Influence of training on the response to exercise of adrenocorticotropin and growth hormone plasma concentrations in human swimmers

The aim of the present study was to evaluate the response of adrenocorticotropin ([ACTH]) and growth hormone ([GH]) concentrations to a typical aerobic swimming set during a training season. Nine top-level male endurance swimmers (age range 17–23 years) were tested during three training sessions occurring 6, 12 and 18 weeks after the beginning of the season. During each session, after a standard warm-up, the swimmers performed a training set of 15?×?200-m freestyle, with 20?s of rest between repetitions, at a predetermined individual speed. Blood samples were collected before warm-up and at the end of the training set. A few days before each session, the individual swimming velocity corresponding to the 4?mmol?·?l^?1 blood lactate concentration (v ₄) was assessed as a standard of aerobic performance. Aerobic training affected v ₄ levels, which were highest 18 weeks after the beginning of the season; at the same time, while [ACTH] response was attenuated, [GH] response was enhanced. These results could be considered as adaptations to the exercise intensity. In our training programme, these adaptations seemed to have occurred between the 12th and 18th weeks of the training season.     

Performance and physiological responses to a 5-week synchronized swimming technical training programme in humans

A synchronized swimming team routine (TR) is composed of figures of varying degrees of difficulty. Swimmers able to perform these figures separately underwent a 5-week technical training programme (TTP) to assemble a TR. Little is known about the physiological responses to this kind of TTP. A group of 13 trained synchronized swimmers [mean age 14 (SD 1) years] were tested before and after a 5-week TTP. The TR lasted 5?min, and 45% of that time was spent underwater. The swimmers' technique scores in the TR improved significantly from 4.5 (SD 1.9) before to 5.8 (SD 2.3) points after the TTP (P?V˙O_2peak), blood lactate concentration, and heart rate measured during a 400-m swim were lower after the TTP. The improvement in the technique scores correlated negatively with the change in V˙O_2peak (r?=??0.57; P?V˙O_2peak. The overall synchronized swimming skill was assessed by the best score the swimmers obtained in four to six competitions over a season. This score was related to the 400-m swimming performance, V˙O_2peak, maximal distance covered in apnoea, and the breath-hold time. The 5-week TTP therefore improved technical performance during the TR without improving physiological, swimming or apnoea performances. However, the physiological profile of each swimmer was linked to the synchronized swimming skill.     

Evaluation of muscle fatigue during 100-m front crawl

The aim of this study was to evaluate muscle fatigue in upper body muscles during 100-m all-out front crawl. Surface electromyogram (EMG) was collected from the pectoralis major, latissimus dorsi and triceps brachii muscles of 11 experienced swimmers. Blood lactate concentration level increased to 14.1?±?2.9?mmol?l^?1 5?min after the swim. The velocity, stroke length and stroke rate calculated based on video analysis decreased by 15.0, 5.8 and 7.4%, respectively, during the swim. EMG amplitude of the triceps and the lower part of the latissimus muscles increased, whilst the mean power frequency (MNF) of all muscles significantly decreased by 20?C25%. No significant differences in the relative MNF decrease were observed amongst the muscles; however, the differences in the rate of the MNF decrease between the lower part of the latissimus and the triceps brachii muscles were found (P?<?0.05). The time of rest between the muscle activation of the two consecutive arm strokes at the end of swimming was extended (P?<?0.05). It was concluded that 100-m all-out crawl induced significant fatigue with no evident differences amongst the analysed muscles.     

Preparatory versus main competitions: differences in performances, lactate responses and pre-competition plasma cortisol concentrations in elite male swimmers

Two groups of elite male swimmers were studied using a similar protocol during the winter training seasons of two consecutive years. In the first season (September 1997–January 1998), eight male swimmers (age 19–25 years) of the Italian National Team participated, after 12 weeks of increased training volume, in a preparatory national competition (PWC) and then, after a further 6 weeks of specific training, in the World Championships (WC, both competitions in a 50-m pool), which represented the main competition at the end of the 18-week-long winter season. In the second season (September 1998–December 1998), a group of ten high-level male swimmers (18–22 years) participated, after 8 weeks of increased training volume, in a preparatory national competition (PIC) and then, after a further 6 weeks of specific training, in the Italian Championships (IC, both competitions in a 25-m pool), the main competition at the end of the 14-week-long winter season. A tapering period lasting 1–3 weeks was observed before the main competition in both seasons. All swimmers were competing at distances of up to 400 m; two of them participated in the study in both seasons. The swimming velocities and post-competition blood lactate concentrations were higher in the main competitions than in the preparatory competitions in both seasons. Pre-competition plasma cortisol (CORT) concentrations were higher than the initial values at the beginning of the season, reaching maximal values at the preparatory competitions and then decreasing before the main competitions in both seasons. The percentage increase in individual swimming velocity from the preparatory to the main competition was positively correlated with the corresponding increase in post-competition blood lactate (r=0.63, P=0.046) in the 1997 season (WC), and negatively correlated with the corresponding decrease in pre-competition CORT concentration (r=−0.66, P=0.019) in the 1998 season (IC). Our results indicate that a decrease in pre-competition CORT could be a prerequisite for an improvement in swimming performance. Accepted: 9 March 2000     

Blood lactate recovery measurements,training, and performance during a 23-week period of competitive swimming

The purpose of this study was to relate measurements of blood lactate concentration, performance during a maximal anaerobic lactic test (MANLT) and training loads during a 23-week swimming season. Six elite 200-m freestyle male swimmers [mean age 19.5 (SD 1.6) years, height 184 (SD 5) cm and body mass 77.7 (SD 9.0) kg], participated in the study. The MANLT consisted of four all-out 50-m swims interspersed with 10-s recovery periods. Blood lactate concentrations were determined at 3 and 12-min post-exercise and were performed on weeks 2, 6,10,14,18 and 21. Swimmers participated in 200-m freestyle competitions on weeks 1, 7,13 and 23 (national championships). During weeks 1–10, training mostly involved aerobic exercise, while during weeks, 11–23, it involved anaerobic exercise. At 3-min and 12-min post-MANLT lactate concentrations varied throughout the season [range from 14.9 (SD 1.2) to 18.7 (SD 1.0) mmol·l^–1] but demonstrated non-systematic variations. In contrast, the percentage of mean blood lactate decrease (% [La-]_recovery) between min 3 and min 12 of the passive recovery post-MANLT increased from week 2 to 10 with aerobic training and decreased from week 10 to 21 with anaerobic training. The MANLT performance improved continuously throughout the season, while competition performance improved during the first three competitions but declined in the final championships, coinciding with the lowest % [La-]_recovery and signs of overtraining, such as bad temper and increased sleeping heart rate. The results of this study indicated that % [La-]_recovery could be an efficient marker for monitoring the impact of aerobic and anaerobic training and avoiding overtraining in elite 200-m swimmers.     

Physiological and muscle enzyme adaptations to two different intensities of swim training

Summary To test the hypothesis that a smaller quantity of high intensity (HI) as opposed to a larger quantity of moderate intensity (MI) swim training would result in adaptations more specific to the short performance times of swimming competitions, two groups of elite university swimmers were tested before and after 6.5 weeks of specific HI or MI intermittent swim training. In training, swimming times were faster and blood lactate concentrations were higher (10.2 vs. 7.5 mM) during HI compared to MI training. No significant differences were observed between the two groups for any of the variables measured, before or after training. However, significant increases with training were observed for the activities of hexokinase, phosphorylase, phosphofructokinase, succinate dehydrogenase, and 3-hydroxyacyl CoA dehydrogenase in the deltoid, but not the gastrocnemius muscles. Training resulted in significant increases in O₂ max during treatmill running, but not during tethered swimming. It is concluded that a larger quantity of MI swim training results in physiological adaptations that are similar to those obtained with a smaller quantity of HI training, at least over a relatively short training period.This study was supported by a grant from the Natural Sciences and Engineering Research Council of Canada     

Comparison of cardiopulmonary responses to two types of dry-land upper-body exercise testing modes in competitive swimmers

In this study we compared cardiopulmonary responses to upper-body exercise in 12 swimmers, using simulation of the front-crawl arm-pulling action on a computer-interfaced isokinetic swim bench and arm cranking on a modified cycle ergometer. Subjects adopted a prone posture; exercise was initially set at 20?W and subsequently increased by 10?W?·?min^?1. The tests were performed in a randomised order at the same time of day, within 72?h. The highest (peak) oxygen consumption (V˙O_2peak), heart rate (HR_peak), blood lactate ([la^?]_peak) and exercise intensity (EI_peak) were recorded at exhaustion. Mean (SEM) peak responses to simulated swimming were higher than those to arm cranking for V˙O_2peak [2.9 (0.2) vs 2.4 (0.1) l?·?min^?1; P?=?0.01], HR_peak [174 (2) vs 161 (2) beats?·?min^?1; P?=?0.03], and EI_peak [122 (6) vs 102 (5) W; P?=?0.02]. However, there were no significant differences in [la^?]_peak [9.6 (0.6) vs 8.2 (0.6) mmol?·?l^?1; P?=?0.08]. Thus simulated swimming is the preferred form of dry-land ergometry for the assessment of swimmers.     

Effect of intensive swimming training on lung volumes, airway resistances and on the maximal expiratory flow-volume relationship in prepubertal girls

The aim of the present study was to analyse the effect of 1 year of intensive swimming training on lung volumes, airway resistance and on the flow-volume relationship in prepubertal girls. Five girls [9.3 (0.5) years old] performing vigorous swimming training for 12?h a week were compared with a control group of 11 girls [9.3 (0.5) years old] who participated in various sport activities for 2 h per week. Static lung volumes, maximal expiratory flows (MEF) at 75, 50 and 25% of vital capacity, 1-s forced expiratory volume (FEV_1.0) and airway resistance (R _aw) were measured by means of conventional body plethysmograph techniques. Prior to the training period there were no significant differences between the two groups for any of the parameters studied. Moreover, for both groups, all parameters were within the normal range for children of the corresponding age. After 1 year of training, vital capacity (VC), total lung capacity (TLC) and functional residual capacity (FRC) were larger (P<0.05) in the girl swimmers than in the control group, while physical development in terms of height and weight was similar. FEV_1.0 (P<0.01), MEF₂₅, MEF₅₀ (P<0.05) and MEF₇₅ as well as the ratio MEF₅₀ / TLC (P<0.05) had increased in the girl swimmers but were unchanged in the control group. R _aw tended to be lower in the girl swimmers and higher in the control group. The results indicate that intensive swimming training prepuberty enhances static and dynamic lung volumes and improves the conductive properties of both the large and the small airways. As to the causative mechanism, it can be speculated that at prepuberty intensive swimming training promotes isotropic lung growth by harmonizing the development of the airways and of alveolar lung spaces.     

Urine citrate and 6-sulfatoximelatonin excretion during a training season in top kayakers

The effects of high training loads during the competitive kayaking season may be reflected in urinary citrate and 6-sulfatoxymelatonin (^αMT6S) excretion. The present study aims to evaluate the influence of a training program on citrate and ^αMT6S excretion in 12 elite kayakers. Urine samples were collected (before bedtime and again in the morning, at first voiding) at the beginning of the season (second half of October), during the macrocycle (specific training period; first week of June), and tapering (precompetitive training period; first week of July) stages. During the training season, urine citrate values (mg/L) were higher in the evening than in the morning in all stages (p?<?0.01). The data obtained in the evening showed the lowest significant values (p?<?0.05) in the beginning stage compared with the macrocycle and tapering stages. The values obtained in the morning showed the lowest significance (p?<?0.05) in the macrocycle stage compared to the beginning and the tapering stages. In all stages, ^αMT6S (ng/mL) evening values were significantly lower (p?<?0.05) than the morning values. The morning/evening ratio, total sum, and nocturnal increment of ^αMT6S did not vary across the training stages. From these results, it can be deduced that the pineal function is unaltered and that citrate turnover is good in elite kayakers during the training season. It was found that urine citrate and ^αMT6S obtained by non-invasive techniques may be used as major markers to evaluate metabolic recovery and stress produced by the training season workload in elite kayakers.     

Effects of swimming with a wet suit on energy expenditure during subsequent cycling.]

The aim of this study was to investigate the effects of swimming with a wetsuit on energy expenditure during subsequent cycling. Nine well-trained triathletes underwent three submaximal trials. The first trial (SC) consisted of a 750-m swim realised at a competition pace, followed by a 10-min cycling exercise at a power output corresponding to the ventilatory threshold . The two other trials were composed of the same cycling exercise, preceded either by a 750-m swim with a wetsuit (WSC) or by a cycling warm-up (Ctrl). The main results are that the WSC trial was characterised by significantly lower swimming cadence (-14%), heart rate (-11%), and lactate values (-47%) compared to the SC trial, p < 0.05. Moreover, cycling efficiency was significantly higher in the WSC trial compared to the SC trial (12.1% difference, p < 0.05). The lower relative intensity observed during swimming with a wetsuit suggest the relative importance of swimming condition on the total performance in a sprint triathlon.     

Redox balance and mitochondrial glycerol phosphate dehydrogenase activity in trained rats

Free radical production is increased in many disease states and during exercise, but in the latter the concurrent stimulation of the antioxidant defense system seems to protect the organism from excessive production of reactive oxygen species. Chronic exercise can exert negative effects on the activity of mitochondrial glycerol phosphate dehydrogenase (mGPdH), which may offer some explanation for the antioxidant effects of training, since this enzyme is a relevant producer of free radicals. To test this correlation, we compared mGPdH activity, two antioxidant defense markers and two markers of oxidative stress in sedentary and trained (Tr) rats. Training was through a swimming exercise 3?days a week. After 8?weeks, Tr rats lasted twice as long as controls in an acute swimming test with a 5% load. Forty-eight hours after the last exercise, the animals were killed to collect blood and tissues. Tr animals presented lower body weight and visceral fat mass with lower triglyceride content in visceral fat and plasma (p?<?0.05). The specific activity of mGPdH in muscle mitochondria was reduced in Tr rats by 88% (p?<?0.05). Total antioxidant capacity, lipid peroxidation and reduced glutathione (GSH) in liver and muscle were unaltered, while plasma GSH increased by 21% (p?<?0.05). These data suggest a profile of successful redox equilibrium maintenance in Tr rats, with a potentially significant contribution from the lower level of mGPdH activity in muscle. This training protocol appears to be suitable for use in detailed studies of biochemical adaptations to oxidative stress.     

Inspiratory muscle training improves 100 and 200 m swimming performance

Inspiratory muscle training (IMT) has been shown to improve time trial performance in competitive athletes across a range of sports. Surprisingly, however, the effect of specific IMT on surface swimming performance remains un-investigated. Similarly, it is not known whether any ergogenic influence of IMT upon swimming performance is confined to specific race distances. To determine the influence of IMT upon swimming performance over 3 competitive distances, 16 competitive club-level swimmers were assigned at random to either an experimental (pressure threshold IMT) or sham IMT placebo control group. Participants performed a series of physiological and performance tests, before and following 6 weeks of IMT, including (1) an incremental swim test to the limit of tolerance to determine lactate, heart rate and perceived exertion responses; (2) standard measures of lung function (forced vital capacity, forced expiratory volume in 1 s, peak expiratory flow) and maximal inspiratory pressure (MIP); and (3) 100, 200 and 400 m swim time trials. Training utilised a hand-held pressure threshold device and consisted of 30 repetitions, twice per day. Relative to control, the IMT group showed the following percentage changes in swim times: 100 m, −1.70% (90% confidence limits, ±1.4%), 200 m, −1.5% (±1.0), and 400 m, 0.6% (±1.2). Large effects were observed for MIP and rates of perceived exertion. In conclusion, 6 weeks of IMT has a small positive effect on swimming performance in club-level trained swimmers in events shorter than 400 m.     

Adaptation of maximal aerobic and anaerobic tests for disabled swimmers

The purpose of the present study was to submit disabled swimmers to two maximal swimming tests, and by comparing the physiological and performance responses of disabled and normal swimmers to determine if these adapted tests can be used to design training programmes for this particular class of swimmer. Two groups of disabled (n = 8 and 6) and two groups of normal competitive swimmers (n = 9 and 13) were respectively submitted to a functional maximal aerobic power test (FMAPT) and a maximal anaerobic lactic test (MANLT). For the disabled, the FMAPT included a slower initial speed and a slower increase in swimming speeds. In the maximal aerobic test, exercise duration, peak heart rate, and the maximal speed relative to the respective best time of a 100-m race [55.5 (SD 3.9) compared to 56.5 (SD 2.8)%] were not significantly different between the disabled and normal swimmers. Peak lactate concentration was, however, higher in the disabled swimmers [10.8 (SD 3.5) compared to 6.8 (SD 1.6) mmol · l^–1]. In the MNALT, peak lactate concentration [14.3 (SD 4) compared to 16.8 (SD 1.9) mmol · l^–1], and the maximal speed relative to the respective best time in a 100-m race [99.1 (SD 3.2) compared to 98.3 (SD 2.5)%] were not significantly different between the disabled and normal swimmers. These results would seem to indicate that functional maximal aerobic and anaerobic field tests could be used to evaluate and design training programmes for disabled competitive swimmers.     

Influence of altitude training modality on performance and total haemoglobin mass in elite swimmers

We compared changes in performance and total haemoglobin mass (tHb) of elite swimmers in the weeks following either Classic or Live High:Train Low (LHTL) altitude training. Twenty-six elite swimmers (15 male, 11 female, 21.4 ± 2.7 years; mean ± SD) were divided into two groups for 3 weeks of either Classic or LHTL altitude training. Swimming performances over 100 or 200 m were assessed before altitude, then 1, 7, 14 and 28 days after returning to sea-level. Total haemoglobin mass was measured twice before altitude, then 1 and 14 days after return to sea-level. Changes in swimming performance in the first week after Classic and LHTL were compared against those of Race Control (n = 11), a group of elite swimmers who did not complete altitude training. In addition, a season-long comparison of swimming performance between altitude and non-altitude groups was undertaken to compare the progression of performances over the course of a competitive season. Regardless of altitude training modality, swimming performances were substantially slower 1 day (Classic 1.4 ± 1.3% and LHTL 1.6 ± 1.6%; mean ± 90% confidence limits) and 7 days (0.9 ± 1.0% and 1.9 ± 1.1%) after altitude compared to Race Control. In both groups, performances 14 and 28 days after altitude were not different from pre-altitude. The season-long comparison indicated that no clear advantage was obtained by swimmers who completed altitude training. Both Classic and LHTL elicited ~4% increases in tHb. Although altitude training induced erythropoeisis, this physiological adaptation did not transfer directly into improved competitive performance in elite swimmers.     

Effect of intense swimming training on rhinitis in high‐level competitive swimmers

Background Rhinitis is commonly reported by swimmers. Seasonal allergic rhinitis may impair athletes' performance and quality of life (QOL). No data are currently available on the changes of nasal symptoms during and after a swimming season. We aimed to determine in competitive swimmers: (1) the prevalence of rhinitis and its impact on their QOL during an intense training programme, (2) the changes in nasal symptoms and QOL after a resting period and (3) the relationship between rhinitis and airway hyperresponsiveness (AHR). Methods Thirty‐nine swimmers and 30 healthy controls answered the Rhinitis Quality of Life Questionnaire (RQLQ) and scored nasal symptoms on a seven‐point Likert scale during the week preceding their visit. Subjects had allergy skin prick tests and a methacholine challenge. Peak nasal inspiratory flows were also measured. The athletes performed these tests during an intense training period (V1), outside the pollen season and after at least 2 weeks without swimming (V2). Results At V1, rhinitis symptoms were reported by 74% of swimmers and 40% of controls (P<0.01). Eighty‐four percent of swimmers and 72% of controls were atopic (NS). RQLQ score was higher in swimmers compared with controls at V1 (27.3 ± 28.5 vs. 9.5 ± 12.7, respectively, P<0.005). The presence of AHR during training did not correlate with the presence of rhinitis symptoms. At V2, the nasal symptoms and RQLQ scores were similar in swimmers and controls. Conclusion Intense swimming training is associated with an increase in nasal symptoms and impairment in QOL in most competitive swimmers. Such an increase is not related to seasonal allergen exposure in atopic athletes and probably results from chlorine derivative exposure. Cite this as: V. Bougault, J. Turmel and L. P. Boulet, Clinical & Experimental Allergy, 2010 (40) 1238–1246.     

Effect of training on hormonal responses to exercise in competitive swimmers

Summary The effects of 9 weeks of training on responses of plasma hormones to swimming were studied in eight competitive swimmers who had not trained for several months. Two types of swimming tests were used: (1) 200 yd, a high intensity, exhausting type of exercise in which maximal effort was required both before and after training, and (2) 1000 yd, a pace type of exercise in which subjects swam as fast as possible prior to training and at the same rate after training. Plasma levels of glucagon increased and of insulin decreased during 1000 yd of swimming, but were not altered by 200 yd of swimming. No training effects were apparent in responses of plasma insulin and glucagon to these short-term, high intensity exercise tests. During the 1000 yd swim, plasma adrenaline was 0.8 ng/ml before vs. 0.1 ng/ml after training. Plasma noradrenaline response decreased from 3.4 to 1.2 ng/ml as a result of training. In the 200 yd swim, adrenaline, but not noradrenaline, was lower after training.R. C. Hickson and R. K. Conlee were postdoctoral research trainees supported by NIH Training Grant AM-05341.J. M. Hagberg was a postdoctoral research trainee supported by NIH Training Grant HL-07081.     

Effects of concurrent inspiratory and expiratory muscle training on respiratory and exercise performance in competitive swimmers

The efficiency of the respiratory system presents significant limitations on the bodys ability to perform exercise due to the effects of the increased work of breathing, respiratory muscle fatigue, and dyspnoea. Respiratory muscle training is an intervention that may be able to address these limitations, but the impact of respiratory muscle training on exercise performance remains controversial. Therefore, in this study we evaluated the effects of a 12-week (10 sessions week^–1) concurrent inspiratory and expiratory muscle training (CRMT) program in 34 adolescent competitive swimmers. The CRMT program consisted of 6 weeks during which the experimental group (E, n=17) performed CRMT and the sham group (S, n=17) performed sham CRMT, followed by 6 weeks when the E and S groups performed CRMT of differing intensities. CRMT training resulted in a significant improvement in forced inspiratory volume in 1 s (FIV_1.0) (P=0.050) and forced expiratory volume in 1 s (FEV_1.0) (P=0.045) in the E group, which exceeded the S groups results. Significant improvements in pulmonary function, breathing power, and chemoreflex ventilation threshold were observed in both groups, and there was a trend toward an improvement in swimming critical speed after 12 weeks of training (P=0.08). We concluded that although swim training results in attenuation of the ventilatory response to hypercapnia and in improvements in pulmonary function and sustainable breathing power, supplemental respiratory muscle training has no additional effect except on dynamic pulmonary function variables.     

Blood lactate responses in older swimmers during active and passive recovery following maximal sprint swimming

Summary The purpose of this study was to determine the effect of age on three blood lactate parameters following maximal sprint swimming. The parameters examined were maximal blood lactate concentration, time to reach maximal blood lactate concentration, and half recovery time to baseline lactate concentration. These parameters were examined in 16 male competitive masters swimmers (n=4 for each age group: 25–35, 36–45, 46–55, and 56 plus years) during both passive and active recovery following a maximal 100 m freestyle sprint. Passive recovery consisted of 60 min sitting in a comfortable chair and active recovery consisted of a 20-min swim at a self-selected pace. Capillary blood samples were obtained every 2 min up to 10 min of recovery then at regular intervals to the end of the recovery period. Curves of blood lactate concentration against time were drawn and the three parameters determined for each condition for each subject. There were no significant differences between age groups in any of the lactate parameters examined. A significant difference (P<0.05) was noted in each of the parameters between active and passive recovery over all age groups. As expected, active recovery produced lower maximal blood lactate concentrations, lower time to maximal blood lactate values, and lower half recovery times. These data suggest that intensive swimming training may prevent or delay the decline with age in the physiological factors affecting blood lactate values following a maximal sprint swim. Older sprint swimmers appeared to be capable of producing and removing lactic acid at the same rate as younger swimmers. These data suggest that the age-related decline in swim-sprint performance may be due to factors other than changes in anaerobic glycolytic capacity.     

Changes in performance, muscle metabolites, enzymes and fibre types after short sprint training

In contrast to endurance training, little research has been carried out to investigate the effects of short (<10?s) sprint training on performance, muscle metabolism and fibre types. Nine fit male subjects performed a mean of 16 outdoor sprint running training sessions over 6 weeks. Distances sprinted were 30–80?m at 90–100% maximum speed and between 20 and 40 sprints were performed in each session. Endurance (maximal oxygen consumption; V˙O_{2 max}), sprint (10?m and 40?m times), sustained sprint (supramaximal treadmill run) and repeated sprint (6?×?40?m sprints, 24?s recovery between each) performance tests were performed before and after training. Muscle biopsy samples (vastus lateralis) were also taken to examine changes in metabolites, enzyme activities and fibre types. After training, significant improvements were seen in 40?m time (P?P?P?V˙O_{2 max} (P?P?P?P?相似文献   

Hormonal responses to training and its tapering off in competitive swimmers: relationships with performance

During a winter training season, the effects of 12 weeks of intense training and 4 weeks of tapering off (taper) on plasma hormone concentrations and competition performance were investigated in a group of highly trained swimmers (n = 8). Blood samples were collected and the swimmers performed their speciality in competition at weeks 10 (mid-season), 22 (pre-taper) and 26 (post-taper). No statistically significant changes were observed in the concentrations of total testosterone (TT), non-sex hormone binding globulin-boundtestosterone (NSBT), cortisol (C), luteinising hormone, thyroid stimulating hormone, triiodothyronine, thyroxine plasma catecholamines, creatine kinase and ammonia during training and taper. Mid-season NSBT: C ratio and the amount of training were statistically related (r = 0.82,P < 0.05). Competition performance slightly declined during intense training [0.52 (SD 2.51) %, NS] and improved during taper [2.32 (SD 1.69)%,P < 0.01]. Changes in performance during training and taper correlated with changes in ratios TT: C (r = 0.86,P < 0.01andr = 0.81,P < 0.05, respectively) and NSBT: C (r = 0.77,P < 0.05 andr = 0.76,P < 0.05, respectively). In summary, these results showed that the monitored plasma hormones and metabolic indices were unaltered by 12 weeks of intense training and 4 weeks of taper. The TT: C and NSBT: C ratios, however, appeared to be effective markers of the swimmers' performance capacities throughout the training season.