Biomechanics and Medicine in Swimming XI

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andomized order. In addition, at rest and 3 minutes after the end of each swim trial, a 5-µL capillary blood sample was drawn from a finger and analyzed (Lactate proTM, LT-1710, Arkray, Inc. Japan). The rates of perceived exertion (RPE, Borg 6-20 scale) were also measured after each swim trial. results The parameters for the long-distance subject are shown in Table 1. Body mass, fat mass, hydrostatic lift, glide distance and torque time were all decreased after the RMET. Chest expansion was also increased. Ventilatory function parameters (FVC, FEV 1 and PEF) were not improved after training, whereas MIP, MEP, the RET and swimming performances increased (+19%, +33%, +12 min.; 50 m: -5.4%; 200 m: -7.2%). The rates of perceived exertion were decreased after the two swim trials (50 m and 200 m). Lactate concentrations were lower after the swim trials (50 m: -0.7 mmol·l -1 ; 200 m: -4.4 mmol·l -1 ). Table 1. Descriptive baseline and post-training characteristics of the long-distance swimmer. Before RMET After RMET Body mass (kg) 71.7 68.6 Fat mass (%) 9.7 8.9 Chest expansion (cm) 9.0 8.9 HL (kg) 3.7 2.9 Glide distance (m) 14.6 13.2 Torque time (s) 7.4 6.8 FVC (L) 7.00 7.07 FEV1 (L) 5.13 5.56 PEF (L.s-1) 11.33 11.24 MIP (kPa) 7.66 9.13 MEP (kPa) 4.00 5.32 RET (min) 16 28 TT50m (s) 28.13 26.69 TT200m (s) 128.02 119.41 RPE50m 13 11 RPE200m 17 16 La50m (mmol·l-1) 4.1 3.4 La200m (mmol·l-1) 10.2 5.8 RMET: respiratory muscle endurance training; HL: hydrostatic lift; FVC: forced vital capacity; FEV1 : forced expiratory volume in one second; PEF: peak expiratory flow; MIP and MEP: maximal inspiratory and expiratory pressure; RET: respiratory endurance test; TT: time trial. dIscussIon The main finding was the improved performance in the swim trials after RMET training and the improved endurance, respiratory muscle force and perceived exertion. The body mass, fat mass, hydrostatic lift, glide distance and torque time were all decreased after the RMET. These results indicated that the swimmer had become thinner during the training period, losing fat mass, which probably reduced his buoyancy and may have modified his glide and Tt. These changes may also have had an impact on performance, especially for the 200 m. The findings were compared with previous RMET findings in swimmers. Greater changes in our swimmer’s performance for TT200m were found, whereas TT50m has never been tested before (Mickleborough et al., 2008; Kilding et al., 2009). It is difficult to compare a case study with other studies to explain why our performance effect was higher (TT200m), but it is noteworthy that our RMET was longer (10 weeks vs. 6 weeks) and our subject was an expert long-distance swimmer. Long-distance swimmers, who undergo more endurance training than other swim- chaPter3.PhysioLogyandBioenergetics mers, are usually mixed in with other swim specialities (50 m to 400 m). It is thus difficult to explain the effect of a specific RMET, such as inspiratory muscle training (IMT), which may not be specific enough for a given swim speciality. RMET seems to be more specific for a long-distance swimmer than IMT. This point may explain in part the differences in performance and respiratory muscle force observed in our study. In previous studies, the tendency toward reduced lactate did not always reach statistical significance (Kilding et al., 2009; Romer et al., 2002). The lactate concentration was also more reduced after the 200-m trial and the RET also increase. Decreased respiratory muscle work and/ or improved leg blood flow could have reduced anaerobic metabolism in respiratory and/or leg muscles. Thus, the RET and the lactate concentration changes indicate that during swimming the respiratory muscle work was probably decreased, and can in turn improve leg blood flow reducing anaerobic metabolism. Those parameters reinforce the hypothesis of beneficial effects of specific respiratory training for swimmers. conclusIon The present individual data suggest that RMET has a beneficial effect on swimming performance (50 m and 200 m), although 200-m performance seemed to be more improved. It may be interesting to compare the effects of respiratory training with the respiratory device adapted to the swimming specialty (sprint: force respiratory device vs. longdistance: endurance respiratory device). Respiratory muscle training can therefore be considered a worthwhile ergogenic aid for competitive swimmers. reFerences Courteix D, Obert P, Lecoq AM, Guenon P, Koch G. (1997). Effect of intensive swimming training on lung volumes, airway resistance and on the maximal expiratory flow-volume relationship in prepubertal girls. Eur J Appl Physiol Occup Physiol, 76, 264–269. Clanton TL, Dixon GF, Drake J, Gadek JE. (1987). Effects of swim training on lung volumes and inspiratory muscle conditioning. J Appl Physiol, 62, 39–46. Doherty M, Dimitriou L. (1997). Comparison of lung volume in Greek swimmers, land based athletes, and sedentary controls using allometric scaling. Br J Sports Med, 31, 337–341. Durnin JV, Womersley J. (1974). Body fat assessed from total body density and its estimation from skinfold thickness: measurements on 481 men and women aged from 16 to 72 years. Br J Nutr, 32, 77-97. Kilding AE, Brown S, McConnell AK. (2009). Inspiratory training improves 100 and 200 m swimming performance. Eur J Appl Physiol, [Epub ahead of print]. Lomax ME, McConnell AK. (2003). Inspiratory muscle fatigue in swimmers after a single 200 m swim. J Sports Sci, 21, 659–664. Mickleborough TD, Stager JM, Chatham K, Lindley MR, Ionescu IA. (2008). Pulmonary adaptations to swim and inspiratory muscle training. Eur J Appl Physiol, 103, 635–646. Quanjer PH, Tammeling GJ, Cotes JE, Pedersen OF, Peslin R, Yernault JC. (1993). Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official Statement of the European Respiratory Society. Eur Respir J, Suppl 16, 5-40. Romer LM, McConnell AK, Jones DA. (2002). Effects of inspiratory muscle training upon recovery on time-trial performance in trained cyclists. J Sports Sci, 20, 547-562. Verges S, Lenherr O, Haner AC, Schulz C, Spengler CM. (2007). Increased fatigue resistance of respiratory muscles during exercise after respiratory muscle endurance training. Am J Physiol, 292, R1246– R1253. Wells GD, Plyley M, Thomas S, Goodman L, Duffin J. (2005). Effects of concurrent inspiratory and expiratory muscle training on respiratory and exercise performance in competitive swimmers. Eur J Appl Physiol, 94, 527-540. 207
BiomechanicsandmedicineinswimmingXi Heart Rate Responses During Gradually Increasing and Decreasing Exercise in Water nishimura, K. 1 , nose, Y. 2 , Yoshioka, A. 2 , Kawano, h. 3 , onodera, s. 4 , takamoto, n. 1 1Hiroshima Institute of Technology, Hiroshima, Japan 2Graduate School of Kawasaki University of Medical Welfare, Kurashiki, Japan 3Waseda University, Tokorozawa, Japan 4Kawasaki University of Medical Welfare, Kurashiki, Japan The purpose of this study was to determine the heart rate (HR) responses during and after gradually increasing and decreasing exercise in water and on land. Eight healthy Japanese males volunteered for this study. Subjects performed arm cranking exercise (calibration and triangular tests) for 32 -min and recovered for 1 -min. HR and cardiac autonomic nervous system activity were continuously measured. The amplitude and phase lags at the top and bottom of the work rate were measured in each cycle. The results were as follows; 1) the HR phase response was shorter in water than on land, but there were no differences in amplitude, 2) reactivation in cardiac parasympathetic nerve was greater in water. Thus, exercise and recovery in water may enhance the stability of autonomic nervous activity, not only during exercise but also after exercise. Key words: arm cranking exercise, gradually increasing and decreasing exercise, water immersion, heart rate response, recovery after excise IntroductIon In water, humans have different physiological responses than on land due to the influence of the physical characteristics of water, such as water temperature (hydrostatic), water pressure, buoyancy and viscosity. Venous return is greater in water than on land, which causes increased stroke volume and cardiac output, decreased heart rate, and increased cardiac parasympathetic nervous system modulation. During arm cranking exercise, there are no significant differences of oxygen uptake between in-water and on-land conditions, despite water immersion-induced bradycardia (Kimura et al., 2001). In addition, the high frequency component in heart rate variability, an index of cardiac autonomic nervous system, is enhanced at the onset of arm cranking exercise in water compared with the on land response. These data suggest that during exercise at the same work-load, heart rate responses including heart rate variability are different between on-land and inwater conditions. Heart rate kinetics (i.e., phase response and amplitude) during sinusoidal exercise are affected by cardiopulmonary fitness (Fukuoka et al., 2002), physical fitness status (Fukuoka et al., 2002) and low intensity aerobic training (Nabekura et al., 2007). In fact, the time delay of heart rate in response to sinusoidal exercise is shorter in highly fit individuals, suggesting that heart rate kinetics in response to sinusoidal exercise may reflect physical fitness. However, the effects of environmental factors, in particular water immersion, on heart rate kinetics in response to gradually increased and decreased exercise workload, such as in sinusoidal or gradually increasing and decreasing exercise, are largely unknown. It has been shown that the time constant of heart rate decline for the first 30 second (T30) after exercise can serve as a specific index to assess post-exercise reactivation of cardiac parasympathetic nerve activity (Imai et al., 1994). Nishimura et al. suggested that supine floating after exercise induced a greater activation in the cardiac parasympathetic nervous system, via increase of central venous pressure and cardiac output, and the subsequent arterial baroreflex response caused by greater venous 208 return, leading to bradycardia (Nishimura et al., 2006). Therefore, it was hypothesized that 1) the phase response and amplitude of heart rate during gradually increasing and decreasing arm cranking exercise in water exercise is higher than on land, and 2) the activation of the cardiac parasympathetic nervous system after exercise in the water is greater than after on-land exercise. To test these hypotheses, the present study was designed to determine the effects of heart rate response during and after gradually increasing and decreasing arm cranking exercise in the water and on land. Methods Eight healthy Japanese males volunteered for this study. Their mean (± SD) age, height, body weight, and % body fat were 20.9 ± 0.6 years, 175.3 ± 4.2 cm, 66.9 ± 4.7 kg, and 13.9 ± 2.8 %, respectively. All subjects signed an informed consent form prior to participation in this study. Subjects performed arm cranking exercise for 32 -minutes and recovered for 1 -minute in a standing position. Subjects performed two types of exercise, a calibration test and a triangular test. The calibration test consisted of three 4-minute bouts of exercise at 20, 60 and 40% of peak oxygen uptake (VO2peak) with a total duration of 12 -minutes. The triangular test consider of 4-minute bouts of gradually increasing and decreasing work load exercise between 20 and 60%VO2peak for 20 -minutes. Both experimental tests were performed on land (L-condition) and in water (W-condition). Water temperature was 30 ºC and water level was at the height of the iliac crest. Heart rate and cardiac autonomic nervous system activity were continuously measured under both conditions. Heart rate maximal and minimal values, amplitude (difference between maximal and minimal values), and phase lags at the top and bottom of the work rate were measured in each exercise cycle. The cardiac autonomic nervous system activity was calculated using the Maximum Entropy Calculation (Mem- Calc) methodology. The heart rate variability frequency domain spectrum was divided into two parts: high frequency (HF; 0.15-0.40Hz) and low frequency (LF; 0.04-0.15Hz). The cardiac autonomic nervous system activity was transformed into natural logarithmic values to obtain a statistically normal distribution. The natural logarithm of HF was taken as an index of cardiac parasympathetic nervous system modulation. T30 reflected reactivation of cardiac parasympathetic was calculated by decrease of heart rate calculated from RR intervals 30 seconds after exercise. All experiments were performed at the same time. All subjects fasted during three hours prior to the experiments, and caffeine intake was not allowed either during that time. Room temperature and humidity were 27.3 ± 1.2ºC and 64.9 ± 5.0%, respectively. All data are expressed as mean ± standard deviation. Two-way analysis of variance for repeated measurements (condition × time course) and paired t-tests were used to compare values obtained during the Lcondition and the W-condition trials. The level of significance was set up at p< 0.05. Table 1. Changes in heart rate during each work load both in the Wcondition and on the L-condition. work load(watt) L-condition(bpm) W-condition(bpm) Rest on land 59.3±7.8 57.0±13.5 Calibration 20 93.0±7.0 84.3±9.4 * Calibration 60 129.1±13.8 119.2±16.2 * Calibration 40 115.8±15.6 102.7±14.5 * Increasing 40 114.7±16.1 99.6±14.5 * Increasing 45 117.8±14.9 102.2±15.5 * Increasing 50 120.7±14.9 104.9±15.0 * Increasing 55 123.9±15.1 108.1±15.3 * Increasing 60 128.1±14.4 110.8±15.3 * Decreasing 55 130.6±15.3 112.6±15.3 *
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Pahlen Norge AS Pahlen Norge AS Cha
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