Biomechanics and Medicine in Swimming XI

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Ribeiro, L. F. P. R., Lima, M. C. V. & Gobatto, C. A. (2010). Changes in physiological and stroking parameters during interval swins at the slope of the d-t relationship. J Sci Med Sport, 13(1), 141-145. Suzuki, F. G., Okuno, N. M., Lima-Silva, A. E., Perandini L. A. B., Kokubun E. & Nakamura F. Y. (2007). Perceived exertion during interval training in swimming at intensities below and above the critical speed. Port Jf Sports Scien, 7(3), 299-307. St Clair Gibson A., Baden, B. A., Lambert, M. I., Lambert, E. V., Harley, Y. X., Hampson, D., Russell, V. A. & Noakes, T. D. (2003). The conscious perception of sensation of fatigue. Sports Med, 33, 167-176. Ueda, T. & Kurokawa, T. (1995). Relationships between perceived exertion and physiological variables during swimming. Int J Sports Med, 16, 385-9. Ulmer, H. V. (1996). Concept of an extracellular regulation of muscular metabolic rate during heavy exercise in humans by psychophysiological feedback. Experientia, 52, 416-420. Wakayoshi, K., Ilkuta, K., Yoshida, T., Udo, M., Moritani, T. & Mutoh, Y. (1992). Determination and validity of critical velocity as an index of swimming performance in the competitive swimmer. Eur J Appl Physiol, 64, 153-7. AcKnoWledGeMents The authors are grateful for Daniel Geremia and Caio Baganholo Contador and athletes; Grupo de Pesquisa em Esportes Aquáticos – GPEA; Grupo de Pesquisa em Biomecânica e Cinesiologia – GPBIC, Universidade Federal do Rio Grande do Sul (UFRGS). chaPter4.trainingandPerformance Ventilatory and Biomechanical Responses in Short vs. Long Interval Training in Elite Long Distance Swimmers. hellard, P. 1,4 , dekerle, J. 2 , nesi, X. 2 , toussaint, J.F. 4 , houel, n. 1 , hausswirth, c. 3 1Département recherche, Fédération Française de Natation, Paris France. 2Chelsea, School, University of Brighton, England. 3Département des Sciences du Sport, INSEP, Paris, France. 4Institut de recherche en médecine et en épidémiologie du sport, IRMES, Paris, France. The objective of this study was to compare in seven elite male longdistance swimmers (Mean ± SD, age 21.4±3.5 yrs; weight 71±5 kg ; height 180±5 cm), physiological responses (mean oxygen uptake ( VO2 � mean ), carbon dioxide production ( VCO 2 � mean ) , ventilation ( E V� mean ) , heart rate (HRmean ) , time sustained above 90% of 2 O V� max , (T90%), blood lactate concentration (BL ), stroke rate (SFmean ), and stroke length (SL mean )) during two different interval training sets (6x500 m (IT6x500 ) and 30x100 (IT30x100 )) performed in random order at the velocity at Lactate Threshold (vLT) with the same work-to-rest ratio (60 vs. 15 s). Compared with the IT30x100 set, the IT6x500 set displayed greater ventilatory responses but with shorter stroke length to maintain a given sub-maximal speed. Short-interval training can be used to develop the distance per stroke while long interval training allows training to prevent the deterioration of stroke mechanics during high oxygen consumption regimens. Key words: Interval training, physiological responses, lactate threshold. IntroductIon The impact of a training set can be modulated by varying the duration, intensity, and the number of repetitions and rest periods between training intervals (Astrand et al., 1960; Bentley et al., 2005; Billat, 2001; Essen et al., 1977; MacDougall and Sale, 1981; Olbrecht et al., 1985). Changes in the parameters of a training set also has an effect on the amount of time the athlete trains at a given percent of 2 O V� max and thus affects long-term physiological adaptations in long distance training (Astrand et al., 1960; Bentley et al., 2005; Billat, 2001; Essen et al., 1977; MacDougall and Sale, 1981; Olbrecht et al., 1985). Intermittent bouts with long intervals in-between, swum at velocities close to maximum lactate steady state (vMLSS) and VO2 � max (v VO2 � max ) enables athletes to maintain higher speeds (Bentley et al., 2005; Billat, 2001; Essen et al., 1977; MacDougall and Sale, 1981; Olbrecht et al., 1985). This range of speeds is associated with preferential catabolism of lipid substrates via the attenuator effect of citrate produced by glycolysis during the intervals of rest (Essen et al., 1977). This leads to less pronounced serum lactate concentrations for equivalent or higher 2 O V� than reached during continuous training performed at lower speeds (Billat, 2001; Olbrecht et al., 1985). Because of the short periods of recovery inbetween repetitions, intermittent training also enables the restitution of myoglobin-bound oxygen stocks and higher muscular concentrations of adenosine triphosphate (ATP) and creatine phosphate (CP) so that during the first phase of a subsequent work, ß-oxydation is favored over glycolysis. Lesser accumulation of lactate at a given VO2 � , appears to be even more attractive in swimming as the stroke efficiency seems to deteriorate passing the anaerobic threshold pace. This is thought to be a consequence of a greater local fatigue (Dekerle et al., 2005). Moreover, intermittent training would enable the swimmer to maintain speeds close to those of competition, which is useful for speed-specific neuromuscular and coordination adaptations (Billat, 2001; Essen, 1977; Olbrecht et al., 1985). It is hypothesized that in high-level long-distance 259
BiomechanicsandmedicineinswimmingXi swimmers, very long training intervals (repetitions of 500 m) swum at lactate threshold would lead to greater oxygen uptake, higher stroke rate, and shorter stroke length than those observed during intervals of shorter distance (repetitions of 100 m). Methods Seven long-distance male swimmers competing at the national and international level participated in this study. Table 1. Individual anthropometric characteristics and training content. S 260 Age (Y) Weight (kg) Height (cm) v LT- (km) v LT+ (km) 1 23 61 176 2100 380 2 22 74 188 1900 290 3 20 75 185 2050 370 4 21 69 175 2200 303 5 20 76 182 2200 320 6 29 69 174 2350 352 7 20 76 182 2200 330 M 22 71 180 2143 335 SE 3.2 5.5 5.4 143 34 v LT-, annual training volume at low intensity below the lactate threshold. v LT+, annual training volume at high intensity above the lactate threshold . All participants completed three experimental sessions in a 50-m open pool (26°C) during one week of standardized training. The first training test consisted in a progressive incremental test to exhaustion. The other tests were two randomized interval sessions – 6 x 500 m (IT6x500 ) or 30x100 m (IT30x100 ) – performed at the velocity corresponding to lactate threshold (vLT). During each IT session, the time spent at 90% above 2 O V� max and 90% above maximal heart rate (HRpeak ) were determined retrospectively. The incremental test included five consecutive 300-m swims separated by 30s of rest. The speed of each increment was determined from the best performance of each swimmer in the 400m freestyle event measured during the month preceding the test. The speed for the first 300-m was 30-s slower than the average 300-m pace over the 400-m best performance and this time was then reduced by increments of 5 s for each consecutive 300-m until the final 300-m at the swimmer’s fastest speed. Swimming speeds were monitored with Aquapacer ‘Solo’ (Challenge and Response, Inverurie, UK) so that each swimmer could match auditory signals with visual markers positioned every 12.5 m along the border of the pool. Blood lactate level (expressed in mM/L) was determined from a fingertip blood sample which was analyzed immediately using a portable lactate analyzer (Lactate Pro, Arkray, Japan). Breath-by-breath respiratory data were collected with a portable gas analyzer (Cosmed K4b2, Rome, Italy) connected to an Aquatrainer snorkel (Cosmed, Rome, Italy). Heart rate (HR) was recorded using a belt system (Polar Electro, Finland). The lactate threshold (LT) was determined by two independent observers using the first inflexion method applied to the linear relationship between lactate level and velocity associated with a 1mmol·l-1 increase in serum lactate above the baseline level. HRpeak (expressed in beats·min-1 ) was defined as the mean highest HR measured over 15s during the test. During the interval training (IT), the swimmers were kept informed of their velocity using the protocol described above. Swimmers were encouraged orally to sustain their velocity despite increasing exhaustion throughout the set. Swim times (s) were systematically recorded for each 500 and 100-m repetition. Because the swimmers were wearing a snorkel, they used open turns. During a pilot run, the time needed to execute a turn with the snorkel was estimated individually with an average time of 1±0.37 s compared with a conventional tumble turn. The velocity (m·s-1 ) was calculated by dividing the length of each repetition (100-m or 500-m) by the time with individual correction for number of turns. The actual velocity for each 5x100m workout was averaged for a comparison with IT6x500 . Mean stroke rate (SR) (cycle·min-1 ) was measured in a 25-m central zone using a base 3 chronometer (Seiko, base 3, Japan). Stroke length (SL) was calculated for each 50 m by dividing the mean velocity by SR. Expired gases collected breath-by-breath were monitored continuously and recorded every 5 s. VO2 � mean for the two IT6x500 and IT30*100 sessions were calculated as was the time of swimming above 90% of VO2 � max (T>90%). Breath samples were then averaged over 30 s and 2 O V� peak and HR peak were measured and expressed in % of VO2 � max. Serum lactate level was measured at the end of eat IT session. results Stroke length was longer during IT 30x100 than IT 6*500 (2.45 ± 0.16 vs. 2.30 ± 0.16 m, P < 0.05) (Figure 1) and stroke rate tended to be lower (35.4 ± 3.3 vs. 37.8 ± 3.2, s·mn -1 , P = 0.08). SL (m) 2,8 2,7 2,6 2,5 2,4 2,3 2,2 2,1 2 1 2 3 4 5 6 Figure 1. Mean ± SE Stroke length (SL) (m·stroke -1 ) during each stage of the 30 x 100-m (IT 30x100 ) (Broken line with white diamonds shaped) and 6 x 500-m (IT 6x500 ) IT sessions (Continuous line with black squares). Stroke length was higher (P < 0.05) for (IT 30x100 ) than for (IT 6x500 ). There was no significant difference in swimming velocity between IT6*500 and IT30*100 for each 500 m. Expressed in % v VO2 � max and % vLT, swimming velocities were 96.4 ± 3.4 and 99.2 ± 3.6% for IT6*500 and 96.7 ± 3.4 and 99.4 ± 4.4% for IT30*100 respectively. Although the swimming velocity was similar during IT6*500 and IT30*100, VO2 � mean , VE � mean , BL and RPE were greater for IT6*500 than IT30*100 (63.8±3.9 vs. 57.3±3.1 mL.kg-1 ·min-1 ; 79.6±18.8 vs. 73.2±10.5 mL·kg-1 ·min-1 ; 4.1±1.2 vs. 3.2±1.4 mmol·L-1 ; 17.3±2.4 vs. 14.7±3.1 a.u. P < 0.05). T>90% was greater for IT6*500 (1357 ± 288 vs. 562 ± 326 s, P < 0.05) (Table 2). dIscussIon The major finding of this study is that the long interval training set (IT6*500m ) which was performed at vLT displayed higher physiological responses and longer time sustained above 90% VO2 � max compared with the shorter interval training (IT30*100m ). This is in agreement with the pioneer work on physiological response to interval training conducted by Astrand et al., (1960) who demonstrated that for exercise performed at 98% of the workload corresponding to VO 2 � max , long interval exercise allowed athletes to attain VO 2 � max whereas short-interval training led to sub-maximal response (63% VO 2 � max ). Conversely, our results are not in agreement with those reported by Bentley et al. (2005) who compared, in eight elite swimmers, two interval training sessions comprising 4 repetitions of 400m or 16 repetitions of 100m completed at a velocity representing 25% of the difference between ventilatory threshold and VO2 � max (Δ25%). They were unable to find any significant difference in the physiological responses. The apparent discordance with our data might be attributed to the shorter intervals (400 vs. 500 m), the smaller exercise volume (1600 vs. 3000 m). For elite long-distance swimmers, training at vLT over long intervals would probably be particularly useful as has already been reported
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Pahlen Norge AS Pahlen Norge AS Cha
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