the sedentary compared with the other groups, suggesting that exercise can modulate the postural control system.

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Pedro Figueiredo, Renata Willig, Francisco Alves, João Paulo Vilas-Boas and Ricardo J. Fernandes

Purpose:

To examine the effect of swimming speed (v) on the biomechanical and physiological responses of a trained front-crawl swimmer with a unilateral arm amputation.

Methods:

A 13-y-old girl with a unilateral arm amputation (level of the elbow) was tested for stroke length (SL, horizontal displacement cover with each stroke cycle), stroke frequency (SF, inverse of the time to complete each stroke cycle), adapted index of coordination (IdCadapt, lag time between propulsive phases), intracycle velocity variation (IVV, coefficient of variation of the instantaneous velocity–time data), active drag (D, hydrodynamic resistance), and energy cost (C, ratio of metabolic power to speed) during trials of increasing v.

Results:

Swimmer data showed a positive relationship between v and SF (R 2 = 1, P < .001), IVV (R 2 = .98, P = .002), D (R 2 = .98, P < .001), and C (R 2 = .95, P = .001) and a negative relationship with the SL (R 2 = .99, P = .001). No relation was found between v and IdCadapt (R 2 = .35, P = .22). A quadratic regression best fitted the relationship between v and general kinematical parameters (SL and SF); a cubic relationship fit the IVV best. The relationship between v and D was best expressed by a power regression, and the linear regression fit the C and IdCadapt best.

Conclusions:

The subject’s adaptation to increased v was different from able-bodied swimmers, mainly on interarm coordination, maintaining the lag time between propulsive phases, which influence the magnitude of the other parameters. These results might be useful to develop specific training and enhance swimming performance in swimmers with amputations.

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Ana Silva, Pedro Figueiredo, Susana Soares, Ludovic Seifert, João Paulo Vilas-Boas and Ricardo J. Fernandes

Our aim was to characterize front crawl swimming performed at very high intensity by young practitioners. 114 swimmers 11–13 years old performed 25 m front crawl swimming at 50 m pace. Two underwater cameras was used to assess general biomechanical parameters (velocity, stroke rate, stroke length and stroke index) and interarm coordination (Index of Coordination), being also identified each front crawl stroke phase. Swimmers presented lower values in all biomechanical parameters than data presented in studies conducted with older swimmers, having the postpubertal group closest values to adult literature due to their superior anthropometric and maturational characteristics. Boys showed higher velocity and stroke index than girls (as reported for elite swimmers), but higher stroke rate than girls (in opposition to what is described for adults). In addition, when considering the total sample, a higher relationship was observed between velocity and stroke length (than with stroke rate), indicating that improving stroke length is a fundamental skill to develop in these ages. Furthermore, only catch-up coordination mode was adopted (being evident a lag time between propulsion of the arms), and the catch and the pull phases presented the highest and smallest durations, respectively.

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Ana Sousa, João Paulo Vilas-Boas, Ricardo J. Fernandes and Pedro Figueiredo

Purpose:

To establish appropriate work intensity for interval training that would elicit maximal oxygen uptake (VO2max) for well-trained swimmers.

Methods:

Twelve male competitive swimmers completed an incremental protocol to determine the minimum velocity at VO2max (νVO2max) and, in randomized order, 3 square-wave exercises from rest to 95%, 100%, and 105% of νVO2max. Temporal aspects of the VO2 response were examined in these latter.

Results:

Swimming at 105% of νVO2max took less (P < .04) absolute time to achieve 90%, 95%, and 100% of VO2max intensities (35.0 ± 7.7, 58.3 ± 15.9, 58.3 ± 19.3 s) compared with 95% (72.1 ± 34.3, 106.7 ± 43.9, 151.1 ± 52.4 s) and 100% (55.8 ± 24.5, 84.2 ± 35.4, 95.6 ± 29.8 s) of VO2max. However, swimming at 95% of νVO2max resulted in longer absolute time (P < .001) at or above the desired intensities (90%: 268.3 ± 72.5 s; 95%: 233.8 ± 74.3 s; 100%: 173.6 ± 78.2 s) and more relative time at or above 95% of VO2max than 105% of νVO2max (68.6% ± 13.5% vs 55.3% ± 11.5%, P < .03), and at or above 100% of VO2max than 100% and 105% of νVO2max (52.7% ± 16.3% vs 28.2% ± 10.5% and 34.0% ± 11.3%, P < .001). At 60 s of effort, swimmers achieved 85.8% ± 11.2%, 88.3% ± 5.9%, and 94.7% ± 5.5% of the VO2max when swimming at 95%, 100%, and 105% of νVO2max, respectively.

Conclusions:

When training to elicit VO2max, using higher swimming intensities will promote a faster VO2 response but a shorter time spent above these intensities. However, lower intensities allow maintaining the desired response for a longer period of time. Moreover, using the 60-s time period seem to be a more adequate stimulus than shorter ones (~30-s), especially when performed at 105% of νVO2max intensity.

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Ricardo Peterson Silveira, Flávio Antônio de Souza Castro, Pedro Figueiredo, João Paulo Vilas-Boas and Paola Zamparo

Purpose:

To analyze the effects of swimming pace on the relative contribution of leg kick to swimming speed and to compare arm-stroke efficiency (ηF) assessed when swimming with the arms only (SAO) and while swimming front crawl (FCS) using individual and fixed adjustments to arm-stroke and leg-kick contribution to forward speed.

Methods:

Twenty-nine master swimmers (21 men, 8 women) performed SAO and FCS at 6 self-selected speeds from very slow to maximal. The average swimming speed (v), stroke frequency (SF), and stroke length (SL) were assessed in the central 10 m of the swimming pool. Then, a 2nd-order polynomial regression was used to obtain values of v at paired SF. The percentage difference in v between FCS and SAO, for each paired SF, was used to calculate the relative contributions of the arm stroke (AC) and leg kick (LC) to FCS. Then ηF was calculated using the indirect “paddle-wheel” approach in 3 different ways: using general, individual, and no adjustments to AC.

Results:

The LC increased with SF (and speed) from –1% ± 4% to 11% ± 1% (P < .05). At the lower FCS speeds, ηF calculated using general adjustments was lower than ηF calculated using individual adjustments (P < .05), but differences disappear at the fastest speeds. Finally, ηF calculated using individual adjustments to LC in the FCS condition did not differ with ηF assessed in the SAO condition at all the investigated speeds.

Conclusions:

The relative contributions of the arm stroke and leg kick should be individually estimated to reduce errors when calculating arm-stroke efficiency at different speeds and in different swimmers.

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Tiago M. Barbosa, Kelly de Jesus, J. Arturo Abraldes, João Ribeiro, Pedro Figueiredo, João Paulo Vilas-Boas and Ricardo J. Fernandes

Background:

The assessment of energetic and mechanical parameters in swimming often requires the use of an intermittent incremental protocol, whose step lengths are corner stones for the efficiency of the evaluation procedures.

Purpose:

To analyze changes in swimming kinematics and interlimb coordination behavior in 3 variants, with different step lengths, of an intermittent incremental protocol.

Methods:

Twenty-two male swimmers performed n × d i variants of an intermittent and incremental protocol (n ≤ 7; d 1 = 200 m, d 2 = 300 m, and d 3 = 400 m). Swimmers were videotaped in the sagittal plane for 2-dimensional kinematical analysis using a dualmedia setup. Video images were digitized with a motion-capture system. Parameters that were assessed included the stroke kinematics, the segmental and anatomical landmark kinematics, and interlimb coordination. Movement efficiency was also estimated.

Results:

There were no significant variations in any of the selected variables according to the step lengths. A high to very high relationship was observed between step lengths. The bias was much reduced and the 95%CI fairly tight.

Conclusions:

Since there were no meaningful differences between the 3 protocol variants, the 1 with shortest step length (ie, 200 m) should be adopted for logistical reasons.

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Ana F. Silva, Pedro Figueiredo, João Ribeiro, Francisco Alves, João Paulo Vilas-Boas, Ludovic Seifert and Ricardo J. Fernandes

To analyze young swimmers’ performance regarding sex and skill level, 23 boys and 26 girls (15.7 ± 0.8 and 14.5 ± 0.8 years old, respectively) were assessed for anthropometry, flexibility, strength, drag, coordination, and biomechanical variables. During a 50-m maximal front-crawl bout, seven aerial and six underwater Qualisys cameras assessed kinematics, and a load cell was used to measure drag (Tedea, United Kingdom) and tethered swimming force. A multivariate analysis of variance test (p < .05) enabled us to observe differences between skill levels in speed, stroke frequency, stroke index, and intracyclic velocity variations, but most relevant differences were noticed when comparing sexes, particularly for anthropometrics, shoulder flexibility, speed, stroke frequency, stroke length, drag, mechanical power, power per stroke, and maximal and mean force. Considering the included variables, only male swimmers’ performance could be predicted through multiple linear regression, with stroke index, left shoulder flexion, and intracycle velocity variations showing great importance in achieving better results.

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Inês Marques-Aleixo, Ana Querido, Pedro Figueiredo, João Paulo Vilas-Boas, Rui Corredeira, Daniel Daly and Ricardo J. Fernandes

This study examined the differences in intracycle velocity variation and arm coordination in front crawl in swimmers with Down syndrome in three breathing conditions. International swimmers with Down syndrome (N = 16) performed 3 × 20 m front crawl at 50 m race speed: without breathing, breathing to the preferred side, and breathing to the nonpreferred side. A two dimensional video movement analysis was performed using the APASystem. Breathing conditions were compared using Repeated Measures ANOVA. Swimming velocity was higher without breathing and intracyclic velocity variation was higher while breathing. Swimmers tended to a catch up arm coordination mode for both breathing conditions and a superposition mode when not breathing. These data reflect arm coordination compromising swimming performance, particularly when comparing with non disabled swimmers in literature. The physical and perhaps cognitive impairment associated with Down syndrome may result in a disadvantage in both propulsion and drag, more evident when breathing.