Biomechanics and Medicine in Swimming XI

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evaluating for 200-m or more events). Finally, C is given in J.kg -1 .m -1 E assuming that 1 mLO2 consumed by the human body yields 20.9 J (Fernandes et al., 2006). ANOVA and the Tukey Post-hoc test were used to analyse the differences between the different sets. Linear regression tests studied the relationships among the physiological parameters (C), motor organisation (IdC), stroke rate (SR) and stroke length (SL). For all tests, the level of significance was fixed at P
BiomechanicsandmedicineinswimmingXi Swimming and Respiratory Muscle Endurance Training: A Case Study lemaître, F., chavallard, F., chollet, d. Centre d’Etudes des Transformations des Activités Physiques et Sportives (CETAPS, EA3832), France The aim of this case study was to investigate whether respiratory muscle endurance training (RMET) would increase performance in a long-distance swimmer. An expert long-distance swimmer trained for 10 weeks in a RMET program (30 minutes a day, 5 days a week) plus his usual swim training. Maximal swim time trials, ventilatory function tests, maximal inspiratory and expiratory pressure (MIP and MEP), and respiratory endurance tests (RET) were done. Ventilatory function parameters were not improved post-training, but MIP, MEP, RET and swimming performance were increased (+19%, +33%, +7 minutes; 50 m: -5.4%; 200 m: -7.2% respectively). RMET may be thus a useful technique to improve performance in long-distance swimmers. Key words: endurance, respiratory muscle, performance IntroductIon The aim of this case study was to investigate whether respiratory muscle endurance training (RMET) would increase performance in a longdistance swimmer. Immersion in water increases the pressure around the thorax, raising ventilatory constraints both at rest and during physical effort. Until lately, ventilation was not considered to be a limiting factor for sub-maximal or maximal effort. However, it was shown that this ventilatory limitation decreases maximal performance in healthy subjects and athletes (Verges et al. 2007). It was thus suggested that training might delay respiratory muscle fatigue and permit better distribution of blood flow to the working muscles. It has often been observed that swimmers have pulmonary volumes that are greater than both predicted values and those of controls (Doherty et al., 1997). The improved pulmonary volumes in swimmers could be due to swim training per se (Clanton et al., 1987), stronger respiratory muscles (Doherty et al., 1997), alveolar hyperplasia (Armour et al., 1993), or accelerated pulmonary growth (Courteix et al., 1993). Clanton et al. (1987) showed that pulmonary function, endurance and respiratory muscle force were improved after swim training, whereas supplementary RMET did not lead to additional change. Similarly, Wells et al. (2005) showed that swim training alone improved pulmonary function and respiratory muscle force to the same extent as RMT associated with swim training. These findings seemed to be confirmed in a more recent study in high-level swimmers (Mickleborough et al., 2008). Moreover, it was recently reported that the impact on swimming performance seems to be limited (Kilding et al., 2009). Methods An expert long-distance swimmer (21 years, 183 cm, 71 kg) trained for 10 weeks in a RMET program plus his usual swim training. The athlete’s speciality was the 1,500-m event and he was a finalist in the French national championships. His best performance time on this distance was thus expressed as a percentage of the current world record, and was 93.4%. He was not asthmatic and consented to the study requirements in writing. The experimental procedures were conducted in accordance with the Declaration of Helsinki and were approved by the local ethics committee. He was evaluated on two occasions: before (1 week) and just after the RMET program. Measurements of body mass and skin folds were generally made between 8.00 and 10.00 A.M.; the swimmer presented after training in a fasted state and all anthropometric parameters were measured by the same investigator. Height was measured to the nearest 0.5 cm (Tanita, 206 Tanita Corp., Arlington Heights, IL, USA). Body composition (fat mass: FM) was estimated with the skinfold method of Durnin and Womersley (1974) using a calibrated skinfold calliper (Model HSK-BI, Baty International, West Sussex, UK). Chest expansion was measured at the level of the xiphoid process using a tape measure. The subject was instructed to perform a maximal exhalation [to residual volume (RV)] and then an inhalation to maximum inspiratory capacity (MIC). Chest expansion was calculated as the difference between circumferences at RV and MIC. The CV of test-retest measurements (within the day) at the level of the xiphoid process was 0.7%. Buoyancy was evaluated by measuring the hydrostatic lift (HL), which is the force that enables swimmers to float when they are immersed in forced inspiration. It was measured at the end of a maximal inspiration when the subject was floating. The subject was in the fetal position, facing downward. A lead mass (0.1-1 kg) was placed on the swimmer’s back between the shoulder blades. The load needed to keep the subject just under the water was taken as the HL. For the glide distance measurement, the subject was asked to adopt a prone position with the arms completely extended at the elbows and wrists, to position the upper arms in contact with the sides of the head (one hand on top of the other), to maintain the feet together with the ankles plantar flexed, to hold onto the wire, and to hold his breath after a maximal inspiration. For the passive torque time (Tt), which can be defined as the time it takes for the body to pass from horizontal to vertical position, the same researcher maintained the swimmer in the horizontal position until a signal was given by another researcher, who then noted the time it took for the swimmer to get into vertical position. The subject was asked to hold his breath after a maximal inspiration until the test ended. Each time (before and after RMET), three glide and three Tt measures are made in order to calculate and average the glide distance. Several parameters were measured for the pulmonary function tests: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and peak expiratory flow (PEF). For each parameter, the best value was chosen from at least three consecutive maneuvers differing by no more than 5% (Quanjer et al. 1993). All parameters were measured with a Microquark spirometer (Cosmed, Rome, Italy) in the same conditions, with the subject in a sitting position and breathing through the mouthpiece with a nose-clip. The spirometer volume was calibrated twice daily with a 3-L calibrated syringe. The results were corrected to BTPS conditions and compared with predicted values (Quanjer et al. 1993). The maximal inspiratory and expiratory pressures (MIP and MEP) were measured in the sitting position at the end of a normal expiration and inspiration (MEPFRC, MIPFRC) using a small portable mouth pressure meter (ZAN 100 USB, ZAN Messgeräte GmbH, Germany). The subject was verbally encouraged to achieve maximal strength. All maneuvers were repeated at least twice. The respiratory endurance test (RET) was performed with the SpiroTiger® device. The subject was asked to sustain a given minute ventilation (VE) with a predetermined tidal volume (VT) and respiratory frequency (fR) for as long as possible; that is, until he could no longer sustain either VT or fR despite three consecutive “warnings” by the experimenter. The RMET was performed 30 minutes a day, 5 days a week, with the same specific device (SpiroTiger®) allowing partial rebreathing of CO2 and thus assuring normocapnic hyperpnea. RMET consisted of voluntary normocapnic hyperpnea at a given VT and fR with a duty cycle of 0.5. The Spirotiger® provided breath-by-breath feedback of fR and VT. The size of the re-breathing bag was set at 50- 60% of vital capacity, and VE of the first training session was set at 60% of the maximal voluntary ventilation. The swimmer was instructed to increase fR after 25 min of training, if he felt he would not be exhausted by 30 min. If he felt he could not sustain the target for 30 min, he was to decrease the fR. The swimmer was instructed to increase fR from one session to the next by 1-2 breaths/min and was monitored by the experimenter at least once a week to verify compliance. The swimming performance was evaluated from the 50-m and 200m time trials (TT50m and TT200m) swum at maximal velocity and in
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Figure 2. Repeatability of the LTin
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Pahlen Norge AS Pahlen Norge AS Cha
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Biomechanics and Medicine in Swimming XI

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