Heart rate variability, training variation and performance in elite swimmers

The aim of the present study was to investigate the relationships between heart rate variability (HRV) changes and both training variations and performances in elite swimmers. A secondary purpose was to measure catecholamine urinary excretion in elite swimmers to validate the HRV indices of sympathetic activity during training. Thirteen swimmers (4 females and 9 males) were tested before and after 4 weeks of intense training (IT) and 3 weeks of reduced training (RT). At the end of each period, the swimmers participated in an official competition of their best event. Individual performances were expressed as percentage of the previous season's best performance. Spectral analysis was used to investigate RR interval variability. HRV indices failed to show any significant changes between the study periods (p>0.05). Pre-IT HF was correlated with performance (r=0.45; p=0.05) and HFnu (r=0.59; p<0.05) during RT. On the other hand, once RT was completed, HFnu was correlated positively to performance (r=0.81; p<0.01) and negatively to fatigue (r=- 0.63; p<0.03). Conversely, the indices of sympathetic activity, i.e., LFnu and LF/HF ratio were inversely related to performance (both r=- 0.81; p<0.01); total fatigue score was correlated to the changes in HFnu (r=- 0.63; p<0.03) and in the LF/HF ratio (r=0.58; p<0.05). Changes in the adrenaline/noradrenaline ratio over the follow-up period were related to the changes in the LF/HF ratio (r=0.45; p<0.03). In highly trained swimmers coping well with a training program, including 4 weeks of IT followed by 3 weeks of RT, HRV indices were unaltered. On the other hand, after the 3 weeks of RT, HFnu was positively related to performance and inversely related to the fatigue score. Thus, elevated initial HF levels could be important in the parasympathetic activity increases during taper and, hence, in swimming performance improvement.     

Time course of the hemoglobin mass response to natural altitude training in elite endurance cyclists

To determine the time course of hemoglobin mass (Hb_mass) to natural altitude training, Hb_mass, erythropoietin [EPO], reticulocytes, ferritin and soluble transferrin receptor (sTfR) were measured in 13 elite cyclists during, and 10 days after, 3 weeks of sea level (n=5) or altitude (n=8, 2760 m) training. Mean Hb_mass, with a typical error of ～2%, increased during the first 11 days at altitude (mean ± standard deviation 2.9 ± 2.0%) and was 3.5 ± 2.5% higher than baseline after 19 days. [EPO] increased 64.2 ± 18.8% after 2 nights at altitude but was not different from baseline after 12 nights. Hb_mass and [EPO] did not increase in sea level. Reticulocytes (%) were slightly elevated in altitude at Days 5 and 12 (18.9 ± 17.7% and 20.4 ± 25.3%), sTfR was elevated at Day 12 (18.9 ± 15.0%), but both returned to baseline by Day 20. Hb_mass and [EPO] decreased on descent to sea level while ferritin increased. The mean increase in Hb_mass observed after 11 days (～300 h) of altitude training was beyond the measurement error and consitent with the mean increase after 300 h of simulated live high:train low altitude. Our results suggest that in elite cyclists, Hb_mass increases progressively with 3 weeks of natural altitude exposure, with greater increases expected as exposure persists.     

Anabolic and catabolic hormonal response of elite runners to training at high altitude

A 2-week training period 2000 meters above sea level performed by 6 male elite Swedish runners influenced neither basal anabolic (total and non-sex hormone-binding globulin (SHBG)-bound testosterone (NST) and insulin-like growth factor-1 (IGF-1) nor catabolic (cortisol) hormones when comparing serum levels prior to and after the training camp. The anabolic vs catabolic hormone balance, expressed as the NST: cortisol ratio, also remained unchanged as well as SHBG and body mass. Thus, training at 2000 meters above sea level, often practised by elite runners to improve performance in competition at sea level, does not result in a catabolic situation after return to sea level, as measured by peripheral hormones. However, the adaptation to high altitude was associated with a slight (NS) decrease in testosterone as well as in anabolic vs catabolic balance as measured the third day at high altitude. Simultaneously, a decrease in subjective performance was claimed by the runners, but could not be shown by objective measurements. From day 3 to day 9 at high altitude, all runners claimed a subjective recuperation of performance. Total and non-SHBG-bound testosterone increased significantly from day 3 at high altitude to the first post-camp sea-level test. The results reflect the necessity of adaptation when travelling to races at different altitudes. The Swedish runners had significantly higher cortisol, total testosterone and NST levels compared with basal values of a group of 17 elite Kenyan runners living and training at high altitude. Since the NST cortisol and IGF-1 values were not lower, a catabolic state or malnutrition was not likely to be present. The results might reflect an adaptation to altitude or ethnic variations.     

The relationship between talent identification testing parameters and performance in elite junior swimmers

Objectives

In elite age-group swimming it is unclear to what degree common assessments of anthropometric, jump performance and front-crawl critical speed (CS) correlate with competition performance.

Cortisol,DHEA, performance and training in elite swimmers

Salivary cortisol (C) and DHEA concentrations were measured in 9 elite swimmers (4 female and 5 male) over a 37-week period, 5 to 12 times per swimmer, before 68 competitions. For female and male swimmers, no significant relationship was found between C, DHEA and performance. For the whole group, C was negatively correlated with week number of training (r = -0.31, p < 0.01). The incorporation of the cumulated distance swum as a second variable in the regression increased r to 0.56 (p < 0.01). The higher the cumulated distance swum, the higher C. No significant relationship was found between DHEA and distance swum. For individual swimmers, 3 of 4 females showed a significant negative relationship between C and cumulated dry-land training. No equivalent relationship was found for DHEA. The 2 males practicing dry-land training showed a significant and negative relationship between DHEA and cumulated dry-land training. No equivalent relationship was found for C. Thus, C and DHEA were not good predictors of swimming performance. C for individual females, and DHEA for individual males were considered useful markers for dry-land training stress.     

Effect of creatine supplementation on training for competition in elite swimmers

PURPOSE: The study was conducted to examine the effects of oral creatine supplementation on training for competition in 20 elite swimmers. METHODS: Subjects performed a maximal sprint test (8 x 50 yd (45.72 m), T1) before loading with creatine (Cr, 20 g.d Cr monohydrate for 5 d), 1 wk later (T2), and following a 22- to 27-wk period of training and competition (T3). Following T2, subjects supplemented with either Cr (3 g + glucose 7 g.d) or placebo (glucose 10 g.d; double blind) for the remainder of the 22- to 27-wk season and then both groups supplemented once more with 20 g.d Cr monohydrate for 5 d before their major competition. Venous and capillary blood samples were obtained pre- and posttest during the repeated sprint tests to determine blood metabolites and hormones. Competition times were recorded, and changes in subjects' best times were used to compare the effect of training and supplementation on competitive performance. RESULTS: Mean competition times in the Cr and control groups changed by+1.90 +/-1.91 and+0.72+/-1.64% for short course (SC, 25-m pool) and by+0.14+/-1.14 and -0.59+/-0.82% long course (LC, 50-m pool), respectively (Cr vs control, NS). No differences between groups were found in blood metabolites, although the human growth hormone (hGH) response to repeated sprints was blunted following Cr loading (T1, 30.42+/-14.60 and 28.95+/-18.27 microg.L; T2, 21.48+/-13.96 and 14.24+/-7.32 microg.L for Cr and control groups, respectively P<0.05). CONCLUSION: No statistically significant differences in performance were observed between groups after long-term maintenance during training, although small differences were observed that might be meaningful for elite performers.     

24-hr urinary catecholamine excretion, training and performance in elite swimmers

The aim of the present study was to investigate the effects of training variations on 24-hr urinary noradrenaline (NA) and adrenaline (Ad) levels and the adrenaline/noradrenaline (Ad/NA) ratio to search for a possible relationship between catecholamine excretion, training, and performance in highly trained swimmers. Fourteen swimmers (5 female and 9 male) were tested after 4 weeks of intense training (IT), 3 weeks of reduced training (RT), and 5 weeks of low training (LT). At the end of each period, the swimmers performed their best event at an official competition. Individual performances were expressed as percentage of the previous season's best performance. The changes in NA levels after 4 weeks of IT were negatively related to changes in training volume (r=-0.70, p<0.01) and total training load (r=-0.68, p<0.02). NA levels measured at the end of IT were positively related to changes in performance after three weeks of RT (r=0.77, p<0.01). The percentage changes in performance between RT and LT were related to NA levels at the end of RT (r=0.60; p<0.04). Ad/NA ratios and Ad were related to performance (r=0.58, p<0.01; r=52, p<0.01; respectively). The differences in Ad/NA ratios and Ad between two consecutive competitions were related to the differences in performance (r=0.59, p<0.01; r=0.49, p<0.01; respectively). 24-hr NA and the Ad/NA excretion ratio were related to both training variations and performance. Thus, 24-hr NA levels and Ad/NA ratio may provide useful markers for monitoring training stress in elite swimmers.     

Arm to leg coordination in elite butterfly swimmers

This study proposed the use of four time gaps to assess arm-to-leg coordination in the butterfly stroke at increasing race paces. Fourteen elite male swimmers swam at four velocities corresponding to the appropriate paces for, respectively, the 400-m, 200-m, 100-m, and 50-m events. The different stroke phases of the arm and leg were identified by video analysis and then used to calculate four time gaps (T1: time gap between entry of the hands in the water and the high break-even point of the first undulation; T2: time gap between the beginning of the hands' backward movement and the low break-even point of the first undulation; T3: time gap between the hands' arrival in a vertical plane to the shoulders and the high break-even point of the second undulation; T4: time gap between the hands' release from the water and the low break-even point of the second undulation), the values of which described the changing relationship of arm to leg movements over an entire stroke cycle. With increases in pace, elite swimmers increased the stroke rate, the relative duration of the arm pull, the recovery and the first downward movement of the legs, and decreased the stroke length, the relative duration of the arm catch phase and the body glide with arms forward (measured by T2), until continuity in the propulsive actions was achieved. Whatever the paces, the T1, T3, and T4 values were close to zero and revealed a high degree of synchronisation at key motor points of the arm and leg actions. This new method to assess butterfly coordination could facilitate learning and coaching by situating the place of the leg undulation in relation with the arm stroke.     

Application of altitude/hypoxic training by elite athletes

At the Olympic level, differences in performance are typically less than 0.5%. This helps explain why many contemporary elite endurance athletes in summer and winter sport incorporate some form of altitude/hypoxic training within their year-round training plan, believing that it will provide the "competitive edge" to succeed at the Olympic level. The purpose of this paper is to describe the practical application of altitude/hypoxic training as used by elite athletes. Within the general framework of the paper, both anecdotal and scientific evidence will be presented relative to the efficacy of several contemporary altitude/hypoxic training models and devices currently used by Olympic-level athletes for the purpose of legally enhancing performance. These include the three primary altitude/hypoxic training models: 1) live high+train high (LH+TH), 2) live high+train low (LH+TL), and 3) live low+train high (LL+TH). The LH+TL model will be examined in detail and will include its various modifications: natural/terrestrial altitude, simulated altitude via nitrogen dilution or oxygen filtration, and hypobaric normoxia via supplemental oxygen. A somewhat opposite approach to LH+TL is the altitude/hypoxic training strategy of LL+TH, and data regarding its efficacy will be presented. Recently, several of these altitude/hypoxic training strategies and devices underwent critical review by the World Anti-Doping Agency (WADA) for the purpose of potentially banning them as illegal performance-enhancing substances/methods. This paper will conclude with an update on the most recent statement from WADA regarding the use of simulated altitude devices.     

Antioxidant‐rich foods and response to altitude training: A randomized controlled trial in elite endurance athletes

High doses of isolated antioxidant supplements such as vitamin C and E have demonstrated the potential to blunt cellular adaptations to training. It is, however, unknown whether intake of high doses of antioxidants from foods has similar effects. Hence, the aim of the study was to investigate whether intake of antioxidant‐rich foods affects adaptations to altitude training in elite athletes. In a randomized controlled trial, 31 national team endurance athletes (23 ± 5 years) ingested antioxidant‐rich foods (n = 16) or eucaloric control foods (n = 15) daily during a 3‐week altitude training camp (2320 m). Changes from baseline to post‐altitude in hemoglobin mass (Hb_mass; optimized CO rebreathing), maximal oxygen uptake (VO _2max; n = 16) or 100 m swimming performance (n = 10), and blood parameters were compared between the groups. The antioxidant group significantly increased total intake of antioxidant‐rich foods (~118%) compared to the control group during the intervention. The total study population improved VO _2max by 2.5% (1.7 mL/kg/min, P  = .006) and Hb_mass by 4.7% (48 g, P  < .001), but not 100 m swimming performance. No difference was found between the groups regarding changes in Hb_mass, VO _2max or swimming performance. However, hemoglobin concentration increased more in the antioxidant group (effect size = 0.7; P  = .045) with a concomitantly larger decrease in plasma and blood volumes compared to control group. Changes in ferritin and erythropoietin from pre‐ to post‐altitude did not differ between the groups. Doubling the intake of antioxidant‐rich foods was well tolerated and did not negatively influence the adaptive response to altitude training in elite endurance athletes.     

Variability in hemoglobin mass response to altitude training camps

The present study investigated whether athletes can be classified as responders or non‐responders based on their individual change in total hemoglobin mass (tHb‐mass) following altitude training while also identifying the potential factors that may affect responsiveness to altitude exposure. Measurements were completed with 59 elite endurance athletes who participated in national team altitude training camps. Fifteen athletes participated in the altitude training camp at least twice. Total Hb‐mass using a CO rebreathing method and other blood markers were measured before and after a total of 82 altitude training camps (1350‐2500 m) in 59 athletes. In 46 (56%) altitude training camps, tHb‐mass increased. The amount of positive responses increased to 65% when only camps above 2000 m were considered. From the fifteen athletes who participated in altitude training camps at least twice, 27% always had positive tHb‐mass responses, 13% only negative responses, and 60% both positive and negative responses. Logistic regression analysis showed that altitude was the most significant factor explaining positive tHb‐mass response. Furthermore, male athletes had greater tHb‐mass response than female athletes. In endurance athletes, tHb‐mass is likely to increase after altitude training given that hypoxic stimulus is appropriate. However, great inter‐ and intra‐individual variability in tHb‐mass response does not support classification of an athlete permanently as a responder or non‐responder. This variability warrants efforts to control numerous factors affecting an athlete's response to each altitude training camp.     

Coordination in front crawl in elite triathletes and elite swimmers

The aim of this study was to compare the arm coordination in 19 elite triathletes and 15 elite swimmers at six different velocities between 80 % and 100 % of their maximal velocity (Vmax). The different phases of the stroke (A: entry; B: pull; C: push; D: recovery) were identified by video analysis. An index of coordination (IdC) was calculated. It was the time that separated the beginning of the propulsive phase of one arm from the end of the propulsive phase of the other arm. IdC allows to express the mode of arm coordination: catch-up, IdC < 0; opposition, IdC = 0; superposition, IdC > 0. Between 80 % and 98 % Vmax, elite triathletes showed similar increases in IdC than swimmers (from -8.8 % to 2.6 % vs from -8.6 % to 0.3 %) switching from a catch-up to a superposition coordination. Between 88 % and Vmax, triathletes increased the propulsive phase (B+C) less (p < 0.01) than swimmers (3.4 % vs 8.5 %) and increased the recovery phase (0.8 %) when swimmers reduced it (-1.6 %). Between V5 and Vmax, both triathletes and swimmers had a significant (p < 0.01) difference in IdC change (-1.7 % vs 2.3 %). Moreover, triathletes reduced the propulsive phase when swimmers increased it (-0.6 % vs 3.2 %). The lower velocity of the triathletes was associated to a shorter stroke length when compared to the swimmers (1.70 m vs 2.15 m at Vmax). The stroke rates were not statistically different (55.1 vs 51.2 stroke x min(-1) at Vmax). Thus, monitoring IdC and stroke length is recommended for triathletes mainly at maximal velocity.     

The 24-h urinary cortisol/cortisone ratio for monitoring training in elite swimmers

PURPOSE: The effect of training variations on 24-h urinary cortisol/cortisone (C/Cn) ratio was investigated in highly trained swimmers to determine whether it could be a good marker of training stress and performance. METHODS: Fourteen swimmers (five female and nine male) were tested after 4 wk of intense training (IT), 3 wk of reduced training (RT), and 5 wk of moderate training (MT). At the end of each period, the swimmers performed in their best event at an official competition. Individual performances were expressed as a percentage of the previous season's best performance. The fatigue state was evaluated with a questionnaire. RESULTS: The C/Cn ratio was statistically different for the three periods (IT: 1.10 +/- 0.7, RT: 0.64 +/- 0.3, and MT: 0.57 +/- 0.2). The differences in the C/Cn ratio between two consecutive performances were related to the differences in performance (r = -0.52, P < 0.01), and the C/Cn ratio was significantly related to the total training (r = 0.32, P < 0.05) and total score of fatigue (TSF) (r = 0.35, P < 0.03) over the follow-up period. Cn levels were related to the dryland training (r = -0.46; P < 0.01) and TSF (r = -0.40; P < 0.02). During IT, variations in the C/Cn ratio were related to the changes in the mean intensity (r = -0.67; P < 0.02) and to TSF (r = 0.69; P < 0.01). CONCLUSION: The 24-h C/Cn ratio was moderately related to both training and performance whereas Cn levels were only related to training. The C/Cn ratio could be a useful indicator for monitoring the overreaching state in elite swimmers.     

Psychological prediction of injury in elite swimmers

Previous research has suggested that psychological factors related to attention and anxiety may identify the injury-prone athlete. In particular, there is some evidence in endurance events that those who utilize a cognitive strategy which associates with sensory feedback pertaining to pace, effort, and fatigue are less likely to be injured. This study investigated the relationship between injury rate and scores on Nideffer's Test of Attentional and Interpersonal Style (TAIS) in 33 elite swimmers resident at the Australian Institute of Sport throughout 1986. The data showed that 56% of the injuries were gradual in onset and resulted from the inability of the swimmer to absorb stress particularly in the upper limbs (overuse). Although these and other intrinsic injuries might theoretically be lower in those with effective internal attentional styles, the data did not support this. Contrary to prediction, the analysis revealed that swimmers with more effective attentional profiles sustained more injuries. Although a number of explanations were offered, the sensitivity of the TAIS to assess appropriate attentional profiles in swimmers was questioned. Future research is suggested which adopts a multidimensional approach in which psychological, physiologic, and situational determinants of injury can be examined. In this way, the contribution of psychological factors to the genesis of swimming injuries can be determined and intervention strategies developed to reduce injury and accelerate recovery.     

Immune status and respiratory illness for elite swimmers during a 12-week training cycle

The impact of a 12-week training program by elite swimmers on systemic and mucosal immunity was studied prospectively to examine the relationship between changes in immune parameters and the incidence of respiratory illness. Saliva was collected before and after selected training sessions at 2 weekly intervals. There were significant decreases in salivary IgA (p=0.05) and salivary IgM (p < 0.0001) concentrations after individual training sessions, but no significant changes in salivary IgG or albumin concentrations. Over the 12-week training program there were small but statistically significant increases in pre-exercise concentrations of salivary IgA (p<0.001), IgM (p=0.015) and IgG (p=0.003) and post-exercise salivary IgA (p <0.001). There were no significant trends over the 12 weeks for any class of serum immunoglobulins but a significant fall in NK-cell numbers (p<0.001). There were no associations between serum or salivary immunoglobulin levels or NK-cell numbers and upper respiratory tract illness (URTI) during the 12-week program. The data indicated that despite changes in some immune parameters during this final training program prior to competition there were no associations detected with URTI for this cohort of elite swimmers.     

The sweating response of elite professional soccer players to training in the heat

Sweat rate and sweat composition vary extensively between individuals, and quantification of these losses has a role to play in the individualisation of a hydration strategy to optimise training and competitive performance. Data were collected from 26 male professional football (soccer) players during one 90 min pre-season training session. This was the 2nd training session of the day, carried out between 19.30 and 21.00 h when the mean +/- SD environment was 32 +/- 3 degrees C, 20 +/- 5 %rh and WBGT 22 +/- 2 degrees C. Training consisted of interval running and 6-a-side games during which the average heart rate was 136 +/- 7 bpm with a maximum rate of 178 +/- 7 bpm (n = 19). Before and after training all players were weighed nude. During training all players had free access to sports drinks (Gatorade) and mineral water (Solan de Cabras). All drink bottles were weighed before and after training. Players were instructed to drink only from their own bottles and not to spit out any drink. No player urinated during the training session. Sweat was collected by patches from the chest, arm, back, and thigh of a subgroup of 7 players. These remained in place for the first 15 - 30 min of the training session, and sweat was analysed for sodium (Na (+)) and potassium (K (+)) concentration. Body mass loss was 1.23 +/- 0.50 kg (ranging from 0.50 to 2.55 kg), equivalent to dehydration of 1.59 +/- 0.61 % of pre-training body mass. The sweat volume lost was 2193 +/- 365 ml (1672 to 3138 ml), but only 972 +/- 335 ml (239 to 1724 ml) of fluid was consumed. 45 +/- 16 % of the sweat volume loss was replaced, but this ranged from 9 % to 73 %. The Na (+) concentration of the subgroup's sweat was 30.2 +/- 18.8 mmol/l (15.5 to 66.3 mmol/l) and Na (+) losses averaged 67 +/- 37 mmol (26 to 129 mmol). The K (+) concentration of the sweat was 3.58 +/- 0.56 mmol/l (2.96 to 4.50 mmol/l) and K (+) losses averaged 8 +/- 2 mmol (5 to 12 mmol). The drinking employed by these players meant that only 23 +/- 21 % of the sweat Na (+) losses were replaced: This ranged from replacing virtually none (when water was the only drink) to replacing 62 % when the sports drink was consumed. These elite soccer players did not drink sufficient volume to replace their sweat loss. This, however, is in accord with data in the literature from other levels of soccer players and athletes in other events. These measurements allow for an individualisation of the club's hydration strategy.