Abstract: The purpose of this study was to analyze the relationship between the intra-cycle variation of the horizontal velocity of displacement of the center of mass (dV), the hand's and feet's velocity, as well as, to identify the variables that most predict the dV's, in butterfly stroke. The study was divided in two parts. The aim of Part I was to investigate the behavior of variables in study at slow swimming velocities and the purpose of Part II was the same but at high swimming velocities. 3 male Portuguese swimmers and 1 female swimmer, of international level were studied in Part I. The swimmers were submitted to an incremental set of 200 m butterfly swims. In the Part II, 7 Portuguese male swimmers of national and international level were studied. Each swimmer performed two maximal 25 m butterfly swims. Both protocols were recorded from four different plans, allowing a 3D analysis. It was calculated the dV, the 3D components (Vx, Vy, Vz) of the hand's velocity and the 2D components (Vx, Vy) of the feet's velocity. Several variables presented significant correlation coefficients with dV at all selected velocities (high velocity ranged from r = 0.58 for Vx-out to r = 0.82 for Vy-1dwn; slow velocity ranged from r = -0.45 for Vx-1dwn to r=0.73 for Vx-ups; overall velocity ranged from r=0.34 for Vz-ent to r = 0.82 for Vx-ins). It was also computed a regression model to predict dV. For high velocity (up to 1.75 +/- 0.09 m. s(-1)), the variables that best predict dV were Vy during the first downbeat, Vx and Vy during the arm's insweep (r(2) = 0.93). At slow velocity (up to 1.48 m. s(-1)), the variables included in the forward step-by-step regression model were Vx during upsweep, Vy and Vx during insweep (r(2) = 0.69). For overall velocity, the variables that most fit the regression model were Vx during upsweep, Vy during second downbeat and Vz during entry (r(2)=0.94). In order to reduce dV, butterfliers should increase hand's velocity in all orthogonal components at the end of the underwater path, should increase the vertical velocity during the downbeats and decrease the velocity during the hand's entry.

Abstract: The purpose of this study was to analyze the relationships between energy cost (C), swimming velocity (v), stroke frequency (SF) and stroke length (SL) in top-level swimmers. Eighteen elite swimmers (four freestylers, five backstrokers, five breaststrokers and four butterflyers) performed an intermittent set of nx200 m swims (n<or=8) with increasing velocity. The oxygen consumption was measured breath-by-breath by a portable metabolic cart (K4 b2, Cosmed, Rome, Italy). A respiratory snorkel and valve system with low hydrodynamic resistance was used to measure pulmonary ventilation and collect expiratory gases. Blood samples were taken from the ear lobe before and after each swim to analyze the blood lactate concentration (YSI 1500L, Yellow Springs, OH, USA). At Backstroke, Breaststroke and Butterfly strokes, increases of SF were associated to increases of C, even when controlling the v. The increases in SL only promoted significant decreases in the C in Breaststroke. There was a significant and polynomial relationship between v and SF for all competitive swimming techniques. The polynomial relationship between v and SL was significant only in Freestyle and Butterfly stroke. Partial correlations between v and SF controlling the effect of SL and between v and SL controlling the effect of SF, were positive and significant for all techniques. It is concluded that manipulation of stroke mechanics variables (SF and SL) may be one of the factors through which C in competitive swimming can be altered for a given v.

Abstract:

Abstract: The purpose of this study is to assess, with elite crawl swimmers, the time limit at the minimum velocity corresponding to maximal oxygen consumption (TLim-vVO2max), and to characterize its main determinants. Eight subjects performed an incremental test for vVO2max assessment and, forty-eight hours later, an all-out swim at vVO2max until exhaustion. VO2 was directly measured using a telemetric portable gas analyzer and a visual pacer was used to help the swimmers keeping the predetermined velocities. Blood lactate concentrations, heart rate and stroke parameter values were also measured. TLim-vVO2max and vVO2max, averaged, respectively, 243.2 +/- 30.5 s and 1.45 +/- 0.08 m . s (-1). TLim-vVO2max correlated positively with VO2 slow component (r = 0.76, p < 0.05). Negative correlations were found between TLim-vVO2max and body surface area (r = - 0.80) and delta lactate (r = - 0.69) (p < 0.05), and with vVO2max (r = - 0.63), v corresponding to anaerobic threshold (r = - 0.78) and the energy cost corresponding to vVO2max (r = - 0.62) (p < 0.10). No correlations were observed between TLim-vVO2max and stroking parameters. This study confirmed the tendency to TLim-vVO2max be lower in the swimmers who presented higher vVO2max and vAnT, possibly explained by their higher surface area, energy cost and anaerobic rate. Additionally, O2SC seems to be a determinant of TLim-vVO2max.

Abstract: The aim of this study was to observe the relationship between time limit at the minimum velocity that elicits maximal oxygen consumption (TLim-v VO2 max) and stroke rate, stroke length, and stroke index. 13 men and 10 women, highly trained swimmers, performed an intermittent incremental test for v VO2 max assessment and an all-out swim to estimate TLim-v VO2 max. The mean +/- SD TLim-v VO2 max, v VO2 max, stroke rate, stroke length, and stroke index values were 233.36 +/- 53.92 sec., 1.40 +/- .06 meter/sec., 35.58 +/- 2.89 cycles/min., 2.39 +/- .22 meter/cycle, and 3.36 +/- .41 meter2/(cycle x sec.), respectively. The correlation between TLim-v VO2 max and stroke rate was -.51 (p < .01), and values for TLim-v VO2 max with stroke length (r = .52, p < .01) and stroke index (r = .45, p < .05). These results seem to suggest that technical skill is a key factor in typical efforts requiring prolonged aerobic power.

Abstract: AIM: The purpose of the present study was to examine the relationship between time limit at the minimum velocity that elicits the individual's maximal oxygen consumption (TLim-v VO2max) and three swimming economy related parameters: the net energy cost corresponding to v VO2max (Cv VO2max), the slope of the regression line obtained from the energy expenditure (E) and corresponding velocities during an incremental test (C(slope)) and the ratio between the mean E value and the velocity mean value of the incremental test (C(inc)). Complementarily, we analysed the influence of Cv VO2max, C(slope) and C(inc) on TLim-v VO2max by swimming level. METHODS: Thirty swimmers divided into 10 low-level (LLS) (4 male and 6 female) and 20 highly trained swimmers (HTS) (10 of each gender) performed an incremental test for v VO2max assessment and an all-out TLim-v VO2max test. RESULTS: TLim-v VO2max, v VO2max, Cv fVO2max, C(slope) and C(inc) averaged, respectively, 313.8+/-63 s, 1.16+/-0.1 m x s(-1), 13.2+/-1.9 J x kg(-1) x m(-1), 28+/-3.2 J x kg(-1) x m(-1) and 10.9+/-1.8 J x kg(-1) x m(-1) in the LLS and 237.3+/-54.6 s, 1.4+/-0.1 m x s(-1), 15.6+/-2.2 J x kg(-1) x m(-1), 36.8+/-4.5 J x kg(-1) x m(-1) and 13+/-2.3 J x kg(-1) x m(-1) in the HTS. TLim-v VO2max was inversely related to C(slope) (r = -0.77, P < 0.001), and to v VO2max (r = -0.35, P = 0.05), although no relationships with the Cv VO2max and the C(inc) were observed. CONCLUSIONS: The findings of this study confirmed exercise economy as an important factor for swimming performance. The data demonstrated that the swimmers with higher and v VO2max performed shorter time in TLim-v VO2max efforts.

Abstract: The need of an electromyographic (EMG) system that works underwater, and more specifically, in swimming pool conditions, leads to the development of new solution of active electrodes, full compatible with current EMG technology used in Biomechanics labs. The active electrodes need to have some electrical requisites in conformity with Basmajian and DeLuca (1985) and also, to have capability to measure 25 meters cabled EMG signals, allowing great swimmer�s mobility. The active electrode configuration uses, in the core, an AD621BN instrumentation amplifier, with a 100 gain and a CMRR of 110 dB. This IC series warranties a low gain error and low noise values. The cable�s length makes the transmission of the signal over 25 meters to became critical, once the signal must be �transported� to the main amplifier, where it will be conditioned and amplified 11 times, in an overall amplification of 1100 in the all system. These two amplifiers stages allow us to achieve quality signals and a proper electrical security (Carvalho et al, 1999), keeping simple the use and maintenance, with great return and protection of investment. The cable electrical parameters reduced the transmission signal problems due to its low impedance. To isolate the active electrode from the water, a special glue was used, that involved all the electronics. The terminal water isolation in the skin was made with special adhesive and some tape. The signals will be acquired by an A/D Biopac module and processed by the ACQ 3.2.5 software. This connectivity to the Biopac allows full dialog with force plates and cameras, either in the perspective of the signal collection as of synchronization. The EMG survived to the underwater tests and the water invasion of the adhesives only added some no significant noise. The signal treatment involved the following steps: (i) mean signal removal; (ii) band-pass filtering; (iii) rectification; (iv) linear envelope and (v) iEMG calculations. The critical cable distance from the amplifier to the pre-amplifier did not affect the signal quality. The electrode isolation

Abstract: The purpose of this study was to measure and compare the total energy expenditure of the four competitive swimming strokes. Twenty-six swimmers of international level were submitted to an incremental set of 200-m swims (5 swimmers at Breaststroke, 5 swimmers at Backstroke, 4 swimmers at Butterfly and 12 swimmers at Front Crawl). The starting velocity was approximately 0.3 m x s (-1) less than a swimmer's best performance and thereafter increased by 0.05 m x s (-1) after each swim until exhaustion. Cardio-pulmonary and gas exchange parameters were measured breath-by-breath (BxB) for each swim to analyze oxygen consumption (VO2) and other energetic parameters by portable metabolic cart (K4b(2), Cosmed, Rome, Italy). A respiratory snorkel and valve system with low hydrodynamic resistance was used to measure pulmonary ventilation and to collect breathing air samples. Blood samples from the ear lobe were collected before and after each swim to analyze blood lactate concentration (YSI 1500 L, Yellow Springs, Ohio, USA). Total energy expenditure (E(tot)), was calculated for each 200-m stage. E (tot) differed significantly between the strokes at all selected velocities. At the velocity of 1.0 m x s (-1) and of 1.2 m x s (-1) the E(tot) was significantly higher in Breaststroke than in Backstroke, in Breaststroke than in Freestyle and in Butterfly than in Freestyle. At the velocity of 1.4 m x s (-1), the E(tot) was significantly higher in Breaststroke than in Backstroke, in Backstroke than in Freestyle, in Breaststroke than in Freestyle and in Butterfly than in Freestyle. At the velocity of 1.6 m x s (-1), the E(tot) was significantly higher in Breaststroke and in Butterfly than in Freestyle. As a conclusion, E(tot) of well-trained competitive swimmers was measured over a large range of velocities utilising a new BxB technique. Freestyle was shown to be the most economic among the competitive swimming strokes, followed by the Backstroke, the Butterfly and the Breaststroke.

Abstract: The aim of this study was to analyse, in swimming pool conditions, the behaviour of kinematic parameters - stroke rate (SR), stroke length (SL) and stroke index (SI) - during a time to exhaustion test performed at the minimum velocity that elicits maximal oxygen uptake (TLimvVO(2)max) in elite freestyle swimmers. Eleven swimmers from the National Portuguese Swimming Team (five male and six female) performed an intermittent incremental test for vVO(2)max assessment and an all-out swim at vVO(2)max to determine TLim-vVO(2)max and to analyse the evolution of the kinematic parameters throughout the test. SR increased and SL (and SI) decreased during the TLim-vVO(2)max test, as a general tendency. When the differences in SR, SL and SI between each 12.5% section of the test were tested, a significant increase in SR and a decrease in SL and SI was verified at 25% [(74.00 (25.83m)], 50% [(148.10 (51.66m)] and 87.5% [(259.15 (90.41m)] of the TLimvVO(2)max duration. These data showed a reduction of the propelling efficiency throughout such a test. These findings could be useful when designing training programmes, namely of middle distance swimmers, taking into consideration maximum aerobic speed, time to exhaustion and propelling efficiency.

Abstract: The purpose of this study was to examine the effect of gender on the relationship between time limit at the minimum velocity that elicits maximal oxygen consumption (TLim-vVO(2)max) and three swimming economy (SE) related parameters: the energy cost corresponding to vVO(2)max (CvVO(2)max), the slope of the regression line obtained from the relationship between energy expenditure (E) and corresponding velocities in a incremental test(C-slope) and the ratio obtained by the mean E value and the velocity mean value of the incremental test (C-inc). Each subject of two gender groups-11 male and 12 female swimmers-performed an incremental test for vVO(2) max assessment and an all-out TLim-vVO(2)max test. TLim-vVO(2)max, vVO(2) max, CvVO(2) max, C-slope and Cinc averaged, respectively, 244.6 +/- 56.5s, 1.45 +/- 0.04m.s(-1), 15.9 +/- 2.2J.kg(-1).m(-1), 35.0 +/- 4.8J.kg(-1).m(-1) and 14.3 +/- 2.4J.kg(-1).m(-1) in the male group and 248.0 +/- 60.5s, 1.33 +/- 0.04m.s(-1), 14.3 +/- 1.8J.kg(-1).m(-1), 35.7 +/- 6.4J.kg(-1).m(-1) and 11.5 +/- 1.5J.kg(-1).m(-1) in the female group. An inverse correlation was found between TLim-vVO(2) max and C-slope for the entire group (r=-0.78, p<.001) and for each gender group (r=-0.90, p<.001 and r=-0.61, p<.05, for female and male respectively), confirming that SE is a very important performance influencing factor. Complementarily, despite the relationship between energy cost and TLim-vVO(2)max efforts is evident in each gender, the TLim-vVO(2)max tests performed by the female swimmers seem to depend more on their own SE than on male swimmers.

Abstract: The purpose of this study was to examine the relationship between the intra-cycle variation of the horizontal velocity of displacement (dV) and the energy cost (EC) in butterfly stroke. Five Portuguese national level swimmers performed one maximal and two sub-maximal 200-m butterfly swims. The oxygen consumption was measured breath-by-breath by portable metabolic cart. A respiratory snorkel and valve system with low hydrodynamic resistance was used to measure pulmonary ventilation and to collect breathing air samples. Blood samples from the ear lobe were collected before and after each swim to analyse blood lactate concentration. Total energy expenditure ( E (tot)) and EC were calculated for each swim. The swims were videotaped in the sagittal plane with a set of two cameras providing dual projection from both underwater and above the water surface. The APAS system was used to analyse dV for the centre of mass. The E (tot) increased linearly with the increasing V, presenting a significant correlation coefficient between these parameters ( r =0.827, P <0.001). The increase in EC was significantly associated with the increase in the dV ( r =0.807, P <0.001). All data were presented as the mean value and the standard deviation. It is concluded that high intra-cycle variation of the velocity of the centre of mass was related to less efficient swimming and vice versa for the butterfly stroke.

Abstract: The purpose of this study was to identify the relationship between the bioenergetical and the biomechanical variables (stroke parameters), through a range of swimming velocities, in butterfly stroke. Three male and one female butterflier of international level were submitted to an incremental set of 200-m butterfly swims. The starting velocity was 1.18 m . s (-1) for the males and 1.03 m . s (-1) for the female swimmer. Thereafter, the velocity was increased by 0.05 m . s (-1) after each swim until exhaustion. Cardio-pulmonary and gas exchange parameters were measured breath by breath for each swim to analyze oxygen consumption and other energetic parameters by portable metabolic cart (K4b (2), Cosmed, Rome, Italy). A respiratory snorkel and valve system with low hydrodynamic resistance was used to measure pulmonary ventilation and to collect breathing air samples. Blood samples from the ear lobe were collected before and after each swim to analyze blood lactate concentration (YSI 1500 L, Yellow Springs, US). Total energy expenditure (E (tot)), energetic cost (EC), stroke frequency (SF), stroke length (SL), mean swimming velocity (V), and stroke index (SI) were calculated for each lap and average for each 200-m stage. Correlation coefficients between E (tot) and V, EC, and SF, as well as between EC and SI were statistically significant. For the relation between EC and SL, only one regression equation presented a correlation coefficient with statistical significance. Relations between SF and V, as well as between SI and V were significant in all of the swimmers. Only two individual regression equations presented statistically significant correlation coefficient values for the relation established between V and the SL. As a conclusion, the present sample of swims demonstrated large inter individual variations concerning the relationships between bioenergetic and biomechanical variables in butterfly stroke. Practitioners should be encouraged to analyze the relationships between V, SF, and SL individually to detect the deflection point in SL in function of swimming velocity to further determine appropriate training intensities when trying to improve EC.

Abstract: The aim of this study was to analyse the variations of the metabolic and technical parameters during a maximal 400-m freestyle event. Seven trained male swimmers swam a maximal 400-m freestyle as if in competition (255.8 +/- 6.9 s). Intermediate time and stroke rate (SR) were recorded at each length (25 m). To estimate the changes in metabolic parameters during the 400-m event, they swam a 300-, 200-, and 100-m test set from each length of the 400-m event results, resting 90 min between each test. The exact speed at each length was given with a visual light pacer. Oxygen uptake (VO(2)) and blood lactate concentration ( [Lac]) were measured before and immediately after each test. VO(2) and [Lac] were stable during the 100-, 200-, and 300-m test but significantly higher (p < 0.05) during 400-m test. The estimated contribution of anaerobic metabolism (EsCANA ) during the first 100-m and the 400-m represented 45 % and 20 % of total energy output, respectively. Speed decreased significantly (p < 0.05) after the first 100-m and remained stable until the end. SR decreased significantly after the first 100-m, then increased until the end, while stroke length (SL) decreased linearly throughout the 400-m. During the first or the last 100-m, EsCANA was not correlated with the changes in V, SR, or SL between the second and the first 100-m, and between the fourth and the third 100-m, respectively. To conclude, this study showed that the swimmers were not able to maintain stable SL during the 400-m event. Thus, to sustain stable velocity and to compensate for the decrease in SL, swimmers increased SR throughout the last 300-m.

Abstract: The purpose of this study was to measure, in swimming pool conditions and with high level swimmers, the time to exhaustion at the minimum velocity that elicits maximal oxygen consumption (TLim at vVO(2)max), and the corresponding VO(2) slow component (O(2)SC). The vVO(2)max was determined through an intermittent incremental test (n = 15). Forty-eight hours later, TLim was assessed using an all-out swim at vVO(2)max until exhaustion. VO(2) was measured through direct oximetry and the swimming velocity was controlled using a visual light-pacer. Blood lactate concentrations and heart rate values were also measured. Mean VO(2)max for the incremental test was 5.09 +/- 0.53 l/min and the corresponding vVO(2)max was 1.46 +/- 0.06 m/s. Mean TLim value was 260.20 +/- 60.73 s and it was inversely correlated with the velocity of anaerobic threshold (r = -0.54, p < 0.05). This fact, associated with the inverse relationship between TLim and vVO(2)max (r = -0.47, but only for p < 0.10), suggested that swimmers' lower level aerobic metabolic rate might be associated with a larger capacity to sustain that exercise intensity. O(2)SC reached 274.11 +/- 152.83 l/min and was correlated with TLim (r = 0.54), increased ventilation in TLim test (r = 0.52) and energy cost of the respiratory muscles (r = 0.51), for p < 0.05. These data suggest that O(2)SC was also observed in the swimming pool, in high level swimmers performing at vVO(2)max, and that higher TLim seems to correspond to higher expected O(2)SC amplitude. These findings seem to bring new data with application in middle distance swimming.

Abstract: The study of the physical characteristics of men has been a concern along the times. The interest for the proportionality comes from several reasons that goes from the selection of sport talents up to aesthetics issues. The aim of this paper is to investigate in the existing literature the procedures for proportionality analysis. For such, a brief historic was made of the antecedents that lead to the development of procedures as the ponderal index, body mass index, esqueletic index, cormic index, upper member length index, acromio-iliac index and the relative span index. After that were verified the procedures for the study of the human proportionality as the Phantom index, the OScale and the allometry. The researched literature led to conclude that the studies in human proportionality must continue in the way to develop a better procedure that best describe the human been leading to a description more realistic of the human form.

Abstract: The purpose of the present study was to analyse the electromyographic activity of the Deltoideus muscle (posterior, middle and anterior portions) in the lateral (LPR) and bend (BRP) arm recovery patterns in front crawl, both in the inspiratory (IC) and non-inspiratory cycles (NIC). A male trained swimmer performed an intermittent protocol of 10 repetitions of 25 m for surface electromyographic activity assessment. In the analysis of the activation time, there were found differences between IC and NIC, in the LRP. When considering the IC, it was observed differences between the two recovery patterns regarding the percentage of activation (%MVC) of the middle portion of the Deltoideus. Regarding the NIC, differences were found in middle and posterior portions of Deltoideus. In LRP, differences were observed between IC and NIC, to the %MVC in posterior and middle portions. In iEMG, differences between recovery techniques were found in NIC (posterior portion) and LRP (posterior and middle portions). Thus, when referring to the muscle activation, it seems that there is not possible to distinguish a better pattern of recovery. Additionally, although IC takes more time to complete the arm action, it allow lower muscular activity.

Abstract: The purpose of this study was to analyse the relationship between the intracyclic speed fluctuations (dv) of the center of mass (CM), in the x,y,z axes, and the Index of Coordination (IdC), as well as to assess the general stroking parameters during the 200 m front crawl event. A good level male swimmer performed the 200 m front crawl at maximum intensity, being video taped by six cameras (2 above and 4 under the water). One complete stroke cycle was analysed in each 50 m of the 200 m test, using the APASystem (Ariel Dynamics Inc). IdC appeared to be well related to dv, both in the horizontal and vertical axes. It was also observed, during the 200 m effort, that the IdC, dv, stroke rate and stroke length changed during the exercise.

Abstract: