Biomechanics and Medicine in Swimming XI

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dIscussIon The present study intended to investigate Glu response during an incremental swimming test and verify whether GT could be determined early in the swimming season. The main finding of this study was the constant Glu level throughout the incremental swimming test and that GT was not observed in competitive swimmers. The subjects in this study trained on a daily basis as they were elite national level competitive swimmer. The physical activity preceding this investigation was not controlled for, which is a limitation in this study. However, physical activity level and nutritional state were controlled on the testing day and the resting Glu and Bla were at a normal level (5.5 ± 0.8 mmol·l -1 and 1.2 ± 0.4 mmol·l -1 , respectively). Previous studies reported that GT was observed during an incremental running test on land and GT significantly correlates with LT, VT and MLSS (Simões et al., 1999; Simões et al., 2003; Sotero et al., 2009). The possible mechanism for the GT observation is speculated to be affected by the activated catecholamine and glucagon responses, thus the different hormonal response between swimming and running could explain the conflicting results in this study. Unfortunately, running and hormone measurements were not performed in the present study. Flynn et al. (1990) investigated the Glu response during 45 min of swimming or running (75% VO2max) and reported that a lower Glu level was observed after swimming than running. In addition, this study demonstrated that epinephrine levels was similar after both trials. However, the Glucagon to Insulin ratio (G:I ratio) was significantly higher for swimming than running. Greater glucagon to insulin ratio represents higher hepatic glucose production, therefore, it is suggested that the energy demand of hepatic glycogen at the same relative exercise intensity may differ between swimming and running. An increased reliance on carbohydrate during swimming is also discussed in the work of Lavoie (1982). It is speculated that swimming may result in a preferential recruitment of type II fibers and thus increase the dependence on glycolytic processes. Considering these studies, it is possible that glucose uptake was higher during the incremental swimming test than in running and Glu did not increase at the higher intensity steps in the present study. Further investigation is needed to examine carbohydrate oxidation and hormonal response during an incremental swimming test to clarify the mechanism of the different Glu responses in swimming. On the other hand, the swimmer’s training state during this investigation may be another factor causing Glu not to increase along with exercise intensity increment. Coggan et al. (1995) investigated the Glu response during 30 min at 80 % VO2max cycling comparing endurance trained cyclists and untrained subjects. They reported that rate of glucose disappearance during exercise was 19 % lower in the trained compared with the untrained subjects (27.0 ± 2.6 vs. 33.2 ± 1.5 mumol·min-1·kg-1; p< 0.001), consequently, during exercise, plasma glucose concentration rose significantly in the trained subjects but did not change in the untrained subjects. Thus, observation of GT during an incremental exercise test may reflect the endurance capacity level of the subject. The present study was conducted 4 – 5 weeks after the winter season commencement. Before the season, all subjects spent a one month resting period, so it could be that the endurance capacity of the present subject was not highly enhanced. As there is no study investigating the effect of endurance training on GT, further study is warranted to examine Glu response during an incremental swimming test at higher levels of endurance, later in the season. conclusIon The present study was intended to investigate Glu response during an incremental swimming test and verify whether GT could be determined early in the swimming season. It was clarified that GT could not be determined during an incremental swimming test. The fact that Glu did not increase was speculated to be the different hormonal response during swimming or the effect of the measurement period when swimmer’s chaPter3.PhysioLogyandBioenergetics endurance capacity was not highly enhanced. Further research is needed to clarify the Glu response during an incremental swimming test by analyzing the physiological responses more precisely. reFerences Coggan A.R., Raguso C.A., Williams B.D., Sidossis L.S., Gastaldelli A. (1995) Glucose kinetics during high-intensity exercise in endurancetrained and untrained humans. J. Appl. Physiol., 80,1073-1075. Flynn M.G., Costill D.L., Kirwan J.P., Mitchell J.B., Houmard J.A., Fink W.J., Beltz J.D., D’Acquisto J. (1990) Fat storage in athlete: Metabolic and hormonal responses to swimming and running. Int. J. Sports Med., 11, 433-440. Hollman L.H. (1985) Historical remarks on the development of the aerobic-anaerobic threshold up to 1966. Int. J. Sports Med., 6: 109- 116. Júnior P.B., Neiva C.M., Denadai B.S. (2001) Effect of an acute betaadrenergic blockade on the blood glucose response during lactate minimum test. J. Sci. Med. Sport., 4, 257-265. Lavoie J.M. (1982) Blood metabolites during prolonged exercise in swimming and leg cycling. Eur. J. Appl. Physiol., 48, 127-133. Newell J., Higgins D., Madden N., Cruickshank J., Einbeck J., McMillan K., McDonald R. (2007) Software for calculating blood lactate endurance markers, J. Sports Sci., 25, 1403-1409. Simões H.G., Grubert Campbell C.S., Kokubun E., Denadai B.S., Baldissera V. (1999) Blood glucose responses in humans mirror lactate responses for individual anaerobic threshold and for lactate minimum in track tests. Eur. J. Appl. Physiol. Occup. Physiol., 80, 34-40. Simões H.G., Campbell C.S., Kushnick M.R., Nakamura A., Katsanos C.S., Baldissera V., Moffatt R.J. (2003) Blood glucose threshold and the metabolic responses to incremental exercise tests with and without prior lactic acidosis induction. Eur. J. Appl. Physiol., 89, 603-611. Sotero R.C., Pardono E., Landwehr R., Campbell S.G., Simoes H.G. (2009) Blood glucose minimum predicts maximal lactate steady state on running. Int. J. Sports Med., 30, 643-646. Tanner R.K., Fuller K.L., Ross M.L. (2010) Evaluation of three portable blood lactate analysers: Lactate Pro, Lactate Scout and Lactate Plus. Eur. J. Appl. Physiol. [ahead of print] Weitgasser R., Gappmayer B., Pichler M. (1999) Newer portable glucose meters – Analytical improvement compared with previous generation devices? Clin. Chem., 45, 1821-1825. 225
BiomechanicsandmedicineinswimmingXi The Effects of Rubber Swimsuits on Swimmers Using a Lactic Acid Curve Test shiraki, t. 1 , Wakayoshi, K. 1 , hata, h. 1 , Yamamoto, t. 2 , tomikawa, M. 3 1 Biwako Seikei Sport College, Japan 2 YAMAMOTO CORPORATION CO., LTD., Japan 3 University of Tsukuba, Japan The rubber swimsuit, made from Neoprene rubber, was one of the causes of the swimming record rush in 2009. The benefits of wearing a wetsuit on swimmers were widely reported. This study verified the influence of wearing the rubber swimsuit on a swimming exercise load. Eight female university swimmers performed 4 x 200 m crawl swimming at incremental speeds, set from the best record of each 200 m freestyle race (80%V 200 , 85% V 200 , 90% V 200 , 95% V 200 ). Four different suits (three types of rubber suits and a cloth swimsuit) were used and lactic acid curve tests were conducted. The blood lactate concentration after 90% V 200 and 95% V 200 trials with rubber swimsuits tended to be lower than those with a cloth swimsuit. An examination of the trials revealed that the total number of arm strokes tended to decrease due to the use of the rubber swimsuits. It is suggested that the rubber swimsuits might improve propulsion efficiency and decreased the swimmer’s exercise load, indicating that the rubber swimsuit may improve the race performance of swimmers. Key words: rubber swimsuit, lactic acid curve test IntroductIon Forty-three new world records were set in 13 th FINA World Championships in Rome 2009. It was not just a historical coincidence that the 43 new world records were established in just one meeting. These records were reached with new swimsuits with high technology. In fact, the rubber swimsuit was one of the causes of this record rush. Being similar to wetsuits, the rubber swimsuit was made from Neoprene rubber. So, rubber swimsuits probably present beneficial characteristics similar to wetsuits. The effects of using wetsuits on swimmers were widely reported:(i) triathletes are able to hold their bodies in a more horizontal position because of the added buoyancy (Chatard et al., 1996, Chatard et al., 1995, Toussaint et al., 1989) and (ii) drag force is reduced by the smooth surface provided by a wetsuit (Chatard et al., 1995, Toussaint et al., 1989). Additionally, Tomikawa et al. (2008) showed that swimming velocity at maximal oxygen consumption with a wetsuit was 5.4% higher than with a swimsuit, and that the swimming energy cost of swimming with a wetsuit was lower by 14.4% at 60% of the velocity corresponding to VO 2 max and 7.5% at 80% of the velocity corresponding to VO 2 max. These results suggest that the benefits of wearing a wetsuit include not only the improvement in swimming propulsion efficiency, but also the reduction in energy consumption. While the thickness of a wetsuit is 2-5mm, a rubber swimsuit is only 0.3mm thick, which seems to imply that the benefits of wearing a rubber swimsuit might be less than those of using a wetsuit. A lactic acid curve test is usually used to determine the anaerobic threshold to monitor training (Maglischo, 2003). The test is an incremental one, allowing that the values of blood lactate concentration be plotted on a graph in combination with the swimming velocity. If the lactate-velocity curve will move to the right when wearing a wetsuit, the swimming performance is improved. This study aimed to verify the influence of wearing a rubber swimsuit on the swimming exercise load by using a lactic-velocity curve test. 226 Methods Eight female university swimmers participated in this study. The average of their best records for 200 m freestyle swimming was 129.8 ± 4.5 seconds. They attended the Japanese inter-college swim meet 2009. Their age, height and weight were 19.8 ± 0.9 years, 160.8 ± 4.2 cm and 58.0 ± 2.8 kg, respectively, and they had a body fat % of 28.4 ± 3.6. Four types of suits were used in this study. Three rubber suits were made from Neoprene rubber: (i) rubber suit A was a commercially available suit: (ii) rubber suit B was made from Neoprene rubber, and metallic minerals were contained between rubber and back fabric layers: (iii) rubber suit C was also made from Neoprene rubber, in which titanium was included in bond part between rubber and back fabric layers. Rubber suit B and C were not commercially available. The 4 th suit type was a cloth swimsuit, being a common water-repellent competitive swimsuit with. All swimsuits were the full-length type, covering from shoulder to ankle. Swimmers performed a 4 x 200 m incremental swimming protocol, the speed of the four stages set from the best record of each 200 m freestyle race (80%V 200 , 85% V 200 , 90% V 200 , 95% V 200 ). The speed was controlled by a pace maker set on the bottom of pool. Blood from the fingertip was taken at 0, 3 and 5 min after each trial. The blood lactate concentration was determined using Lactate Pro analyzer (ARKRAY, Inc.). Arm strokes in the trials were counted each 25 m (LAP 1 to 8). The mean and standard deviation were computed for all variables. ANOVA with repeated measures was used to compare the data obtained in the wetsuits and a swimsuit condition. A probability level of 5% was selected for tests of statistical significance. results The mean ± SD values of blood lactate concentrations in each trial are shown in Table 1. No significant differences were found in blood lactate concentration between different rubber suit conditions. Table 1. Means ± SD of Blood lactate concentration in each suit condition NS mmol·L -1 RS-A mmol·L -1 RS-B mmol·L -1 RS-C mmol·L -1 80%V200 1.49 ± 0.45 1.61 ± 0.54 1.54 ± 0.51 1.30 ± 0.47 85%V200 2.11 ± 0.59 1.95 ± 0.88 1.83 ± 0.69 1.78 ± 0.61 90%V200 3.89 ± 1.37 3.20 ± 1.73 2.89 ± 1.21 2.95 ± 1.45 95%V200 10.46 ± 2.37 8.68 ± 2.66 9.35 ± 2.24 8.18 ± 2.98 However, the blood lactate concentration after 90% V 200 and 95% V 200 trials with rubber swimsuits tended to be lower than those with a cloth swimsuit (Figure 1). Especially, when wearing rubber suit C, the blood lactate concentration tended to be lower than wearing other suits. The blood lactate concentrations after 90% V 200 and 95% V 200 trials with the four suits were at the same level. Fig 1. The blood lactate concentration-Swimming velocity curve in an experimental suits conditions
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Pahlen Norge AS Pahlen Norge AS Cha
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