Effect of cardiorespiratory fitness level on physiological responses and task performance during a high-rise firefighting task

OBJECTIVES

To determine the impact of cardiorespiratory fitness (CRF) on physiological and performance outcomes during a 120-m vertical high-rise ascent in firefighters with CRF levels at or above (higher-fit (HF)) and below (lower-fit (LF)) the national recommended minimum physical employment standard (O2max 42.3 ml·kg-1·min-1).

METHODS

Twenty-eight firefighters completed two high-rise firefighting trials (continuous and discontinuous ascent with pre-determined 1-min rest breaks). Task time (TT), heart rate (HR), ratings of perceived exertion (RPE), core body temperature (CT) and thermal comfort (TC) were recorded at predetermined elevations.

RESULTS

TT was significantly longer in both trials for the LF group. RPE and TC were also significantly higher in the LF group, with three times more LF firefighters being unable to complete the ascent without sounding their low-air alarm.

CONCLUSIONS

Higher CRF improves performance and efficiency during stair-climbing in simulated high-rise firefighting tasks.

Physiological Responses and Performance of Simulated High-Rise Firefighting

OBJECTIVE

The aim of the study is to determine the physiological effects of breathing apparatus and ascent strategies during a simulated 120-m vertical high-rise firefighting ascent.

METHODS

Twenty-eight firefighters completed four high-rise firefighting trials wearing standard- or extended-duration breathing apparatus with continuous ascent (SDBA-C/EDBA-C) or with breaks (SDBA-B/EDBA-B). Task time, heart rate, ratings of perceived exertion, core body temperature, and thermal comfort were recorded at predetermined elevations.

RESULTS

Task time took significantly longer during the EDBA-C compared with SDBA-C trial. Heart rate (at 40, 80, and 100 m) was significantly lower in trials following breaks compared with the continuous trials. Core body temperature rose by 0.11°C every 10 m of ascent. During the SDBA trials, 89% to 96% of firefighters activated their low air alarm compared with only 7% in EDBA.

CONCLUSIONS

Firefighters should wear EDBA beyond 80 m of ascent and are encouraged to take regular breaks.

Influence of smoking status on acute biomarker responses to successive days of arduous military training

INTRODUCTION

Habitual smoking is highly prevalent in military populations despite its association with poorer training outcomes. Smoking imposes challenges on the immune and endocrine systems which could alter how smokers acutely respond to, and recover from, intensive exercise particularly over multiple days of training.

METHODS

Over a two-day period, 35 male British Army recruits (age 22±3 years; mass 76.9±8.0 kg; height 1.78±0.06 m; 15 smokers) completed a 16.1 km loaded march (19.1 kg additional mass) on the first morning and a best-effort 3.2 km 'log race' (carrying a 60 kg log between six and eight people) on the subsequent morning. Blood samples were obtained on waking and immediately postexercise on both days and analysed for C reactive protein (CRP), interleukin 6 (IL-6), testosterone to cortisol ratio and insulin-like growth factor 1 (IGF-1).

RESULTS

Independent of smoking group, the exercise bouts on both days evoked significant increases in IL-6 (p<0.001) and decreases in testosterone to cortisol ratio (p<0.05). CRP concentrations on day 2 were significantly higher than both time points on day 1 (p<0.001), and a 9% decline in IGF-1 occurred over the two-day period, but was not significant (p=0.063). No significant differences were observed between smokers and non-smokers (p>0.05).

CONCLUSIONS

Military-specific tasks elicited inflammatory and endocrine responses, with systemic CRP and IGF-1 indicating that the physiological stress generated during the first training day was still evident on the second day. Despite the well-established impacts of smoking on resting levels of the markers examined, responses to two days of arduous military-specific training did not differ by smoking status.

Prior arm crank exercise has no effect on postprandial lipaemia in non-disabled adults

A single bout of cycling or running performed in the evening can reduce postprandial lipaemia (PPL) the following morning, although this is currently unknown for upper-body exercise. The aim of this study was to determine if a bout of arm crank exercise (high-intensity interval [HIIE] or moderate-intensity continuous [MICE]), can attenuate PPL in non-injured individuals. Eleven healthy and recreationally active participants (eight males, three females; age: 27 ± 7 yr; body mass index: 23.5 ± 2.5 kg · m-2) volunteered to participate in three trials: HIIE (10 x 60 s at 80% peak power output), MICE (50% peak power output of isocaloric duration), and a no-exercise control condition. Each exercise bout was performed at 18:00, and participants consumed a standardized evening meal at 20:00. Following an overnight fast, a 5-h mixed-macronutrient tolerance test was performed at 08:00. There were no significant differences in triglyceride incremental area under the curve between HIIE (192 ± 94 mmol. L-1 per 300 min), MICE (184 ± 111 mmol. L-1 per 300 min), and the no-exercise condition (175 ± 90 mmol. L-1 per 300 min) (P=0.46). There were no significant differences in incremental area under the curve for glucose (P=0.91) or insulin (P=0.59) between conditions. Upper-body MICE and HIIE performed in the evening do not influence PPL the following morning, in normotriglyceridemic individuals. Clinical Trials Registration: NCT04277091 Novelty: • Arm crank exercise has no effect on PPL when performed the evening prior to a mixed-macronutrient meal test • Upper-body sprint interval exercise should be investigated as a potential solution to reduce PPL.

Joint position statement of the International Federation of Sports Medicine (FIMS) and European Federation of Sports Medicine Associations (EFSMA) on the IOC framework on fairness, inclusion and non-discrimination based on gender identity and sex variations

The IOC recently published its framework on fairness, inclusion and non-discrimination based on gender identity and sex variations. This framework is drafted mainly from a human rights perspective, with less consideration for medical/scientific issues. The framework places the onus for gender eligibility and classification entirely on the International Federations (IFs), even though most will not have the capacity to implement the framework. The position of no presumption of advantage is contrary to the 2015 IOC consensus. Implementation of the 2021 framework will be a major challenge for IFs that have already recognised the inclusion of trans and women athletes with differences of sexual development (DSD) using a scientific/medical solution. The potential consequences for sports that need to prioritise fairness or safety could be one of two extremes (1) exclusion of all transgender or DSD athletes on the grounds of advantage or (2) self-identification that essentially equates to no eligibility rules. Exclusion of all transgender or DSD athletes is contrary to the Olympic charter and unlawful in many countries. While having no gender eligibility rules, sport loses its meaning and near-universal support. Athletes should not be under pressure to undergo medical procedures or treatment to meet eligibility criteria. However, if an athlete is fully informed and consents, then it is their free choice to undergo carefully considered or necessary interventions for gender classification for sport to compete fairly and safely in their chosen gender. Free choice is a fundamental human right, but so is the right to fair and safe competition.

Integrating Transwomen and Female Athletes with Differences of Sex Development (DSD) into Elite Competition: The FIMS 2021 Consensus Statement

Sport is historically designated by the binary categorization of male and female that conflicts with modern society. Sport’s governing bodies should consider reviewing rules determining the eligibility of athletes in the female category as there may be lasting advantages of previously high testosterone concentrations for transwomen athletes and currently high testosterone concentrations in differences in sex development (DSD) athletes. The use of serum testosterone concentrations to regulate the inclusion of such athletes into the elite female category is currently the objective biomarker that is supported by most available scientific literature, but it has limitations due to the lack of sports performance data before, during or after testosterone suppression. Innovative research studies are needed to identify other biomarkers of testosterone sensitivity/responsiveness, including molecular tools to determine the functional status of androgen receptors. The scientific community also needs to conduct longitudinal studies with specific control groups to generate the biological and sports performance data for individual sports to inform the fair inclusion or exclusion of these athletes. Eligibility of each athlete to a sport-specific policy needs to be based on peer-reviewed scientific evidence made available to policymakers from all scientific communities. However, even the most evidence-based regulations are unlikely to eliminate all differences in performance between cisgender women with and without DSD and transwomen athletes. Any remaining advantage held by transwomen or DSD women could be considered as part of the athlete’s unique makeup.

Sport and exercise genomics: the FIMS 2019 consensus statement update

Rapid advances in technologies in the field of genomics such as high throughput DNA sequencing, big data processing by machine learning algorithms and gene-editing techniques are expected to make precision medicine and gene-therapy a greater reality. However, this development will raise many important new issues, including ethical, moral, social and privacy issues. The field of exercise genomics has also advanced by incorporating these innovative technologies. There is therefore an urgent need for guiding references for sport and exercise genomics to allow the necessary advancements in this field of sport and exercise medicine, while protecting athletes from any invasion of privacy and misuse of their genomic information. Here, we update a previous consensus and develop a guiding reference for sport and exercise genomics based on a SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis. This SWOT analysis and the developed guiding reference highlight the need for scientists/clinicians to be well-versed in ethics and data protection policy to advance sport and exercise genomics without compromising the privacy of athletes and the efforts of international sports federations. Conducting research based on the present guiding reference will mitigate to a great extent the risks brought about by inappropriate use of genomic information and allow further development of sport and exercise genomics in accordance with best ethical standards and international data protection principles and policies. This guiding reference should regularly be updated on the basis of new information emerging from the area of sport and exercise medicine as well as from the developments and challenges in genomics of health and disease in general in order to best protect the athletes, patients and all other relevant stakeholders.

Recommendations for return to sport during the SARS-CoV-2 pandemic

In this viewpoint we make specific recommendations that can assist and make the return to sport/exercise as safe as possible for all those impacted - from the recreational athlete to the elite athlete. We acknowledge that there are varying rules and regulations around the world, not to mention the varying philosophies and numerous schools of thought as it relates to return to sport/exercise and we have been cognisant of this in our recommendations. Despite the varying rules and circumstances around the world, we believe it is essential to provide some helpful and consistent guidance for return to training and sport for sport and exercise physicians around the world at this most difficult time. The present viewpoint provides practical and medical recommendations on the resumption to sport process.

Lifestyle behaviours and perceived well-being in different fire service roles

Background

Aspects of the work environment influence employee well-being. However, it is unclear how employee lifestyle behaviours, health characteristics and well-being may differ within a broader occupational sector.

Aims

To investigate the health characteristics, lifestyle behaviours and well-being of three Fire and Rescue Service (FRS) occupational groups that differ in shift work and occupational demands: operational firefighters (FF), emergency control (EC) and administrative support (AS) workers.

Methods

Data were obtained via an online survey using previously validated questionnaires to assess health characteristics, lifestyle behaviours and perceived well-being. Differences between groups were explored, controlling for confounding variables, using analysis of covariance (ANCOVA) methods. Effect sizes are reported where appropriate to demonstrate clinical significance.

Results

Four thousand five hundred and sixty-four FRS personnel volunteered, with 3333 (73%) completing the survey out of a total workforce of 60000 (8%). FF reported the lowest prevalence of chronic medical conditions (10%), compared with AS (21%) and EC (19%) workers. Total physical activity (PA) was 66% higher among FF compared with EC and AS workers. Components of sleep and self-rated health were independent predictors of well-being irrespective of FRS role.

Conclusions

FF reported the highest levels of PA and highest perceptions of well-being, and the lowest prevalence of obesity and chronic medical conditions, compared with other FRS occupational groups. These findings may be used to inform FRS workplace intervention strategies.

Development of role-related minimum cardiorespiratory fitness standards for firefighters and commanders

A minimum cardiorespiratory fitness standard was derived for firefighters following a metabolic demands analysis. Design and minimal acceptable performance of generic firefighting task simulations (i.e. hose running, casualty evacuation, stair climb, equipment carry, wild-land fire) were endorsed by a panel of operationally experienced experts. Sixty-two UK firefighters completed these tasks wearing a standard protective firefighting ensemble while being monitored for peak steady-state metabolic demand and cardiovascular strain. Four tasks, endorsed as valid operational simulations by ≥90% of participants (excluding wild-land fire; 84%), were deemed to be a sufficiently valid and reliable basis for a fitness standard. These tasks elicited an average peak steady-state metabolic cost of 38.1 ± 7.8 ml kg^-1 min^-1. It is estimated that healthy adults can sustain the total duration of these tasks (~16 min) at ≤90% maximum oxygen uptake and a cardiorespiratory fitness standard of ≥42.3 ml kg^-1 min^-1 would be required to sustain work. Practitioner Summary: A cardiorespiratory fitness standard for firefighters of ≥42.3 ml kg^-1 min^-1 was derived from monitoring minimum acceptable performance of essential tasks. This study supports the implementation of a routine assessment of this fitness standard for all UK operational firefighters, to ensure safe physical preparedness for occupational performance.

Reliability of Time to Exhaustion Treadmill Running as a Measure of Human Endurance Capacity

Little if any research has examined the variability in time to exhaustion (TTE) during submaximal treadmill running. This study investigated the test-retest reliability of submaximal treadmill TTE as a measure of endurance capacity. 16 endurance-trained males (n=14) and females (n=2) completed a run to exhaustion at 70% V̇O2max (T1) and repeated the same run 3 weeks later (T2). At 30-min intervals during each run, expired gas, heart rate (HR) and ratings of perceived exertion (RPE) were collected. Mean ± SD TTE was 96 ± 20 min in T1 vs. 101 ± 29 min in T2 (P=0.3). The mean ± 95% confidence intervals (CI) of the coefficient of variance (CV) was 5.4% (1.4-9.6). The average intraclass correlation coefficient (± 95% CI) was 0.88 (0.67-0.96) between trials. The respiratory-exchange ratio was not different between trials, T1: 0.87 ± 0.1 and T2: 0.89 ± 0.1 (P>0.05) and neither was total whole-body carbohydrate oxidation (2.1 ± 0.4 g·min(-1) and 2.3 ± 0.6 g·min(-1)), fat oxidation (0.6 ± 0.2 g·min(-1)), HR (178 ± 8 and 175 ± 7 beats·min(-1)) or RPE (17 ± 3 and 16 ± 3). These results suggest that use of prolonged treadmill-based TTE can be a reliable research tool to assess human endurance capacity in aerobically-trained men and women.

A comparison of two commercially available ELISA methods for the quantification of human plasma heat shock protein 70 during rest and exercise stress

This study compared resting and exercise heat/hypoxic stress-induced levels of plasma extracellular heat shock protein 70 (eHSP70) in humans using two commercially available enzyme-linked immunosorbent assay (ELIS)A kits. EDTA plasma samples were collected from 21 males during two separate investigations. Participants in part A completed a 60-min treadmill run in the heat (HOT70; 33.0 ± 0.1 °C, 28.7 ± 0.8 %, n = 6) at 70 % V̇O2max. Participants in part B completed 60 min of cycling exercise at 50 % V̇O2max in either hot (HOT50; 40.5 °C, 25.4 relative humidity (RH)%, n = 7) or hypoxic (HYP50; fraction of inspired oxygen (FIO2) = 0.14, 21 °C, 35 % RH, n = 8) conditions. Samples were collected prior to and immediately upon termination of exercise and analysed for eHSP70 using EKS-715 high-sensitivity HSP70 ELISA and new ENZ-KIT-101 Amp'd(™) HSP70 high-sensitivity ELISA. ENZ-KIT was superior in detecting resting eHSP70 (1.54 ± 3.27 ng · mL(-1); range 0.08 to 14.01 ng · mL(-1)), with concentrations obtained from 100 % of samples compared to 19 % with EKS-715 assay. The ENZ-KIT requires optimisation prior to running samples in order to ensure participants fall within the standard curve, a step not required with EKS-715. Using ENZ-KIT, a 1:4 dilution allowed for quantification of resting HSP70 in 26/32 samples, with a 1:8 (n = 3) and 1:16 (n = 3) dilution required to determine the remaining samples. After exercise, eHSP70 was detected in 6/21 and 21/21 samples using EKS-715 and ENZ-KIT, respectively. eHSP70 was increased from rest after HOT70 (p < 0.05), but not HOT50 (p > 0.05) or HYP50 (p > 0.05) when analysed using ENZ-KIT. It is recommended that future studies requiring the precise determination of resting plasma eHSP70 use the ENZ-KIT (i.e. HSP70 Amp'd(®) ELISA) instead of the EKS-715 assay, despite additional assay development time and cost required.

Predicting physical activity energy expenditure in wheelchair users with a multisensor device

Aim

To assess the error in predicting physical activity energy expenditure (PAEE), using a multisensor device in wheelchair users, and to examine the efficacy of using an individual heart rate calibration (IC) method.

Methods

15 manual wheelchair users (36±10 years, 72±11 kg) completed 10 activities: resting, folding clothes, wheelchair propulsion on a 1% gradient (3456 and 7 km/h) and propulsion at 4 km/h (with an additional 8% of body mass, 2% and 3% gradient) on a motorised wheelchair treadmill. Criterion PAEE was measured using a computerised indirect calorimetry system. Participants wore a combined accelerometer and heart rate monitor (Actiheart). They also performed an incremental arm crank ergometry test to exhaustion which permitted retrospective individual calibration of the Actiheart for the activity protocol. Linear regression analysis was conducted between criterion (indirect calorimetry) and estimated PAEE from the Actiheart using the manufacturer's proprietary algorithms (group calibration, GC) or IC. Bland-Altman plots were used and mean absolute error was calculated to assess the agreement between criterion values and estimated PAEE.

Results

Predicted PAEE was significantly (p<0.01) correlated with criterion PAEE (GC, r=0.76 and IC, r=0.95). The absolute bias ±95% limits of agreement were 0.51±3.75 and −0.22±0.96 kcal/min for GC and IC, respectively. Mean absolute errors across the activity protocol were 51.4±38.9% using GC and 16.8±15.8% using IC.

Summary

PAEE can be accurately and precisely estimated using a combined accelerometer and heart rate monitor device, with integration of an IC. Interindividual variance in cardiovascular function and response to exercise is high in this population. Therefore, in manual wheelchair users, we advocate the use of an IC when using the Actiheart to predict PAEE.

Influence of accelerometer type and placement on physical activity energy expenditure prediction in manual wheelchair users

PURPOSE

To assess the validity of two accelerometer devices, at two different anatomical locations, for the prediction of physical activity energy expenditure (PAEE) in manual wheelchair users (MWUs).

METHODS

Seventeen MWUs (36 ± 10 yrs, 72 ± 11 kg) completed ten activities; resting, folding clothes, propulsion on a 1% gradient (3,4,5,6 and 7 km·hr-1) and propulsion at 4km·hr-1 (with an additional 8% body mass, 2% and 3% gradient) on a motorised wheelchair treadmill. GT3X+ and GENEActiv accelerometers were worn on the right wrist (W) and upper arm (UA). Linear regression analysis was conducted between outputs from each accelerometer and criterion PAEE, measured using indirect calorimetry. Subsequent error statistics were calculated for the derived regression equations for all four device/location combinations, using a leave-one-out cross-validation analysis.

RESULTS

Accelerometer outputs at each anatomical location were significantly (p < .01) associated with PAEE (GT3X+-UA; r = 0.68 and GT3X+-W; r = 0.82. GENEActiv-UA; r = 0.87 and GENEActiv-W; r = 0.88). Mean ± SD PAEE estimation errors for all activities combined were 15 ± 45%, 14 ± 50%, 3 ± 25% and 4 ± 26% for GT3X+-UA, GT3X+-W, GENEActiv-UA and GENEActiv-W, respectively. Absolute PAEE estimation errors for devices varied, 19 to 66% for GT3X+-UA, 17 to 122% for GT3X+-W, 15 to 26% for GENEActiv-UA and from 17.0 to 32% for the GENEActiv-W.

CONCLUSION

The results indicate that the GENEActiv device worn on either the upper arm or wrist provides the most valid prediction of PAEE in MWUs. Variation in error statistics between the two devices is a result of inherent differences in internal components, on-board filtering processes and outputs of each device.

Sports injuries in Brazilian blind footballers

The purpose of this study was to assess the characteristics and prevalence of sports-related injuries in visually disabled athletes of the Brazilian football 5-a-side team. The participants were 13 male athletes, all classified as B1 visual class, members of the Brazilian team, who played in five consecutive international competitions. Data were collected using the Brazilian Paralympic Committee and the Brazilian Confederation of Sports for the Blind report form. From the total of 13 athletes, 11 succumbed to some form of injury during the 5 competitions, which incorporated 23 matches, representing a prevalence of 84.6%. A total of 35 sports injuries were recorded, giving a clinical incidence of 2.7 injuries per athlete and an injury risk of 0.85 and an incidence rate of 0.12 injuries per match. Traumatic injuries (80%) were more common than overuse injuries (20%) (p<0.05). The highest distribution of injury was in the lower limbs (80%), followed by the head (8.6%), spine (5.7%) and upper limbs (5.7%). The body regions most affected were the knee (28.6%), feet (17.1%), ankle (11.4%) and thigh (11.4%). Contusions (31.4%), sprains (25.7%) and tendinopathy (8.6%) were the most frequent diagnoses. This is the first study to describe the nature and prevalence of sports-related injuries in 5-a-side football in blind athletes. The results are important in guiding strategies to inform the implementation of preventive pathways and provide a strong rationale for the compulsory use of additional protective equipment.

Reliability and validity of the 3DNX accelerometer during mechanical and human treadmill exercise testing

OBJECTIVE

This study aimed to assess the validity and reliability of the 3DNX triaxial accelerometer in a laboratory and mechanical setting.

METHODS

Experiment 1: A total of 10 units were fixed to a Multi-axis shaker table. A schedule comprising a range of accelerations was repeated on two occasions along each of the three measurement axes. Experiment 2: A total of 11 recreationally active individuals completed a treadmill protocol (4-20 km hr(-1)) on two occasions. Two 3DNX accelerometers were secured to the lower back, logging data every 5 s. Oxygen uptake was measured using the Douglas Bag technique. Reliability inter- and intra-units were assessed using a combination of limits of agreement (LoA), coefficient of variation (CV) and intra-class correlation coefficient (ICC). Validity was assessed using simple linear regression. All data are expressed in counts per 5 s (counts 5 s(-1)).

RESULTS

Experiment 1: CV(intra) ranged from 0.0 to 8.9% in all axes. The absolute bias±95% LoA values were all below four counts 5 s(-1). CV(inter) did not rise above 4.5%. ICCs were 1.0 for all stages in all axes. The relationship between 3DNX counts and acceleration yielded an R(2) value of 0.99 and a standard error of the estimate (SEE) of six counts 5 s(-1). Experiment 2: CV(inter) ranged from 7.7 to 16.0% for trial 1 and from 7.7 to 16.2% for trial 2. ICCs between units ranged from 0.95 to 1.00 for trial 1 and from 0.90 to 0.99 for trial 2. Mean ratio bias±95% LoA values for intra-unit and inter-unit reliability were -0.7% (P>0.05)±12.4% and 0.4% (P>0.05)±5.6%, respectively. The relationship between VO(2) and 3DNX counts for walking and running was linear (R(2)=0.65, SEE=1.42 ml kg(-1) min(-1); R(2)=0.62, SEE=3.63 ml kg(-1) min(-1)).

CONCLUSION

The 3DNX accelerometer is a reliable and valid device for measuring acceleration in a mechanical setting and during human treadmill exercise.

The validity of wireless iButtons and thermistors for human skin temperature measurement

Skin temperature is a fundamental variable in human thermo-physiology, and yet skin temperature measurement remains impractical in most free-living, exercise and clinical settings, using currently available hard-wired methods. The purpose of this study was to compare wireless iButtons and hard-wired thermistors for human skin temperature measurement. In the first of two investigations, iButtons and thermistors monitored temperature in a controlled water bath (range: 10-40 degrees C) and were referenced against a certified, mercury thermometer. In the second investigation, eight healthy males completed three randomized trials (ambient temperature = 10 degrees C, 20 degrees C and 30 degrees C) while both devices recorded skin temperature at rest (in low and high wind velocities) and during cycle-ergometry exercise. The results are as follows. Investigation 1: both devices displayed very high validity correlation with the reference thermometer (r > 0.999). Prior to correction, the mean bias was +0.121 degrees C for iButtons and +0.045 degrees C for thermistors. Upon calibration correction the mean bias for iButtons and thermistors was not significantly different from zero bias. Interestingly, a typical error of the estimate of iButtons (0.043 degrees C) was 1.5 times less than that of thermistors (0.062 degrees C), demonstrating iButtons' lower random error. Investigation 2: the offset between iButton and thermistor readings was generally consistent across conditions; however, thermistor responses gave readings that were always closer to ambient temperature than those given by iButtons, suggesting potential thermistor drift towards environmental conditions. Mean temperature differences between iButtons and thermistors during resting trials ranged from 0.261 degrees C to 1.356 degrees C. Mean temperature differences between iButtons and thermistors during exercise were 0.989 degrees C (ambient temperature = 10 degrees C), 0.415 degrees C (ambient temperature = 20 degrees C) and 0.318 degrees C (ambient temperature = 30 degrees C). Observed error estimates were within the acceptable limits for the skin temperature method comparison, with typical errors <0.3 degrees C, correlation coefficients >0.9 and CV <1% under all conditions. These findings indicate that wireless iButtons provide a valid alternative for human skin temperature measurement during laboratory and field investigations particularly when skin temperature measurement using other currently available methods may prove problematic.

Generic task-related occupational requirements for Royal Naval personnel

Physical tests and selection criteria have historically been used by many military organizations. However, the standards associated with them have come under increasing scrutiny in recent years. This paper describes a series of experiments that were conducted to establish task-related occupational tests and standards (TBTs) for Royal Naval (RN) personnel. A total of 172 (106 male and 66 female) RN personnel volunteered for these experiments, which were designed to: identify the anthropometric requirements for operating various safety hatches and doors on board a RN Frigate (TBT1); quantify the metabolic demands of shipboard firefighting tasks and establish an aerobic fitness standard (TBT2); and identify a battery of tests to predict performance of shipboard casualty-carrying tasks (TBT3). Whilst all subjects completed the criterion tasks during TBT1, performance of the bulkhead door (BD) escape task was related to height (r = 0.50- 0.62, P < 0.05) and vertical reach (r = 0.42-0.54, P < 0.05), with shorter subjects struggling to perform the task. During TBT2, the mean metabolic demand of representative firefighting tasks was 38 ml/min/kg, which must be sustained for 20-30 min. Finally, a battery of tests incorporating measures of lean body mass, fat mass, standing broad jump, 20 m sprint, press-ups, sit-ups and grip strength produced a high correlation (r = 0.89, P < 0.01) with casualty-carrying task performance. From the results of these experiments, it is recommended that RN personnel perform the BD simulation task at the recruitment stage (TBT1), to prove that they possess the anthropometric characteristics commensurate with survival at sea. Secondly, personnel should be frequently screened to ascertain whether they have the maximal aerobic power (41 ml/min/kg) commensurate with shipboard firefighting for 20-30 min (TBT2). Finally, they should perform the battery of proposed tests and score at least 34 points, in order to establish whether they have the anaerobic and strength capacity commensurate with shipboard casualty-carrying tasks (TBT3).

Influence of glucose ingestion by humans during recovery from exercise on substrate utilisation during subsequent exercise in a warm environment

Carbohydrate (CHO) ingestion during short-term recovery from prolonged running has been shown to increase the capacity for subsequent exercise in a warm environment. The aim of this study was to examine the effects of the amount of glucose given during recovery on substrate storage and utilisation during recovery and subsequent exercise in a warm environment. A group of 11 healthy male volunteers took part in two experiments in a controlled warm environment (35 degrees C, 40% relative humidity), 1 week apart. On each occasion the subjects completed two treadmill runs (T1 and T2) at a speed equivalent to 60% of maximal oxygen uptake, for 90 min, until they were fatigued, or until aural temperature (T(aur)) reached 39 degrees C. The two runs were separated by a 4 h recovery period (REC), during which subjects consumed 55 g of naturally enriched [U-(13)C]-glucose in the form of a 7.5% carbohydrate-electrolyte solution (CES, mass of solution 667 g) immediately after T1. The subjects then consumed either: the same quantity of CES, or an equivalent volume of an electrolyte placebo, at 60, 120 and 180 min during REC, providing a total of 220 g (C220) or 55 g (C55) of [U-(13)C]-glucose, respectively. Expired gases were collected at 15 min intervals during exercise and 60 min intervals during REC, for determination of total CHO and fat oxidation by indirect respiratory calorimetry, and orally ingested [U-(13)C]-glucose oxidation, estimated from the (13)C:(12)C ratio of expired CO(2). Substrate metabolism did not differ between conditions during T1. Despite the fact that total CHO (P < 0.05) and ingested glucose oxidation (P < 0.01) were greater during REC of the C220 condition, glycogen synthesis was estimated to be approximately fivefold greater (P < 0.01) than in the C55 condition. During T2 the rate of total CHO oxidation was higher (P < 0.01) and total fat oxidation lower (P < 0.01) at all times during the C220 compared to the C55 condition. The greater CHO oxidation during C220 appeared to be met from ingested sources, as the rate of [U-(13)C]-glucose oxidation was greater (P < 0.01) at all times during T2, compared to C55. Whilst more of the ingested substrate remained unoxidised on completion of T2 during C220, exercise duration was similar in the two experimental conditions, and was limited by thermoregulatory incapacity (T(aur) > 39 degrees C) rather than substrate availability per se.