Physical employment standards for U.K. fire and rescue service personnel.

BACKGROUND: Evidence-based physical employment standards are vital for recruiting, training and maintaining the operational effectiveness of personnel in physically demanding occupations. AIMS: (i) Develop criterion tests for in-service physical assessment, which simulate the role-related physical demands of UK fire and rescue service (UK FRS) personnel. (ii) Develop practical physical selection tests for FRS applicants. (iii) Evaluate the validity of the selection tests to predict criterion test performance. METHODS: Stage 1: we conducted a physical demands analysis involving seven workshops and an expert panel to document the key physical tasks required of UK FRS personnel and to develop 'criterion' and 'selection' tests. Stage 2: we measured the performance of 137 trainee and 50 trained UK FRS personnel on selection, criterion and 'field' measures of aerobic power, strength and body size. Statistical models were developed to predict criterion test performance. Stage 3: matter experts derived minimum performance standards. RESULTS: We developed single person simulations of the key physical tasks required of UK FRS personnel as criterion and selection tests (rural fire, domestic fire, ladder lift, ladder extension, ladder climb, pump assembly, enclosed space search). Selection tests were marginally stronger predictors of criterion test performance (r = 0.88-0.94, 95% Limits of Agreement [LoA] 7.6-14.0%) than field test scores (r = 0.84-0.94, 95% LoA 8.0-19.8%) and offered greater face and content validity and more practical implementation. CONCLUSIONS: This study outlines the development of role-related, gender-free physical employment tests for the UK FRS, which conform to equal opportunities law.

Insulated skin temperature as a measure of core body temperature for individuals wearing CBRN protective clothing.

This study assessed the validity of insulated skin temperature (Tis) to predict rectal temperature (Tre) for use as a non-invasive measurement of thermal strain to reduce the risk of heat illness for emergency service personnel. Volunteers from the Police, Fire and Rescue, and Ambulance Services performed role-related tasks in hot (30 °C) and neutral (18 °C) conditions, wearing service specific personal protective equipment. Insulated skin temperature and micro climate temperature (Tmc) predicted Tre with an adjusted r(2) = 0.87 and standard error of the estimate (SEE) of 0.19 °C. A bootstrap validation of the equation resulted in an adjusted r(2) = 0.85 and SEE = 0.20 °C. Taking into account the 0.20 °C error, the prediction of Tre resulted in a sensitivity and specificity of 100% and 91%, respectively. Insulated skin temperature and Tmc can be used in a model to predict Tre in emergency service personnel wearing CBRN protective clothing with an SEE of 0.2 °C. However, the model is only valid for Tis over 36.5 °C, above which thermal stability is reached between the core and the skin.

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.

Physical demands of firefighter search and rescue in ambient environmental conditions.

This study investigated the physiological responses and limitations to a simulated search and rescue scenario in a high-rise building under ambient conditions. Sixteen firefighters performed the scenario under four conditions: standard duration breathing apparatus (SDBA) and 45 mm hose; extended duration breathing apparatus (EDBA) and 45 mm hose; SDBA and 70 mm hose; EDBA and 70 mm hose. Core temperature, skin temperature and heart rate were monitored. In four of 32 trials the casualty was rescued; the remainder of the trials were terminated for safety, high core temperature or shortage of air. Final core temperature and heart rate were higher in the EDBA (39.1 degrees C; 72% heart rate reserve (HRR)) than SDBA conditions (38.6 degrees C; 67%HRR). No differences were observed between hose sizes. The scenario proved too onerous to complete successfully in the majority of cases. Replacing SDBA with EDBA eliminates air supply as a limiting factor, but brings with it challenges of managing thermal strain.

Can simple anthropometric and physical performance tests track training-induced changes in maximal box-lifting ability?

The objective of this research was to determine if tests of lifting strength and anthropometry could be used to assess training-induced changes in box-lift performance. Ninety-two British Army recruits completed a 10-week training programme. Isometric and dynamic lifting strength, body composition and maximal box-lift to 1.45 m and 1.70 m were assessed before and after training. Training significantly increased box-lift performance, dynamic lifting strength and fat-free mass, and reduced body fat. Statistically significant regression models (adjusted R(2) of 0.299 and 0.152) were produced that predicted the changes in box-lift performance from changes in body composition and lifting strength. However, the 95% limits of agreement between the observed and predicted change in box-lift performance showed wide margins of error (11-13 kg; 26-29%). Training-induced changes in box-lift performance appear to be highly specific, which suggests that both training and testing procedures should also be specific to box-lift performance.

Higher dietary carbohydrate content during intensified running training results in better maintenance of performance and mood state.

The aim of this study was to determine whether consumption of a diet containing 8.5 g carbohydrate (CHO) x kg(-1) x day(-1) (high CHO; HCHO) compared with 5.4 g CHO x kg(-1) x day(-1) (control; Con) during a period of intensified training (IT) would result in better maintenance of physical performance and mood state. In a randomized cross-over design, seven trained runners [maximal O(2) uptake (Vo(2 max)) 64.7 +/- 2.6 ml x kg(-1) x min(-1)] performed two 11-day trials consuming either the Con or the HCHO diet. The last week of both trials consisted of IT. Performance was measured with a preloaded 8-km all-out run on the treadmill and 16-km all-out runs outdoors. Substrate utilization was measured using indirect calorimetry and continuous [U-(13)C]glucose infusion during 30 min of running at 58 and 77% Vo(2 max). Time to complete 8 km was negatively affected by the IT: time significantly increased by 61 +/- 23 and 155 +/- 38 s in the HCHO and Con trials, respectively. The 16-km times were significantly increased (by 8.2 +/- 2.1%) during the Con trial only. The Daily Analysis of Life Demands of Athletes questionnaire showed significant deterioration in mood states in both trials, whereas deterioration in global mood scores, as assessed with the Profile of Mood States, was more pronounced in the Con trial. Scores for fatigue were significantly higher in the Con compared with the HCHO trial. CHO oxidation decreased significantly from 1.7 +/- 0.2 to 1.2 +/- 0.2 g/min over the course of the Con trial, which was completely accounted for by a decrease in muscle glycogen oxidation. These findings indicate that an increase in dietary CHO content from 5.4 to 8.5 g CHO x kg(-1)x day(-1) (41 vs. 65% total energy intake, respectively) allowed better maintenance of physical performance and mood state over the course of training, thereby reducing the symptoms of overreaching.

Effect of eccentric exercise on patients with chronic exertional compartment syndrome.

There are a number of similarities between chronic exertional compartment syndrome (CECS) and the effects of high force eccentric contractions in healthy controls. We hypothesised that CECS patients would be particularly susceptible to pain, fatigue and swelling after eccentric exercise. Ten CECS patients [aged 30.3 (8.0) years, mean (SD)], 7 males) and 14 healthy controls [aged 32.3 (9.0) years, 7 males] performed 40 maximal eccentric contractions of the anterior tibial muscles at an angular velocity of 90(o) s(-1). Maximal voluntary isometric contractions (MVC), force generated by electrical stimulation at 10 Hz and 50 Hz and muscle thickness (measured by real-time ultrasound scanning) were measured before exercise and for 10 min afterwards. Ratings of pain and tenderness were made before exercise, then 24 h and 48 h later. The two groups were comparable for initial isometric strength and muscle size. MVC force immediately after exercise fell to 90 (2.5)% [mean (SEM)] in patients and 86.5 (2.4)% in controls (P<0.0005 for both groups) and had not recovered after 10 min. Preferential loss of force at the low stimulation frequency occurred in both groups to a similar extent (20%, P<0.0005) and continued to decline over 10 min of recovery. There was no significant change in muscle thickness in either group. Only mild pain and tenderness were reported by the controls. The patients showed great individual variation but their mean pain scores were significantly higher during dorsiflexion and palpation (P<0.05) 24 h after exercise. After 48 h the patients reported more pain during dorsiflexion (P=0.005), plantarflexion (P<0.05) and palpation (P<0.05). These results suggest that some, but not all, CECS patients may be more susceptible to the pain associated with eccentric contractions that is thought to be the cause of damage and inflammation of connective tissue.

Resistance training and the enhancement of the gains in material-handling ability and physical fitness of British Army recruits during basic training.

The aim was to evaluate the efficacy of a modified British Army basic training that included resistance training in improving material-handling performance and physical fitness, and to compare the modified training directly with the normal basic training. Forty-three males [19.2 (2.6) years of age, 1764 (72) mm in height, 73.0 (10.6) kg in mass] and nine females [19.1 (2.2) years, 1641 (67) mm, 62.0 (7.2) kg] performed the modified basic training. Testing occurred in the week before and in the final week of the 11-week basic training. Improvements with the modified training were observed for all six material-handling tests, including 8-12% for maximal box lifting, 15-19% for repetitive lifting and carrying and 9-17% for loaded marching (all p < 0.01), and other established measures of aerobic fitness, strength and kinanthropometric characteristics. Significantly greater improvements were observed for the modified training compared with the normal training in maximal box lift to 1.45 m (12.4 versus 1.7%, p < 0.01), 3.2 km loaded march performance with 15 kg (8.9 versus 3.6%, p < 0.05), estimated fat-free mass (4.2 versus 1.5%, p < 0.001), predicted VO(2max) (1 min(-1)) (9.3 versus 4.1%, p < 0.01) and dynamic lift to 1.45 m (15.5 versus 0.2%, p < 0.001). It was concluded that the improvements in material-handling ability and other aspects of physical fitness brought about in recruits by British Army basic training can be enhanced by the use of a physical training programme that includes a carefully designed resistance training element. Of particular note are the improvements shown in performance on material-handling tasks that require muscular strength, as these represent many of the tasks that soldiers encounter in their military careers.

Endurance enhancement related to the human angiotensin I-converting enzyme I-D polymorphism is not due to differences in the cardiorespiratory response to training.

Human physical performance is strongly influenced by genetic factors. We have previously reported that the I variant of the human angiotensin I-converting enzyme (ACE) gene is associated with greater endurance performance in mountaineers and Olympic runners and improved performance in army recruits. In this study we examined whether this effect is mediated by improvements in cardiovascular fitness with training in 58 army recruits homozygous for the insertion (I, ACE genotype II) or deletion (D, ACE genotype DD) allele. A submaximal and maximal exercise protocol was used to calculate both the heart rate/oxygen uptake (VO2) relationship and changes in maximal oxygen uptake (VO2max), respectively. There was no significant intergroup difference in VO2max at baseline (P=0.19) or after training (P=0.22). There was no difference between genotypes with training in the heart rate/VO2 elevation (P = 0.79 for the mean difference in mean adjusted heart rates). However, VO2 at all exercise intensities in the submaximal test was lower for all subjects after training and at 80 W the reduction in VO2 was greater for the II subjects compared to DD subjects [mean(SEM)] [1.6 (0.27) and 0.68 (0.27) ml kg(-1) min(-1), respectively; P = 0.02 for mean difference]. The I/D polymorphism may play a role in enhanced endurance performance but this is not mediated by differences in VO2max or the heart rate/VO2 relationship in response to training.

Characterization of the metabolic demands of simulated shipboard Royal Navy fire-fighting tasks.

The purpose of this study was to quantify the metabolic demand of simulated shipboard fire-fighting procedures currently practised by men and women in the Royal Navy (RN) and to identify a minimum level of cardiovascular fitness commensurate with satisfactory performance. Thirty-four males (M) and 15 females (F) volunteered as subjects for this study (n=49). Maximal oxygen uptake (VO2max) and heart rate (fcmax) of each subject was assessed during a standardized treadmill test. During the main trials, volunteers were randomly assigned to complete several 4-min simulated shipboard fire-fighting tasks (boundary cooling (BC), drum carry (DC), extinguisher carry (EC), hose run (HR), ladder climb (LC)), at a work rate that was endorsed as a minimum acceptable standard. Heart rate (fc) and oxygen uptake (VO2) were recorded at 10-s intervals during rest, exercise and recovery. Participants completed all tasks within an allocated time with the exception of the DC task, where 11 subjects (all females) failed to maintain the endorsed work rate. The DC task elicited the highest (p<0.01) group mean peak metabolic demand (PMD) in males (43 ml min(-1) kg(-1)) and females (42 ml min(-1) kg (-1)) who were able to maintain the endorsed work rate. The BC task elicited the lowest PMD (23 ml min(-1) kg(-1)), whilst the remaining three tasks elicited a remarkably similar PMD of 38-39 ml min(-1) kg(-1). The human endurance limit while wearing a self-contained breathing apparatus (SCBA) dictates that RN personnel are only able to fire-fight for 20-30 min, while wearing a full fire-fighting ensemble (FFE) and performing a combination of the BC, HR and LC tasks, which have a group mean metabolic demand of 32.8 ml min(-1) kg(-1). Given that in healthy subjects fire-fighting can be sustained at a maximum work intensity of 80% VO2max when wearing SCBA for this duration, it is recommended that all RN personnel achieve a VO2max of 41 ml min(-1) kg(-1) as an absolute minimum standard. Subjects with a higher VO2max than the above quoted minimum are able to complete the combination of tasks listed with greater metabolic efficiency and less fatigue.

Fitness for work: the need for conducting a job analysis.

Ensuring that employees are both physically fit for work by matching their capabilities with the physical requirements of their job, and physically fit for life by promoting health-related physical activities, are important and under-utilized tools in a company's arsenal for reducing absence and ill-health retirement (IHR). Both the Health and Safety at Work Act (1974) and the Disability Discrimination Act (1995) require evidence-based approaches to setting physical and medical employment standards. Proven fitness-related strategies include redesigning the most demanding tasks, selecting and training personnel who possess the necessary physical attributes, and assessing and redeploying personnel to jobs within their capability. An essential precursor to pursuing these strategies is to conduct a job analysis to quantify the physical demands of the job.

Effects of basic training on material handling ability and physical fitness of British Army recruits.

No study has yet evaluated the efficacy of British Army basic training in improving material handling performance. Therefore, the purpose of this study was to evaluate the efficacy of the current British Army basic training in improving material handling performance and physical fitness. Forty-seven males (19.4 (3.2) years of age, 1753 (59) mm in height, 71.0 (9.6) kg in weight) and 10 females (21.5 (3.5) years, 1623 (45) mm, 62.5 (5.2) kg) served as subjects. Testing was carried out in the week prior to, and in the final week of, an 11-week basic training course. Maximal box lifts to two different heights, and repetitive lifting and carrying of a 10 kg load did not improve with training. Static (38 cm upright pull) and dynamic (incremental dynamic lift to 145 cm) lifting strength data concurred with the maximal box lift data in that no improvement was observed. Repetitive lifting and carrying of a 22 kg load improved (29.5%, p < 0.001), as did 3.2 km loaded march performance with 25 kg (15.7%, p < 0.001), but march performance with a 15 kg load did not. Predicted VO2max improved from 48.4 to 51.4 ml.kg-1.min-1, a change of 6.1% (p < 0.05). Fat-free mass increased by 0.9 kg (1.5%, p < 0.01), and body fat reduced by 2.7% of body mass (20.1%, p < 0.001), resulting in a loss of 1.2 kg of body mass (1.7%, p < 0.01). It is concluded that basic training in the British Army produces some favourable adaptations in recruits, especially in terms of aerobic fitness. However, the poor development of strength and material handling ability during training fails to improve the ability of soldiers to perform simulated military tasks, and it does little to reduce future injury risk while performing these tasks.

Fitness, performance, and risk of injury in British Army officer cadets.

The objectives of this study were to investigate the effectiveness of the Commissioning Course (CC) to develop and maintain standards of fitness, to assess capability to perform military tasks, and to determine the relationship between fitness and risk of injury in 106 British Army officer cadets (OCdts). Aerobic fitness, muscular strength, endurance, and body composition were regularly assessed. Performance on four representative military tasks was measured at the end of the CC. All injuries in term 1 were documented. Over the CC, changes in fitness were generally modest and equivocal. Aerobic fitness improved by approximately 10% (p < 0.01), strength by 5 to 9% (p < 0.05 to p < 0.01), and muscular endurance by 55% (p < 0.01). Reductions in fat (p < 0.01) and gains in fat free mass (p < 0.05) averaged 3%. The females demonstrated greater improvements than the males. The majority of OCdts passed the representative military tasks, although females in some trades showed high failure rates. Forty-six percent of OCdts sustained injuries in the first term, resulting in 5% of man-days lost. No gender difference was found in injury rates. The least aerobically fit OCdts sustained more injuries than their fitter counterparts. In conclusion, there is scope for optimizing the effectiveness of the CC to enhance fitness and improve the focus of physical training on maximizing military task performance.

Heart rate and oxygen uptake relationship: a comparison of loaded marching and running in women.

Heart rate (beats.min-1; fc) measured during marching with a load is often used to predict the oxygen cost (l.min-1; VO2) of the activity. The prediction comes from the fc/VO2 relationship determined from laboratory measures of fc and VO2 during treadmill running. Studies in men have suggested that this may not be appropriate although this has yet to be examined in women. This study, therefore, compared the fc/VO2 relationship between loaded marching and maximal running protocols in women. Sixteen female subjects [mean (SD), age 21.9 (2.3) years, height 6 (0.06) m, weight 62.6 (7.6) kg] had their fc (from three-lead chest electrodes) and VO2 measured first during standard treadmill run protocols, and again 1 week later during loaded marching protocols. The slopes and intercepts determined from linear regression of fc on VO2 for each individual for each protocol were compared as were the maximal fc(fcmax), VO2 and ratings of perceived exertion (RPE) from the last work period of each protocol in paired t-tests. The fc/VO2 slopes (P < 0.01) and intercepts (P < 0.05) differed significantly between loaded marching and running. fcmax for loaded marching were 90% of fcmax for running (P < 0.01) and VO2peak for loaded marching were 80% of those for running (P < 0.01). However, RPE at the final levels for the two protocols were not significantly different. The data suggest that in women the fc/VO2 relationships for loaded marching and for running are different. This difference is similar to that found in men when speed is held constant and the load and gradient are varied. The results suggest that it would be erroneous to use fc and VO2 measured during running protocols in the laboratory to estimate energy expenditure and work intensity during loaded marching in the field.