Well-trained Triathletes Research Articles

Effect of sulphurous mineral water in haematological and biochemical markers of muscle damage after an endurance exercise in well-trained athletes

To investigate the effects of sulphurous mineral water (SMW) after a hydroponic treatment on muscle damage, antioxidant activity and peripheral blood changes induced by submaximal exercise. Thirty well-trained male triathletes were supplemented with SMW or placebo: 3 weeks of placebo, 30 days of wash out and 3 weeks of SMW. After both periods, participants ran for 2 h at 70% maximal aerobic speed. Antioxidant enzymes, lipid peroxidation, antioxidant capacity and blood cell markers were compared between placebo and SMW at pre-exercise (T0), immediately post-exercise (T1), 24 h post-exercise (T2) and 48 h post-exercise (T3). Total thiols decreased until T3 vs. T0 for both placebo and SMW; transient red blood cells, haemoglobin and haematocrit increased were shown at T1 vs. T0 and for leucocytes until T2 vs. T0, only for placebo group. Total thiols increased significantly in SMW vs. placebo at T0; Thiobarbituric acid reactive species was significantly higher at T0, T1, T2 and T3; catalase increased significantly at T1; creatine phosphokinase decreased significantly at T1, T2 and T3, although no significant differences were found at T0. Furthermore, red blood cells, haemoglobin and haematocrit were significantly higher and leucocytes were significantly lower at T0 and T1 in SMW group vs. placebo group. This study suggests that three weeks of SMW supplementation may protect from exercise-induced muscle damage.

Interactions between immune, stress-related hormonal and cardiovascular systems following strenuous physical exercise.

Physical exercise represents a eustress condition that promotes rapid coordinated adjustments in the immune, stress-related hormonal and cardiovascular systems, for maintaining homeostasis in response to increased metabolic demands. Compared to the tight multisystem coordination during exercise, evidence of between-systems cross talk in the early post exercise is still lacking. This study was aimed at identifying possible interactions between multiple systems following strenuous physical exercise (Ironman race) performed by twenty well-trained triathletes. Cardiac hemodynamics, left ventricle systolic and diastolic function and heart rate variability were measured along with plasma concentrations of immune messengers (cytokines and C-reactive protein) and stress-related hormones (catecholamines and cortisol) both 24h before and within 20 min after the race. Observed changes in antiinflammatory pathways, stress-related hormones and cardiovascular function were in line with previous findings; moreover, correlating parameters' changes (post versus pre-race) highlighted a dependence of cardiovascular function on the post-race biohumoral milieu: in particular, individual post-race variations of heart rate and diastolic function were strongly correlated with individual variations of anti-inflammatory cytokines, while individual baroreflex sensitivity changes were linked to IL-8 increase. Multiple correlations between anti-inflammatory cytokines and catecholamines were also found according with the autonomic regulation of immune function. Observed post-race cytokine and hormone levels were presumptively representative of the increases reached at the effort end while the cardiovascular parameters after the race were measured during the cardiovascular recovery; thus, results suggest that sustained strenuous exercise produced a stereotyped cardiovascular early recovery, whose speed could be conditioned by the immune and stress-related hormonal milieu.

A Comparison of Caffeine versus Pseudoephedrine on Cycling Time-Trial Performance

Both caffeine (CAF) and pseudoephedrine (PSE) are proposed to be central nervous system stimulants. However, during competition, CAF is a permitted substance, whereas PSE is a banned substance at urinary levels >150 μg · ml(-1). As a result, this study aimed to compare the effect of CAF versus PSE use on cycling time trial (TT) performance to explore whether the legal stimulant was any less ergogenic than the banned substance. Here, 10 well-trained male cyclists or triathletes were recruited for participation. All athletes were required to attend the laboratory on four separate occasions--including a familiarization trial and three experimental trials, which required participants to complete a simulated 40 km (1,200 kJ) cycling TT after the ingestion of either 200 mg CAF, 180 mg PSE or a nonnutritive placebo (PLA). The results showed that the total time taken and the mean power produced during each TT was not significantly different (p > .05) between trials, despite a 1.3% faster overall time (~57 s) after CAF consumption. Interestingly, the time taken to complete the second half of the TT was significantly faster (p < .05) in CAF as compared with PSE (by 99 s), with magnitude based inferences suggesting a 91% beneficial effect of CAF during the second half of the TT. This investigation further confirms the ergogenic benefits of CAF use during TT performances and further suggests this legal CNS stimulant has a better influence than a supra-therapeutic dose of PSE.

Shoe cleat position during cycling and its effect on subsequent running performance in triathletes

Research with cyclists suggests a decreased load on the lower limbs by placing the shoe cleat more posteriorly, which may benefit subsequent running in a triathlon. This study investigated the effect of shoe cleat position during cycling on subsequent running. Following bike-run training sessions with both aft and traditional cleat positions, 13 well-trained triathletes completed a 30 min simulated draft-legal triathlon cycling leg, followed by a maximal 5 km run on two occasions, once with aft-placed and once with traditionally placed cleats. Oxygen consumption, breath frequency, heart rate, cadence and power output were measured during cycling, while heart rate, contact time, 200 m lap time and total time were measured during running. Cardiovascular measures did not differ between aft and traditional cleat placement during the cycling protocol. The 5 km run time was similar for aft and traditional cleat placement, at 1084 ± 80 s and 1072 ± 64 s, respectively, as was contact time during km 1 and 5, and heart rate and running speed for km 5 for the two cleat positions. Running speed during km 1 was 2.1% ± 1.8 faster (P < 0.05) for the traditional cleat placement. There are no beneficial effects of an aft cleat position on subsequent running in a short distance triathlon.

Interactions between immune, stress-related hormonal and cardiovascular systems following strenuous physical exercise

Physical exercise represents a eustress condition that promotes rapid coordinated adjustments in the immune, stress-related hormonal and cardiovascular systems, for maintaining homeostasis in response to increased metabolic demands. Compared to the tight multisystem coordination during exercise, evidence of between-systems cross talk in the early post exercise is still lacking. This study was aimed at identifying possible interactions between multiple systems following strenuous physical exercise (Ironman race) performed by twenty well-trained triathletes. Cardiac hemodynamics, left ventricle systolic and diastolic function and heart rate variability were measured along with plasma concentrations of immune messengers (cytokines and C-reactive protein) and stress-related hormones (catecholamines and cortisol) both 24h before and within 20 min after the race. Observed changes in antiinflammatory pathways, stress-related hormones and cardiovascular function were in line with previous findings; moreover, correlating parameters’ changes (post versus pre-race) highlighted a dependence of cardiovascular function on the post-race biohumoral milieu: in particular, individual post-race variations of heart rate and diastolic function were strongly correlated with individual variations of anti-inflammatory cytokines, while individual baroreflex sensitivity changes were linked to IL-8 increase. Multiple correlations between anti-inflammatory cytokines and catecholamines were also found according with the autonomic regulation of immune function. Observed post-race cytokine and hormone levels were presumptively representative of the increases reached at the effort end while the cardiovascular parameters after the race were measured during the cardiovascular recovery; thus, results suggest that sustained strenuous exercise produced a stereotyped cardiovascular early recovery, whose speed could be conditioned by the immune and stress-related hormonal milieu.

Alteration in neuromuscular function after a 5 km running time trial

The aim of this study was to characterize the effect of a 5 km running time trial on the neuromuscular properties of the plantar flexors. Eleven well-trained triathletes performed a series of neuromuscular tests before and immediately after the run on a 200 m indoor track. Muscle activation (twitch interpolation) and normalized EMG activity were assessed during maximal voluntary contraction (MVC) of plantar flexors. Maximal soleus H-reflexes and M-waves were evoked at rest (i.e. H (MAX) and M (MAX), respectively) and during MVC (i.e. H (SUP) and M (SUP), respectively). MVC significantly declined (-27%; P < 0.001) after the run, due to decrease in muscle activation (-8%; P < 0.05) and M (MAX)-normalized EMG activity (-13%; P < 0.05). Significant reductions in M-wave amplitudes (M (MAX): -13% and M (SUP): -16%; P < 0.05) as well as H (MAX)/M (MAX) (-37%; P < 0.01) and H (SUP)/M (SUP) (-25%; P < 0.05) ratios occurred with fatigue. Following exercise, the single twitch was characterized by lower peak torque (-16%; P < 0.001) as well as shorter contraction (-19%; P < 0.001) and half-relaxation (-24%; P < 0.001) times. In conclusion, the reduction in plantar flexors strength induced by a 5 km running time trial is caused by peripheral adjustments, which are attributable to a failure of the neuromuscular transmission and excitation-contraction coupling. Fatigue also decreased the magnitude of efferent motor outflow from spinal motor neurons to the plantar flexors and part of this suboptimal neural drive is the result of an inhibition of soleus motoneuron pool reflex excitability.

Age-related changes in cardio-respiratory responses and muscular performance following an Olympic triathlon in well-trained triathletes

The aim of the present study was to compare the maximal isometric torque and cardio-respiratory parameters in well-trained young and master triathletes prior to and following an Olympic distance triathlon. One day before and 24 h following the event, participants performed three maximum voluntary isometric knee extensions and flexions and an incremental running test on a treadmill to determine the maximal isometric torque, maximal oxygen uptake VO(2max), speed at VO(2max) (vVO(2)max), speed at ventilatory thresholds (VT1 and VT2) and submaximal running economy. Prior to the event VO(2max), vVO(2)max, speed at ventilatory thresholds and running economy were significantly lower in master athletes, but maximal voluntary torque was similar between the groups. 24 h following the race, a similar significant decrease in VO(2max) (-3.1% in masters, and -6.2% in young, p < 0.05), and vVO(2)max (-9.5% in masters, and -5.6% in young, p < 0.05) was observed in both the groups. The speed at VT2 significantly decreased only in master athletes (-8.3%, p < 0.05), while no change was recorded in maximal voluntary torque or submaximal running economy following the event. The results indicate that for well-trained subjects, the overall relative exercise intensity during an Olympic distance triathlon and the fatigue 24 h following the event seem to be independent of age.

The effect of carbohydrate feeding during cycling on run performance within a simulated Olympic-distance triathlon

Introduction: The purpose of the present study was to examine the effects of carbohydrate ingestion during the cycle leg of a simulated Olympic-distance triathlon (1500-m swim, 40-km cycle, 10-km run) on subsequent running performance. Methods: Five well-trained triathletes (4 male, 1 female) volunteered to participate (mean±SD age: 23.6±4.2 y, body mass: 63.0±7.6 kg and VO2max: 64.0±9.0 ml kg-1 min-1). Participants attended three separate testing sessions separated by at least five days. The first session involved a 1500-m swim time-trial (STT) followed approximately 30 min later by a graded cycle test to exhaustio nfor the evaluation of maximal aerobic power (MAP). The two subsequent sessions required participants to complete a simulated Olympic-distance triathlon involving a 1500-m pool swim to within 5% of the STT, a 40-km stationary cycle at 75% of MAP and a 10-km running time trial. Participants randomly consumed either a 14.4% carbohydrate drink containing 1.2 g min-1 of glucose and 0.6 g min-1 of fructose (CHO) or a fruit squash placebo (PLA) throughout the cycle leg of the triathlon. Fingertip blood samples were collected after every 5 km of the cycle leg and at the end of the run and were subsequently analysed for blood glucose (GLU) and lactate (LAC) concentrations. Rating of perceived exertion (RPE) and perceived stomach upset (PSU) were also measured after each 5-km cycle period and at the end of the run. Heart rate (HR) was measured throughout the cycle leg only. Results and conclusion: The 10-km run time was 4.2% faster following CHO (38 min 08 s ± 2 min 46 s) compared with PLA (39 min 44 s ±3 min 13 s; P 0.05) and significantly lower RPE scores in the CHO compared with the PLA trial (P < 0.05). These results show that a 10-km run at the end of an Olympic-distance triathlon may be significantly improved following ingestion of a 14.4% glucose-fructose beverage at a rate of 1.8 g min−1 compared with a fruit squash placebo, with no additional gastro-intestinal stress. This improvement in run performance in the CHO trial may be due to muscle and liver glycogen sparing during the cycle leg, which increased carbohydrate metabolism in the latter stages of the triathlon.

Pseudoephedrine Ingestion and Cycling Time-Trial Performance

The aim of the current study was to investigate the effect of 180 mg of pseudoephedrine (PSE) on cycling time-trial (TT) performance. Six well-trained male cyclists and triathletes (age 33 +/- 2 yr, mass 81 +/- 8 kg, height 182.0 +/- 6.7 cm, VO2max 56.8 +/- 6.8 ml x kg(-1) x min(-1); M +/- SD) underwent 2 performance trials in which they completed a 25-min variable-intensity (50-90% maximal aerobic power) warm-up, followed by a cycling TT in which they completed a fixed amount of work (7 kJ/kg body mass) in the shortest possible time. Sixty minutes before the start of exercise, they orally ingested 180 mg of PSE or a cornstarch placebo (PLA) in a randomized, crossover, double-blind manner. Venous blood was sampled immediately pre- and postexercise for the analysis of pH plus lactate, glucose, and norepinephrine (NE). PSE improved cycling TT performance by 5.1% (95% CI 0-10%) compared with PLA (28:58.9 +/- 4:26.5 and 30:31.7 +/- 4:36.7 min, respectively). There was a significant Treatment x Time interaction (p = .04) for NE, with NE increasing during the PSE trial only. Similarly, blood glucose also showed a trend (p = .06) for increased levels postexercise in the PSE trial. The ingestion of 180 mg of PSE 60 min before the onset of high-intensity exercise improved cycling TT performance in well-trained athletes. It is possible that changes in metabolism or an increase in central nervous system stimulation is responsible for the observed ergogenic effect of PSE.

Changes in leg-spring behavior during a 5000 m self-paced run in differently trained athletes

Summary Aims To explore whether fatigue-induced changes in spring-mass behavior during a 5000 m self-paced run varied according to the runner's training status. Methods and results Six highly- and six well-trained triathletes completed a 5000 m time trial. Running velocity and vertical stiffness decreased significantly ( P P Conclusions During a 5000 m self-paced run, impairments in leg-spring behavior that occur with fatigue are not affected by athletes’ training status.

Accuracy and Repeatability of the Polar®RS800sd to Evaluate Stride Rate and Running Speed

The purpose of this study was to evaluate the accuracy and the repeatability of a new running computer system (RS800sd, Polar, Kempele, Finland) which included the measurement of running speed (RS) and stride rate (SR). Eight well-trained triathletes participated in this study. First, they completed an incremental continuous maximum test on a treadmill (from 12 km x h (-1) to 18 km x h (-1)) at 0% grade. Then the subjects took part in a second test to determine RS800sd intra-reproducibility to evaluate running speed. They ran twice during 5 min at a pace corresponding to their maximal lactate steady-state. During these two tests, RS and SR were recorded by the RS800sd system, by an optical sensor system (for RS) and a force-sensitive device (for SR). No difference was found between the RS800sd system and the reference systems both for RS (ICC=0.95) and SR (ICC=0.69). Moreover RS measures were statistically repeatable. This study provided evidence for the validity of the RS800sd system for measuring the kinematic characteristics of running (speed and frequency). Further investigations are needed to replicate these findings at lower running speeds, notably during walking to assess its capacity to evaluate physical activity in natural conditions.

Intérêt de la spectroscopie dans le proche infrarouge de l'hémoglobine pour l'étude de l'oxygénation musculaire du vastus lateralis lors d'une épreuve d'effort

Aims We study the muscle oxygenation of the vastus lateralis muscle (VL) during an incremental exercise and the local changes of muscle oxygenation with fatigue. Methods Seven well-trained triathletes and runners (age: 26.4 ± 1.3 years) performed an incremental exercise on a treadmill (beginning: 12 km.h −1; added 1 km.h −1 every 2 min up to exhaustion). O 2 uptake ( V . O 2 ), heart rate (HR) and ventilatory components were recorded with a Cosmed K4 at rest, during exercise and 6 min recuperation (3 min walking, 3 min standing). Determination of the aerobic threshold (AT) and of the respiratory compensation point (RCP) was realised by the V- slope method. The near infrared spectroscopy of haemoglobin allowed the measurement of the concentration of the vastus lateralis muscle (VL) oxygenation. The probe was fixed on the left VL at 15 cm of the knee joint, along the vertical axis of the thigh. Results Our results showed that AT and RCP corresponded to 70 ± 2.8% and 88 ± 2.8% of the V . O 2 max. During exercise, [HbO 2]/[Hbtot] signal showed two breaking point (D1, D2) corresponding to 70.6 ± 0.6% and 89.1 ± 1.1% of the V . O 2 max. D2 correlated with RCP (R = 0.558, p < 0.05), but D1 and AT had only a similar evolution. HR correlated with [HbO 2]/[Hbtot], (R = 0.986, p < 0.001). Conclusion Using the near infrared spectroscopy of haemoglobin method during incremental exercise allowed the detection of the aerobic–anaerobic threshold of the exercising muscle.

The effects of exercise intensity or drafting during swimming on subsequent cycling performance in triathletes

The purpose of this study was to compare the affects of drafting or a reduction of exercise intensity during swimming on the power output sustained (P(mean)) during a subsequent cycle time trial (TT). In addition the relationship between peak power output (PPO) and P(mean) generated during the cycle TT after swimming was examined. Nine well-trained triathletes performed an incremental cycling test to exhaustion for determination of PPO. In addition, each subject performed three swim-cycle (SC) trials consisting of 20 min cycle TT preceded by a 400 m swimming trial completed as (1) "all out" and in a non-drafting situation (SC(100%)); (2) at 90% of SC(100%) in a non-drafting situation (SC(90%)); (3) in a drafting position at the same controlled velocity as SC(100%) (SC(drafting)). Swimming velocity (ms(-1)) was significantly (p<0.01) lower at each time point during the 400 m swimming trial in SC(90%) compared with SC(100%) and SC(drafting). There was no significant difference in velocity between SC(100%) and SC(drafting). Blood lactate (BLA) concentration was also significantly (p<0.01) lower after swimming in SC(90%) compared to SC(100%) and SC(drafting) (3.8+/-0.9 versus 7.3+/-2.4 and 7.9+/-2.4mM). The Pmean was also significantly (p<0.05) lower in SC(100%) relative to the SC(90%) and SC(drafting) (226+/-15 versus 253+/-33 and 249+/-36W). There was no significant correlation between PPO (W) and P(mean) for SC(100%) (r=-0.32), SC(90%) (r=0.65; p=0.058) or SC(drafting) (r=0.54). This study indicates that drafting or swimming at a lower velocity did not induce any conflicting affects on power output during a subsequent cycle TT. However, this study confirms that P(mean) during a cycle TT is reduced when prior swimming is performed. Furthermore the positive relationship typically observed between PPO and P(mean) is disrupted by swimming activity performed before a cycling TT. This factor should be considered in terms of physiological analysis of triathletes.

Dynamic Pacing Strategies during the Cycle Phase of an Ironman Triathlon

A nonlinear dynamic systems model has previously been proposed to explain pacing strategies employed during exercise. This study was conducted to examine the pacing strategies used under varying conditions during the cycle phase of an Ironman triathlon. The bicycles of six well-trained male triathletes were equipped with SRM power meters set to record power output, cadence, speed, and heart rate. The flat, three-lap, out-and-back cycle course, coupled with relatively consistent wind conditions (17-30 km x h(-1)), enabled comparisons to be made between three consecutive 60-km laps and relative wind direction (headwind vs tailwind). Participants finished the cycle phase (180 km) with consistently fast performance times (5 h, 11 +/- 2 min; top 10% of all finishers). Average power output (239 +/- 25 to 203 +/- 20 W), cadence (89 +/- 6 to 82 +/- 8 rpm), and speed (36.5 +/- 0.8 to 33.1 +/- 0.8 km x h(-1)) all significantly decreased with increasing number of laps (P < 0.05). These variables, however, were not significantly different between headwind and tailwind sections. The deviation (SD) in power output and cadence did not change with increasing number of laps; however, the deviations in torque (6.8 +/- 1.6 and 5.8 +/- 1.3 N x m) and speed (2.1 +/- 0.5 and 1.6 +/- 0.3 km x h(-1)) were significantly greater under headwind compared with tailwind conditions, respectively. The median power frequency tended to be lower in headwind (0.0480 +/- 0.0083) compared with tailwind (0.0531 +/- 0.0101) sections. These data show evidence that a nonlinear dynamic pacing strategy is used by well-trained triathletes throughout various segments and conditions of the Ironman cycle phase. Moreover, an increased variation in torque and speed was found in the headwind versus the tailwind condition.

HDL capacity to inhibit LDL oxidation in well-trained triathletes

Physical activity is known to play a cardioprotective role. Nevertheless, a paradox seems to arise when considering that aerobic exercise enhances oxidative stress. In previous works, we showed that free radical formation during physical activity was counteracted by an increase in antioxidant defenses. Low density lipoprotein (LDL) oxidation is a crucial step in atherosclerosis, process that can be inhibited by high density lipoprotein (HDL) through its oxidable components or associated enzymes like paraoxonase (PON) and platelet-activating factor acetylhydrolase (PAF-AH). In this study, we evaluated copper-induced oxidation in isolated LDL and HDL fractions, and the effect of HDL on LDL oxidation in samples from well trained amateur athletes who were participating in an ultra-distance triathlon ( n = 18) in comparison with healthy sedentary controls ( n = 18). PON and PAF-AH activities and PON phenotype were also evaluated. The oxidability of isolated lipoproteins, as well as HDL antioxidant capacity, was similar in both groups of subjects. After classification by paraoxonase phenotype, only sportsmen belonging to the QR phenotype showed higher HDL susceptibility to in vitro oxidation (thiobarbituric reactive substances, TBARS) than controls ( p < 0.05). HDL oxidability exhibited a positive correlation with its triglyceride content ( r = 0.58; p < 0.01). Similarly, HDL capacity to inhibit LDL oxidation was increased in athletes ( p < 0.05) which was positively associated with HDL oxidability (HDL-TBARS: r = 0.55, p < 0.005; HDL- lag time: r = 0.45, p < 0.01; HDL-D max: r = 0.35, p < 0.05). In conclusion, regular aerobic exercise was associated to a more efficient antioxidant function played by HDL from PON-QR carriers, which could constitute an adaptive response to the increased oxidative stress.

Does Prior 1500-m Swimming Affect Cycling Energy Expenditure in Well-Trained Triathletes?

The purpose of this study was to determine the effects of a 1,500-m swim on energy expenditure during a subsequent cycle task. Eight well-trained male triathletes (age 26.0 +/- 5.0 yrs; height 179.6 +/- 4.5 cm; mass 71.3 +/- 5.8 kg; VO(2)max 71.9 +/- 7.8 ml.kg(-1).min(-1)) underwent two testing sessions in counterbalanced order. The sessions consisted of a 30-min ride on the cycle ergometer at 75% of maximal aerobic power (MAP), and at a pedaling frequency of 95 rev.min(-1), preceded either by a 1,500-m swim at 1.20 m.s(-1) (SC trial) or by a cycling warm-up at 30% of MAP (C trial). Respiratory and metabolic data were collected between the 3rd and the 5th min, and between the 28th and 30th min of cycling. The main results indicated a significantly lower gross efficiency (13.0%) and significantly higher blood lactate concentration (56.4%), VO(2) (5.0%), HR (9.3%), VE (15.7%), and RF (19.9%) in the SC compared to the C trial after 5 min, p < 0.05. After 30 min, only VE (7.9%) and blood lactate concentration (43.9%) were significantly higher in the SC compared to the C trial, p < 0.05. These results confirm the increase in energy cost previously observed during sprint-distance triathlons and point to the importance of the relative intensity of swimming on energy demand during subsequent cycling.

Swimming and Cycling Overloaded Training in Triathlon has no Effect on Running Kinematics and Economy

The aim of the study was to verify whether an overloaded training (OT) in triathlon deteriorates running kinematics (RK) and running economy (RE). Thirteen well-trained male long-distance triathletes (age: 28.1 +/- 4.3 yrs; V.O (2max): 65.0 +/- 3.1 ml O (2) . min (-1) . kg (-1)) were divided into two groups: completed an individualized OT program (OG; n = 7) or maintained a normal level of training (NT) (CG; n = 6) for a duration of 3 weeks. Every week, each triathlete completed a standardized questionnaire to quantify the influence of training loads on mood state. To reach OT, total training load (h . 3 wk (-1)) was increased by 24 %; swimming and cycling total volumes were increased by 46 and 57 %, respectively, but the distance run was not modified in order to limit the risk of injuries. RK and RE were determined on treadmill test at 12 km . h (-1) before and after the 3 weeks. The 3-week swimming and cycling OT in triathlon was sufficiently stressful to alter mood state but not to deteriorate the running kinematics and economy parameters in our previously well-trained male long-distance triathletes.

Time course of neuromuscular alterations during a prolonged running exercise.

This study investigated the time course of contractile and neural alterations of knee extensor (KE) muscles during a long-duration running exercise. Nine well-trained triathletes and endurance runners sustained 55% of their maximal aerobic velocity (MAV) on a motorized treadmill for a period of 5 h. Maximal voluntary contraction (MVC), maximal voluntary activation level (%VA), and electrically evoked contractions (single and tetanic stimulations) of KE muscles were evaluated before, after each hour of exercise during short (10 min) interruptions, and at the end of the 5-h period. Oxygen uptake was also measured at regular intervals during the exercise. Reductions of MVC and %VA were significant after the 4th hour of exercise and reached -28% (P < 0.001) and -16% (P < 0.01) respectively at the end of the exercise. The reduction in MVC was highly correlated with the decline of %VA (r = 0.98, P < 0.001). M-wave was also altered after the fourth hour of exercise (P < 0.05) in both vastus lateralis and rectus femoris muscles. Peak twitch was potentiated at the end of the exercise (+18%, P = 0.01); 20- and 80-Hz maximal tetanic forces were not altered by the exercise. Oxygen uptake increased linearly during the running period (+18% at 5 h, P < 0.001). These findings suggest that KE maximal voluntary force generating capability is depressed in the final stages of a 5-h running exercise. Central activation failure and alterations in muscle action potential transmission were important mechanisms contributing to the impairment of the neuromuscular function during prolonged running.

Comparison of W peak, VO 2peak and the ventilation threshold from two different incremental exercise tests: Relationship to endurance performance

This report presents data comparing the peak rate of oxygen consumption (VO2(peak)), peak power output (W(peak)) and the ventilation threshold (VT) obtained from two different incremental cycle exercise tests performed by nine well trained triathletes (Mean +/- SD age 32 +/- 3 yrs; body mass 77.4 +/- 4.9 kg and height 185 +/- 3 cm). Furthermore, the relationship between these variables and the average sustained power output (W) during a 90 min cycle time trial (TT) was also determined. The two incremental exercise tests involved a 'short' test, which commenced at 150 W with 30 W increments every 60 s until exhaustion. The second ('long') incremental test commenced at a power output representing 50% of the W(peak) obtained in the short test. The subjects were then required to increase the power output by 5% every 3 min until exhaustion. The results showed the W(peak) (W) in the short test was significantly (p < 0.01) higher than in the long test. However, there was no significant difference in the VO2(peak) (1 x min(-1)) between the two tests. There was a weak but significant correlation between W(peak) (W) and VO2(peak) (l x min(-1)) (r = 0.72: p < 0.05) in the short (60 s stage) test but not the long (3 min stage) test (r = 0.52). There were no significant differences and good agreement between for the heart rate (HR) (b x min(-1)) and oxygen consumption (VO2) corresponding to the VT. In contrast, the power output (W) corresponding to the VT was significantly different and not comparable between the long and short incremental tests. The cycle TT performance was most correlated to the W(peak) (W) (r = 0.94; p < 0.01) and the VT (W) (r = 0.75; p < 0.05) from the long test as well as the VO2(peak) (l x min(-1)) obtained from the short incremental test (r = 0.75; p < 0.01). These data suggest that the length of stages during incremental cycle exercise may influence the W(peak) and in turn the relationship of this variable to VO2(peak). Furthermore, the W(peak) obtained from a test incorporating 3 min stage increments represents the best indicator of 90 min cycle performance in well-trained triathletes.

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.