Effect of protective gloves on hand movement: an exploratory study

This exploratory study was conducted to determine whether wearing protective gloves limits the range of motion that the hand can complete. The kinematic motion of the hand/wrist/forearm of two participants was analysed during the performance of two tasks typical of pesticide applicators. High-speed cinematography was used to collect data which were then digitized and combined to produce three-dimensional data. Graphs of the transformed data showed that in comparison with the barehanded state, the protective glove decreased the abduction/adduction and supination/pronation ranges that the hand could complete. Extension/flexion did not appear to be affected. Overall, kinematic motion of the hand appeared to decrease while wearing protective gloves.     

Stepping over obstacles of different heights and varied shoe traction alter the kinetic strategies of the leading limb

This study aims to investigate the effects of shoe traction and obstacle height on friction during walking to better understand the mechanisms required to avoid slippage following obstacle clearance. Ten male subjects walked at a self-selected pace during eight different conditions: four obstacle heights (0%, 10%, 20% and 40% of limb length) while wearing two different pairs of shoes (low and high traction). Frictional forces were calculated from the ground reaction forces following obstacle clearance, which were sampled with a Kistler platform at 960 Hz. All frictional peaks increased with increases in obstacle height. Low traction shoes yielded smaller peaks than high traction shoes. The transition from braking to propulsion occurred sooner due to altered control strategies with increased obstacle height. Collectively, these results provided insights into kinetic strategies of leading limb when confronted with low traction and high obstacle environments. This study provides valuable information into the adaptations used to reduce the potential of slips/falls when confronted with environments characterised by low shoe-floor friction and obstacles. It also provides the necessary foundation to explore the combined effects of shoe traction and obstacle clearance in elderly people, more sensitive to slippage.     

A review of: “Human Motor Actions: Bernstein Reassessed.” Edited by H. T. A. WHITING. (Oxford: North-Holland, 1984.) [Pp. xxxv + 633.] ISBN 0-444-86813-5.

The physical work performance of eight fit fire fighters wearing fire brigade uniforms and wearing breathing apparatus was assessed. They were tested in a climatic chamber set at temperatures of 15 and 45°C respectively. The test was performed with and without fire fighting equipment. The subjects walked on a treadmill at a speed of 3.5km/h, which produce a workload equivalent of 20% of the subjects' maximal oxygen uptake without equipment, and 30% with equipment. The test lasted for 60 min. Heart rate, oxygen uptake, skin and deep body temperatures were measured during the test. The subjects estimated perceived physical exertion and perceived temperature. Wearing fire fighting equipment increased the oxygen uptake by 0.4 1min^-1. Heart rate at the end of the experiments reached near-maximum levels when the temperature was 45°C with equipment, and deep body temperature increased to an average of 38.7°C. The subjects' ratings of perceived exertion were highly correlated to heart rate. The loading induced by heat and protective equipment reduced the ability to perform strenuous work. The combination of thick clothing and heavy breathing apparatus was found to have a significant limiting effect on the endurance of fire fighters.     

Restriction to movement in fire-fighter protective clothing: evaluation of alternative sleeves and liners

The purpose of this study was to evaluate alternative designs and liner configurations in fire-fighter protective clothing, or 'turnout gear', to determine the restriction to wearer movement imposed by each. The independent variables were: (1) two alternative sleeve designs (i e, a 'traditional' sleeve design and a prototype sleeve design, featuring additional gusset width and altered armseye position) plus a station uniform worm without any protective clothing and/or equipment; (2) three liner configuration variations (i e, a 'traditional' liner configuration, incorporation of one additional liner, and incorporation of two additional liners); and (3) wearing or not wearing an SCBA (self-contained breathing apparatus). The dependent variables for this study were: (1) range of movement in four upper body joints; and (2) a semantic differential scale to evaluate wearers' subjective evaluation of each protective ensemble. Nine male subjects were used. For each of the four joint movements measured (i e, shoulder flexion/extension, shoulder adduction/abduction, shoulder rotation, elbow flexion/extension), a Leighton Flexometer was strapped to the subject at the appropriate body location. The subject was instructed to take the body position indicated. A reading was taken, then the subject was asked to move the body segment to the fullest extent possible in the direction indicated by the researcher. A second reading (representing range of movement) was taken. This procedure was repeated three times for each movement. After the test, subjects were instructed to fill out a semantic differential scale which described their subjective evaluations of the clothing/ equipment configuration. Results showed greater wearer range of movement in the elbow area for the prototype sleeve design over the more traditional sleeve design. Incorporation of additional liners resulted in higher wearer acceptability for the turnout coats than when these liners were not used. As expected, use of an SCBA was extremely restrictive to mobility, and made the protective ensemble less acceptable to wearers.     

Defining soldier equipment trade space: load effects on combat marksmanship and perception–action coupling

Soldier equipment compromises task performance as temporal constraints during critical situations and load increase inertial and interactive forces during movement. Methods are necessary to optimise equipment that relate task performance to underlying coordination and perception–action coupling. Employing ecological task analysis and methods from dynamical systems theory, equipment load and coordination was examined during two sub-tasks embedded in combat performance, threat discrimination and dynamic marksmanship. Perception–action coupling was degraded with load during threat discrimination, leading to delays in functional reaction time. Reduced speed and accuracy during dynamic marksmanship under load was related to disrupted segmental coordination and adaptability during postural transitions between targets. These results show how reduced performance under load relates to coordination changes and perception–action coupling. These changes in functional capability are directly related to soldier survivability in combat. The methods employed may aid equipment design towards more optimised performance by modifying equipment or its distribution on humans.     

电力无线单兵检测设备参数实时监测技术研究

针对传统电力无线单兵检测设备的实时估计能力低等问题,提出一种基于统计特征分析的电力无线单兵检测设备参数实时监测技术,通过对该设备参数进行实时监测,提高其性能监测和实时估计能力。采用无线传感器技术采集电力无线单兵检测设备参数实时数据,结合大数据统计特征分析方法对获得参数数据进行信息融合处理,并完成电力无线单兵检测设备参数实时统计,提取设备参数的谱特征量,通过时频分析和小波尺度分解方法,实现对电力无线单兵检测设备参数实时监测。实验结果表明,采用该方法监测电力无线单兵检测设备参数的实时估计能力高,稳定收敛性好,监测误差低。     

The effect of flexible body armour on pulmonary function

The additional mass and fit of current military in-service body armour (ISBA) can reduce pulmonary function in a way that is characteristic of a restrictive respiratory impairment. This could ultimately impair exercise capacity and military performance. This study compared pulmonary function (forced vital capacity [FVC] and forced expiratory volume in 1 s [FEV₁]) in UK ISBA (15.3 kg) and three flexible body armours (BAs) (FA1: 10 kg; FA2: 7.8 kg; FA3: 10 kg) in eight male soldiers. The design of the ballistic plates differed between the BAs to improve the flexibility. FVC and FEV₁ were reduced by 4–6%, without reduction in FEV₁/FVC for ISBA, FA2 and FA3, when compared to NoBA (p < 0.05). No difference was observed between FA1 and NoBA. As expected, wearing BA caused a mild restrictive ventilatory impairment; however, modifications to BA design can reduce the degree of this impairment.

Practitioner Summary: This study showed that wearing body armour caused a mild restrictive ventilatory impairment. However, the design of the armour can be modified to reduce the degree of this impairment. This may lead to improvements in soldier performance during tasks that require body armour.     

The influence of firefighter boot type on balance

A firefighter's boots play a critical role in working effectiveness and personal safety. OSHA 1910.156 contains standards for personal protective equipment of fire brigades. Firefighters use either rubber or leather boots that meet these requirements. The purpose of the study was to examine the differences in balance in professional firefighters wearing rubber and leather boots when participating in a fire simulation activity. Twelve professional firefighters performed 2 sets of a three-minute simulated firefighter stair climb wearing a 50 lb weighted vest to simulate their typical personal protective equipment and two 5.68 kg weights on the shoulders to simulate the weight of a high-rise pack (hose bundle). On each condition day (leather, rubber) the firefighter conducted a balance assessment. Following the initial balance protocol, the firefighter conducted a Simulated Firefighter Stair Climb for 3 min at a rate of 60 steps per/min. At the completion of the stair climb, the firefighter repeated the balance procedure. Following a 3-minute rest period, the complete procedure (balance, stair climb) was repeated. A total of 3 balance procedures and 2 stair climbs were completed. Significant differences were found in sway velocity between the pre and post test measures and among the two different boots. These results suggest that the rubber boots elicit greater postural instability. These findings provide practical information on work practices and PPE usage decisions.Relevance to industryIndustry standards dictate the protective variables of boots used by fire brigades, but do not consider the influence on gait and balance. This study provides evidence that the rubber boots used by firefighters may impair specific balance parameters which are critical for firefighter safety.     

The addition of stripes (a version of the ‘horizontal-vertical illusion’) increases foot clearance when crossing low-height obstacles

Trips over obstacles are one of the main causes of falling in older adults, with vision playing an important role in successful obstacle negotiation. We determined whether a horizontal-vertical illusion, superimposed onto low-height obstacles to create a perceived increase in obstacle height, increased foot clearances during obstacle negotiation thus reducing the likelihood of tripping. Eleven adults (mean ± 1?SD: age 27.3 ± 5.1 years) negotiated obstacles of varying heights (3, 5, 7 cm) with four different appearance conditions; two were obstacles with a horizontal-vertical illusion (vertical stripes of different thickness) superimposed on the front, one was a plain obstacle and the fourth a plain obstacle with a horizontal black line painted on the top edge. Foot clearance parameters were compared across conditions. Both illusions led to a significant increase in foot clearance when crossing the obstacle, compared to the plain condition, irrespective of obstacle height. Superimposing a horizontal-vertical illusion onto low-height obstacles can increase foot clearance, and its use on the floor section of a double-glazing door frame for example may reduce the incidence of tripping in the home.

Practitioner Summary: Low-height obstacles such as the floor section of a double-glazing door frame are potential tripping hazards. In a gait lab-based study we found that a horizontal-vertical illusion superimposed onto low-height obstacles led to significantly higher foot clearances; indicating their potential as a useful safety measure.     

Effects of chemical protective equipment on team process performance in small unit rescue operations

In the event of a nuclear, biological, or chemical terrorist attack against civilians, both military and civilian emergency response teams must be able to respond and operate efficiently while wearing protective equipment. Chemical protective equipment protects the user by providing a barrier between the individual and hazardous environment. Unfortunately, the same equipment that is designed to support the user can potentially cause heat stress, reduced task efficiency, and reduced range-of-motion. Targeted Acceptable Responses to Generated Events of Tasks (TARGETS), an event-based team performance measurement methodology was used to investigate the effects of Mission Oriented Protective Posture (MOPP) on the behavioral processes underlying team performance during simulated rescue tasks. In addition, this study determined which team processes were related to team performance outcomes. Results of six primary analyses indicated that team process performance was not degraded by MOPP 4 on any rescue task and that the team processes critical for successful task performance are task-dependent. This article discusses the implications of these results with respect to the study design and the limitations of using an event-based team performance measurement methodology.     

Statistical prediction of eye locations for drivers of military ground vehicles

In this paper, a statistical model is developed to predict the driver eye locations in military ground vehicles. The data were taken from a study on soldier driving postures and seating positions. The distribution of eye locations is represented by an “eyellipse”, a geometric construction that approximates the distribution of the eye locations using an ellipse. Eyellipses have been widely used for the design of passenger cars and commercial trucks. The location and dimensions of the soldier eyellipse were developed based on the data from 145 male and female soldiers who selected their preferred driving postures in a range of vehicle layouts presented in a vehicle mockup. Driver eye locations were modeled using regression analysis. The model predicts the distribution of eye locations as a function of vehicle interior layout for a soldier population defined by the gender ratio (fraction male) and the distribution of body dimensions within each gender. This is the first eyellipse model taking into account the effects of protective equipment and body-borne gear. The model has broad applicability to the design of tactical, truck-like vehicles with fixed accelerator heel points.     

Protective clothing systems: A technique for evaluating restriction of wearer mobility

To allow designers to evaluate presently available protective clothing systems (as well as aiding the development of less restrictive systems), it is necessary to develop evaluation techniques to quantify the loss of mobility associated with wearing protective clothing. Using fire fighter turnout gear, this study illustrated the application of the Leighton Flexometer for the measurement of restriction to body movement caused by wearing protective clothing and equipment. Statistical analyses indicated significant differences in restriction to body movement between the designs of protective clothing and equipment configurations tested. Additionally, correlation coefficients between trials established values for tes-retest reliability.     

Skin sites to predict deep-body temperature while wearing firefighters’ personal protective equipment during periodical changes in air temperature

The aim of this study was to investigate stable and valid measurement sites of skin temperatures as a non-invasive variable to predict deep-body temperature while wearing firefighters’ personal protective equipment (PPE) during air temperature changes. Eight male firefighters participated in an experiment which consisted of 60-min exercise and 10-min recovery while wearing PPE without self-contained breathing apparatus (7.75 kg in total PPE mass). Air temperature was periodically fluctuated from 29.5 to 35.5 °C with an amplitude of 6 °C. Rectal temperature was chosen as a deep-body temperature, and 12 skin temperatures were recorded. The results showed that the forehead and chest were identified as the most valid sites to predict rectal temperature (R² = 0.826 and 0.824, respectively) in an environment with periodically fluctuated air temperatures. This study suggests that particular skin temperatures are valid as a non-invasive variable when predicting rectal temperature of an individual wearing PPE in changing ambient temperatures.

Practitioner Summary: This study should offer assistance for developing a more reliable indirect indicating system of individual heat strain for firefighters in real time, which can be used practically as a precaution of firefighters’ heat-related illness and utilised along with physiological monitoring.     

Additional helmet and pack loading reduce situational awareness during the establishment of marksmanship posture

Abstract

The pickup of visual information is critical for controlling movement and maintaining situational awareness in dangerous situations. Altered coordination while wearing protective equipment may impact the likelihood of injury or death. This investigation examined the consequences of load magnitude and distribution on situational awareness, segmental coordination and head gaze in several protective equipment ensembles. Twelve soldiers stepped down onto force plates and were instructed to quickly and accurately identify visual information while establishing marksmanship posture in protective equipment. Time to discriminate visual information was extended when additional pack and helmet loads were added, with the small increase in helmet load having the largest effect. Greater head-leading and in-phase trunk–head coordination were found with lighter pack loads, while trunk-leading coordination increased and head gaze dynamics were more disrupted in heavier pack loads. Additional armour load in the vest had no consequences for Time to discriminate, coordination or head dynamics. This suggests that the addition of head borne load be carefully considered when integrating new technology and that up-armouring does not necessarily have negative consequences for marksmanship performance.

Practitioner Summary: Understanding the trade-space between protection and reductions in task performance continue to challenge those developing personal protective equipment. These methods provide an approach that can help optimise equipment design and loading techniques by quantifying changes in task performance and the emergent coordination dynamics that underlie that performance.     

“Extra-Ordinary” Ergonomics: How to Accommodate Small and Big Persons,the Disabled and Elderly,Expectant Mothers,and Children

Abstract

Data from a previous study of soldier driving postures and seating positions were analysed to develop statistical models for defining accommodation of driver seating positions in military vehicles. Regression models were created for seating accommodation applicable to driver positions with a fixed heel point and a range of steering wheel locations in typical tactical vehicles. The models predict the driver-selected seat position as a function of population anthropometry and vehicle layout. These models are the first driver accommodation models considering the effects of body armor and body-borne gear. The obtained results can benefit the design of military vehicles, and the methods can also be extended to be utilised in the development of seating accommodation models for other driving environments where protective equipment affects driver seating posture, such as vehicles used by law-enforcement officers and firefighters.

Practitioner Summary: A large-scale laboratory study of soldier driving posture and seating position was designed to focus on tactical vehicle (truck) designs. Regression techniques are utilised to develop accommodation models suitable for tactical vehicles. These are the first seating accommodation models based on soldier data to consider the effects of personal protective equipment and body-borne gear.     

The effects of shoe traction and obstacle height on lower extremity coordination dynamics during walking

This study aims to investigate the effects of shoe traction and obstacle height on lower extremity relative phase dynamics (analysis of intralimb coordination) during walking to better understand the mechanisms employed to avoid slippage following obstacle clearance. Ten participants walked at a self-selected pace during eight conditions: four obstacle heights (0%, 10%, 20%, and 40% of limb length) while wearing two pairs of shoes (low and high traction). A coordination analysis was used and phasing relationships between lower extremity segments were examined. The results demonstrated that significant behavioral changes were elicited under varied obstacle heights and frictional conditions. Both decreasing shoe traction and increasing obstacle height resulted in a more in-phase relationship between the interacting lower limb segments. The higher the obstacle and the lower the shoe traction, the more unstable the system became. These changes in phasing relationship and variability are indicators of alterations in coordinative behavior, which if pushed further may have lead to falling.     

The effects of wearing respirators on human fine motor,visual, and cognitive performance

When selecting a respirator, it is important to understand how employees' motor, visual and cognitive abilities are impacted by the personal protective equipment. This study compares dust, powered-air-purifying and full-face, negative-pressure respirators. Thirty participants performed three varied tasks. Each participant performed each task without a respirator and while wearing the three respirator types. The tasks included a hand tool dexterity test, the Motor-Free Visual Perception Test and the Serial Sevens Test to evaluate fine motor, visual and cognitive performance, respectively. The time required for task completion and the errors made were measured. Analysis showed no significant effect due to respirator use on the task completion time. A significant increase was found in the error rate when participants performed the cognitive test wearing the full-face, negative-pressure respirator. Participants had varying respirator preferences. They indicated a potential for full-face, negative-pressure respirators to negatively affect jobs demanding high cognitive skills such as problem solving and decision-making.

Practitioner summary: while respirators are life-saving personal protective equipment (PPE), they can unintentionally reduce human performance, especially if job characteristics are not considered during PPE selection. An experiment was conducted to compare three respirators (dust respirator, powered-air-purifying respirators and full-face respirator) for varying task types. The full-face respirator was found to affect human cognitive performance negatively.     

Effects of wearing aircrew protective clothing on physiological and cognitive responses under various ambient conditions

Heat stress can be a significant problem for pilots wearing protective clothing during flights, because they provide extra insulation which prevents evaporative heat loss. Heat stress can influence human cognitive activity, which might be critical in the flying situation, requiring efficient and error-free performance. This study investigated the effect of wearing protective clothing under various ambient conditions on physiological and cognitive performance. On several occasions, eight subjects were exposed for 3 h to three different environmental conditions; 0 degrees C at 80% RH, 23 degrees C at 63% RH and 40 degrees C at 19% RH. The subjects were equipped with thermistors, dressed as they normally do for flights (including helmet, two layers of underwear and an uninsulated survival suit). During three separate exposures the subjects carried out two cognitive performance tests (Vigilance test and DG test). Performance was scored as correct, incorrect, missed reaction and reaction time. Skin temperature, deep body temperature, heart rate, oxygen consumption, temperature and humidity inside the clothing, sweat loss, subjective sensation of temperature and thermal comfort were measured. Rises in rectal temperature, skin temperature, heart rate and body water loss indicated a high level of heat stress in the 40 degrees C ambient temperature condition in comparison with 0 degrees C and 23 degrees C. Performance of the DG test was unaffected by ambient temperature. However, the number of incorrect reactions in the Vigilance test was significantly higher at 40 degrees C than at 23 degrees C (p = 0.006) or 0 degrees C (p = 0.03). The effect on Vigilance performance correlated with changes in deep-body temperature, and this is in accordance with earlier studies that have demonstrated that cognitive performance is virtually unaffected unless environmental conditions are sufficient to change deep body temperature.     

Heat stress while wearing long pants or shorts under firefighting protective clothing

It was the purpose of this study to examine whether replacing long pants (P) with shorts (S) would reduce the heat stress of wearing firefighting protective clothing during exercise in a warm environment. Twenty-four Toronto Firefighters were allocated to one of four groups that performed heavy (H, 4.8 km x h(-1), 5% grade), moderate (M, 4.5 km x h(-1), 2.5% grade), light (L, 4.5 km x h(-1)) or very light (VL, 2.5 km x h(-1)) exercise while wearing their full protective ensemble and self-contained breathing apparatus. Participants performed a familiarization trial followed by two experimental trials at 35 degrees C and 50% relative humidity wearing either P or S under their protective overpants. Replacing P with S had no impact on the rectal temperature (Tre) or heart rate response during heavy or moderate exercise where exposure times were less than 1 h (40.8 +/- 5.8 and 53.5 +/- 9.2 min for H and M, respectively while wearing P, and 43.5 +/- 5.3 and 54.2 +/- 8.4 min, respectively while wearing S). In contrast, as exposure times were extended during lighter exercise Tre was reduced by as much as 0.4 degrees C after 80 min of exercise while wearing S. Exposure times were significantly increased from 65.8 +/- 9.6 and 83.5 +/- 11.6 min during L and VL, respectively while wearing P to 73.3 +/- 8.4 and 97.0 +/- 12.5 min, respectively while wearing S. It was concluded that replacing P with S under the firefighting protective clothing reduced the heat stress associated with wearing the protective ensemble and extended exposure times approximately 10 - 15% during light exercise. However, during heavier exercise where exposure times were less than 1 h replacing P with S was of little benefit.     

Measuring the effects of structural turnout suits on firefighter range of motion and comfort

Abstract

Range of motion (ROM) can be restricted by wearing stiff and bulky clothing. This is particularly true of firefighter suits that are constructed using fabric layers to provide thermal protection from fire. This study developed an evaluation technique to quantify the loss of mobility associated with wearing firefighters’ protective suits that were deliberately selected to represent similar ergonomic design features. The ROM of 10 firefighters was measured using electro-goniometers attached to their bodies while they wore uniforms and a reference outfit, and performed specific movements. The most restrictive uniform is the Bulky suit that contained additional layers of materials in sleeves and on the knees. The Traditional Suit was more ROM restrictive than Ergonomic. The subjective evaluation of suits supported the objective assessments provided by the electro-goniometers. A 3-D body scanning technique was employed to establish a correlation between the bulkiness of firefighter outfits and subject ROM.

Practitioner Summary: This study presents a methodology for measurements of range of motion (ROM) in firefighters wearing personal protective equipment (PPE). Even small differences in designs of PPE may impact firefighters’ ROM, which can be detected by electro-goniometers providing measurements if they are attached along the joint to measure limb angular movement.