Biomechanics and Medicine in Swimming XI

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The trials were controlled by a pace maker. When wearing rubber swimsuits, most subjects could swim 2.0-2.9% faster than the velocity (95% V 200 trials) set by the pace maker (Fig1, Table 2). Table 2. Means and Standard Deviations of Swimming velocity in each suit condition NS m·s-1 RS-A m·s-1 RS-B m·s-1 RS-C m·s-1 80%V200 1.24 ± 0.04 1.25 ± 0.04 1.25 ± 0.04 1.25 ± 0.04 85%V200 1.32 ± 0.04 1.32 ± 0.04 1.32 ± 0.05 1.32 ± 0.05 90%V200 1.39 ± 0.05 1.40 ± 0.05 1.40 ± 0.05 1.40 ± 0.05 95%V200 1.49 ± 0.04 1.50 ± 0.04 1.51 ± 0.06 1.51 ± 0.06 No significant differences were found in the number of arm strokes per 25m between suit conditions. Conversely, an examination of the trials revealed that the total number of arm strokes tended to decrease due to the use of the rubber swimsuits in 90%V200 and 95%V200 swimming (Fig2 and 3). Fig 2. The total number of arm strokes in 90%V 200 swimming in different suit condition Fig 3. The total number of arm strokes in 95% V 200 swimming in different suit condition dIscussIon No significant differences were found in blood lactate concentration between the suit conditions. However, Figure. 1 shows that the blood lactate concentration after 90% V 200 and 95% V 200 trials with rubber swimsuits tended to be lower by 1.1 to 2.2 mmol·L -1 than those with a cloth swimsuit. Even though the swimming velocity was controlled chaPter3.PhysioLogyandBioenergetics by a pace maker on the bottom of the pool, some subjects could swim faster at 90% V 200 and 95% V 200 trials with rubber swimsuits. The results suggested that wearing rubber swimsuits might improve the propulsion efficiency and reduce anaerobic energy consumption at a comparable swimming velocity. In previous studies, it was assumed that wearing a wetsuit might reduce the exercise intensity during swimming (Bentley et al., 2002). Tomikawa et al. (2008) reported that even if triathletes have similar VO 2 in the wetsuit and swimsuit conditions, they swam 5.4% faster with a wetsuit. Given this result, it was considered that the effects of wearing a rubber swimsuit were similar to those of wearing a wetsuit, although a rubber swimsuit was thinner than a wetsuit. When wearing a wetsuit, since triathletes float in a more horizontal position because of the added buoyancy, they are able to devote more energy to their arm propelling motion, and to increase their stroke rates with lengthening or retaining stroke lengths (Chatard et al., 1995, Tomikawa et al., 2003). In this study, an examination of the trials revealed that the total number of arm strokes tended to decrease due to the use of the rubber swimsuits (Figs. 2 and 3), while no significant differences were found in the total number of arm strokes between the suit conditions. It was suggested that swimmers could devote more energy to the propulsive force because of the added buoyancy, when wearing rubber swimsuits. conclusIon The results showed that the beneficial characteristics of rubber swimsuits might be similar to wetsuits. Since rubber swimsuits were thinner than wetsuits, the effects of wearing a rubber swimsuit on swimmers were obviously smaller. Therefore, it is suggested that the rubber swimsuits might improve the propulsion efficiency and reduce the exercise intensity during swimming, indicating that the rubber swimsuit may improve the race performance of swimmers. reFerences Bentley, D.J., Millet, G-P., Vlek, V-E. & McNaughton LR (2002). Specific aspect of contemporary triathlon: implications for physiological analysis and performance. Sports Med, 32, 345-59. Chatard, J.C. & Millet, G. (1996). Effects of wetsuit use in swimming events. Sports Med, 22, 70-75. Chatard, J.C., Senegas, X., Selles, M., Dreanot, P. & Geyssant A. (1995). Wetsuit effect: a comparison between competitive swimmers and triathletes. Med Sci Sports Exerc, 27(4), 580-86 Maglischo, E.W. (2003). Swimming Fastest. Champaign: Human Kinetics. Tomikawa, M. & Nomura T (2009). Relationships between swim performance, maximal oxygen uptake and peak power output when wearing a wetsuit. Journal of Science & Medicine in Sport, 12, 317-22. Tomikawa, M., Shimoyama, Y. & Nomura T (2008). Factors related to the advantageous effects of wearing a wetsuit during swimming at different submaximal velocity in triathletes. Journal of Science & Medicine in Sport, 11, 417-23. Tomikawa, M., Shimoyama, Y., Ichikawa, H. & Nomura T (2003). The effects of triathlon wetsuits on stroke parameters, physiological parameters and performance during swimming. In: Chatard JC editor. Biomechanics and Medicine in swimming, vol. Ⅸ. Saint-Etienne: University of Saint-Etienne, 517-22. Toussaint, H.M., Bruinink, L., Coste,r R., De, Looze M, Van Rossem, B., Van Veenen R. & De Groot, G (1989). Effects of a triathlon wetsuit on drag during swimming. Med Sci Sports Exerc, 21, 325-28. 227
BiomechanicsandmedicineinswimmingXi Some Factors Limiting Energy Supply in 200m Front Crawl Swimming strumbelj, B., usaj, A., Kapus, J., Bednarik, J. University of Ljubljana, Faculty of Sport, Ljubljana, Slovenia The aim of this research was to establish whether any measured factors could limit energy supply on 200 m front crawl swimming. Twelve male swimmers performed 4 swims of 200 m crawl at intensities of 80%, 90%, 100% and 110% (until exhaustion) on separate days with a swimming snorkel. Respiratory parameters (V E , Vo 2 ), blood parameters (pH, [LA - ]) and heart rate (HR) were measured. The results demonstrate that limitations in V E , Vo 2 and HR during swimming occur during supra maximal swims (no further increase of measured maximal parameters and time constant parameters) in comparison to maximal swims. Limitations in obtained maximal [LA - ] and minimal pH values were found. It is possible to conclude that individual limitations in V E , Vo 2 , HR and consequently acidosis could be limiting factors of individual performance on 200 m front crawl because of energy supply limitations. Key words: swimming, front crawl, energetics, maximal, supra maximal performances IntroductIon Maximal performances in swimming depend on the maximal metabolic power of the athlete and on the economy of locomotion. The amount of metabolic energy spent in transporting the body mass of the subject over a unit of distance has been defined as the energy cost of locomotion (di Prampero, 1986). Energy during swimming is estimated as the sum of the energy derived from alactic (AnAl), lactic (AnL) and aerobic (Aer) processes. The amount of metabolic energy spent during supra maximal swims (E, kilojoules) was assumed to be the sum of three terms: E = Ean + αVO2maxtp + αVO2max π(1 – e –t p π -1 ) where α is the energy equivalent for O2 , assumed to be equal to 20.9 kJ . l-1 , π is the time constant for the attainment of VO2max from the onset of exercise, Ean is the amount of energy derived from the use of anaerobic energy stores, tp is the performance time, and V O2max (litres per second) includes VO2 at rest (Capelli et al. 1998). Energy cost of front-crawl swimming (Capelli et al., 1998; Zamparo et al., 2000, Poujade et al., 2002) and factors affecting energy cost at different intensities of swimming were studied in many researches (Lavoie and Montpetit 1986; Toussaint and Hollander 1994). However, little evidence was found that some of the before mentioned factors could represent limits in energy supply with increasing swimming velocity and consequently limits in performance. The aim of this study was to establish whether measured aerobic and anaerobic lactate parameters could limit energy supply for 200m front crawl and consequently affect the performance during supra maximal swimming. Methods Twelve male swimmers (age: 24 ± 3 yrs; height: 181 ± 9 cm; body mass: 77 ± 13 kg) volunteered to participate in this study. All subjects had a minimum of eight years competition swimming experience and considered front crawl their best stroke. The subjects were informed of the risks involved in the experiment before they agreed to participate. All swims were performed using the front crawl stroke in a 25 m indoor swimming pool. The temperature of the water was 27° C. Each swimmer performed 4 swims of 200 m crawl at intensities of 80%, 90%, 100% and 110% (until exhaustion) on separate days with a swimming snorkel (Toussaint et al. 1987). First, the swimmers performed a maximal 200 m front crawl swim. Thereafter, they performed sub/maximal 228 swims with 80% and 90% of maximal 200 m front crawl velocity. Finally, the swimmers performed a supra-maximal swim with 110 % velocity until exhaustion (on average they were able to swim 113.8 ± 17.0 m).. A light leader was used to keep even pace during swimming with submaximal and supra-maximal intensities. Arterial blood samples (20 µl) were collected from the earlobe after a warm up and at 1, 3 and 5 minutes of recovery after swimming and analyzed for blood lactate concentration ([LA-]) using a Kodak Ektachrome analyzer. At the same time, arterial blood samples (60 - 80 µl) were collected and analyzed for pH with an ABL5 analyzer (Radiometer Copenhagen). Calibration of the equipment was performed every six samples with standard lactate and pH solution, respectively. Maximal measured [LA-] and minimal pH obtained values were analyzed. Ventilation (VE) and O2 uptake (VO2) were measured using a portable respiratory gas analyzer METAMAX 2 (Cortex, Germany) adapted to measurements with a swimming snorkel made by Toussaint et al.(1987). Average data for every 10-s period were recorded after warm up, during swimming and 5 minutes after the end of each swim. The flow meter was calibrated with a syringe of known volume (3.0 l). The gas analyzer was calibrated by known standard gases. Heart rate (HR) was measured using heart rate monitors POLAR S-610 (Polar, Finland). Average data for 10 –s period were recorded after warm up, during swimming and 5 minutes after the end of each swim. From all obtained data of heart rate values in the rest were excluded to observe relative change. Means and standard deviations were computed for all variables. Individual one-way repeated measures ANOVAs were employed to test for any significant differences between the measured parameters. Significance was accepted when p
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Pahlen Norge AS Pahlen Norge AS Cha
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