US Army Accession and Retention Standards: Impact on Obesity and Medical Readiness.

Introduction: Military body fat standards were implemented in the 1980s to prevent obesity and associated poor military readiness. In the past 2 decades, enforcement of existing Army body composition standards has been eroded by the steady increase in national obesity rates, the demand for new recruits especially during the 2007 surge in Iraq, and the COVID epidemic in 2020. The diminishing qualified recruit pool puts a new focus on accession standards.

Reliability, biological variability, and accuracy of multi-frequency bioelectrical impedance analysis for measuring body composition components.

Introduction: Bioelectrical impedance analysis (BIA) systems are gaining popularity for use in research and fitness assessments as the technology improves and becomes more affordable and easier to use. Multifrequency BIA (MF-BIA) may improve accuracy and precision using octopolar contacts for segmental analyses.

Purpose: Evaluate reliability, biological variability, and accuracy of component measures (total body water, mass, and composition) of commercially available MF-BIA system (InBody 770, Cerritos, California, USA).

The impact of a 20-h rotating watch schedule on cognitive and mood states in submarine operations.

This is the first study to provide valuable insights into the effects of the Israeli Navy's 20-h rotating watch schedule on submariners' alertness, mood states, risk-taking behaviours, and sleep. Specifically, we assessed the impact of the non-circadian-aligned schedule on cognitive performance, mood, and behavioural outcomes in a highly controlled submarine environment. A total of 20 male submariners participated in an at-sea mission, where their cognitive performance, mood states, risk-taking propensity, and caffeine consumption were measured.

Characterizing PTSD symptom profiles in special forces operators and support personnel: Justification for a Precision Medicine Approach.

Given the large number and diverse types of PTSD symptoms, examination of subtypes within the comprehensive PTSD criteria is necessary. This is especially true for subpopulations of active-duty service members such as specialized military units that undergo assessment and selection, receive extensive training, and have significant operational experience and trauma exposure. The current study identified PTSD subtypes in 16,284 U.

Energy expenditure during physical work in cold environments: physiology and performance considerations for military service members.

Effective execution of military missions in cold environments requires highly trained, well-equipped, and operationally ready service members. Understanding the metabolic energetic demands of performing physical work in extreme cold conditions is critical for individual medical readiness of service members. In this narrative review, we describe ) the extreme energy costs of performing militarily relevant physical work in cold environments, ) key factors specific to cold environments that explain these additional energy costs, ) additional environmental factors that modulate the metabolic burden, ) medical readiness consequences associated with these circumstances, and ) potential countermeasures to be developed to aid future military personnel.

The 300 Marines: characterizing the US Marines with perfect scores on their physical and combat fitness tests.

Unlabelled: Few US Marines earn perfect 300 scores on both their Physical Fitness Test (PFT) and Combat Fitness Test (CFT). The number 300 invokes the legendary 300 Spartans that fought at the Battle of Thermopylae, which inspired high physical fitness capabilities for elite ground forces ever since.

Purpose: Determine distinguishing characteristics of the "300 Marines" (perfect PFT and CFT scores) that may provide insights into the physical and physiological requirements associated with this capability.

Resistance Training in the Heat: Mechanisms of Hypertrophy and Performance Enhancement.

Pryor, JL, Sweet, D, Rosbrook, P, Qiao, J, Hess, HW, and Looney, DP. Resistance training in the heat: Mechanisms of hypertrophy and performance enhancement. J Strength Cond Res 38(7): 1350-1357, 2024-The addition of heat stress to resistance exercise or heated resistance exercise (HRE) is growing in popularity as emerging evidence indicates altered neuromuscular function and an amplification of several mechanistic targets of protein synthesis.

Endocrine Responses to Heated Resistance Exercise in Men and Women.

Pryor, JL, Sweet, DK, Rosbrook, P, Qiao, J, Looney, DP, Mahmood, S, and Rideout, T. Endocrine responses to heated resistance exercise in men and women. J Strength Cond Res 38(7): 1248-1255, 2024-We examined the endocrine responses of 16 (female = 8) resistance trained volunteers to a single bout of whole-body high-volume load resistance exercise in hot (HOT; 40° C) and temperate (TEMP; 20° C) environmental conditions.

Estimating Metabolic Energy Expenditure During Level Running in Healthy, Military-Age Women and Men.

Looney, DP, Hoogkamer, W, Kram, R, Arellano, CJ, and Spiering, BA. Estimating metabolic energy expenditure during level running in healthy, military-age women and men. J Strength Cond Res 37(12): 2496-2503, 2023-Quantifying the rate of metabolic energy expenditure (Ṁ) of varied aerobic exercise modalities is important for optimizing fueling and performance and maintaining safety in military personnel operating in extreme conditions.

Peak performance and cardiometabolic responses of modern US army soldiers during heavy, fatiguing vest-borne load carriage.

Introduction: Physiological limits imposed by vest-borne loads must be defined for optimal performance monitoring of the modern dismounted warfighter.

Purpose: To evaluate how weighted vests affect locomotion economy and relative cardiometabolic strain during military load carriage while identifying key physiological predictors of exhaustion limits.

Methods: Fifteen US Army soldiers (4 women, 11 men; age, 26 ± 8 years; height, 173 ± 10 cm; body mass (BM), 79 ± 16 kg) performed four incremental walking tests with different vest loads (0, 22, 44, or 66% BM).

Verification Phase Confirms V̇O 2max in a Hot Environment in Sedentary Untrained Males.

Purpose: This study aimed to assess the V̇O 2 uptake obtained during a GXT and subsequent verification phase in untrained participants in a hot environment.

Methods: Twelve sedentary males completed a GXT followed by a biphasic supramaximal-load verification phase in a hot environment (39°C, 32% relative humidity). Rest between tests occurred in a temperate chamber and lasted until gastrointestinal temperature returned to baseline.

Body surface area equations for physically active men and women.

Objectives: To improve predictive formulae for estimating body surface area (BSA) in healthy men and women using a modern three-dimensional scanner technology.

Methods: Body surface areas were obtained from a convenience sample of 1267 US Marines (464 women and 803 men) using a whole body surface scanner (Size Stream SS20). The reliability of SS20 measures of total and regional BSA within participants was compared across triplicate scans.

Diver Underwater Cycling Endurance After Short-Term Warm and Hot Water Acclimation.

Introduction: It is unclear whether immersion heat acclimation benefits exercise in warm water conditions. This study examined the effects of heat acclimation strategies on heart rate (HR), core temperature, and time to exhaustion (TTE) during cycling exercise in varying warm water conditions.

Methods: Twenty male divers completed this study at the Navy Experimental Diving Unit.

Abstracts from The Cold Weather Operations Conference 2021.

A common effort for both military and civil healthcare is to achieve knowledge-based health care in cold weather injuries and fatal accidents in harsh arctic environment. The in November 2021, having more than 300 participants from 20 countries, was addressing the prevention and treatment of injuries and trauma care in cold weather conditions and the challenges for military prehospital casualty care. The intention of the programme was to stimulate further research and systematic knowledge-based clinical work.

Much work remains to reach consensus on musculoskeletal injury risk in military service members: A systematic review with meta-analysis.

Musculoskeletal injuries are the most common reason military service members cannot perform their military duties. Not only are they costly and associated with long-term disability, often long after completion of military service, but injuries also adversely affect the military readiness of a nation. This can be seen as a threat to national security and part of the impetus behind many efforts to better understand, predict, and mitigate injury risk in the military.

Multisensory Sensitivity is Related to Deep-Tissue but Not Cutaneous Pain Sensitivity in Healthy Individuals.

Purpose: Some individuals with chronic pain find daily life sensations (eg, noise, light, or touch) aversive. This amplification of multisensory sensations has been associated with centrally mediated plasticity; for example, greater multisensory sensitivity (MSS) occurs in patients with fibromyalgia than rheumatoid arthritis. However, whether MSS preferentially relates to pain measures which reflect central influences (eg, dynamic quantitative sensory testing (QST) or referred pain), or whether the MSS-pain relationship requires priming from chronic pain, is unknown.

Verification Testing to Confirm V˙O2max in a Hot Environment.

Purpose: This study aimed to evaluate the validity and reliability of a verification test to confirm GXT V˙O2max in a hot environment.

Methods: Twelve recreationally trained cyclists completed a two-test protocol that included a GXT progressing 20 W·min-1 followed by a biphasic supramaximal-load verification test (1 min at 60% increasing to 110% maximal GXT wattage until failure) in a hot environment (39°C, 32% relative humidity). Rest between tests occurred in a thermoneutral room and was anchored to the duration required for gastrointestinal temperature to return to baseline.

Fluid Balance and Hydration Considerations for Women: Review and Future Directions.

Although it is well understood that dehydration can have a major impact on exercise performance and thermoregulatory physiology, the potential for interactions between female sex hormone influences and the impact of dehydration on these variables is poorly understood. Female reproductive hormonal profiles over the course of the menstrual cycle have significant influences on thermoregulatory and volume regulatory physiology. Increased insight into the interactions among dehydration and menstrual cycle hormonal influences may have important implications for safety, nutritional recommendations, as well as optimal mental and physical performance.

Divers risk accelerated fatigue and core temperature rise during fully-immersed exercise in warmer water temperature extremes.

Physiological responses to work in cold water have been well studied but little is known about the effects of exercise in warm water; an overlooked but critical issue for certain military, scientific, recreational, and professional diving operations. This investigation examined core temperature responses to fatiguing, fully-immersed exercise in extremely warm waters. Twenty-one male U.

Relationships between use of dietary supplements, caffeine and sensation seeking among college students.

Caffeine and dietary supplement (DS) use by college students is not well-documented. Given reported associations between energy drink consumption and sensation seeking, we used the Sensation Seeking Scale Form V (SSS-V) to assess relationships between sensation-seeking, caffeine, and DS use. Data from 1,248 college students from five US institutions were collected from 2009 to 2011.

Metabolic Costs of Military Load Carriage over Complex Terrain.

Introduction: Dismounted military operations often involve prolonged load carriage over complex terrain, which can result in excessive metabolic costs that can directly impair soldiers' performance. Although estimating these demands is a critical interest for mission planning purposes, it is unclear whether existing estimation equations developed from controlled laboratory- and field-based studies accurately account for energy costs of traveling over complex terrain. This study investigated the accuracy of the following equations for military populations when applied to data collected over complex terrain with two different levels of load carriage: American College of Sports Medicine (2002), Givoni and Goldman (1971), Jobe and White (2009), Minetti et al (2002), Pandolf et al (1977), and Santee et al (2003).

Intake of caffeine from all sources and reasons for use by college students.

Background & Aims: Caffeine intake in a convenience sample of U.S. college students (N = 1248) was surveyed at five geographically-dispersed United States (U.