The effect of firefighter protective garments, self-contained breathing apparatus and exertion in the heat on postural sway

Determination of dynamic air gap thickness and analysis of its relationship with firefighters' joint movement

Objectives. The purpose of this study was to calculate the dynamic air gap thickness between the human body and the turnout gear. Relationships between the air gap thickness and joint range of motion (ROM) were also explored. Methods. The air gap thickness and joint ROM of 12 male firefighters walking in a control condition with no self-contained breathing apparatus (SCBA) and three varying-strapped SCBAs were measured using three-dimensional (3D) body scanning and 3D inertial motion capture. The interpolation technique was employed to predict the air gap thickness curve during walking. The dynamic air gap thickness was compared with the joint ROM to see how they relate to the location and percentage of movement restriction. Results. During the walking, the air gap fluctuated as a sine curve. Carrying SCBA reduced the air gap thickness at the trunk most (F = 11.17, p < 0.001, η2 = 0.63), and adjusting the shoulder strap length altered the air gap distribution at the trunk. The reduced air gap at the pelvis caused an incremental restriction on pelvis rotation. Conclusions. A compatibility design of the shoulder strap and hip belt in SCBA with the turnout jacket is suggested.

A biomechanical evaluation of firefighters' musculoskeletal loads when carrying self-contained breathing apparatus in walking and running

INTRODUCTION

Musculoskeletal loading data are needed to design ergonomic intervention for firefighters. This study aimed to quantify the firefighters' musculoskeletal loads during self-contained breathing apparatus (SCBA) carriage and evaluate the effectiveness of shoulder strap length variation for the prevention of SCBA-related injuries.

METHOD

Twelve firefighters (height: 174.6 ± 2.4 cm, mass: 67 ± 3.5 kg, BMI = 22 ± 1 kg/m2) participated the walking and running protocols with no SCBA equipped and three varying-strapped SCBAs conditions. Joint range of motion and surface electromyography (sEMG) were synchronously measured. Subsequently, joint kinematics was inputted for subject-specific musculoskeletal modeling to estimate muscle forces and joint reaction forces, while the sEMG was used to validate the model. Repeated measures analysis of variance was used for the main effects (p < 0.05). Independent samples t-test was performed to determine differences between walking and running.

RESULTS

Walking with SCBA increased the rectus femoris force and hip reaction force by 34.92% [F = 53.629; p < 0.001; η2 = 0.317] and 34.71% [F = 53.653; p < 0.001; η2 = 0.517], the growth rate was 54.2% [F = 76.487; p < 0.001; η2 = 0.418] and 51.19% [F = 69.201; p < 0.001; η2 = 0.652] during running, respectively. Running with SCBA significantly increased the knee reaction force by 63.04% [F = 83.960; p < 0.001; η2 = 0.797], while only 18.49% increase during walking. Adjusting SCBA shoulder strap length significantly altered the rectus abdominis force and L4/L5 reaction force during walking and running.

CONCLUSIONS

Results revealed that rectus femoris activity, hip and knee exertion was sensitive to SCBA carriage. The variation of shoulder strap length has potential to influence the risk of low back pain (LBP).

PRACTICAL APPLICATIONS

The findings suggest that fire services promote targeting physical training at firefighters' hip and knee regions. Test firefighters in this study were not advisable to adjust their shoulder strap at loose-fitting condition. The compatibility design of the trunk morphology and SCBA back-mounted frame was suggested for the management of LBP.

Effect of cooling on static postural balance while wearing firefighter's protective clothing in a hot environment

Objectives. Postural imbalance can result from hyperthermia-mediated muscular fatigue and is a major factor contributing to injuries from falling. The objective of this study was to investigate the effect of exercise-induced hyperthermia and the impact of cooling on postural balance while wearing firefighters' protective clothing (FPC) in a hot environment. Methods. A portable force platform measured postural balance characterized by postural sway patterns using center of pressure metrics. Twelve healthy, physically fit males were recruited to stand on the force platform once with eyes open and once with eyes closed before and after treadmill exercise (40% V ˙ O 2 max ) inside an environmental chamber under hot and humid conditions (30 °C and 70% relative humidity) while wearing FPC. Subjects participated in two randomly assigned experimental phases: control and cooling intervention. Results. A significant increase in physiological responses and postural balance metrics was observed after exercising in the heat chamber while wearing FPC. Cooling resulted in a significant effect only on postural sway speed after exercise-induced hyperthermia. Conclusions. Hyperthermia can negatively alter postural balance metrics, which may lead to an increased likelihood of falling. The utilization of body cooling reduced the thermal strain but had limited impact on postural balance stability.

Does the fit of personal protective equipment affect functional performance? A systematic review across occupational domains

OBJECTIVE

To explore the effect of personal protective equipment (PPE) fit on functional performance across a range of occupational domains.

BACKGROUND

PPE introduces an ergonomic, human systems integration, and mass burden to the wearer, and these factors are thought to be amplified if PPE is ill-fitting. However, few studies have considered the role of fit (static, dynamic, and cognitive) when evaluating PPE-related performance detriments in occupational settings.

METHOD

A systematic literature review was conducted to identify relevant studies, which were then critically appraised based on methodological quality and collated to compare key findings and present evidence-based recommendations for future research directions across a range of occupational domains.

RESULTS

16 published studies met the inclusion criteria, 88% of which found that the fit of PPE had a statistically significant effect on occupational performance. Poorly sized PPE resulted in slower or increased reaction time; decreased range of motion or mobility; decreased endurance or tolerance; decreased pulmonary function; and altered muscle activation. Limited research met the inclusion criteria and those that did had risks of bias in methodology quality.

CONCLUSION

Future research evaluating the effect of PPE on performance in occupational settings should aim to recruit a more representative population; consider sex as a covariate; quantify and evaluate PPE fit and performance when integrated with all relevant equipment items; include outcome measures related to all three categories of fit (static, dynamic, cognitive); and assess performance of operationally relevant tasks.

Firefighters' feet: Differences by sex and weight-bearing

Firefighters have reported their protective boots to be bulky and ill-fitting, which they believe restrict the lower body movement on the unpredictable fireground. This study used 3D foot scanning to compare the shape of firefighters' feet to the general population, the shape of female firefighters' feet to males, and the impact of the heavy fire gear on foot shape. The results found the foot breadth of firefighters was larger than the general population and the feet of female firefighters were slimmer than males. Furthermore, it revealed that the feet of firefighters became longer, wider, and flatter when bearing the weight of fire gear. Protective boots should be designed based on the foot shape and dimensions of the actual population, with consideration of sex differences and the impact of weight-bearing for their safety.

Simultaneous assessment of motor and cognitive tasks reveals reductions in working memory performance following exercise in the heat

This study tested the hypothesis that, following exercise in the heat, motor task performance will be impaired when assessed simultaneously with a cognitive task. In a randomized, crossover and counterbalanced design, twelve healthy adults (23 ± 2 years, 5 women) completed four 10-minute exercise circuits involving upper and lower body exercise in a moderate (18.1 ± 1.7°C, 38 ± 10% relative humidity) and a hot (40.3 ± 1.1°C, 26 ± 5% relative humidity) environment. Experimental testing was completed in a temperate thermal environment before exercise (~25°C) and in either the moderate or hot environment following exercise. The 3 Back test (a test of working memory) was used as the cognitive task and postural sway was used as the motor task. Cognitive and motor task performance assessments were conducted both individually (solo) and simultaneously (dual). At the end of exercise, core temperature (by 0.4 ± 0.3°C, P < 0.001), heart rate (by 12 ± 18 bpm, P = 0.025), and mean skin temperature (by 7.6 ± 0.8°C, P < 0.001) were higher in the Hot trial compared to Moderate. During solo testing, postural sway increased from pre- to post-exercise in the Hot (P ≤ 0.028), but not the Moderate (P ≥ 0.261) trial. During dual testing, postural sway did not differ between trials (P ≥ 0.065) or over time (P ≥ 0.094). During solo testing, 3 Back performance did not differ between trials (P = 0.810) or over time (P = 0.707), but during dual testing 3 Back performance following exercise was reduced in the Hot compared to the Moderate trial (P = 0.028). Simultaneous assessment of motor and cognitive tasks reveals that motor performance is reduced following exercise in the heat. .

Implementation of Kinetic and Kinematic Variables in Ergonomic Risk Assessment Using Motion Capture Simulation: A Review

Work-related musculoskeletal disorders (WMSDs) are among the most common disorders in any work sector and industry. Ergonomic risk assessment can reduce the risk of WMSDs. Motion capture that can provide accurate and real-time quantitative data has been widely used as a tool for ergonomic risk assessment. However, most ergonomic risk assessments that use motion capture still depend on the traditional ergonomic risk assessment method, focusing on qualitative data. Therefore, this article aims to provide a view on the ergonomic risk assessment and apply current motion capture technology to understand classical mechanics of physics that include velocity, acceleration, force, and momentum in ergonomic risk assessment. This review suggests that using motion capture technologies with kinetic and kinematic variables, such as velocity, acceleration, and force, can help avoid inconsistency and develop more reliable results in ergonomic risk assessment. Most studies related to the physical measurement conducted with motion capture prefer to use non-optical motion capture because it is a low-cost system and simple experimental setup. However, the present review reveals that optical motion capture can provide more accurate data.

The Effects of Firefighter Equipment and Gear on the Static and Dynamic Postural Stability of Fire Cadets

BACKGROUND

Slips, trips, falls, and jumps were the second leading cause of injuries at the fireground.

RESEARCH QUESTION

The purpose of this study was to explore the effects of firefighter equipment and gear (EQG) on postural stability and determine if load per kg of body mass (L/BM) is associated with postural stability.

METHODS

26 male fire cadets (26.15 ± 4.16 yr., 178.92 ± 6.92 cm, 86.61 ± 9.09 kg) were included in the analyses. Participants performed 3 single-leg landings (SLL) with and without EQG. The first 3 seconds of ground reaction forces following initial ground contact were used to calculate dynamic postural stability index (DPSI). Participants completed 2 static balance tasks (normal stability and limits of stability (LoS)) with and without EQG. Main outcome measures were overall LoS score (LoSS), direction-specific LoSS, and LoS distance (cm) of COP excursion (LoSD) in the anterior, posterior, right, and left directions. Separate paired-samples t-tests were run to determine the differences between load conditions for DPSI, overall LoSS, direction-specific LoSS, and LoSD in all directions. Bivariate correlations were conducted to determine the relationship of L/BM to DPSI, overall LoSS, and LoSS and LoSD in the anterior, posterior, right and left directions.

RESULTS

Due to the use of multiple statistical tests, a Bonferroni correction was used, and the alpha level of .05 was adjusted to .005. DPSI was significantly higher loaded than unloaded, t(25) = -13.965, p < .001, d = 7.032, 95% CI, -0.133 to -0.099. No other comparisons were significant. A significant strong positive correlation (r(24) = .665, p < .001) was observed between L/BM and DPSI. No other correlations were significant.

SIGNIFICANCE

This study demonstrates that firefighter EQG may significantly impact a cadet's ability to maintain postural stability while performing their duties.

A novel assessment for Readiness Evaluation during Simulated Dismounted Operations: A reliability study

Objective

To determine the intersession reliability of the Readiness Evaluation during Simulated Dismounted Operations (REDOp), a novel ecologically-based assessment for injured Service Members, provide minimal detectable change values, and normative reference range values. To evaluate the ability to differentiate performance limitations between able-bodied and injured individuals using the REDOp.

Design

Repeated measures design and between group comparison.

Setting

Outpatient rehabilitative care setting.

Participants

Service Members who were able-bodied (n = 32) or sustained a traumatic lower extremity injury (n = 22).

Interventions

During the REDOp, individuals walked over variable terrain as speed and incline progressively increased; they engaged targets; and carried military gear.

Main outcome measures

Endurance measured using total distance traveled; walking stability measured using range of full-body angular momentum; and shooting accuracy, precision, reaction time and acquisition time.

Results

Intersession reliability analyses were conducted on a sub-group of 18 able-bodied Service Members. Interclass correlation coefficient values were calculated for distance traveled (0.91), range of angular momentum about three axes (0.78–0.93), shooting accuracy (0.61), precision (0.47), reaction time (0.21), and acquisition time (0.77). Service Members with lower extremity injury demonstrated significantly less distance traveled with a median distance of 0.89 km compared to 2.73 km for the able-bodied group (p < 0.001). Service Members with lower extremity injury demonstrated significantly less stability in the frontal and sagittal planes than the able-bodied group (p < 0.001). The primary performance limiter was endurance followed by pain for both groups. There was no evidence of ceiling effects.

Conclusions

The REDOp is a highly reliable, military-relevant assessment that can be used to measure performance and identify deficits across the domains of activity tolerance, gait stability, and shooting performance.

Firefighter protective clothing and self contained breathing apparatus does not alter balance testing using a standard sensory organization test or motor control test in healthy, rested individuals

BACKGROUND

There is a high rate of injury associated with firefighting: in 2016, 21% of all fireground injuries were attributed to falls, jumps and slips. Examining factors related to balance, including experience in wearing firefighter gear, may assist in reducing injury related to falls.

OBJECTIVES

To assess the effects of wearing firefighter gear on postural balance in firefighters and non-firefighters in a rested condition.

METHODS

Each subject attended two sessions. In session 1, informed consent was obtained, a threshold audiogram was collected, and the sensory organization test (SOT) and motor control test (MCT) were administered with the subject dressed in street clothes. The second session was comprised of three different conditions with the order of testing randomized across subjects: street clothing, firefighter protective garments (coat, pants, helmet, hood) with breathing apparatus but no facemask, and firefighter protective garments with breathing apparatus and facemask. Twenty subjects participated: ten firefighters (8 males) and sex and age-matched non-firefighters (8 males) completed the study.

RESULTS

SOT scores were obtained for each sub-condition, including the overall performance score and sensory weightings. For the MCT, latency and amplitude data were obtained for the three forward and three reverse translation conditions. A significant difference was found for large forward surface translations in the MCT in firefighters.

CONCLUSION

In spite of the altered center of balance created by breathing apparatus and the altered visual cues created by the facemask, wearing firefighter gear did not substantively affect anterior-posterior postural stability or motor response to linear translation in rested, healthy individuals. Firefighters and non-firefighters performed similarly across all except one of the experimental conditions.

The effect of firefighter personal protective equipment on static and dynamic balance

Firefighters work in unpredictable conditions, necessitating the use of personal protective equipment (PPE). However, the additional weight from the PPE and self-contained breathing apparatus (SCBA) alters their centre of mass (COM), restricts movement and limits vision (face mask) contributing to a firefighters' challenge of maintaining balance. Thus, the purpose of this study was to quantify the effects of firefighter PPE on static and dynamic balance. Participants performed two sets of three functional balance tests: (1) Static Single Leg (SSL); (2) Dynamic Single Leg (DSL); (3) Limits of Stability (LOS). The balance tests were performed under one control and three randomised PPE conditions: (1) athletic clothing; (2) turnouts; (3) turnouts + SCBA; (4) turnouts + SCBA + face mask. Our study found turnouts + SCBA both with and without the face mask negatively affected dynamic balance. These findings identify factors in fall-related injuries and strategies to reduce occupational risk. Practitioner summary: Slips, trips and falls are the most common cause of injury in firefighters. Our study investigated the effects of firefighter personal protective equipment (PPE) on static and dynamic balance utilising a computerised balance instrument. We found that turnouts with a self-contained breathing apparatus (SCBA) with or without face mask negatively affected balance.

Postural stability pattern as an important safety factor of firefighters

BACKGROUND

Firefighting is a hazardous profession that involves high fall risk and is crucial component for the safety of people.

OBJECTIVE

The aim of this study was to identify factors that impact on postural stability patterns of firefighters.

METHODS

The study examined 177 Polish firefighters from the National Firefighting and Rescue System (NFRS) aged 31.9±10.1 years, with body height of 179.6±5.93, body mass of 83.9±11.0 and BMI of 26.0±3.03. Postural stability was evaluated by means of the Balance System SD (Biodex USA) set at the level 12 of instability, in a sportswear, bunker gear, with and without visual input. The fall risk test (FRI) was also performed. Four indices were analysed: overall stability index (OSI), anterior-posterior stability index (APSI), medial-lateral stability index (MLSI), and fall risk index (FRI).

RESULTS

Mean results for fall risk index (FRI) were in the normal range for all age groups regardless of the type of clothing the firefighters were wearing. Individual results obtained in the fall risk test, 128 firefighters were in the normal range for their age, furthermore, 10 firefighters obtained better results than the normal range, 34 firefighters had worse results and 5 people failed to complete the test. Postural stability with eyes closed was found to decline with age. Wearing bunker gear did not have an effect on postural stability.

CONCLUSIONS

Balance tests should be integrated into the firefighting training routines in order to improve balance and support fall prevention. Exercises with reduced visual input should also be incorporated into the training methodology.

Using trunk posture to monitor heat strain at work

This study aimed to determine if trunk posture during walking is related to increases in rectal temperature (T_re). 24 males treadmill walked in one of four conditions (1): 30 min at 3.0 mph and 0% grade, 20 °C and 50% relative humidity (RH), wearing healthcare worker (HCW) PPE; (2): 30 min at 3.0 mph and 0% grade, 27.5 °C and 60% RH, HCW PPE; (3): 30 min at 3.0 mph and 0% grade, 32.5 °C and 70% RH, HCW PPE; and (4): 40 min at 40% VO₂max, 30 °C and 70% RH, wearing firefighter PPE. Trunk posture (Zephyr BioHarness 3) and T_re were measured continuously. T_re was positively related to trunk posture, controlling for covariates (B = 3.49, p < .001). BMI and age moderated this relationship (T_re×age, B = 0.76, p < .001; T_re*BMI, B = -1.85, p < .001). Trunk posture measurement may be useful in monitoring fall potential and magnitude of heat stress of workers in hot environments. Practitioner Summary: Occupational hyperthermia increases worker risk for heat illness and injury but is difficult to monitor in the field. This investigation shows that trunk posture is independently and positively related to core temperature. Non-invasive measurement or visual inspection of trunk posture could provide novel insight on individual heat strain level.