Thermal, physiological and perceptual strain mediate alterations in match-play tennis under heat stress.

OBJECTIVES: This study compared the thermal, physiological and perceptual responses associated with match-play tennis in HOT (∼34°C wet-bulb-globe temperature (WBGT)) and COOL (∼19°C WBGT) conditions, along with the accompanying alterations in match characteristics. METHODS: 12 male tennis players undertook two matches for an effective playing time (ie, ball in play) of 20 min, corresponding to ∼119 and ∼102 min of play in HOT and COOL conditions, respectively. Rectal and skin temperatures, heart rate, subjective ratings of thermal comfort, thermal sensation and perceived exertion were recorded, along with match characteristics. RESULTS: End-match rectal temperature increased to a greater extent in the HOT (∼39.4°C) compared with the COOL (∼38.7°C) condition (p<0.05). Thigh skin temperature was higher throughout the HOT match (p<0.001). Heart rate, thermal comfort, thermal sensation and perceived exertion were also higher during the HOT match (p<0.001). Total playing time was longer in the HOT compared with the COOL match (p<0.05). Point duration (∼7.1 s) was similar between conditions, while the time between points was ∼10 s longer in the HOT relative to the COOL match (p<0.05). This led to a ∼3.4% lower effective playing percentage in the heat (p<0.05). Although several thermal, physiological and perceptual variables were individually correlated to the adjustments in time between points and effective playing percentage, thermal sensation was the only predictor variable associated with both adjustments (p<0.005). CONCLUSIONS: These adjustments in match-play tennis characteristics under severe heat stress appear to represent a behavioural strategy adopted to minimise or offset the sensation of environmental conditions being rated as difficult.

Coping with heat stress during match-play tennis: does an individualised hydration regimen enhance performance and recovery?

OBJECTIVES: To determine whether an individualised hydration regimen reduces thermal, physiological and perceptual strain during match-play tennis in the heat, and minimises alterations in neuromuscular function and physical performance postmatch and into recovery. METHODS: 10 men undertook two matches for an effective playing time (ball in play) of 20 min (∼113 min) in ∼37°C and ∼33% RH conditions. Participants consumed fluids ad libitum during the first match (HOT) and followed a hydration regimen (HYD) in the second match based on undertaking play euhydrated, standardising sodium intake and minimising body mass losses. RESULTS: HYD improved prematch urine specific gravity (1.013±0.006 vs 1.021±0.009 g/mL; p<0.05). Body mass losses (∼0.3%), fluid intake (∼2 L/h) and sweat rates (∼1.6 L/h) were similar between conditions. Core temperature was higher during the first 10 min of effective play in HOT (p<0.05), but increased similarly (∼39.3°C) on match completion. Heart rate was higher (∼11 bpm) throughout HOT (p<0.001). Thermal sensation was higher during the first 7.5 min of effective play in HOT (p<0.05). Postmatch knee extensor and plantar flexor strength losses, along with reductions in 15 m sprint time and repeated-sprint ability (p<0.05), were similar in both conditions, and were restored within 24 h. CONCLUSIONS: Both the hydration regimen and ad libitum fluid consumption allowed for minimal body mass losses (<1%). However, undertaking match-play in a euhydrated state attenuated thermal, physiological and perceptual strain. Maximal voluntary strength in the lower limbs and repeated-sprint ability deteriorated similarly in both conditions, but were restored within 24 h.

The impact of match-play tennis in a hot environment on indirect markers of oxidative stress and antioxidant status.

OBJECTIVES: The purpose of this study was to determine the impact of changes in oxidative stress and antioxidant status in response to playing tennis in HOT (∼36°C and 35% relative humidity (RH)) and COOL (∼22°C and 70% RH) conditions. METHODS: 10 male tennis players undertook two matches for an effective playing time (ie, ball in play) of 20 min, corresponding to ∼122 and ∼107 min of total play in HOT and COOL conditions, respectively. Core body temperature, body mass and indirect markers of oxidative stress (diacrons reactive oxygen metabolic test) and antioxidant status (biological antioxidant potential test) were assessed immediately prematch, midmatch and postmatch, and 24 and 48 h into recovery. RESULTS: Regardless of the condition, oxidative stress remained similar throughout play and into recovery. Likewise, match-play tennis in the COOL had no impact on antioxidant status. However, antioxidants status increased significantly in the HOT compared with COOL environment (p<0.05). Body mass losses (∼0.5 kg) were similar between conditions. Rectal temperature increased during both matches (p<0.05), but with a greater magnitude in the HOT (39.3±0.5°C) versus COOL (38.7±0.2°C) environment (p<0.05). CONCLUSIONS: Match-play tennis in the heat does not exacerbate the development of oxidative stress, but significantly increases antioxidant status. These data suggest that the heat stress observed in the HOT environment may provide a necessary signal for the upregulation of antioxidant defence, dampening cellular damage.

Voluntary muscle and motor cortical activation during progressive exercise and passively induced hyperthermia.

This study examined whether central fatigue was exacerbated by an increase in muscle contractile speed caused by passive hyperthermia (PaH) and whether exercise-induced hyperthermia (ExH) combined with related peripheral fatigue influenced this response. The ExH was induced by cycling at 60% of maximal oxygen uptake in 38°C conditions and the PaH by sitting in a 48°C climate chamber. Ten men performed brief (≈ 5 s) and sustained (30 s) maximal voluntary isometric contractions (MVCs) of the knee extensors at baseline (CON, ∼37.1°C) and during moderate (MOD, ≈ 38.5°C) and severe (SEV, ∼39.5°C) hyperthermia. Motor nerve and transcranial magnetic stimulation were used to assess voluntary muscle and cortical activation level, along with contractile properties. Brief MVC force decreased to a similar extent during SEV-ExH (-8%) and SEV-PaH (-6%; P < 0.05 versus CON). Sustained MVC force also decreased during MOD-ExH (-10%), SEV-ExH (-13%) and SEV-PaH (-7%; P < 0.01 versus CON). Motor nerve and cortical activation were reduced on reaching MOD (≈ 3%) and SEV (≈ 5%) ExH and PaH during the brief and sustained MVCs (P < 0.01 versus CON). Peak twitch force decreased on reaching SEV-ExH and SEV-PaH (P < 0.05 versus CON). Following transcranial magnetic stimulation, during the brief and sustained MVCs the peak muscle relaxation rate increased in ExH and PaH (P < 0.01 versus CON). The increase was greatest during the sustained contraction in SEV-PaH (P < 0.01), but this did not exacerbate central fatigue relative to ExH. These results indicate that during fatiguing cycling exercise in the heat, quadriceps peak relaxation rate increases. However, the centrally mediated rate of activation appears sufficient to overcome even the largest increase in muscle relaxation rate, seen during SEV-PaH.

Gender differences in fat distribution and inflammatory markers among Arabs.

UNLABELLED: Recent studies from the Gulf region suggest that compared to men, women have a greater risk of developing metabolic syndrome (MeS). OBJECTIVE: To investigate gender differences in body composition, adipokines, inflammatory markers, and aerobic fitness in a cohort of healthy Qatari adults. Participants. Healthy Qatari (n = 58) were matched for age, gender, and body mass index. METHODS: Body composition and regional fat distribution were determined by dual-energy X-ray absorptiometry and computerized tomography. Laboratory assessments included serum levels of fasting glucose, insulin, lipid profile analysis, adipokines, and inflammatory markers. Subjects were also evaluated for aerobic fitness. RESULTS: Women had more adipose tissue in the total abdominal (P = 0.04) and abdominal subcutaneous (P = 0.07) regions compared to men. Waist circumference and indices of insulin sensitivity were similar; however, women had a more favourable lipid profile than men. Serum adiponectin and leptin levels were significantly higher in women, whereas inflammatory profiles were not different between men and women. Aerobic fitness was lower in women and was associated with abdominal fat accumulation. CONCLUSION: In premenopausal women, higher levels of adiponectin may support maintenance of insulin sensitivity and normolipidemia despite greater adiposity. However, poor aerobic fitness combined with abdominal fat accumulation may explain their greater future risk of MeS compared with men.

The prevalence of vitamin supplementation in ultraendurance triathletes.

Ultraendurance exercise training places large energy demands on athletes and causes a high turnover of vitamins through sweat losses, metabolism, and the musculoskeletal repair process. Ultraendurance athletes may not consume sufficient quantities or quality of food in their diet to meet these needs. Consequently, they may use oral vitamin and mineral supplements to maintain their health and performance. We assessed the vitamin and mineral intake of ultraendurance athletes in their regular diet, in addition to oral vitamin and mineral supplements. Thirty-seven ultraendurance triathletes (24 men and 13 women) completed a 7-day nutrition diary including a questionnaire to determine nutrition adequacy and supplement intake. Compared with dietary reference intakes for the general population, both male and female triathletes met or exceeded all except for vitamin D. In addition, female athletes consumed slightly less than the recommended daily intake for folate and potassium; however, the difference was trivial. Over 60% of the athletes reported using vitamin supplements, of which vitamin C (97.5%), vitamin E (78.3%), and multivitamins (52.2%) were the most commonly used supplements. Almost half (47.8%) the athletes who used supplements did so to prevent or reduce cold symptoms. Only 1 athlete used supplements on formal medical advice. Vitamin C and E supplementation was common in ultraendurance triathletes, despite no evidence of dietary deficiency in these 2 vitamins.

An evaluation of 30-km cycling time trial (TT30) pacing strategy through time-to-exhaustion at average TT30 pace.

A paucity of research is available on the optimal pacing strategy for cycling events longer than 4 km. Anecdotal evidence suggests that an even pacing strategy is most suitable; however, controlled studies have only determined that a slow start is more suitable than a fast start pacing strategy. Currently, it is unclear which strategy is more effective for endurance cycling time trials. This study sought to identify differences in 30-km cycling time trial (TT30) performance related to pacing strategies by comparing individually chosen pacing strategy with time-to-exhaustion (TE) at the average power output achieved during TT30. Eight moderately trained male cyclists (Vo2max = 50.9 +/- 5.2 mlxkgxmin) performed 2 TT30 tests and 2 TE tests at the average power output of TT30 on a Velotron cycle ergometer at the same time of day, separated by at least 48 hours. During TT30, participants generally chose to use a 'fast start' pacing strategy, cycling at a speed relative to the TT average (TTAvg) of 103.1 +/- 2.2% during the first 5 km. There was no significant difference in performance time between the TE test and TT30. Starting pace (TT0-5) was significantly correlated with finishing pace (TT25-30) (r = -0.91; p < 0.01) and TE (r = 0.85; p < 0.01). Subjects cycling at a relative starting speed (RS0-5) >105% had a significantly longer TE than subjects cycling at <105%, whereas TT30 performance time was not different between the two groups. The present investigation provided indirect evidence that a fast start pacing strategy decreases finishing speed and overall performance in TT30, and increased TT performance can be achieved by selecting a starting pace no more than 5% above TTAvg.

The effects of increased absolute training intensity on adaptations to endurance exercise training.

"Progressive overload" is regarded an important principle to consider in maximising endurance training adaptations, yet little scientific evidence supports this concept. The aim of the present study was to compare differences in endurance performance after a training regime where treadmill-running intensity was incrementally elevated to a regime where running intensity remained unchanged. Twenty-eight healthy untrained males and females were randomly and equally assigned into both regimes. All participants performed 20 min treadmill-running sessions 3 times a week for 6 weeks. Prior to and after training, maximum oxygen uptake (VO2max), oxygen uptake and velocity at the lactate threshold (LTVO(2) and LTv) and maximum treadmill velocity (Vmax) were measured in an incremental treadmill test. 5000 m time trial performance was also assessed. In the incremental intensity regime treadmill velocity commenced at 0.8 km x h(-1) below the LTv and was increased by 0.1 km x h(-1) every session. In the constant intensity regime treadmill speed was kept constant at 0.8 km x h(-1) below the LTv for the duration of the training. The study revealed that both regimens increased VO2max, Vmax LTVO(2), LTv and decreased 5000 m time trial significantly after training. There were no significant differences in the changes between regimens for VO2max, Vmax and 5000 m time trial. However, the increase in LTVO(2) and LTv were significantly greater in the incremental intensity regime compared to the constant intensity regime. The present data show that 20 min treadmill-running sessions performed 3 times a week for 6 weeks improves endurance performance and that progressively elevating exercise intensity is important to maximise improvements in LTVO(2) and LTv.

Caffeine has a small effect on 5-km running performance of well-trained and recreational runners.

The purpose of this study was to investigate if caffeine ingestion improves 5-km time-trial performance in well-trained and recreational runners. Using a double-blind placebo-controlled design, 15 well-trained and 15 recreational runners completed two randomized 5-km time-trials, after ingestion of either 5mgkg(-1) of caffeine or a placebo. Caffeine ingestion significantly improved 5-km running performance in both the well-trained and recreational runners. In comparison to the placebo trial, the caffeine trial resulted in 1.1% (90% CI 0.4-1.6) and 1.0% (0.2-2%) faster times for the well-trained and recreational runners. Reliability testing of the recreational runners indicated a test-retest error of measurement of 1.4%. We conclude that caffeine ingestion is likely to produce small but significant gains in 5-km running performance for both well-trained and recreational runners.

Central hemodynamics in ultra-endurance athletes.

Central hemodynamics such as ascending aortic blood pressure (BP), wave reflection and myocardial perfusion are clinically important in the context of cardiovascular health. Ultra-endurance athletes may be at greater risk of cardiovascular abnormalities due to chronically increased physiological stress placed on the cardiovascular system. This study was a cross-sectional investigation that compared central hemodynamics in ultra-endurance athletes and matched controls. Forty-four athletes (36 males; aged mean+/-S.D., 34+/-8 years) undergoing ultra-endurance training (16.3+/-3.7 h/week) were compared to 44 matched recreationally active (1.2+/-0.9 h/week) controls (36 males; aged 34+/-8 years). Brachial BP was measured using an oscillometric device while central hemodynamics including ascending aortic BP, wave reflection (augmentation index, AIx), ejection duration, sub-endocardial perfusion (SEVR) and timing of the reflected wave (T(R)) were determined by applanation tonometry and pulse wave analysis. There were no significant (P>0.05) differences between groups in AIx (athletes and controls; 6+/-12% versus 6+/-13%, respectively), T(R) (athletes and controls; 165+/-22 ms versus 165+/-19 ms, respectively), brachial (athletes and controls; 51+/-9 mmHg versus 48+/-12 mmHg, respectively) or central pulse pressure (33+/-5 mmHg versus 31+/-7 mmHg). However, athletes had significantly increased SEVR (226+/-42% versus 198+/-46%; P<0.001) despite having a longer ejection duration (348+/-19 ms versus 339+/-18 ms; P<0.05). Furthermore, the amount of exercise training volume was significantly related to central (r=-0.46; P=0.002), but not brachial pulse pressure (r=-0.28; P>0.05). Ultra-endurance athletes had increased sub-endocardial perfusion capacity and the quantity of exercise training was associated with central rather than peripheral hemodynamics.

The effects of interval-exercise duration and intensity on oxygen consumption during treadmill running.

The magnitude of improvement in peak oxygen uptake (V(o)(2peak))) and performance to an exercise training regime is related to the V(o)(2) of prior accumulated exercise training bouts. However, it is unclear whether constant rate training (CRT) or interval training (INT) preferentially alters the V(o)(2) of running exercise. Therefore, the purpose of this study was to compare the acute V(o)(2) response to constant, and interval training sessions. Consequently, this study compared the mean average V(o)(2) of 17 moderately trained participants to a 20-min CRT and two different 20min INT treadmill runs. Participants completed three treatments (twice) in random order over 3 weeks. In 1min INT participants completed 10x1min efforts at the velocity corresponding to V(o)(2peak) (V(peak)) interspersed with 10x1min efforts at 0.5V(peak). In the 2min INT, participants completed 5x2min efforts at the V(peak) interspersed with 5x2min efforts at 0.5 at V(peak). In CRT participants ran at a velocity equivalent to the mean velocity of INT (75% V(peak)). Mean average V(o)(2) for 2min INT, 1min INT and CRT were, respectively, 3200+/-661; 3076+/-6041; 2909+/-584mlmin(-1). Both INT sessions resulted in a significantly higher mean average V(o)(2) than CRT. Furthermore, 2min INT resulted in 90% of V(o)(2peak) being exceeded more frequently than 1min INT. We conclude that INT serves as a more potent stimulus for improvement in V(o)(2peak) and subsequent endurance performance than CRT.

A deterministic model of the vertical jump: implications for training.

Increasing vertical jump height is a critical component for performance enhancement in many sports. It takes on a number of different forms and conditions, including double and single legged jumps and stationary and run-up jumps. In an attempt to understand the factors that influence vertical jump performance, an extensive analysis was undertaken using the deterministic model. Once identified, practical training strategies enabling improvement in these factors were elucidated. Our analysis showed that a successful vertical jump performance was the result of a complex interplay of run-up speed, reactive strength, concentric action power of the take-off leg(s), hip flexors, shoulders, body position, body mass, and take-off time. Of special interest, our analysis showed that the concentric action power of the legs was the critical factor affecting stationary double leg vertical jumps, whereas reactive strength was the critical component for a single leg jump from a run-up.

Oxidative stress in half and full Ironman triathletes.

INTRODUCTION: Ultraendurance athletes who maintain a very high volume of exercise may, as a result of greater production of reactive oxygen species (ROS), be particularly susceptible to oxidative damage. PURPOSE: This study sought to examine and compare pre- and postrace markers of oxidative stress in ultraendurance athletes training for, and competing in, either a half or a full Ironman triathlon. METHODS: Resting and postexercise blood was sampled from 16 half Ironman triathletes, 29 full Ironman triathletes, and age-matched, relatively inactive controls. Blood was analyzed for markers of oxidative stress (malondialdehyde (MDA) concentration) and antioxidant status (glutathione peroxidase (GPX), catalase (CAT), and superoxide dismutase (SOD) activities). RESULTS: Compared with controls, the half Ironman triathletes had significantly (P < 0.001) higher erythrocyte GPX activity at rest, whereas the Ironman triathletes had significantly (P < 0.05) lower resting plasma MDA and significantly (P < 0.05) greater resting activities of GPX and CAT compared with controls. As a result of the half Ironman triathlon, there was a significant (P < 0.05) increase in MDA and significant (P < 0.05) decreases in erythrocyte GPX, SOD, and CAT activities. These changes also occurred in response to the Ironman triathlon; MDA significantly (P < 0.05) increased, and there were significant (P < 0.001) decreases in GPX, CAT, and SOD activities. Users of antioxidant supplements in both the half and full Ironman races had significantly (P < 0.05) elevated MDA after races compared with nonsupplementers. CONCLUSION: The present investigation indicates that training for and competing in half and full Ironman triathlons has different effects on erythrocyte antioxidant enzyme activities and oxidative stress.

Ultra-endurance exercise and oxidative damage : implications for cardiovascular health.

At least 30 minutes of moderate-intensity physical activity accumulated on most, preferably all days is considered the minimum level necessary to reduce the risk of developing cardiovascular disease. Despite an unclear explanation, some epidemiological data paradoxically suggest that a very high volume of exercise is associated with a decrease in cardiovascular health. Although ultra-endurance exercise training has been shown to increase antioxidant defences (and therefore confer a protective effect against oxidative stress), an increase in oxidative stress may contribute to the development of atherosclerosis via oxidative modification of low-density lipoprotein (LDL). Research has also shown that ultra-endurance exercise is associated with acute cardiac dysfunction and injury, and these may also be related to an increase in free radical production. Longitudinal studies are needed to assess whether antioxidant defences are adequate to prevent LDL oxidation that may occur as a result of increased free radical production during very high volumes of exercise. In addition, this work will assist in understanding the accrued effect of repeated ultra-endurance exercise-induced myocardial damage.

A comparison of the effects of fatigue on subjective and objective assessment of situation awareness in cycling.

Maximal effort on a 30 km Time Trial (TT30) was examined to assess whether it would elicit changes in objective and subjective tests of the participants' perception of the environment and their ability to anticipate future occurrences (situation awareness; SA) and to determine the effect of post-exercise recovery on SA. Nine experienced (5.22 ± 2.77 years) road cyclists had their objective and subjective levels of SA assessed prior to and at the completion of two TT30. The participants' results were compared to measurements of maximal oxygen uptake (VO2max), peak power output (PPO), age and years of competitive cycle racing experience. Fatigue resulting from maximal effort on a TT30 produced significant changes in both the objective and subjective test of SA. Effect sizes of 0.93 and 0.99 indicated that the first and second TT30 were likely or almost certain to have a beneficial effect on the objective assessment of SA. However, the effect sizes of 0.97 and 0.95 relating to the subjective assessment of cognitive performance on the first and second TT30 showed that it was very likely the participants' had an increased difficulty in maintaining SA. A recovery period of up to three minutes post TT30 had no effect on SA. Changes in SA had no relationship with measurements of VO2max, peak power output (PPO), age and years of competitive cycle racing experience. The findings suggest that within a laboratory environment, participants consistently underestimate their ability to make accurate assessments of their cycling environment compared to objective measures of their SA. Key PointsExhaustive exercise from a TT30 produces significant changes in both subjective and objective SA.This study indicates that fatigued participants underestimate their ability to maintain SA.A time period of three minutes is not enough to observe a recovery effect on subjective or objective SA.Both the objective and subjective tests proved to be reliable assessments of SA.

Relationship between laboratory-measured variables and heart rate during an ultra-endurance triathlon.

The aim of the present study was to examine the relationship between the performance heart rate during an ultra-endurance triathlon and the heart rate corresponding to several demarcation points measured during laboratory-based progressive cycle ergometry and treadmill running. Less than one month before an ultra-endurance triathlon, 21 well-trained ultra-endurance triathletes (mean +/- s: age 35 +/- 6 years, height 1.77 +/- 0.05 m, mass 74.0 +/- 6.9 kg, = 4.75 +/- 0.42 l x min(-1)) performed progressive exercise tests of cycle ergometry and treadmill running for the determination of peak oxygen uptake (VO2peak), heart rate corresponding to the first and second ventilatory thresholds, as well as the heart rate deflection point. Portable telemetry units recorded heart rate at 60 s increments throughout the ultra-endurance triathlon. Heart rate during the cycle and run phases of the ultra-endurance triathlon (148 +/- 9 and 143 +/- 13 beats x min(-1) respectively) were significantly (P < 0.05) less than the second ventilatory thresholds (160 +/- 13 and 165 +/- 14 beats x min(-1) respectively) and heart rate deflection points (170 +/- 13 and 179 +/- 9 beats x min(-1) respectively). However, mean heart rate during the cycle and run phases of the ultra-endurance triathlon were significantly related to (r = 0.76 and 0.66; P < 0.01), and not significantly different from, the first ventilatory thresholds (146 +/- 12 and 148 +/- 15 beats x min(-1) respectively). Furthermore, the difference between heart rate during the cycle phase of the ultra-endurance triathlon and heart rate at the first ventilatory threshold was related to marathon run time (r = 0.61; P < 0.01) and overall ultra-endurance triathlon time (r = 0.45; P < 0.05). The results suggest that triathletes perform the cycle and run phases of the ultra-endurance triathlon at an exercise intensity near their first ventilatory threshold.

Effects of electrical muscle stimulation on oxygen consumption.

Electrical muscle stimulation (EMS) devices are being marketed as weight/ fat loss devices throughout the world. Commercially available stimulators have the ability to evoke muscle contractions that may affect caloric expenditure while the device is being used. The aim of this study was to test the effects of two different EMS devices (Abtronic and Feminique) on oxygen consumption at rest. Subjects arrived for testing after an overnight fast, had the devices fitted, and then positioned supine with expired air measured to determine oxygen consumption. After a 10-minute acclimation period, oxygen consumption was measured for 20 minutes with the device switched off (resting) then 20 minutes with the device switched on (stimulated). There were no significant differences (p > 0.05) in oxygen consumption between the resting and stimulated periods with either the Abtronic (mean +/- SD; resting, 3.40 +/- 0.44; stimulated, 3.45 +/- 0.53 ml of O(2).kg(-1).min(-1)) or the Feminique (resting, 3.73 +/- 0.45; stimulated, 3.75 +/- 0.46 ml of O(2).kg(-1).min(-1)). In summary, the EMS devices tested had no effect on oxygen consumption during muscle stimulation.

Alpha-lipoic acid does not acutely affect resistance and conduit artery function or oxidative stress in healthy men.

AIMS: Alpha-lipoic acid (ALA) is a thiol compound with antioxidant properties used in the treatment of diabetic polyneuropathy. ALA may also improve arterial function, but there have been scant human trials examining this notion. This project aimed to investigate the effects of oral and intra-arterial ALA on changes in systemic and regional haemodynamics, respectively. METHODS: In study 1, 16 healthy older men aged 58 +/- 7 years (mean +/- SD) received 600 mg of ALA or placebo, on two occasions 1 week apart, in a randomized cross-over design. Repeated measures of peripheral and central haemodynamics were then obtained for 90 min. Central blood pressure and indices of arterial stiffness [augmentation index (AIx) and estimated aortic pulse wave velocity] were recorded non-invasively using pulse wave analysis. Blood samples obtained pre- and post-treatments were analysed for erythrocyte antioxidant enzyme activity, plasma nitrite and malondialdehyde. In study 2 the effects of incremental cumulative doses (0.5, 1.0, 1.5 and 2.0 mg ml(-1) min(-1)) of intra-arterial ALA on forearm blood flow (FBF) were assessed in eight healthy subjects (aged 31 +/- 5 years) by conventional venous occlusion plethysmography. RESULTS: There were no significant changes on any of the central or peripheral haemodynamic measures after either oral or direct arterial administration of ALA. Plasma ALA was detected after oral supplementation (95% confidence intervals 463, 761 ng ml(-1)), but did not alter cellular or plasma measures of oxidative stress. CONCLUSIONS: Neither oral nor intra-arterial ALA had any effect on regional and systemic haemodynamics or measures of oxidative stress in healthy men.