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Purpose: The first aim of this experiment was to evaluate the appropriateness of linear and non-linear (allometric) models to scale peak aerobic power (oxygen consumption) against body mass. The possibilities that oxygen consumption would scale allometrically across the complete metabolic range, and that the scaling exponents would differ significantly between basal and maximal-exercise states, were then evaluated. It was further hypothesised that the scaling exponent would increase in a stepwise manner with elevations in exercise intensity. Finally, the utility of applying the scaling exponent derived for peak aerobic power to another population sample was evaluated., Methods: Basal, steady-state walking and peak (treadmill) oxygen-consumption data were measured using 60 relatively homogeneous men (18-40 year; 56.0-117.1 kg), recruited across five mass classes. Linear and allometric regressions were applied, with the utility of each scaling method evaluated., Results: Oxygen consumption scaled allometrically with body mass across the complete metabolic range, and was always superior to both ratiometric analysis and linear regression. The scaling exponent increased significantly from rest (mass 0.57 ) to maximal exercise (mass 0.75 ; P < 0.05), but not between steady-state walking (mass 0.87 ) and maximal exercise (P > 0.05). When used with an historical database, the maximal-exercise exponent successfully removed the mass bias., Conclusion: It has been demonstrated that the oxygen consumption of healthy humans scales allometrically with body mass across the entire metabolic range. Moreover, only two scaling exponents (rest and exercise) were required to produce mass-independent outcomes from those data. Accordingly, ratiometric and linear regression analyses are not recommended as scaling methods., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This investigation determined the influence of technique and experience on arm retraction force required to apprehend a non-compliant suspect. Phase-One: Nine experienced RAAF military-police completed four apprehension simulations, peak arm retraction force was measured; i) Control( CON ), ii) Pressure-Point( PP ), iii) Targeted-Striking( TS ) and iv) 2-Person( 2Per ) techniques. Phase-Two: Experienced ( EXP , n  = 8 ) or Inexperienced ( INEXP , n  = 22) military-police completed CON , PP and Pressure-Point + Coaching( PP + C ). Strength was assessed in INEXP . EXP produced more force (178.7 N ± 25.9) than INEXP during CON , but no participant successfully apprehended the suspect. All EXP were successful with PP , arm retraction force 357 N (CI: 233.7,480.2) was lower compared to CON, but no difference was observed between PP and CON for INEXP . PP + C , 82% of INEXP were successful, force declined 138.2 N (CI: 67.8,208.5) compared to CON . All EXP required PP for successful apprehension. INEXP required PP + C for apprehension success. Muscular strength had a limited relationship with arm retraction force. Practitioner summary: For law enforcement personnel, apprehension of a suspect is a critical and physically demanding task, where success is associated with muscular strength and technique. We observed success in the apprehension of a simulated suspect by military law enforcement personnel was primarily determined by participant skill and experience and not muscular strength.

Purpose: In tachymetabolic species, metabolic rate increases disproportionately with body mass, and that inter-specific relationship is typically modelled allometrically. However, intra-specific analyses are less common, particularly for healthy humans, so the possibility that human metabolism would also scale allometrically was investigated., Methods: Basal metabolic rate was determined (respirometry) for 68 males (18-40 years; 56.0-117.1 kg), recruited across five body-mass classes. Data were collected during supine, normothermic rest from well-rested, well-hydrated and post-absorptive participants. Linear and allometric regressions were applied, and three scaling methods were assessed. Data from an historical database were also analysed (2.7-108.9 kg, 4811 males; 2.0-96.4 kg, 2364 females)., Results: Both linear and allometric functions satisfied the statistical requirements, but not the biological pre-requisite of an origin intercept. Mass-independent basal metabolic data beyond the experimental mass range were not achieved using linear regression, which yielded biologically impossible predictions as body mass approached zero. Conversely, allometric regression provided a biologically valid, powerful and statistically significant model: metabolic rate = 0.739 * body mass 0.547 (P < 0.05). Allometric analysis of the historical male data yielded an equivalent, and similarly powerful model: metabolic rate = 0.873 * body mass 0.497 (P < 0.05)., Conclusion: It was established that basal and resting metabolic rates scale allometrically with body mass in humans from 10-117 kg, with an exponent of 0.50-0.55. It was also demonstrated that ratiometric scaling yielded invalid metabolic predictions, even within the relatively narrow experimental mass range. Those outcomes have significant physiological implications, with applications to exercising states, modelling, nutrition and metabolism-dependent pharmacological prescriptions.

A cardiovascular requirement to facilitate thermal homeostasis may partly contribute to the elevated heart rate during eccentric cycling. This study compared the body temperature response to a bout of eccentric (ECC) and concentric (CON) cycling to account for the difference in heart rate. Eight ( N = 8) aerobically trained males (age 35 y [SD 8], peak oxygen consumption 3.82 L.min -1 [SD 0.79]) completed an ECC cycling trial (60% PPO) followed by an oxygen consumption/duration matched CON trial (30   ∘ C , 35% RH) on a separate day. Trial termination was determined as an elevation in aural temperature, a surrogate of deep body temperature, by +0.5   ∘ C during ECC. Mean skin (8-sites) and body temperature (weighting of 80:20 for auditory canal and mean skin temperature) were calculated. Matching the oxygen consumption between the trials increased external work during ECC cycling (CON: 71 [SD 14] ECC: 194 [SD 38] W, p < 0.05) and elevated aural temperature (+0.5   ∘ C ) by 20 min 32 s [SD 9 min 19 s] in that trial. The peak rate of rise in aural temperature was significantly greater in ECC (CON: 0.012 [SD 0.007] ECC: 0.031 [SD 0.002] o C.s -1 , p < 0.05). Aural, mean skin and body temperature were significantly higher during the ECC trial (p < 0.05) and this was accompanied by elevated mean heart rate (CON: 103 [SD 14] ECC: 118 [SD 12] b.min -1 , p < 0.05) and thermal discomfort (p < 0.05). Moderate load eccentric cycling imposes an elevated thermal strain when compared to concentric cycling. This requirement for dissipating heat, in part, explains the elevated heart rate during eccentric cycling., Competing Interests: There are no personal, professional, or financial conflicts of interest for any of the authors of this submitted work., (© 2020 Informa UK Limited, trading as Taylor & Francis Group.)

Eccentric and concentric exercise is associated with disparate acute and chronic responses. We uniquely interspersed workload equivalent eccentric cycling during each recovery period of a high intensity interval training (HIIT) cycling trial to determine acute cardiopulmonary, thermal and psycho-physiological responses. Twelve males [age 28 years (SD 6), peak oxygen consumption 48 mL ⋅ kg -1 ⋅ min -1 (SD 6)] completed two high intensity interval cycling trials [4 × 5 min, 60% peak power output (PPO)] separated by 7-10 days. The CON R trial required participants to cycle concentrically during each recovery period (5 min, 30% PPO). The ECC R trial modified the recovery to be eccentric cycling (5 min, 60% PPO). High intensity workload ( CON R : 187 ± 17; ECC R : 187 ± 21 W), oxygen consumption ( CON R : 2.55 ± 0.17; ECC R : 2.68 ± 0.20 L ⋅ min -1 ), heart rate ( CON R : 165 ± 7; ECC R : 171 ± 10 beats ⋅ min -1 ) and RPE legs ( CON R : 15 ± 3; ECC R : 15 ± 3) were equivalent between trials. Eccentric cycling recovery significantly increased external workload ( CON R : 93 ± 18; ECC R : 196 ± 24 W, P < 0.01) yet lowered oxygen consumption ( CON R : 1.51 ± 0.18; ECC R : 1.20 ± 0.20 L ⋅ min -1 , P < 0.05) while heart rate ( CON R : 132 ± 13; ECC R : 137 ± 12 beats ⋅ min -1 ) and RPE of the legs ( CON R : 11 ± 7; ECC R : 12 ± 7) remained equivalent. There was no significant difference in the aural temperature between the trials ( ECC R : 37.3 ± 0.1°C; CON R : 37.4 ± 0.1°C, P > 0.05), yet during recovery periods mean skin temperature was significantly elevated in the ECC R ( ECC R : 33.9 ± 0.2°C; CON R : 33.3 ± 0.2°C, P < 0.05). Participants preferred ECC R (10/12) and rated the ECC R as more achievable (82.8 ± 11.4 mm) than CON R (79.4 ± 15.9 mm, P < 0.01). In conclusion, eccentric cycling during the recovery period of a HIIT training session, offers a novel approach to concurrent training methodology. The unique cardiopulmonary and skeletal muscle responses facilitate the achievement of both training stimuli within a single exercise bout., (Copyright © 2020 Harrison, Burdon, Groeller and Peoples.)

Objective: The aim of this study was to determine an appropriate method to characterize Royal Australian Navy intermittent intensity tasks., Method: Sixteen personnel performed four scenarios: (1) storing: repeatedly handle a 10 to 15 kg crate; (2) firefighting: walk 45 m wearing protective equipment and fighting a fire; (3) and (4) toxic hazard response: casualty evacuation tasks wearing protective equipment. Heart rate and oxygen consumption ((Equation is included in full-text article.)) were measured continuously. Mean and peak values and time spent in incremental zones were calculated., Results: Scenario 2 elicited the highest oxygen cost (18.1 L, mean (Equation is included in full-text article.)1.5 L.min, time >2.5 L.min: 0.8%), yet scenario 4 elicited the highest mean (Equation is included in full-text article.)(1.8 L.min, oxygen cost 14.4 L), and participants spent a greater duration >2.5 L.min(Equation is included in full-text article.)(23.3% or 1 minute 55 seconds)., Conclusions: A small difference (0.3 L.min) was observed between scenarios 2 and 4 for mean (Equation is included in full-text article.), yet (Equation is included in full-text article.)>2.5 L.min demonstrated scenario 4 had a higher metabolic demand.

Herein we describe two experiments in which the recruitment and pressure-induced modifications of human eccrine sweating were investigated. In one experiment, the longstanding belief that glandular recruitment follows a gradual, caudal-to-rostral (dermatomal) recruitment pattern was re-evaluated. The onset of sweating was simultaneously determined (ventilated capsules) from four spinal (dermatomal) segments (forehead, dorsal hand, lower chest and dorsal foot) during the passive heating of supine participants (N = 8). No evidence was found to support either dermatomal or simultaneous glandular recruitment patterns. Instead, the results were more consistent with individualised (random) patterns of regional activation (P > 0.05), with significant time delays among sites. Such delays in the appearance of discharged sweat may reflect differences in neurotransmitter sensitivity, precursor sweat production or ductal reabsorption. In the second experiment, the pressure-induced hemihidrotic reflex (contralateral sudomotor enhancement) was revisited, using pressures applied over 10 cm 2 areas of the chest (left side: 6 N cm -2 ) and left heel (3 N cm -2 ) during both supine and seated postures (N = 12). Participants were passively heated and thermally clamped before pressure application. Hemihidrosis was not observed from the contralateral surfaces within the same (chest) or lower spinal segments (abdomen; both P > 0.05) during chest pressure, but a generalised enhancement followed heel pressure when supine. We suggest that previous observations of hemihidrosis possibly resulted from elevated heat storage, rather than a neural reflex. Chest pressure significantly inhibited ipsilateral sweating (forehead, hand, chest; all P < 0.05), and that influence is hypothesised to result from interactions between ascending mechanoreceptor afferents and the descending sudomotor pathways., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this experiment, psychogenic (mental arithmetic), thermogenic (mean body temperature elevation of 0.6 °C) and combined thermo-psychogenic treatments were used to explore eccrine sweat-gland recruitment from glabrous (volar hand and forehead) and non-glabrous skin surfaces (chest). It was hypothesised that each treatment would activate the same glands, and that glandular activity would be intermittent. Nine individuals participated in a single trial with normothermic and mildly hyperthermic phases. When normothermic, a 10-min arithmetical challenge was administered, during which sudomotor activity was recorded. Following passive heating and thermal clamping, sweating responses were again evaluated (10 min). A second arithmetical challenge (10 min) was administered during clamped hyperthermia, with its sudorific impact recorded. The activity of individual sweat glands was recorded at 60-s intervals, using precisely positioned, and uniformly applied, starch-iodide papers. Those imprints were digitised and analysed. Peak activity typically occurred during the thermo-psychogenic treatment, revealing physiologically active densities of 128 (volar hand), 165 (forehead) and 77 glands.cm -2 (chest). Except for the hand (46%), glands uniquely activated by one treatment were consistently <10% of the total glands identified. Glandular activations were most commonly of an intermittent nature, particularly during the thermogenic treatment. Accordingly, we accepted the hypothesis that psychogenic, thermogenic and thermo-psychogenic stimuli activate the same sweat glands in both the glabrous and non-glabrous regions. In addition, this investigation has provided detailed descriptions of the intermittent nature of sweat-gland activity, revealing that a consistent proportion of the physiologically active glands are recruited during these thermal and non-thermal stimuli., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

There is now strong evidence that radiofrequency electromagnetic field (RF-EMF) exposure influences the human electroencephalogram (EEG). While effects on the alpha band of the resting EEG have been repeatedly shown, the mechanisms underlying that effect have not been established. The current study used well-controlled methods to assess the RF-EMF exposure effect on the EEG and determine whether that effect might be thermally mediated. Thirty-six healthy adults participated in a randomized, double-blind, counterbalanced provocation study. A water-perfusion suit (34 C) was worn throughout the study to negate environmental influences and stabilize skin temperature. Participants attended the laboratory on four occasions, the first being a calibration session and the three subsequent ones being exposure sessions. During each exposure session, EEG and skin temperature (8 sites) were recorded continuously during a baseline phase, and then during a 30 min exposure to a 920 MHz GSM-like signal (Sham, Low RF-EMF (1 W/kg) and High RF-EMF (2 W/kg)). Consistent with previous research, alpha EEG activity increased during the High exposure condition compared to the Sham condition. As a measure of thermoregulatory activation, finger temperature was found to be higher during both exposure conditions compared to the Sham condition, indicating for the first time that the effect on the EEG is accompanied by thermoregulatory changes and suggesting that the effect of RF-EMF on the EEG is consistent with a thermal mechanism., Competing Interests: The authors declare no conflict of interest.

Background: Given the physical demands of mining and rescue operations, a physical employment standard was warranted to ensure capable workers are selected. While evaluations of muscular strength and muscular and cardiorespiratory endurance domains are common, assessment of a worker's ability to meet the physically demanding postural requirements is often neglected., Objective: The aim of this investigation was to develop a valid assessment for NSW Mines Rescue Brigadesmen that replicated the combined muscular and cardiorespiratory endurance and postural demands of constructing a timber pillar., Methods: Oxygen consumption () V̇O2) was measured and dominant postures identified when incumbent Brigadesmen constructed a timber pillar. A shelf-stacking assessment was designed and validated., Results: When Brigadesmen performed the block placement role, the task elicited a mean V̇O2 of 1.6 L.min-1, and required repeated placement of ∼8.7 kg blocks from 0 to 3.0 m. A shelf stacking assessment (5 min, mean V̇O2 1.7 L.min-1) replicating dominant postures and requiring repeated block placement at 0, 0.65, 1.10, 1.64 and 2.20 m was developed. The demand of the test, performed within a discontinuous circuit, was subsequently verified (1.6 L.min-1)., Conclusions: A valid, physiological aptitude test that considered the job-related movement patterns, in addition to cardiorespiratory and muscular endurance requirements, was developed for Brigadesmen.

Objective: To use improved methods to address the question of whether acute exposure to radio-frequency (RF) electromagnetic fields (RF-EMF) affects early (80-200 ms) sensory and later (180-600 ms) cognitive processes as indexed by event-related potentials (ERPs)., Methods: Thirty-six healthy subjects completed a visual discrimination task during concurrent exposure to a Global System for Mobile Communications (GSM)-like, 920 MHz signal with peak-spatial specific absorption rate for 10 g of tissue of 0 W/kg of body mass (Sham), 1 W/kg (Low RF) and 2 W/kg (High RF). A fully randomised, counterbalanced, double-blind design was used., Results: P1 amplitude was reduced (p = .02) and anterior N1 latency was increased (p = .04) during Exposure compared to Sham. There were no effects on any other ERP latencies or amplitudes., Conclusions: RF-EMF exposure may affect early perceptual (P1) and preparatory motor (anterior N1) processes. However, only two ERP indices, out of 56 comparisons, were observed to differ between RF-EMF exposure and Sham, suggesting that these observations may be due to chance., Significance: These observations are consistent with previous findings that RF-EMF exposure has no reliable impact on cognition (e.g., accuracy and response speed)., (Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Burdon, CA, Park, J, Tagami, K, Groeller, H, and Sampson, JA. Effect of practice on performance and pacing strategies during an exercise circuit involving load carriage. J Strength Cond Res 32(3): 700-707, 2018-Pacing is critical for athletic endeavors, and the strategies used by athletes are often modified after practice. The importance of practice when completing occupational assessments has been established; however, the effect of load carriage and discrete subtask activities on strategies to modulate physical exertion to complete a work task simulation is currently unknown. Therefore, we sought to investigate the effect of practice on pacing strategies used to complete a physiological aptitude assessment circuit. Twenty-five participants completed an assessment designed for firefighters on 3 occasions. The circuit comprised 6 disparate tasks (including unilateral load carriage, static holds and fire-hose drags) with lap and task completion times recorded. Pacing strategies were examined relative to the effect of practice throughout (globally) and within the assessment (discrete tasks). By the second visit, overall test performance and discrete task performance of the first, fourth, and fifth tasks improved, respectively, by 12.6% (95% confidence interval: ±3.6%, p < 0.01), 12.4% (±6.0%, p < 0.01), 11.7% (±4.9%, p < 0.01), and 17.8% (±10.0%, p < 0.03). Compared with visit 1, significant improvements in performance were observed on the second and third visit. However, no significant additional improvement was noted between visits 2 and 3. Therefore, to reliably assess performance of the occupational test, 1 practice session (2 visits) is required. Practice is important to allow individuals to optimize their pacing strategy for successful performance.

Background: Low glycemic index (GI) pre-exercise meals may enhance endurance performance by maintaining euglycemia and altering fuel utilization. However, evidence for performance benefits is equivocal., Objective: To evaluate the effect of a low GI (LGI) versus a high GI (HGI) pre-exercise meal on endurance performance using meta-analyses., Methods: Data sources included MEDLINE, SPORTDiscus, AUSPORT, AusportMed, Web of Science, and Scopus. Eligibility criteria were randomized, crossover trials with an endurance exercise (≥60 min) component, e.g., time trial (TT), time to exhaustion (TTE) test, or submaximal bout followed by TT or TTE. Participants were healthy, active individuals aged ≥16 years. Interventions included a LGI (≤55) and HGI (≥70) meal ingested 30-240 min before exercise. Study quality was assessed using an adapted version of the validated Downs and Black tool. Effect size (ES) and 95 % confidence interval were calculated for each study and pooled according to performance test type and whether exogenous carbohydrate (CHO) was given during exercise. Potential effect modifiers including exercise duration, pre-exercise meal timing, glycemic load (GL), and fitness were assessed using meta-regression., Results: The search netted 3431 citations with 19 studies eligible for inclusion (totaling 188 participants; 91 % male; VO 2max : >50 ml/kg/min). Meals with 0.18-2 g CHO/kg body mass, and a mean GI and glycemic load of 82 (GL: 72) and 35 (GL: 32) for HGI and LGI, respectively, were given between 30 and 210 min before exercise. All test types without CHO ingestion during exercise showed slightly improved performance with LGI, but no significant pooled effects were observed (ES: -0.17 to -0.36; p > 0.05). Studies where exogenous CHO was ingested during exercise showed conflicting results (ES: -0.67 to 0.11; p = 0.04 to 0.94). No significant relationship was observed with any of the effect modifiers (p > 0.05). No consistent metabolic responses (glucose, insulin, lactate, respiratory exchange ratio) during exercise were observed with either meal type., Limitations: There were small numbers of studies within each exercise testing protocol and limited statistical power within studies. Pre-exercise meal timing, GL, meal composition and participant fitness varied across studies, limiting the capacity to assess the influence of these factors on study outcomes., Conclusion: There was no clear benefit of consuming a LGI pre-exercise meal for endurance performance regardless of carbohydrate ingestion during exercise.

In this experiment, hand and forearm vasomotor activity was investigated during localised, but stable heating and cooling of the face, hand and thigh, under open-loop (clamped) conditions. It was hypothesised that facial stimulation would provoke the most potent vascular changes. Nine individuals participated in two normothermic trials (mean body temperature clamp: 36.6°C; water-perfused suit and climate chamber) and two mildly hyperthermic trials (37.9°C). Localised heating (+5°C) and cooling (-5°C) stimuli were applied to equal surface areas of the face, hand and thigh (perfusion patches: 15min), while contralateral forearm or hand blood flows (venous-occlusion plethysmography) were measured (separate trials). Thermal sensation and discomfort votes were recorded before and during each thermal stimulation. When hyperthermic, local heating induced more sensitive vascular responses, with the combined thermosensitivity of both limb segments averaging 0.011mL·100mL -1 ·min -1 ·mmHg -1 ·°C -1 , and 0.005mL·100mL -1 ·min -1 ·mmHg -1 ·°C -1 during localised cooling (P<0.05). Inter-site comparisons among the stimulated sites yielded minimal evidence of variations in local thermal sensation, and no differences were observed for vascular conductance (P>0.05). Therefore, regional differences in vasomotor and sensory sensitivity appeared not to exist. When combined with previous observations of sudomotor sensitivity, it seems that, during mild heating and cooling, regional representations within the somatosensory cortex may not translate into meaningful differences in thermal sensation or the central integration of thermoafferent signals. It was concluded that inter-site variations in the cutaneous thermosensitivity of these thermolytic effectors have minimal physiological significance over the ranges investigated thus far., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This project was based on the premise that decisions concerning the ballistic protection provided to defence personnel should derive from an evaluation of the balance between protection level and its impact on physiological function, mobility, and operational capability. Civilians and soldiers participated in laboratory- and field-based studies in which ensembles providing five levels of ballistic protection were evaluated, each with progressive increases in protection, mass (3.4-11.0 kg), and surface-area coverage (0.25-0.52 m(2)). Physiological trials were conducted on volunteers (N = 8) in a laboratory, under hot-dry conditions simulating an urban patrol: walking at 4 km·h(-1) (90 min) and 6 km·h(-1) (30 min or to fatigue). Field-based trials were used to evaluate tactical battlefield movements (mobility) of soldiers (N = 31) under tropical conditions, and across functional tests of power, speed, agility, endurance, and balance. Finally, trials were conducted at a jungle training centre, with soldiers (N = 32) patrolling under tropical conditions (averaging 5 h). In the laboratory, work tolerance was reduced as protection increased, with deep-body temperature climbing relentlessly. However, the protective ensembles could be grouped into two equally stressful categories, each providing a different level of ballistic protection. This outcome was supported during the mobility trials, with the greatest performance decrement evident during fire and movement simulations, as the ensemble mass was increased (-2.12%·kg(-1)). The jungle patrol trials similarly supported this outcome. Therefore, although ballistic protection does increase physiological strain, this research has provided a basis on which to determine how that strain can be balanced against the mission-specific level of required personal protection.

Objective: Firefighter physical aptitude tests were administered to unskilled subjects and operational firefighters to evaluate the impact that testing bias associated with gender, age, activity-specific skills, or task familiarity may have upon establishing performance thresholds., Methods: These tests were administered in sequence, simulating hazmat incidents, ventilation fan carriage (stairs), motor-vehicle rescues, bushfire incidents, fire attacks, and a firefighter rescue. Participants included two unskilled samples (N = 14 and 22) and 143 firefighters., Results: Firefighter performance was not significantly different from the unskilled subjects. Participants from both genders passed the test, with scores unrelated to performance skill or age; however, familiarization significantly improved performance when the test was repeated., Conclusion: These outcomes confirmed this test to be gender-, age-, and skill-neutral. Familiarization effects could be removed through performing a single, pre-selection trial of the test battery.

The aim of this study was to determine the effect of exercise in the heat on thermoregulatory responses and plasma vasoactive intestinal peptide concentration (VIP) and whether it is modulated by ice-slushy consumption. Ten male participants cycled at 62% V̇O2max for 90min in 32°C and 40% relative humidity. A thermoneutral (37°C) or ice-slushy (-1°C) sports drink was given at 3.5mlkg(-1) body mass every 15min during exercise. VIP and rectal temperature increased during exercise (mean±standard deviation: 4.6±4.4pmolL(-1), P=0.005; and 1.3±0.4°C, P<0.001 respectively) and were moderately associated (r=0.35, P=0.008). While rectal temperature and VIP were not different between trials, ice-slushy significantly reduced heat storage (P=0.010) and skin temperature (time×trial interaction P=0.038). It appears that VIP does not provide the signal linking cold beverage ingestion and lower skin temperature in the heat., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

This study aimed to investigate the effect of exercise-induced hyperthermia on central fatigue and force decline in exercised and nonexercised muscles and whether ingestion of ice slushy (ICE) ameliorates fatigue. Eight participants (5 males, 3 females) completed 45 s maximal voluntary isometric contractions (MVIC) with elbow flexors and knee extensors at baseline and following an exercise-induced rectal temperature (Trec) of 39.3 ± 0.2 °C. Percutaneous electrical muscle stimulation was superimposed at 15, 30 and 44 s during MVICs to assess muscle activation. To increase Trec to 39.3 °C, participants cycled at 60% maximum power output for 42 ± 11 min in 40 °C and 50% relative humidity. Immediately prior to each MVIC, participants consumed 50 g of ICE (-1 °C) or thermoneutral drink (38 °C, CON) made from 7.4% carbohydrate beverage. Participants consumed water (19 °C) during exercise to prevent hypohydration. Voluntary muscle force production and activation in both muscle groups were unchanged at Trec 39.3 °C with ICE (knee extensors: 209 ± 152 N) versus CON (knee extensors: 255 ± 157 N, p = 0.19). At Trec 39.3 °C, quadriceps mean force (232 ± 151 N) decreased versus baseline (302 ± 180 N, p < 0.001) and mean voluntary activation was also decreased (by 15% ± 11%, p < 0.001). Elbow flexor mean force decreased from 179 ± 67 N to 148 ± 65 N when Trec was increased to 39.3 °C (p < 0.001) but mean voluntary activation was not reduced at 39.3 °C (5% ± 25%, p = 0.79). After exercise-induced hyperthermia, ICE had no effect on voluntary activation or force production; however, both were reduced from baseline in the exercised muscle group. Peripheral fatigue was greater than the central component and limited the ability of an intervention designed to alter central fatigue.

Purpose: The purpose of this study was to establish whether sensory factors associated with cold-beverage ingestion exert an ergogenic effect on endurance performance independent of thermoregulatory or cardiovascular factors., Methods: Ten males performed three trials involving 90 min of steady state cycling (SS; 62% VO2max) in the heat (32.1 ± 0.9 °C, 40 ± 2.4% relative humidity) followed by a 4 kJ/kg body mass time trial (TT). During SS, participants consumed an identical volume (260 ± 38 g) of sports beverage (7.4% carbohydrate) every 15 min as either ice slushy (-1 °C; ICE), thermoneutral liquid (37 °C; CON), or thermoneutral liquid consumption with expectorated ice slushy mouthwash (WASH)., Results: Rectal temperature, hydration status, heart rate, and skin blood flow were not different between trials. Gastrointestinal (pill) temperature was lower in ICE (35.6 ± 2.7 °C) versus CON (37.4 ± 0.7 °C, p = .05). Heat storage tended to be lower with ICE during SS (14.7 ± 8.4 W.m(-2), p = .08) and higher during TT (68.9 ± 38.6 W.m(-2), p = .03) compared with CON (22.1 ± 6.6 and 31.4 ± 27.6 W.m(-2)). ICE tended to lower the rating of perceived exertion (RPE, 12.9 ± 0.6, p = .05) and improve thermal comfort (TC, 4.5 ± 0.2; p = .01) vs. CON (13.8 ± 1.0 and 5.2 ± 0.2 respectively). WASH RPE (13.0 ± 0.8) and TC (4.8 ± 0.2) tended to be lower versus CON (p = .07 and p = .09 respectively). ICE improved performance (18:28 ± 1:03) compared with CON (20:24 ± 1:46) but not WASH (19:45 ± 1:43)., Conclusion: Improved performance with ICE ingestion likely resulted from the creation of a gastrointestinal heat sink, reducing SS heat storage. Although the benefits of cold-beverage consumption are more potent when there is ingestion, improved RPE, TC, and meaningful performance improvement with WASH supports an independent sensory effect of presenting a cold stimulus to the mouth.

Purpose: The aim of this study was to measure the effect of environmental conditions and aid-station beverage- cooling practices on the temperature of competitor beverages., Methods: Environmental and beverage temperatures were measured at three cycling and two run course aid stations at the 2010 Langkawi, Malaysia (MA), and Port Macquarie, Australia (AU), Ironman triathlon events. To measure the specific effect of radiant temperature, additional fluid-filled (600 ml) drink bottles (n = 12) were cooled overnight (C) and then placed in direct sun (n = 6) or shade (n = 6) near to a cycle aid station at AU., Results: During both events, beverage temperature increased over time (p < .05) as environmental conditions, particularly radiant temperature increased (p < .05). Mean beverage temperature ranged between 14-26°C and during both events was above the palatable range (15-22°C) for extended periods. At AU, bottles placed in direct sunlight heated faster (6.9 ± 2.3 °C·h-1) than those in the shade (4.8 ±1.1°C·h-1, p = .05)., Conclusion: Simple changes to Ironman aid-station practices, including shade and chilling beverages with ice, result in the provision of cooler beverages. Future studies should investigate whether provision of cool beverages at prolonged endurance events influences heat-illness incidence, beverage-consumption patterns, and competitor performance.

Unlabelled: Beverage palatability is known to influence fluid consumption during exercise and may positively influence hydration status and help prevent fatigue, heat illness, and decreased performance., Purpose: The aims of this review were to evaluate the effect of beverage temperature on fluid intake during exercise and investigate the influence of beverage temperature on palatability., Methods: Citations from multiple databases were searched from the earliest record to November 2010 using the terms beverage, fluid, or water and palatability, preference, feeding, and drinking behavior and temperature. Included studies (N = 14) needed to use adult (≥18 yr) human participants, have beverage temperatures ≤50 °C, and measure consumption during exercise and/or palatability., Results: All studies reporting palatability (n = 10) indicated that cold (0-10 °C) or cool (10-22 °C) beverages were preferred to warmer ones (control, ≥22 °C). A meta-analysis on studies reporting fluid consumption (n = 5) revealed that participants consumed ~50% (effect size = 1.4, 0.75-2.04, 95% CI) more cold/cool beverages than control during exercise. Subanalysis of studies assessing hydration status (n = 4) with consumption of cool/cold vs. warm beverages demonstrated that dehydration during exercise was reduced by 1.3% of body weight (1.6-0.9%, 95% CI; p < .001)., Conclusion: Cool beverage temperatures (<22 °C) significantly increased fluid palatability, fluid consumption, and hydration during exercise vs. control (≥22 -°C).

Non-alcoholic fatty liver disease (NAFLD) is a frequent accompaniment of obesity and insulin resistance. With the prevalence approaching 85% in obese populations, new therapeutic approaches to manage NAFLD are warranted. A systematic search of the literature was conducted for studies pertaining to the effect of omega-3 polyunsaturated fatty acid (PUFA) supplementation on NAFLD in humans. Primary outcome measures were liver fat and liver function tests: alanine aminotransferase (ALT) and aspartate aminotransferase [1]. Data were pooled and meta-analyses conducted using a random effects model. Nine eligible studies, involving 355 individuals given either omega-3 PUFA or control treatment were included. Beneficial changes in liver fat favoured PUFA treatment (effect size=-0.97, 95% CI: -0.58 to -1.35, p<0.001). A benefit of PUFA vs. control was also observed for AST (effect size=-0.97, 95% CI: -0.13 to -1.82, p=0.02). There was a trend towards favouring PUFA treatment on ALT but this was not significant (effect size=-0.56, 95% CI: -1.16 to 0.03, p=0.06). Sub-analyses of only randomised control trials (RCTs) showed a significant benefit for PUFA vs. control on liver fat (effect size=-0.96, 95% CI: -0.43 to -1.48, p<0.001), but not for ALT (p=0.74) or AST (p=0.28). There was significant heterogeneity between studies. The pooled data suggest that omega-3 PUFA supplementation may decrease liver fat, however, the optimal dose is currently not known. Well designed RCTs which quantify the magnitude of effect of omega-3 PUFA supplementation on liver fat are needed., (Copyright © 2011 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

This study was a systematic review with meta-analysis examining the efficacy of carbohydrate (CHO) ingestion compared with placebo (PLA) on endurance exercise performance in adults. Relevant databases were searched to January 2011. Included studies were PLA-controlled, randomized, crossover designs in which CHO ingestion not exceeding 8% and between 30 and 80 g/h during exercise of ≥1 h was evaluated via time trial (TT) or exercise time to exhaustion (TTE). The between-trial standardized mean differences [effect size (ES)] and pooled estimates of the effect of CHO ingestion were calculated. Of the 41,175 studies from the initial search, 50 were included. The ES for submaximal exercise followed by TT was significant (ES = 0.53; 95% CI = 0.37-0.69; P < 0.001) as was the ES for TT (ES = 0.30; 95% CI = 0.07-0.53; P = 0.011). The weighted mean improvement in exercise performance favored CHO ingestion (7.5 and 2.0%, respectively). TTE (ES = 0.47; 95% CI = 0.32-0.62; P < 0.001) and submaximal exercise followed by TTE (ES = 0.44; 95% CI = 0.08-0.80; P = 0.017) also showed significant effects, with weighted mean improvements of 15.1 and 54.2%, respectively, with CHO ingestion. Similar trends were evident for subanalyses of studies using only male or trained participants, for exercise of 1-3 h duration, and where CHO and PLA beverages were matched for electrolyte content. The data support that ingestion of CHO between 30 and 80 g/h enhances endurance exercise performance in adults.

Purpose: Increased core temperature (T(c)), impaired cardiovascular function, and dehydration contribute to fatigue during prolonged exercise in the heat. Although many studies have examined mechanisms addressing these factors, few have investigated the effect of cold beverage temperature on thermoregulation and exercise performance in the heat., Methods: Citations from MEDLINE (Ovid), Sport Discus (EBSCOhost), AUSPORT and AusportMed (Informit), Web of Science, and SCOPUS were identified from the earliest record until September 2008 using the search terms: drink temperature, beverage temperature, fluid temperature, water temperature, and cold fluid combined with body temperature and thermoregulation. To be included, studies needed to assess core or rectal temperature during exercise in moderate or hot environmental conditions. After quality rating was completed by two reviewers, the difference in mean Tc and exercise performance was calculated., Results: Ten studies meeting search inclusion criteria were available for analysis. Three were excluded because sufficient detail or statistical data were not reported. A meta-analysis was not performed because the studies were deemed too different to group. Three of the remaining 7 studies found modulated T(c) with cold beverage consumption, and from the 4 that conducted exercise performance tests, performance improved by 10% with cold fluids., Conclusion: Cold fluid may attenuate T(c) rise and improve exercise performance in the heat; however, study findings are mixed. Research using well-trained athletes and fluid-ingestion protocols replicating competition scenarios is required. Potential sensory effects of cold fluid in maintaining motivation also need to be assessed as a mechanism underpinning improved performance.