Well-trained Triathletes Research Articles

The acute effect of respiratory muscle training on cortisol, testosterone, and testosterone-to-cortisol ratio in well-trained triathletes - exploratory study

The study investigated acute changes in cortisol (C) and testosterone (T) associated with a popular RMT method, voluntary isocapnic hyperpnoea (VIH), in well-trained triathletes. 19 athletes (7 females, 12 males) performed a VIH training session with pre- and post- serum C and T measurements. Repeated measures ANOVA was employed to analyze hormone changes during VIH, with additional time-sex interaction. Pearson correlation coefficient has been computed to identify the relationship between hormonal changes and age, anthropometric indices, respiratory muscle strength, and training experience. There was a statistically significant effect for C changes (F = 13.101, p = 0.002, ηp2 = 0.421, ω2 = 0.08). The C concentration was significantly lower after VIH (Mean Difference = −32.49 ± 39.13 nmol*L−1). No significant effects for T, T/C ratio, and time-sex interactions were observed (p > 0.05). Amongst many, significant correlations between the percentage of body fat and changes in C (r=-0.464, p=0.045), body mass and changes in T (r=0.516, p=0.024), height and changes in T (r=0.509, p=0.026) were found. VIH significantly lowered C concentration. No significant effects for T, T/C ratio, and no between-sex differences were observed. Noteworthy individual variability was observed in all the monitored indices. Significant correlations were found between acute hormone changes associated with VIH and selected anthropometric indices. The study provides initial insight into VIH’s role in athletes’ hormonal balance to possibly guide exercise prescription, autoregulation, arousal state management, and recovery practices in athletes.

Differences between indoor and outdoor field cycling tests in triathletes are associated with training environment history and BMI: analysis and prediction formula.

Patients underwent cyclists and triathletes test, train, and race both indoors and outdoors. However, the differences between indoor and outdoor performance remain understudied. This study aimed to analyze the relationship between indoor and outdoor performance in cycling. We investigated the influence of training environment history (indoor vs. outdoor) and application of e-sport platform on the aforementioned relationship. Forty-three well-trained triathletes performed indoor and outdoor field tests to establish maximum sprint power (MSP) and functional threshold power (FTP). The main effects for FTP and MSP were assessed by repeated-measures ANOVA to analyze the differences between power output obtained indoors and outdoors. Multiple covariates, including training environment history and application of ZWIFT e-sport platform, were applied. Multiple linear regression was performed to investigate outdoor FTP prediction based on indoor testing. No significant differences were found for MSP and FTP obtained indoors and outdoors. However, the high individual variability in the disparity between indoor and outdoor power output (PO) in triathletes was observed. There was a statistically significant interaction between FTP and training environment history (P<0.001 for FTP expressed in W*kg-1 and W) and FTP and BMI (P=0.042 and P=0.034 for FTP expressed in W*kg-1 and W, respectively). The prediction formulas to establish outdoor FTP based on indoor testing had high accuracy (R2 0.80 and 0.68 for full and simple model, respectively). The study underlines the crucial role of the appropriate testing environment, corresponding to the training environment and racing demands. A high individual variability in the disparity between indoor and outdoor PO at FTP are associated with training environment history and BMI. No such interactions were found for MSP.

Respiratory muscle training induces additional stress and training load in well-trained triathletes-randomized controlled trial.

Background: Respiratory muscle training (RMT) has been investigated in the context of improved athletic performance and pulmonary function. However, psychophysiological costs of RMT remain understudied. Voluntary isocapnic hyperpnoea (VIH) and inspiratory pressure threshold loading (IPTL) are widely applied RMT methods. The main purposes of this study were to assess whether RMT induces additional load on well-trained triathletes and determine differences in RMT-induced load between sexes and applied methods. Materials and Methods: 16 well-trained triathletes (n = 16, 56% males) underwent 6weeks of VIH or IPTL program with progressive overload. Blood markers, subjective measures, cardiac indices, near-infrared spectroscopy indices, inspiratory muscle fatigue, and RMT-induced training load were monitored pre-, in and post-sessions. We used multiple ANOVA to investigate effects of sex, training method, and time on measured parameters. Results: There were significant interactions for acid-base balance (p = 0.04 for sex, p < 0.001 for method), partial carbon dioxide pressure (p = 0.03 for sex, p < 0.001 for method), bicarbonate (p = 0.01 for method), lactate (p < 0.001 for method), RMT-induced training load (p = 0.001 for method for single session, p = 0.03 for method per week), average heart rate (p = 0.03 for sex), maximum heart rate (p = 0.02 for sex), intercostales muscle oxygenation (p = 0.007 for testing week), and intercostales muscle oxygenation recovery (p = 0.003 for testing week and p = 0.007 for method). Conclusion: We found that RMT induced additional load in well-trained triathletes. Elicited changes in monitored variables depend on sex and training method. VIH significantly increased subjective training load measures. IPTL was associated with disbalance in blood gasometry, increase in lactate, and reports of headaches and dizziness. Both methods should be applied with consideration in high-performance settings.

The effects of simulated duathlon on multisegment running external and internal load in well-trained triathletes

ABSTRACT Duathlon is a rapidly promoting sport, so it is necessary to identify the factors that influence performance. This study aimed to analyse internal and external loads and the interactions between them during running legs before and after cycling in duathlon. Twenty-three male and female athletes participated in a simulated duathlon (5k-20k-5k). Internal workload was assessed using the rate of perceived exertion (RPE) and heart rate (maximum: HRMAX; average: HRAVG; R-R interval), whereas external workload was assessed using inertial sensors (Player Load by RealTrack, PLRT) attached to six body locations. The results showed that both running legs presented an increasing trend in RPE, HRMAX, and HRAVG throughout the kilometres, while the R–R interval decreased. The PLRT of the upper and lower back, knee, and ankle increased throughout the first running leg but not in the second. The PLRT was greater in the lower body than in the upper body because of energy absorption. RPE was higher in the second running leg than in the first leg. In conclusion, the cycling leg affects the internal and external load between running legs in duathlon. Load monitoring can help coaches understand duathletes’ performance and design specific training strategies to reduce fatigue during competition.

Discovering the sluggishness of triathlon running - using the attractor method to quantify the impact of the bike-run transition.

Running in a triathlon, a so-called brick run, is uniquely influenced by accumulated load from its preceding disciplines. Crucially, however, and irrespective of race type, the demands of a triathlon always exceed the sum of its parts. Triathletes of all levels commonly report subjectively perceived incoordination within the initial stages of the cycle run transition (T2). Although minimizing it, and its influence on running kinematics, can positively impact running and overall triathlon performance, the mechanisms behind the T2 effect remain unclear. In the present study, we assessed the influence of the pre-load exercise mode focusing on the biomechanical perspective. To analyze inertial sensor-based raw data from both legs, the so-called Attractor Method was applied. The latter represents a sensitive approach, allowing to quantify subtle changes of cyclic motions to uncover the transient effect, a potentially detrimental transient phase at the beginning of a run. The purpose was to analyze the impact of a pre-load on the biomechanics of a brick run during a simulated Olympic Distance triathlon (without the swimming section). Therefore, we assessed the influence of pre-load exercise mode on running pattern (δM) and precision (δD), and on the length of the transient effect (tT) within a 10 km field-based run in 22 well-trained triathletes. We found that δD, but not δM, differed significantly between an isolated run (IRun) and when it was preceded by a 40 km cycle (TRun) or an energetically matched run (RRun). The average distance ran until overcoming the transient phase (tT) was 679 m for TRun, 450 m for RRun, and 29 4 m for IRun. The results demonstrated that especially the first kilometer of a triathlon run is prone to an uncoordinated running sensation, which is also commonly reported by athletes. That is, i) the T2 effect appeared more linked to variability in running style than to running style per se ii) run tT distance was influenced by preceding exercise load mode, being greater for a TRun than for the RRun condition, and iii) the Attractor Method seemed to be a potentially promising method of sensitively monitoring T2 adaptation under ecologically valid conditions.

Neuromuscular changes after a Long Distance Triathlon World Championship

ABSTRACT This study aimed to determine the neuromuscular changes in muscle contractile properties and countermovement jump (CMJ) performance after a long distance (LD) triathlon, inquiring to what extent it is influenced by gender and the evaluated muscle, and to explore for response differences. Four elite (2 females and 2 males) and 18 well-trained triathletes (3 females and 15 males) who competed in the 2019 LD Triathlon World Championship undergone, prior and post-race, a CMJ and a muscle contractile properties assessment in vastus lateralis (VL) and biceps femoris (BF) using tensiomyography. A mixed ANOVA was carried out to detect triathletes’ neuromuscular changes after the competition. A large decrease in jump height and flight time was found in CMJ (p = 0.001, ηp 2 = 0.767) with gender differences (ηp 2 = 0.308). contraction (Tc), delay (Td) and sustain times (Ts) also showed a large decrease (p = 0.001, ηp 2 = 0.174–0.413). However, maximum radial muscle belly displacement was not altered by the competition, but did greatly increase radial displacement velocity (p = 0.031; ηp 2 = 0.212). No gender differences were found in contractile properties. Correlation analysis between race performance and the jumping and tensiomyography parameters only showed a moderate negative correlation with Tc of the BF in pre- and post-competition (r = −0.44; −0.43; p = 0.05). In conclusion, triathletes after a LD World Championship suffer a sharp drop in jump performance and variations in VL’s and BF’s contractile properties, showing decreases in Tc, Td and Ts without gender differences. The regular use of these parameters can allow the monitoring of triathlete's neuromuscular fatigue and aid in the distribution of more efficient loads in their training cycles. Highlights Trainers and researchers in neuromuscular fatigue can have reference data of elite and well-trained triathletes after performing LD race. The magnitude of change in the CMJ and the contractile properties of BF and VL achieved in competition by these elite reference triathletes can guide to modulate triathletes training. The regular use of the parameters using these references can allow an exhaustive neuromuscular fatigue monitoring during the sessions or training cycles throughout the season.

Effects of periodic carbohydrate ingestion on endurance and cognitive performances during a 40-km cycling time-trial under normobaric hypoxia in well-trained triathletes

ABSTRACTThe purpose of this study was to examine CHO ingestion on a cognitive task using a field-simulated time-trial (TT) under hypoxia in well-trained triathletes. Ten male triathletes (age: 22.1 ± 1.1 years; VO2max: 59.4 ± 1.4 ml/kg/min) participated in this double-blind/crossover/counter-balanced design study. Participants completed 3 TT trials: 1) normoxic placebo (NPLA; FiO2 = 20.9%), 2) hypoxic placebo (HPLA; FiO2 = 16.3%), and 3) hypoxic CHO (HCHO; 6% CHO provided as 2 ml/kg/15 min; FiO2 = 16.3%). During the TT, physiological responses (SpO2, HR, RPE, and blood glucose/lactate), cognitive performance, and cerebral haemodynamics were measured. Hypoxia reduced TT performance by ~3.5–4% (p < 0.05), but CHO did not affect TT performance under hypoxia. For the cognitive task, CHO slightly preserved exercise-induced cognitive reaction speed but did not affect response accuracy during hypoxic exercise. However, CHO did not preserve the decreased Hb-Diff (cerebral blood flow, CBF) and increased HHb in the prefrontal lobe (p < 0.05) during hypoxic exercise, and CHO failed to preserve hypoxia-suppressed prefrontal CBF and tissue oxygen saturation. In conclusion, the present study demonstrates that CHO is effective in sustaining reaction speed for a cognitive task but not promoting TT performance during hypoxic exercise, which would be important for strategy-/decision-making when athletes compete at moderate high-altitude.

Responsiveness of Time and Cost-Efficient Monitoring Measures on Triathlon Training a Call for Individualized Training Monitoring

Objective: We aimed to assess the responsiveness of monitoring measures on cumulative training from the previous 1 up to 7 days in elite triathletes. Methods: Six male well-trained triathletes (31.8 ± 6.8 yrs, VO2max 70.5 ± 4.0 ml/kg/min) participated in a 9 weeks observational study during the pre-competition training period. Training load and time spent in different training intensity zones, morning measures of objective monitoring variables including resting heart rate, heart rate variability (HRV) and sleep duration and subjective monitoring variables including subjectively felt daily condition, energy level, willingness to train, muscle soreness, general stress, general fatigue and quality of sleep were assessed daily. Training data were retrospectively correlated with objective and subjective measures Results: On a group level, higher cumulative training time spent in high-intensity running but not swimming or cycling lead to moderate increase in muscle soreness (R=0.344 for 5-days cumulative high-intensity running, p=0.043), small increase in subjectively felt general stress (R=0.168 for 4-days. Cumulative high-intensity training time (cHITT), p=0.043 and R=0.221 for 6-days cHITT, p=0.043), a small decrease in daily condition (R=-0.113 for 7-days cHIIT, p=0.043) and willingness to train (R=-0.169 for 7-days cHIIT, p=0.043) but did not affect any objective monitoring variables.There were remarkable individual differences in correlations between cumulative training load, time spent in different training intensity zones and objective and subjective variables Conclusion: Since the responsiveness of objective and subjective monitoring parameters to training was very individual, not only training loads but also the selection of objective and subjective measures should be individualized for monitoring triathletes.

Quantification of improvement in triathlon swimming performance by textile speedsuits

To quantify swimwear-induced differences under triathlon-specific conditions, we compare the swimming performance, the metabolic cost, and the standardised passive drag of well-trained triathletes when wearing (1) five speedsuit models by different manufacturers from 2017, (2) usual swimming trunks/swimsuits (men/women), and (3) individually preferred competition trisuits. Because of the complexity of the underlying hydrodynamic and biomechanical effects, three separate experimental stages were realized, each with 6–12 well-trained short- and middle-distance triathletes (male and female, mean age 22 ± 5 years) from the German national elite or junior elite level. All measurements were conducted on the basis of real athletes’ motion in the water to correctly account for all relevant effects, including skin and muscle vibrations. First, the athletes took part in a series of 100 m short-distance tests at maximal effort in a long-course pool to quantify swim-time differences in absolute terms. Second, the subjects completed multiple submaximal 400 m tests at 95% of their individual maximal speed in a swimming flume, with their swimwear-related differences in metabolic load being explored in terms of blood lactate and heart rate. Third, the passive drag of the triathletes was measured in the flume during a towing test under standardised conditions in velocity steps of 0.2 m/s within the triathlon-relevant range of 1.1–1.7 m/s. In all three test stages, the speedsuits exhibited performance advantages over trunks/swimsuits: in the 100 m maximal test, the mean swim time with speedsuits decreased by 0.99 ± 0.30 s (≙ − 1.5%). During the 400 m submaximal flume test, the mean heart rate showed a reduction of 7 ± 2 bpm (≙ − 4.0%), while the post-exercise blood lactate accumulation decreased by 1.0 ± 0.2 mmol/L (≙ − 26.2%). Similarly, the passive drag in the towing test was lowered by 3.2 ± 1.0 W (≙ − 6.9% as for normalised power and − 5.2% as for normalised force) for the speedsuits. Wearing speedsuits instead of usual trunks/swimsuits is shown to improve the swimming performance and to reduce the metabolic cost for well-trained triathletes under triathlon-specific test conditions. The reduction in passive drag of the passively towed athlete’s body due specific speedsuit surface textures seems to be only one reason for performance advantages: the effective reduction in muscular, soft tissue, and skin vibrations at the trunk and thighs during active propulsive motion of the swimmer seems to further contribute substantially.

Optimizing Heat Acclimation for Endurance Athletes: High- Versus Low-Intensity Training.

To determine the effect of high- versus low-intensity training in the heat and ensuing taper period in the heat on endurance performance. In total, 19 well-trained triathletes undertook 5 days of normal training and a 1-wk taper including either low- (heat acclimation [HA-L], n = 10) or high-intensity (HA-H, n = 9) training sessions in the heat (30°C, 50% relative humidity). A control group (n = 10) reproduced their usual training in thermoneutral conditions. Indoor 20-km cycling time trials (35°C, 50% relative humidity) were performed before (Pre) and after the main heat exposure (Mid) and after the taper (Post). Power output remained stable in the control group from Pre to Mid (effect size: -0.10 [0.26]) and increased from Mid to Post (0.18 [0.22]). The HA-L group demonstrated a progressive increase in performance from Pre to Mid (0.62 [0.33]) and from Mid to Post (0.53 [0.30]), alongside typical physiological signs of HA (reduced core temperature and heart rate and increased body-mass loss). While the HA-H group presented similar adaptations, increased perceived fatigue and decreased performance at Mid (-0.35 [0.26]) were evidenced and reversed at Post (0.50 [0.20]). No difference in power output was reported at Post between the HA-H and control groups. HA-H can quickly induce functional overreaching in nonacclimatized endurance athletes. As it was associated with a weak subsequent performance supercompensation, coaches and athletes should pay particular attention to training monitoring during a final preparation in the heat and reduce training intensity when early signs of functional overreaching are identified.

Effects of 4 Weeks High-Intensity Training on Running and Cycling Performance in Well-Trained Triathletes

Effects of 4 Weeks High-Intensity Training on Running and Cycling Performance in Well-Trained Triathletes

Effects of 4 weeks high-intensity training on running and cycling performance in well-trained triathletes

Effects of 4 weeks high-intensity training on running and cycling performance in well-trained triathletes

Pacing Adjustments Associated With Familiarization: Heat Versus Temperate Environments.

To describe the effect of the initial perceptual experience from heat familiarization on the pacing profile during a freepaced endurance time trial (TT) compared with temperate conditions. Two groups of well-trained triathletes performed two 20-km TTs in either hot (35°C and 50% relative humidity [RH], n = 12) or temperate (21°C and 50% RH, n = 22) conditions, after standardization of training for each group before both trials. To ensure no physiological acclimation differences between conditions, the TTs for both groups were separated by 11 ± 4 d. Performance improvement in the heat (11 ± 24 W) from the 1st to 2nd trial appeared comparable to that in temperate conditions (8 ± 14 W, P = .67). However, the specific alteration in pacing profile in the heat was markedly different than temperate conditions, with a change from "positive" to an "even" pacing strategy. Altered perceptions of heat during heat familiarization, rather than physiological acclimatization per se, may mediate initial changes in pacing and TT performance in the heat. These results highlight the need for athletes without time for sufficient heat acclimatization to familiarize themselves with hot conditions to reduce the uncertainty from behavior-based outcomes that may impede performance.

No difference in muscle damage between well-trained masters and young triathletes following regular intense endurance exercise

No difference in muscle damage between well-trained masters and young triathletes following regular intense endurance exercise

Prooxidant/Antioxidant Balance in Hypoxia: A Cross-Over Study on Normobaric vs. Hypobaric "Live High-Train Low".

“Live High-Train Low” (LHTL) training can alter oxidative status of athletes. This study compared prooxidant/antioxidant balance responses following two LHTL protocols of the same duration and at the same living altitude of 2250 m in either normobaric (NH) or hypobaric (HH) hypoxia. Twenty-four well-trained triathletes underwent the following two 18-day LHTL protocols in a cross-over and randomized manner: Living altitude (PIO2 = 111.9 ± 0.6 vs. 111.6 ± 0.6 mmHg in NH and HH, respectively); training “natural” altitude (~1000–1100 m) and training loads were precisely matched between both LHTL protocols. Plasma levels of oxidative stress [advanced oxidation protein products (AOPP) and nitrotyrosine] and antioxidant markers [ferric-reducing antioxidant power (FRAP), superoxide dismutase (SOD) and catalase], NO metabolism end-products (NOx) and uric acid (UA) were determined before (Pre) and after (Post) the LHTL. Cumulative hypoxic exposure was lower during the NH (229 ± 6 hrs.) compared to the HH (310 ± 4 hrs.; P<0.01) protocol. Following the LHTL, the concentration of AOPP decreased (-27%; P<0.01) and nitrotyrosine increased (+67%; P<0.05) in HH only. FRAP was decreased (-27%; P<0.05) after the NH while was SOD and UA were only increased following the HH (SOD: +54%; P<0.01 and UA: +15%; P<0.01). Catalase activity was increased in the NH only (+20%; P<0.05). These data suggest that 18-days of LHTL performed in either NH or HH differentially affect oxidative status of athletes. Higher oxidative stress levels following the HH LHTL might be explained by the higher overall hypoxic dose and different physiological responses between the NH and HH.

Individual variability of high-sensitivity cardiac troponin levels after aerobic exercise is not mediated by exercise mode

We compared the response of high-sensitivity cardiac troponin T (hs-cTnT) after 60 min of swimming, running and cycling in well-trained triathletes. The maximal increase in hs-cTnT was similar in all exercise bouts (swimming 453%, cycling 349% and running 471%) although there was substantial individual variability in peak hs-cTnT. The post-exercise kinetics for hs-cTnT was consistent. The change in hs-cTnT was correlated between trials. In all trials, hs-cTnT had largely returned to baseline levels 24 h post-exercise. In summary, an increase in hs-cTnT was apparent in all triathletes independent of exercise mode and despite variable peak data the consistent kinetics over 24 h post-exercise would suggest this represents a physiological phenomenon.

Impact of Cycling Intensity on Cycle-run Transition in Female Triathletes

PURPOSE: The purpose of the study was to determine the impact of intensity during the final km of a cycling bout on subsequent run and overall cycle-run (CR) performance. A secondary aim of the study was to examine how manipulations in cycling power affect cycle-run performance in female triathletes exclusively. METHODS: Nine well-trained female triathletes participated in the study. The triathletes completed two CR sessions (20 km cycle, 5 km run). The intensity of the first 19 km of cycling was equivalent to peak power at 70% of peak oxygen consumption (O 2 peak) and the final 1 km varied between power achieved at 95% of O 2 peak (high intensity, HI) and power achieved at 50% of O 2 peak (low intensity, LI). The 5 km run was completed as fast as possible. RESULTS: Mean blood lactate concentration [La - ] was significantly higher during the run following the cycling bout ending with a HI rather than a LI (11.5 ± 0.64 mmol/L vs. 9.3 ± 0.72 mmol/L). Run performance was not significantly different between HI and LI (24:54 ± 02:53 min vs. 00:24:36 ± 00:03:17 min). As well, no significant differences were found between overall CR sessions (01:23:23 h ± 00:05:47 min vs. 01:23:50 h ± 00:07:01 min). CONCLUSION: Despite increases in [La - ], cycling intensity during the final stages of a 20 km cycling bout does not impact run or CR performance in well-trained female triathletes.

Age difference in efficiency of locomotion and maximal power output in well-trained triathletes.

The aim of this study was to examine the influence of age on cycling efficiency and sprint power output in well-trained endurance masters athletes. The investigation was conducted on 60 healthy well-trained triathletes separated into six separate groups (n = 10) depending on age: 20-29 years old; 30-39 years old; 40-49 years old; 50-59 years old; 60-69 years old; 70 years old. Each participant attended the laboratory on three separate occasions to perform (1) an incremental cycling test, (2) maximal peak sprint power test, involving three 5-s sprint efforts (3) and a 10-min sub-maximal cycling test for determination of cycling efficiency. Cycling efficiency decreased beyond 50 years (50-59 years compared with 20-29 years: -7.3 ± 1.8%; p < 0.05) and continued to decrease beyond 60 years (60-69 years compared with 50-59 years: -10.7 ± 2.4%; p < 0.05), no further decrease was observed after 70 years. A continuous impairment in maximal sprint power output was observed after the age of 50 years leading to an overall decrease of 36% between 20-29 years and >70 years. Significant positive relationships were observed between maximal sprint power output and both cycling efficiency (r(2) = 0.64, p < 0.05) and maximal aerobic power (r(2) = 0.42 and p < 0.05). The present data indicates a significant effect of ageing on cycling efficiency and maximal sprint power output after 50 years and a significant relationship was found between these two parameters.

Effect of N-acetylcysteine on Cycling Performance after Intensified Training

This investigation examined the ergogenic effect of short-term oral N-acetylcysteine (NAC) supplementation and the associated changes in redox balance and inflammation during intense training. A double-blind randomized placebo-controlled crossover design was used to assess 9 d of oral NAC supplementation (1200 mg·d) in 10 well-trained triathletes. For each supplement trial (NAC and placebo), baseline venous blood and urine samples were taken, and a presupplementation cycle ergometer race simulation was performed. After the loading period, further samples were collected preexercise, postexercise, and 2 and 24 h after the postsupplementation cycle ergometer race simulation. Changes in total antioxidant capacity, ferric reducing ability of plasma, reduced glutathione, oxidized glutathione, thiobarbituric acid-reactive substances, interleukin 6, xanthine oxidase, hypoxanthine, monocyte chemotactic protein 1, nuclear factor κB, and urinary 15-isoprostane F2t concentration were assessed. The experimental procedure was repeated with the remaining supplement after a 3-wk washout. Eight participants completed both supplementation trials. NAC improved sprint performance during the cycle ergometer race simulation (P < 0.001, ηp = 0.03). Supplementation with NAC also augmented postexercise plasma total antioxidant capacity (P = 0.005, ηp = 0.19), reduced exercise-induced oxidative damage (plasma thiobarbituric acid-reactive substances, P = 0.002, ηp = 0.22; urinary 15-isoprostane F2t concentration, P = 0.010, ηp = 0.431), attenuated inflammation (plasma interleukin 6, P = 0.002, ηp = 0.22; monocyte chemotactic protein 1, P = 0.012, ηp = 0.17), and increased postexercise nuclear factor κB activity (P < 0.001, ηp = 0.21). Oral NAC supplementation improved cycling performance via an improved redox balance and promoted adaptive processes in well-trained athletes undergoing strenuous physical training.

Relationship between physiological parameters and performance during a half-ironman triathlon in the heat

Triathlon is a popular outdoor endurance sport performed under a variety of environmental conditions. The aim of this study was to assess physiological variables before and after a half-ironman triathlon in the heat and to analyse their relationship with performance. Thirty-four well-trained triathletes completed a half-ironman triathlon in a mean dry temperature of 29 ± 3ºC. Before and within 1 min after the end of the race, body mass, core temperature, maximal jump height and venous blood samples were obtained. Mean race time was 315 ± 40 min, with swimming (11 ± 1%), cycling (49 ± 2%) and running (40 ± 3%) representing different amounts of the total race time. At the end of the competition, body mass changed by −3.8 ± 1.6% and the change in body mass correlated positively with race time (r = 0.64; P < 0.001). Core temperature increased from 37.5 ± 0.6ºC to 38.8 ± 0.7ºC (P < 0.001) and post-race core temperature correlated negatively with race time (r = −0.47; P = 0.007). Race time correlated positively with the decrease in jump height (r = 0.38; P = 0.043), post-race serum creatine kinase (r = 0.55; P = 0.001) and myoglobin concentrations (r = 0.39; P = 0.022). In a half-ironman triathlon in the heat, greater reductions in body mass and higher post-competition core temperatures were present in faster triathletes. In contrast, slower triathletes presented higher levels of muscle damage and decreased muscle performance.