Anthropometrics and body composition predict performance during a simulated direct-fire engagement.

This study determined anthropometric and body composition predictors of performance during a simulated direct-fire engagement. Healthy subjects (N = 33, age = 25.7 ± 7.0 yr) underwent anthropometric and body composition assessments before completing a simulated direct-fire engagement - consisting of marksmanship with cognitive workload assessment and a fire-and-move drill (16 × 6-m sprints) while wearing combat load. Susceptibility to enemy fire was modelled on sprint duration. Partial correlations and multiple linear regressions established the relationships between predictors and performance outcomes, controlling for age and sex. Significance was p ≤ 0.05. Higher percent body fat, fat mass, fight load index predicted greater susceptibility to enemy fire (r = 0.40 to 0.42) and lower cognitive performance (r= -0.45 to -0.49). Higher BMI also predicted lower cognitive performance (r= -0.49). Shorter stature/hand length predicted higher marksmanship accuracy (r= -0.40), while higher fat-free mass/fat-free mass index predicted slower reaction times (r = 0.36-0.41). These data suggest anthropometric and body composition measures modulate combat effectiveness and reinforce body composition standards in military organisations.Practitioner summary: This study identified field-expedient anthropometric and body composition predictors of a simulated direct-fire engagement that evaluated survivability (i.e. susceptibility to enemy fire) and lethality (i.e. marksmanship, cognitive performance) outcomes. Our findings suggest that anthropometric and body composition measures may play a role in soldier survivability and lethality during simulated direct-fire engagements.

Lower-body muscular power and exercise tolerance predict susceptibility to enemy fire during a tactical combat movement simulation.

This study examined if field-expedient physical fitness/performance assessments predicted performance during a simulated direct-fire engagement. Healthy subjects (n = 33, age = 25.7 ± 7.0 years) completed upper- and lower-body strength and power assessments and a 3-min all-out running test to determine critical velocity. Subjects completed a simulated direct-fire engagement that consisted of marksmanship with cognitive workload assessment and a fire-and-move drill (16 × 6-m sprints) while wearing a combat load. Susceptibility to enemy fire was modelled on average sprint duration during the fire-and-move drill. Stepwise linear regression identified predictors for the performance during the simulated direct-fire engagement. Critical velocity (ß = -0.30, p < 0.01) and standing broad jump (ß = -0.67, p < 0.001) predicted susceptibility to enemy fire (R2 = 0.74, p < 0.001). All predictors demonstrated poor relationships with marksmanship accuracy and cognitive performance. These data demonstrate the importance of exercise tolerance and lower-body power during simulated direct-fire engagements and provide potential targets for interventions to monitor and enhance performance and support soldier survivability. Practitioner Summary: This study identified field-expedient physical fitness/performance predictors of a simulated direct-fire engagement which evaluated susceptibility to enemy fire, marksmanship, and cognitive performance. Our findings suggest that high-intensity exercise tolerance and lower-body power are key determinants of performance that predicted susceptibility to enemy fire.

Non-Traditional Physical Education Classes Improve High School Students' Movement Competency and Fitness: A Mixed-Methods Program Evaluation Study.

Non-traditional physical education (PE) programs may facilitate functional movement patterns and develop fitness and work capacity to facilitate long-term physical activity. This program evaluation study compared changes in body composition, movement competency, work capacity, and fitness for high school students in CrossFit or weight training PE; both classes were hypothesized to improve each area, with greater improvements in the CrossFit class. Students participated in 57 min classes 4 days per week for 9 months. Measures including body composition, movement competencies (squat, lunge, push-up, pull-up, hinge, and brace), work capacity (two CrossFit workouts), and fitness (air squats, push-ups, inverted row, plank hold, horizontal and vertical jumps, 5 rep max back squat and press, 500 m bike, and 12 min run) were taken at baseline, midpoint, and post-test. Focus groups to assess students' experiences and outcomes were conducted at post-test. Students significantly improved in movement competencies (ps = 0.034 to <0.001), work capacity (ps < 0.001), and all fitness tests (ps = 0.036 to <0.001). The CrossFit class was only superior on the 500 m bike. Four themes were identified from the focus groups: (1) increased self-confidence, (2) health improvements, (3) newfound community, and (4) translational sports improvements. Future research should examine changes using an experimental design.

Effects of the COVID-19 Pandemic on Physical Activity Behavior across Domains and Settings.

COVID-19 restrictions and alterations to daily living (e.g. working from home, caregiving responsibilities) necessitated changes in physical activity (PA) behavior. The purpose of this study was to understand how PA within specific domains and behavior settings changed during the COVID-19 pandemic, as well as the extent to which PA increased or decreased as a function of participants' gender, work location (i.e., home vs. jobsite) and caregiving responsibilities. An e-survey, conducted April-June 2020, examined changes in PA across domains and settings in a national sample of 805 adults. Respondents reported domain-specific increases in household and recreational PA, but decreases in active transportation, occupational PA, and public transportation use. Weekly minutes of PA changed significantly across all behavior settings, with reported increases in home-based, neighborhood, parks/trails, and total PA, and decreases in PA through recreational sports and fitness facilities. Total weekly PA minutes increased by 10.6%. Those with caregiving responsibilities reported increases in household PA and PA frequency, whereas those without caregiving responsibilities were more likely to report increases in sitting. Those working from home reported a larger increase in neighborhood PA. Those working at a jobsite with caregiving responsibilities reported less weekly PA, while those working from home with caregiving responsibilities reported greater weekly PA. The overall increase in weekly PA minutes and ability to adapt to different domains/settings was encouraging. Future interventions should capitalize on domain- and setting-specific changes, while considering work location and caregiving responsibilities to develop innovative PA promotion strategies.

Effects of Caffeine on Exercise Duration, Critical Velocity, and Ratings of Perceived Exertion During Repeated-Sprint Exercise in Physically Active Men.

Caffeine improves short-to-moderate distance running performance, but the effect of caffeine on repeated sprints are equivocal. This research determined if caffeine improved exercise tolerance during repeated-sprint exercise. iCV is a running velocity that distinguishes intermittent running velocities (velocities ≤ iCV) that are sustainable from those resulting in a predictable time to exhaustion (velocities > iCV). Seven physically active men (age = 21.6 ± 1.5 years, body mass = 72.8 ± 5.1 kg, VO2max = 56.9 ± 9.8 mL/kg/min) ingested caffeine (5 mg/kg) or placebo (crossover design) 60 min prior to an intermittent critical velocity (iCV) test. The treadmill grade and velocity at VO2max (vVO2max) were used for iCV testing, and consisted of 3 bouts (10 sec running and 10 sec passive rest) at 130, 110 and 120% vVO2max. Each bout continued until volitional exhaustion and was separated by 20 min of passive rest. Total distance and duration were recorded to determine exercise tolerance using the iCV model. Caffeine ingestion increased running duration at 110% vVO2max (p = 0.02), but not at 120 (p = 0.93) and 130% vVO2max (p = 0.14). Caffeine did not improve iCV model parameters. A single dose of caffeine consumed 60 min before repeated-sprints can improve performance at 110% vVO2max, but not at higher velocities.

Caffeine Gum Does Not Improve Marksmanship, Bound Duration, Susceptibility to Enemy Fire, or Cognitive Performance During Tactical Combat Movement Simulation.

BACKGROUND: Military personnel supplement caffeine as a countermeasure during unavoidable sustained wakefulness. However, its utility in combat-relevant tasks is unknown. This study examined the effects of caffeinated gum on performance in a tactical combat movement simulation. MATERIALS AND METHODS: Healthy men (n = 30) and women (n = 9) (age = 25.3 ± 6.8 years; mass 75.1 ± 13.1 kg) completed a marksmanship with a cognitive workload (CWL) assessment and a fire-andmove simulation (16 6-m bounds) in experimental conditions (placebo versus caffeinated gum, 4mg/kg). Susceptibility to enemy fire was modeled on bound duration during the fireand- move simulation. RESULTS: Across both conditions, bound duration and susceptibility to enemy fire increased by 9.3% and 7.8%, respectively (p = .001). Cognitive performance decreased after the fire-and-move simulation across both conditions (p < .05). However, bound duration, susceptibility to enemy fire, marksmanship, and cognitive performance did not differ between the caffeine and placebo conditions. CONCLUSION: These data do not support a benefit of using caffeinated gum to improve simulated tactical combat movements.