Occupational Experience Effects on Physiological and Perceptual Responses of Common Soldiering Tasks.

ABSTRACT: Cohen BS, Redmond JE, Haven CC, Foulis SA, Canino MC, Frykman PN, Sharp MA. Occupational Experience Effects on Physiological and Perceptual Responses of Common Soldiering Tasks. J Strength Cond Res 37(4): 894-901, 2023-This study measured the impact of occupational experience (i.e., time spent deployed, in military service, and in job and task performance frequency in training, deployment, and study practice) on the physiological (heart rate [HR] and oxygen consumption [VO 2 ]) and perceptual (rate of perceived exertion [RPE]) responses to performance of critical physically demanding tasks (CPDTs). Five CPDTs (road march, build a fighting position, move under fire, evacuate a casualty, and drag a casualty to safety), common to all soldiers, were performed by 237 active duty soldiers. Linear regression models examined the association between measures of experience and physiological and perceptual performance responses to task demands. The level of significance was adjusted for multiple comparisons and set at ρ ≤ 0.0125 for this study. Significant and notable effect sizes included the impact of time spent deployed on the physiological measures of the road march (PostHR F = 24.84, p < 0.0001, ß=-9.65), sandbag fill (PostHR F = 8.26, p = 0.005, ß = -2.83), and sandbag carry (MeanHR F = 7.51, p = 0.007, ß = -1.12; PostHR F = 7.35, p = 0.007, ß = -0.87). For the road march task, there was a nearly 10 bpm decrease in postperformance HR for every year spent deployed. Road march, sandbag fill, and sandbag carry tasks PostHRs were also notably negatively associated with the experience measures of time in their MOS (job and time in military service but not for other physiological and perceptual responses, including VO 2 and RPE. Frequency of task performance in training, deployment, and study practice was not meaningfully associated with experience. The results suggest that increasing task familiarization through on-the-job occupational operational experience may result in greater proficiency and reduced physiological effort.

Predicting changes in performance due to cognitive fatigue: A multimodal approach based on speech motor coordination and electrodermal activity.

OBJECTIVE: Military job and training activities place significant demands on service members' (SMs') cognitive resources, increasing risk of injury and degrading performance. Early detection of cognitive fatigue is essential to reduce risk and support optimal function. This paper describes a multimodal approach, based on changes in measures of speech motor coordination and electrodermal activity (EDA), for predicting changes in performance following sustained cognitive effort. METHODS: Twenty-nine active duty SMs completed computer-based cognitive tasks for 2 h (load period). Measures of speech derived from audio were acquired, along with concurrent measures of EDA, before and after the load period. Cognitive performance was assessed before and during the load period using the Automated Neuropsychological Assessment Metrics Military Battery (ANAM MIL). Subjective assessments of cognitive effort and alertness were obtained intermittently. RESULTS: Across the load period, participants' ratings of cognitive workload increased, while alertness ratings declined. Cognitive performance declined significantly during the first half of the load period. Three speech and arousal features predicted cognitive performance changes during this period with statistically significant accuracy: EDA (r = 0.43, p = 0.01), articulator velocity coordination (r = 0.50, p = 0.00), and vocal creak (r = 0.35, p = 0.03). Fusing predictions from these features predicted performance changes with r = 0.68 (p = 0.00). CONCLUSIONS: Results suggest that speech and arousal measures may be used to predict changes in performance associated with cognitive fatigue. This work supports ongoing efforts to develop reliable, unobtrusive measures for cognitive state assessment aimed at reducing injury risk, informing return to work decisions, and supporting diverse mobile healthcare applications in civilian and military settings.

Effect of Environmental Temperature and Humidity on Permethrin Biomarkers of Exposure in U.S. Soldiers Wearing Permethrin-Treated Uniforms.

Environmental factors, including high temperature and humidity, can influence dermal absorption of chemicals. Soldiers can be dermally exposed to permethrin while wearing permethrin-treated uniforms. This study aimed at examining the effects of high temperature and a combined high temperature and humid environment on permethrin absorption compared with ambient conditions when wearing a permethrin-treated uniform. Twenty-seven male enlisted soldiers wore study-issued permethrin-treated army uniforms for 33 consecutive hours in three different environments: 1) simulated high temperature (35°C, 40% relative humidity [rh]) (n = 10), 2) simulated high temperature and humidity (30°C, 70% rh) (n = 10), and 3) ambient conditions (13°C, 60% rh) (n = 7). Spot urine samples, collected at 21 scheduled time points before, during, and after wearing the study uniforms, were analyzed for permethrin exposure biomarkers (3-phenoxybenzoic acid, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid) and creatinine. Biomarker concentrations were 60-90% higher in the heat and combined heat/humidity groups (P < 0.001-0.022) than the ambient group. Also, the average daily permethrin dose, calculated 12 hours after removing the treated uniforms, was significantly higher in the heat (P = 0.01) and the heat/humidity (P = 0.03) groups than the ambient group. There were no significant differences in biomarker concentrations or computed average daily dose between the heat and the heat/humidity groups. Both hot and combined hot and humid environmental conditions significantly increased permethrin absorption in soldiers wearing permethrin-treated uniforms.

Relationship of Anthropometric Measures on Female Trainees' and Active Duty Soldiers' Performance of Common Soldiering Tasks.

INTRODUCTION: This study compared the relationship between height (HT), body mass (BM), and body mass index (BMI) of female trainees and active duty female soldiers and their performance on simulated common soldiering tasks (CSTs) with high physical demands. METHODS: Female trainees (n = 133) and soldiers (n = 229) completed the following CSTs: sandbag carry, move under fire, casualty drag, casualty evacuation, and road march. Quartiles were created among HT, BM, and BMI by which task performance was compared using ANOVAs with Tukey post hoc comparisons. RESULTS: For both trainees and soldiers, HT, BM, and BMI were positively associated with improved road march, casualty drag, casualty evacuation, and sandbag carry performance. On the move under fire task, only soldier HT was positively associated with improved performance. CONCLUSION: Female trainees and soldiers who are taller and heavier with a higher BMI may demonstrate better performance on CSTs required of all soldiers. In addition to task-specific training, performance of CSTs may be enhanced in tasks requiring strength and power by recruiting and retaining taller and heavier females with a higher BMIs. Allowances should be considered for soldiers and trainees who can successfully perform soldiering tasks with high physical demands despite less desirable anthropometric measurements.

The Effect of Body Composition and Energy Expenditure on Permethrin Biomarker Concentrations Among US Army National Guard Members.

OBJECTIVE: To examine relationships between percent body fat (%BF) and total energy expenditure (TEE) on permethrin exposure among Army National Guard (ARNG) Soldiers wearing permethrin-treated uniforms. METHODS: ARNG members (n = 47) participated in a 9-day study. Repeated body composition (height, weight, %BF) measurements and daily urine samples, analyzed for permethrin and N,N-diethyl-meta-toluamide (DEET) metabolites, were collected. TEE was determined via doubly labeled water protocol. Linear mixed and regression models were used for analyses. RESULTS: Neither %BF nor TEE were significantly associated with permethrin or DEET biomarkers. However, a significant interaction effect (F = 10.76; P = 0.0027) between laundering history and %BF was observed; 10% higher %BF was significantly associated with 25% higher permethrin biomarker concentrations among those wearing uniforms washed less than or equal to 25 (compared with more than 25) times. CONCLUSIONS: Uniform laundering history significantly affects the association between %BF and permethrin-treated uniform exposure.

Permethrin exposure from wearing fabric-treated military uniforms in high heat conditions under varying wear-time scenarios.

This study examined the effect of high-temperature conditions and uniform wear time durations (expeditionary, 33 h continuous wear; garrison, 3 days, 8 h/day wear) on permethrin exposure, assessed by urinary permethrin biomarkers, from wearing post-tailored, factory-treated military uniforms. Four group study sessions took place over separate 11-day periods, involving 33 male Soldiers. Group 1 (n = 10) and Group 2 (n = 8) participants wore a study-issued permethrin-treated Army uniform under high heat environment (35 °C, 40% relative humidity (rh)) and expeditionary and garrison wear-time conditions, respectively. For comparison, Group 3 (n = 7) and Group 4 (n = 8) participants wore study-issued permethrin-treated uniforms in cooler ambient conditions under operational and garrison wear-time conditions, respectively. Urinary biomarkers of permethrin (3-phenoxybenzoic acid, and the sum of cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid) were significantly higher under high temperature compared to ambient conditions, regardless of wear-time situations (Group 1 vs. Group 3; Group 2 vs. Group 4; p < 0.001, for both). Under high-temperature conditions, expeditionary (continuous) compared to garrison wear-time resulted in significantly (p < 0.001) higher urinary biomarker concentrations (Group 1 vs. Group 2). Differences related to wear-time under the ambient conditions (Group 3 vs. Group 4) were not statistically significant. Findings suggest that wearing permethrin-treated clothing in heat conditions results in higher internal dose of permethrin above that observed under ambient conditions.

Role of body composition and physical activity on permethrin urinary biomarker concentrations while wearing treated military uniforms.

Wearing of permethrin treated clothing is becoming more prevalent in military and outdoor occupational and recreational settings, as a personal protection measure against vector borne diseases transmitted through arthropods (e.g., malaria, Lyme disease). The goal of the study was to prospectively examine permethrin exposure among new U.S. Army recruits who had just been issued permethrin-treated uniforms over a 10-week military training period and whether individual body composition (percent body fat, %BF) and physical workload (total energy expenditure, TEE) influenced the exposure. Exposure was assessed by quantification in urine of three permethrin metabolites, 3-phenoxybenzoic acid (3-PBA), and cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid. Although there was individual variability, urinary concentrations and estimated dose levels decreased over the 10-week period. Mixed models demonstrated that 10% higher %BF was significantly associated with 4.42% higher 3-PBA concentrations and a 10% higher daily TEE was significantly associated with a 10.57% higher 3-PBA concentrations. Additional factors influencing exposure included sex, number of uniform launderings, and wear- time (hours per previous day).