Match demands of professional Futsal: A case study

Despite its popularity and competitive status there have been only few scientific studies that have examined Futsal in professional players. Consequently the aim of this study was to examine the physiological responses and activity pattern to Futsal simulated game-play in professional players. Eight full-time professional outfield Futsal players volunteered for this study: age 22.4 (95% CI 18.8–25.3) years, body mass 75.4 (60–91) kg, height 1.77 (1.59–1.95) m and VO_2max 64.8 (53.8–75.8) ml kg^?1 min^?1. Physiological measurements were assessed during highly competitive training games (4 × 10-min quarters) and consisted of game VO₂, game blood-lactate concentration ([la]_b) and game heart rates (HRs). Game activities were assessed using a computerised video-analysis system. During simulated game-play players attained 75% (59–92) and 90% (84–96) of VO_2max and HR_max, respectively. Mean game VO₂ was 48.6 (40.1–57.1) ml kg^?1 min^?1. Peak game VO₂ and HRs were 99% (88–109) and 98% [90–106] of laboratory maximal values, respectively. Players spent 46 and 52% of the playing time at exercise intensities higher than 80 and 90% of VO_2max and HR_max, respectively. Mean [la]_b was 5.3 (1.1–10.4) mmol l^?1. Players covered 121 (105–137) m min^?1 and 5% (1–11) and 12% (3.8–19.5) of playing time spent performing sprinting and high-intensity running, respectively. On average players performed a sprint every ～79 s during play. These results show that Futsal played at professional level is a high-intensity exercise heavily taxing the aerobic and anaerobic pathways.     

The upper limit of the cardiorespiratory training zone (40–84%HRR) is overestimated for postmenopausal women

Objective: The purpose of this study was to examine the heart rate reserve (HRR) at first and second ventilatory thresholds (VT's) in postmenopausal women and compare it with optimal intensity range recommended by the ACSM (40–84%HRR). An additional aim was to evaluate whether a higher aerobic power level corresponded to a higher HRR at VT's.Methods: Fifty-eight postmenopausal women participated in this study (aged 48–69). A graded 25 W min^?2 cycle ergometer (Monark E839) exercise protocol was performed in order to assess aerobic power. The heart rate and gas-exchange variables were measured continuously using a portable gas analyzer system (Cosmed K4b). The first (VT₁) and the second (VT₂) VT's were determined by the time course curves of ventilation and O₂ and CO₂ ventilatory equivalents. A K-means clustering analysis was used in order to identify VO_2max groups (cut-off of 30.5 ml kg^?1 min^?1) and differences were evaluated by an independent sample t-test. Bland–Altman plots were performed to illustrate the agreement between methods.Results: The women's HRR values at VT₁ were similar to 40%HRR in both VO_2max groups. At VT₂ both VO_2max groups exhibited negative differences (P < 0.01) for the predicted 84%HRR intensity (?14.46% in the lower VO_2max group and ?16.32% in the higher VO_2max group).Conclusions: An upper limit of 84% overestimates the %HRR value for the second ventilatory threshold, suggesting that the cardiorespiratory target zone for this population should be lower and narrower (40–70%HRR).     

Sodium bicarbonate improves sprint performance in endurance cycling

ObjectivesOral sodium bicarbonate intake (NaHCO₃) may improve performance in short maximal exercise by inducing metabolic alkalosis. However, it remains unknown whether NaHCO₃ also enhances all-out performance at the end of an endurance competition. Therefore, the present study investigated the effect of stacked NaHCO₃ loading on sprint performance following a 3-h simulated cycling race.DesignDouble-blind randomized placebo-controlled cross-over study.MethodsEleven trained male cyclists (22.3 (18.3–25.3) year; 73.0 (61.5–88) kg; VO₂max: 63.7 (57–72) ml kg^?1 min^?1) ingested either 300 mg kg^?1 body weight NaHCO₃ (BIC) or NaCl (PL). NaHCO₃ or NaCl was supplemented prior to (150 mg kg^?1) and during (150 mg kg^?1) a 3-h simulated cycling race with a 90-s all-out sprint (90S) at the end. Capillary blood samples were collected for determination of blood pH, lactate and HCO₃^? concentrations. Analysis of variance (lactate, pH, HCO₃^?) and paired t-test (power) were applied to compare variables across condition (and time).ResultsNaHCO₃ intake improved mean power during 90S by ～3% (541 ± 59 W vs. 524 ± 57 W in PL, p = 0.047, Cohen’s D = 0.28, medium). Peak blood lactate concentration and heart rate at the end of 90S were higher (p < 0.05) in BIC (16.2 ± 4.1 mmol l ¹, 184 ± 7 bpm) than in PL (12.4 ± 4.2 mmol l^?1, 181 ± 5 bpm). NaHCO₃ ingestion increased blood [HCO₃^?] (31.5 ± 1.3 vs. 24.4 ± 1.5 mmol l^?1 in PL, p < 0.001) and blood pH (7.50 ± 0.01 vs. 7.41 ± 0.03 in PL, p < 0.05) prior to 90S.ConclusionsNaHCO₃ supplementation prior and during endurance exercise improves short all-out exercise performance at the end of the event. Therefore, sodium bicarbonate intake can be applied as a strategy to increase success rate in endurance competitions.     

Effect of stage duration on maximal heart rate and post-exercise blood lactate concentration during incremental treadmill tests

ObjectivesThis study compared the responses during maximal incremental treadmill tests of 1-min, 2-min, and 3-min stage durations mainly in terms of maximal heart rate (HR_max) and peak blood lactate concentration (LA_peak).DesignRepeated-measures.MethodsThirty-four male, recreational, endurance-trained runners (40 ± 13 years) performed three tests on a motorized treadmill. The tests started at 8 km h^?1 with increments of 1 km h^?1 every 1 min for the short-stage protocol, every 2 min for the intermediate-stage protocol, and every 3 min for the long-stage protocol. LA_peak was defined for each subject as the highest value among the lactate concentrations determined at the end of each test and at the third, fifth and seventh minutes after test, during passive recovery.ResultsAnalysis of variance revealed a significant effect of the stage duration on the HR_max (p = 0.003) and LA_peak (p = 0.001). The HR_max was higher in the intermediate-stage compared to the short-stage protocol (184.8 ± 12.7 vs. 181.8 ± 12.1 beats min^?1, p < 0.001), but no significant differences were found between the long-stage (183.1 ± 12.1 beats min^?1) and the intermediate-stage or short-stage protocols (p > 0.05). The LA_peak was lower in the long-stage compared to the short-stage and intermediate-stage protocols (7.9 ± 2.2 vs. 9.4 ± 2.2 and 9.2 ± 1.9 mmol L^?1, respectively, p < 0.05). Further, blood lactate reached peak concentration at the fifth minute after test for all the protocols.ConclusionsThus, HR_max and LA_peak depend on the stage duration of the incremental test, but the moment at which blood lactate reaches peak concentration is independent of the duration. Further, we suggest 2-min stage duration protocols to determine HR_max.     

Epo production at altitude in elite endurance athletes is not associated with the sea level hypoxic ventilatory response

The level of circulating erythropoietin (EPO) in response to a fixed level of hypoxia shows substantial inter-individual variability, the source of which is undetermined. Arterial PO₂ at altitude is regulated in part by the hypoxic ventilatory response, which also shows a wide inter-individual variability. We asked if the ventilatory response to hypoxia is related to the magnitude of EPO release at moderate altitude. Twenty-six national class US distance runners (17 M, 9 F) participated in a test of isocapnic hypoxic ventilatory response (HVR) at sea level, 2–7 days prior to departure to altitude. EPO measures were obtained at sea level and after 20 h at 2500 m. HVR for all subjects was 0.21 ± 0.16 L min^?1 %SaO₂^?1 (range 0.01–0.61 L min^?1 %SaO₂^?1), with no significant difference between men and women. EPO was significantly increased from pre-altitude (8.6 ± 2.6 ng ml^?1, range 4.0–14.6 ng ml^?1) to acute altitude (16.6 ± 4.4 ng ml^?1, range 5.0–27.0 ng ml^?1), an increase of 92.2 ± 70.1%. There was no significant sex difference in the EPO increase. ΔEPO for all subjects was not correlated with HVR (r = ?0.17). Similarly, a statistically or physiologically significant correlation was not present between ΔEPO and HVR within the group of men (r = ?0.22) or women (r = ?0.19). The variability in the acute EPO response to moderate altitude is not explained by differences in peripheral chemoresponsiveness in elite distance runners. These results suggest that factors acting downstream from the lung influence the magnitude of the acute EPO response to altitude.     

Heart rate-index estimates aerobic metabolism in professional soccer players

ObjectivesThis study aimed at proposing a new heart rate (HR) method to track aerobic metabolism in soccer by: (i) validating a recently developed HR index (HR_index) in professional soccer players, (ii) comparing HR_index vs the most common HR parameters and (iii) testing the agreement between measured and estimated VO₂ values using HR_index.Designcross-sectional.Methods184 professional soccer players performed a step incremental running test on a treadmill while VO₂ and HR were recorded. HR_index was calculated (actual HR/resting HR) and its relationship with VO₂ was compared with the relationships with the metabolism of actual HR, net HR, and % of HR reserve. Finally, HR_index was used to predict VO₂ = ((HR_index · 6) − 5) · 3.5) and measured and estimated VO₂ were compared by 2W RM-ANOVA and Bland–Altman analysis.ResultsHR_index/VO₂ relationship explained 85% of the variability in data, showing a higher performance than actual HR (77%) and similar values to the other parameters. Measured and estimated VO₂ were not significantly different ≤14 km h⁻¹, whereas at speeds ≥14 km h⁻¹ measured VO₂ was higher than estimated VO₂. Finally, measured and estimated VO₂ were highly correlated (R² = 0.85, p = 0.000), and showed no significant bias (bias = −1.03, z = −0.69, precision = 3.75 ml kg min⁻¹).ConclusionsWe validated the HR_index/VO₂ relationship in professional soccer players. HR_index showed better agreement with metabolism than actual HR and similar agreement to the other HR parameters. HR_index allowed to estimate VO₂, but at very high-intensity HR_index underestimated VO₂. Future studies should test this in real game conditions. HR_index could offer a time-efficient and easy-to-use “field” method to monitor aerobic metabolism in soccer.     

The effect of astaxanthin supplementation on performance and fat oxidation during a 40 km cycling time trial

ObjectivesThis study aimed to investigate whether supplementation with 12 mg?day^?1 astaxanthin for 7 days can improve exercise performance and metabolism during a 40 km cycling time trial.DesignA randomised, double-blind, crossover design was employed.MethodsTwelve recreationally trained male cyclists (VO_2peak: 56.5 ± 5.5  mL?kg^?1?min^?1, W_max: 346.8 ± 38.4  W) were recruited. Prior to each experimental trial, participants were supplemented with either 12 mg?day^?1 astaxanthin or an appearance-matched placebo for 7 days (separated by 14 days of washout). On day 7 of supplementation, participants completed a 40 km cycling time trial on a cycle ergometer, with indices of exercise metabolism measured throughout.ResultsTime to complete the 40 km cycling time trial was improved by 1.2 ± 1.7% following astaxanthin supplementation, from 70.76 ± 3.93 min in the placebo condition to 69.90 ± 3.78 min in the astaxanthin condition (mean improvement = 51 ± 71 s, p = 0.029, g = 0.21). Whole-body fat oxidation rates were also greater (+0.09 ± 0.13 g?min^?1, p = 0.044, g = 0.52), and the respiratory exchange ratio lower (?0.03 ± 0.04, p = 0.024, g = 0.60) between 39–40 km in the astaxanthin condition.ConclusionsSupplementation with 12 mg?day^?1 astaxanthin for 7 days provided an ergogenic benefit to 40 km cycling time trial performance in recreationally trained male cyclists and enhanced whole-body fat oxidation rates in the final stages of this endurance-type performance event.     

Coinciding exercise with peak serum caffeine does not improve cycling performance

ObjectivesTo investigate whether coinciding peak serum caffeine concentration with the onset of exercise enhances subsequent endurance performance.DesignRandomised, double-blind, crossover.MethodsIn this randomised, placebo-controlled, double-blind crossover study, 14 male trained cyclists and triathletes (age 31 ± 5 year, body mass 75.4 ± 5.7 kg, VO₂max 69.5 ± 6.1 mL kg^?1 min^?1 and peak power output 417 ± 35 W, mean ± SD) consumed 6 mg kg^?1 caffeine or a placebo either 1 h (C_1 h) prior to completing a 40 km time trial or when the start of exercise coincided with individual peak serum caffeine concentrations (C_peak). C_peak was determined from a separate ‘caffeine profiling’ session that involved monitoring caffeine concentrations in the blood every 30 min over a 4 h period.ResultsFollowing caffeine ingestion, peak serum caffeine occurred 120 min in 12 participants and 150 min in 2 participants. Time to complete the 40 km time trial was significantly faster (2.0%; p = 0.002) in C_1 h compared to placebo. No statistically significant improvement in performance was noted in the C_peak trial versus placebo (1.1%; p = 0.240). Whilst no differences in metabolic markers were found between C_peak and placebo conditions, plasma concentrations of glucose (p = 0.005), norepinephrine and epinephrine (p ≤ 0.002) were higher in the C_1 h trial 6 min post-exercise versus placebo.ConclusionsIn contrast to coinciding peak serum caffeine concentration with exercise onset, caffeine consumed 60 min prior to exercise resulted in significant improvements in 40 km time trial performance. The ergogenic effect of caffeine was not found to be related to peak caffeine concentration in the blood at the onset of endurance exercise.     

Post marathon cardiac troponin T is associated with relative exercise intensity

Objectives

This study aimed to investigate whether measures of cardiopulmonary fitness and relative exercise intensity were associated with high sensitivity cardiac troponin T (cTnT) rise after a road marathon.

The energy cost for the step-to-step transition in amputee walking

The purpose of this study was to investigate whether the increased energy cost of amputee gait could be accounted for by an increase in the mechanical work dissipated during the step-to-step transition in walking. Eleven transtibial amputees (AMP) and 11 age-matched controls (CO) walked at both comfortable (CWS) and fixed (FWS, 1.3 m/s) walking speed, while external mechanical work of each separate leg and metabolic energy consumption were measured. At FWS the metabolic energy consumption (?_met) was significantly higher in AMP compared to CO (3.34 J kg^?1 s^?1 vs. 2.73 J kg^?1 s^?1). At CWS, no difference in energy consumption was found (3.56 J kg^?1 s^?1 vs. 3.58 J kg^?1 s^?1) but CWS was significantly lower in AMP compared to CO (1.35 m s^?1 vs. 1.52 m s^?1). In conjunction with the higher ?_met at FWS, the negative work generated by the intact leading leg for the step-to-step transition in double support was significantly higher for AMP than CO at FWS. A moderate though significant correlation was found between negative mechanical power generated during the step-to-step transition and metabolic power (CWS: r = ?0.56, p = 0.007; FWS: r = ?0.50, p = 0.019). Despite the difference in negative work during the step-to-step transition, the total absolute mechanical work over a stride did not differ between groups. This could possibly be attributed to exchange of internal positive and negative work during single support, which remains unnoticed in the external work calculations. It was concluded that the increased mechanical work for the step-to-step transition from prosthetic to intact limb contributes to the increased metabolic energy cost of amputee walking.     

Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat

ObjectivesThis study investigated the effect of 7 days’ supplementation with New Zealand blackcurrant extract on thermoregulation and substrate metabolism during running in the heat.DesignRandomized, double-blind, cross-over study.MethodsTwelve men and six women (mean ± SD: Age 27 ± 6 years, height 1.76 ± 0.10 m, mass 74 ± 12 kg, V̇O_2max 53.4 ± 7.0 mL kg⁻¹ min⁻¹) completed one assessment of maximal aerobic capacity and one familiarisation trial (18 °C, 40% relative humidity, RH), before ingesting 2 × 300 mg day⁻¹ capsules of CurraNZ™ (each containing 105 mg anthocyanin) or a visually matched placebo (2 × 300 mg microcrystalline cellulose M102) for 7 days (washout 14 days). On day 7 of each supplementation period, participants completed 60 min of fasted running at 65% V̇O_2max in hot ambient conditions (34 °C and 40% relative humidity).ResultsCarbohydrate oxidation was decreased in the NZBC trial [by 0.24 g min⁻¹ (95% CI: 0.21–0.27 g min^-1)] compared to placebo (p =  0.014, d = 0.46), and fat oxidation was increased in the NZBC trial [by 0.12 g min⁻¹ (95% CI: 0.10 to 0.15 g min⁻¹)], compared to placebo (p = 0.008, d = 0.57). NZBC did not influence heart rate (p = 0.963), rectal temperature (p = 0.380), skin temperature (p = 0.955), body temperature (p = 0.214) or physiological strain index (p = 0.705) during exercise.ConclusionsSeven-days intake of 600 mg NZBC extract increased fat oxidation without influencing cardiorespiratory or thermoregulatory variables during prolonged moderate intensity running in hot conditions.     

DHA-rich fish oil lowers heart rate during submaximal exercise in elite Australian Rules footballers

Omega-3 fatty acids (n-3) can improve cardiovascular (CV) function. This study examined the effects of n-3 on endurance performance, recovery and CV risk factors in elite Australian Rules football players. 25 players were randomised, double-blind, to 6 g/day of docosahexaenoic acid (DHA)-rich fish oil (FO; n = 12) or sunflower oil (SO; n = 13) during 5 weeks of training. At baseline erythrocyte n-3 content, resting blood pressure (BP), fasting serum triglycerides (TG) and heart rate (HR) during treadmill running at 10 km/h were assessed. Two treadmill runs (T1 and T2) to exhaustion, separated by 5 min, were then performed at the average speed for a recent 2200 m time-trial. After 5 weeks, erythrocyte n-3 increased (FO 3.8 ± 0.6%, SO 0.6 ± 0.3%; P < 0.001) while TG (FO ?0.32 ± 0.09 mmol l^?1, SO 0.08 ± 0.05 mmol l^?1; P < 0.001), diastolic BP (FO 1.3 ± 1.3 mmHg, SO 6.8 ± 1.7 mmHg; P = 0.04) and HR during submaximal exercise (FO ?7.8 ± 2.3 beats min^?1, SO ?1.9 ± 1.9 beats min^?1; P = 0.03) decreased in FO compared with SO. Time to exhaustion (TTE) during T1 increased by Week 5 (FO 10.2 ± 2.2%, SO 17.3 ± 4.3%; P < 0.001 for time). Recovery (TTE for T2 as % T1) decreased in both groups (FO, ?3.4 ± 4.5%, SO ?8.8 ± 3.9%; P = 0.05 for time). We conclude that 5 weeks of supplementation with FO improved CV function and reduced CV risk factors, but did not improve endurance performance or recovery in elite Australian Rules footballers.     

Investigating the reproducibility of maximal oxygen uptake responses to high-intensity interval training

ObjectivesTo test the hypothesis that observed maximal oxygen uptake (VO₂max) and time to fatigue (TTF) responses to two identical periods of standardized high-intensity interval training are reproducible.DesignFourteen recreationally active and healthy young males completed two identical four-week periods of high-intensity interval training (4 × 4-min intervals at 90–95% maximum heart rate [HR_max] separated by 3-min periods of active recovery at 70–75% HR_max). Training periods were separated by a three-month washout period.MethodsVO₂max and TTF were assessed via incremental tests with supramaximal verification before and after each training period. Pearson correlation coefficients (r), intraclass correlation coefficients (ICC), and within-subjects coefficients of variation (CV) were used to assess reproducibility of observed VO₂max and TTF responses.ResultsVO₂max and TTF values before the second training period were not significantly higher than baseline values and there were no significant (p > 0.05) interaction effects (period 1: VO₂max: +4.04 ± 2.29 mL/kg/min, TTF: +70.75 ± 35.87 s; period 2: VO₂max: +2.83 ± 2.74 mL/kg/min, TTF: +83.46 ± 34.55 s). We found very weak-to-moderate correlations and poor reproducibility for observed VO₂max (mL/kg/min: r = 0.40, ICC = 0.369, CV = 74.4) and TTF (r = 0.11. ICC = 0.048, CV = 45.6) responses to training periods 1 and 2.ConclusionsOur ANOVA results confirmed that the three-month washout period returned VO₂max and TTF levels to baseline and prevented carryover effects. Contrary to our hypothesis, our results suggest that individual observed VO₂max and TTF responses to identical training stimuli are not reproducible.     

Association with physical fitness,serum hormones and sleep during a 15-day military field training

The present study aimed to investigate the association between physical fitness, sleep duration and hormonal responses during a 15-day military field training (MFT). The purpose of MFT was to practice offensive manoeuvres in a countryside area. Nine army officers volunteered to participate, and their daily working routine mainly consisted of tasks in the headquarters that required on-call-duty at all times. Physical fitness and body composition were measured just before MFT. Serum testosterone (TES) and cortisol (COR) concentrations and sex-hormone-binding globulin (SHBG) were measured before MFT, as well as 8 and 15 days after the beginning of MFT. Heart rate (HR) was recorded for approximately 24 h on days 8, 11 and 15 of MFT. Based on HR responses, there was no evidence of cardiorespiratory strain, hormonal responses or energy deficit during MFT. Although the changes in hormonal concentrations were insignificant, they were well correlated with physical fitness (r = 0.67, p = 0.05). Furthermore, the TES/SHGB ratio decreased by 28% in subjects whose VO₂max was under 44 ml kg^?1 min^?1. On average, subjects slept for 6.20 h per day, but the sleeping rhythm was disturbed due to military tasks. This diurnal sleeping time was strongly associated with TES/COR ratio (r = 0.78, p = 0.01). These results indicate that MFT causes very individual stress reactions, despite the low levels of physical strain and energy deficit. We therefore concluded that the observed hormonal responses were mainly due to sleep deprivation and low physical fitness.     

Relationship between rowing ergometer performance and physiological responses to upper and lower body exercises in rowers

The aim of this investigation was to compare the physiological responses of 2000 m rowing ergometer test with 7-min bench pull and leg press tests. We hypothesised that leg press exercise contributes to 2000 m rowing ergometer test results, rather than bench pull performed by arms. College level rowers (n = 12) performed 2000 m rowing test and after one day 7-min bench pull and leg press (50% from the 1 RM). Stroke rate, heart rate (HR), blood lactate (LA) and ratings of perceived exertion (RPE) were measured during all tests. The number of repetitions was highest during 2000 m rowing test (194.2 ± 19.5) and lowest during bench pull (122.6 ± 17.7) (during leg press 173.5 ± 11.8). Differences between 2000 m rowing test, leg press and bench pull tests were significant in mean and maximal HR. In LA concentration, the highest values were at 3rd min of recovery after rowing test (14.8 ± 1.7 mmol l^?1). Between bench pull (8.8 ± 1.9 and 8.5 ± 2.7 mmol l^?1) and leg press (11.8 ± 2.5 and 11.2 ± 2.3 mmol l^?1) tests, the difference in LA concentration was not significant (p > 0.05). Ratings of perceived exertion were highest in 2000 m rowing test (19.3 ± 0.9), difference with leg press and bench pull tests was not significant. There were significant relationships in mean and maximal HR (r = 0.713–0.767) and Borg scale (r = 0.764) during rowing test and leg press. The number of repetitions during leg press exercise correlated significantly with rowing test time (r = ?0.677). In conclusion, this study suggests that in rowers there are major differences in the physiological adaptation to upper body and leg exercise, performed at similar intensities. Leg press exercise could be used to measure sport-specific strength endurance in rowers.     

Aluminium salt-based antiperspirant coated prosthesis liners do not suppress local sweating during moderate intensity exercise in hot and temperate conditions

ObjectiveTo determine whether coating prosthesis liners with a 5% aluminium zirconium tetrachlorohydrate antiperspirant solution (AZCH) reduces local sweating on the thigh.DesignDouble-blinded counter-balanced crossover designMethodsFourteen able-bodied participants (age: 28 ± 5 y; body mass: 73.9 ± 7.9 kg, height: 1.73 ± 0.09 m; peak oxygen consumption [VO_2peak]: 50.7 ± 9.1 mlO₂⋅ kg⁻¹⋅ min⁻¹) simultaneously wore a prosthesis liner on each leg, one treated with AZCH and one untreated, for four days prior to running at 50% of VO_2peak for 60 min in a temperate (23.7 ± 0.7 °C and 42.2 ± 2.6% relative humidity) or hot (34.0 ± 1.6 °C and 40.8 ± 6.1% relative humidity) environment. Rectal temperature (T_re) and whole-body sweat rates (WBSR) were measured to characterize thermal strain. Local sweat rate (LSR) was measured bilaterally underneath the liners, continuously, and heat-activated-sweat gland density (HASGD) was measured bilaterally every 15 min.ResultsIn temperate condition, the mean change in T_re was 1.2±0.4 °C and WBSR was 723 ± 129 g⋅ h⁻¹, whereas in the hot condition, change in T_re was 1.2±0.5 °C and WBSR was 911 ± 231 g⋅ h⁻¹. In the temperate condition, AZCH treatment did not alter LSR (treated: 0.50±0.17 mg·cm^–2 min^–1, untreated: 0.50±0.17 mg·cm^–2 min^–1; P = 0.87) or HASGD (treated: 54±14 glands·cm^–2, untreated 55±14 glands·cm^–2; P = 0.38). In the hot condition, AZCH treatment paradoxically increased LSR (treated: 0.88 ± 0.38 mg·cm^–2 min^–1, untreated: 0.74 ± 0.28 mg·cm^–2 min^–1; P = 0.04) but not HASGD (treated: 52 ± 17 glands·cm^–2, untreated: 48 ± 19 glands·cm^–2; P = 0.77).ConclusionThese results indicate coating prosthesis liners with 5% AZCH is ineffective at reducing local sweating.     

Dose characterization of the rad sourceTM 2400 X-ray irradiator for oyster pasteurization

The RS 2400's cylindrical X-ray source yields dose rates high enough to allow the irradiator to replace widely used gamma irradiators. Except for the leftmost 5 cm, beam uniformity is within 10% at the tube surface. At maximum operating parameters, the beam has HVL₁=13.66 mm aluminum, HC=0.47, and hν_eq=88.5 keV. Maximum dose rates to tissue are 65 Gy min⁻¹±3.1% at tube surface, 37 Gy min⁻¹±3.1% at center of canisters, 14.1 Gy min⁻¹±6.5% for thin-shelled oysters, and 12.3 Gy min⁻¹±6.2% for thick-shelled oysters.     

Test‐retest variability of VO2max using total‐capture indirect calorimetry reveals linear relationship of VO2 and Power

This study aimed to analyze the intra‐individual variation in VO_2max of human subjects using total‐capture and free‐flow indirect calorimetry. Twenty‐seven men (27 ± 5 year; VO_2max 49‐79 mL?kg^?1?min^?1) performed two maximal exertion tests (CPETs) on a cycle ergometer, separated by a 7 ± 2 day interval. VO₂ and VCO₂ were assessed using an indirect calorimeter (Omnical) with total capture of exhalation in a free‐flow airstream. Thirteen subjects performed a third maximal exertion test using a breath‐by‐breath calorimeter (Oxycon Pro). On‐site validation was deemed a requirement. For the Omnical, the mean within‐subject CV for VO_2max was 1.2 ± 0.9% (0.0%‐4.4%) and for ergometer workload P _max 1.3 ± 1.3% (0%‐4.6%). VO_2max values with the Oxycon Pro were significantly lower in comparison with Omnical (P < 0.001; t test) with mean 3570 vs 4061 and difference SD 361 mL?min^?1. Validation results for the Omnical with methanol combustion were ?0.05 ± 0.70% (mean ± SD; n = 31) at the 225 mL?min^?1 VO₂ level and ?0.23 ± 0.80% (n = 31) at the 150 mL?min^?1 VCO₂ level. Results using gas infusion were 0.04 ± 0.75% (n = 34) and ?0.99 ± 1.05% (n = 24) over the respective 500‐6000 mL?min^?1 VO₂ and VCO₂ ranges. Validation results for the Oxycon Pro in breath‐by‐breath mode were ‐ 2.2 ± 1.6% (n = 12) for VO₂ and 5.7 ± 3.3% (n = 12) for VCO₂ over the 1000‐4000 mL?min^?1 range. On a Visual analog scale, participants reported improved breathing using the free‐flow indirect calorimetry (score 7.6 ± 1.2 vs 5.1 ± 2.7, P = 0.008). We conclude that total capturing free‐flow indirect calorimetry is suitable for measuring VO₂ even with the highest range. VO_2max was linear with the incline in P _max over the full range.     

Heart rate and blood lactate responses during Taekwondo training and competition

ObjectiveThe study investigated physical fitness characteristics of elite Taekwondo (TKD) players as well as their heart rate (HR) response and blood lactate concentration changes during TKD specific exercises and simulated competition.MethodsAnaerobic and aerobic power has been evaluated in eight elite TKD players (age: 20 ± 1 years, body mass: 70.8 ± 6 kg, Ht: 179.9 ± 4 cm). We also measured heart rate and blood lactate concentration during competition and specific-exercises (front kicks during 10 s, 1 and 3 min).ResultsMaximum oxygen uptake (VO₂max) and peak anaerobic power (Wpeak) averaged 56.22 ± 2.57 ml min^–1 kg^–1 and 12.1 ± 1.7 W kg^–1, respectively. HR and blood lactate [La] concentrations increased significantly during competition (F = 19.4, P < 0.001; F = 21.3, P < 0.001) compared to the resting value. HR and [La] values were significantly correlated with those measured during 10 s (R = 0.85, P < 0.05 and R = 0.79, P < 0.05, respectively) and 3-min specific exercises (R = 0.95, P < 0.01 and R = 0.76, P < 0.05).ConclusionsTKD requires high levels of both aerobic and anaerobic physical fitness. The correlation between specific exercises and competition is of practical interest for TKD players and trainers.     

Effect of the glycaemic index of a pre-exercise meal on metabolism and cycling time trial performance

This study investigated the effects of low or high glycaemic index (GI) foods consumed prior to a 40 km time trial (TT) on metabolism and subsequent endurance performance. Ten male cyclists consumed high GI or low GI meals, providing 1 g kg^?1 body mass of carbohydrate, 45 min prior to the TT. The TT performance was significantly (p = 0.009) improved in the low (93 ± 8 min) compared to the high GI trial (96 ± 7 min). Low GI carbohydrate oxidation rate (2.51 ± 1.71 g min^?1) was higher (p = 0.003) than the HGI carbohydrate oxidation rate (2.14 ± 1.5 g min^?1). Fat oxidation rate was significantly higher (p = 0.002) for the high (0.27 ± 0.17 g min^?1) than the low GI trial (0.16 ± 0.14 g min^?1). Insulin rose significantly following the high compared to the low GI meal (p = 0.008) but dropped significantly to similar values throughout the TT. No significant differences in either TGA or FFA concentration were observed between the trials. The low GI meal led to an increase in the availability of carbohydrate and a greater carbohydrate oxidation throughout the exercise period, which may have sustained energy production towards the end of exercise and led to the improved TT performance observed.