Nutritional Considerations in Exercise-Based Heat Acclimation: A Narrative Review.

In addition to its established thermoregulatory and cardiovascular effects, heat stress provokes alterations in macronutrient metabolism, gastrointestinal integrity, and appetite. Inadequate energy, carbohydrate, and protein intake have been implicated in reduced exercise and heat tolerance. Classic exercise heat acclimation (HA) protocols employ low-to-moderate-intensity exercise for 5-14 days, while recent studies have evolved the practice by implementing high-intensity and task-specific exercise during HA, which potentially results in impaired post-HA physical performance despite adequate heat adaptations.

Heat stress increases carbohydrate oxidation rates and oxygen uptake during prolonged load carriage exercise.

Military missions are conducted in a multitude of environments including heat and may involve walking under load following severe exertion, the metabolic demands of which may have nutritional implications for fueling and recovery planning. Ten males equipped a military pack loaded to 30% of their body mass and walked in 20°C/40% relative humidity (RH) (TEMP) or 37°C/20% RH (HOT) either continuously (CW) for 90 min at the first ventilatory threshold or mixed walking (MW) with unloaded running intervals above the second ventilatory threshold between min 35 and 55 of the 90 min bout. Pulmonary gas, thermoregulatory, and cardiovascular variables were analyzed following running intervals.

Load-Velocity Profiles Before and After Heated Resistance Exercise.

Sweet, DK, Qiao, J, Rosbrook, P, and Pryor, JL. Load-velocity profiles before and after heated resistance exercise. J Strength Cond Res 38(6): 1019-1024, 2024-This study examined neuromuscular performance using load-velocity (L-V) profiles in men and women before and after resistance exercise (RE) in hot (HOT; 40° C) and temperate (TEMP; 21° C) environments.

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.

Plateau in Core Temperature during Shorter but Not Longer Work/Rest Cycles in Heat.

This study compared physiological responses to two work/rest cycles of a 2:1 work-to-rest ratio in a hot environment. In a randomized crossover design, fourteen participants completed 120 min of walking and rest in the heat (36.3 ± 0.

Metabolic Costs of Walking with Weighted Vests.

Introduction: The US Army Load Carriage Decision Aid (LCDA) metabolic model is used by militaries across the globe and is intended to predict physiological responses, specifically metabolic costs, in a wide range of dismounted warfighter operations. However, the LCDA has yet to be adapted for vest-borne load carriage, which is commonplace in tactical populations, and differs in energetic costs to backpacking and other forms of load carriage.

Purpose: The purpose of this study is to develop and validate a metabolic model term that accurately estimates the effect of weighted vest loads on standing and walking metabolic rate for military mission-planning and general applications.

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.

Persistent Knowledge Gaps Regarding Exertional Heat Stroke Treatment.

Individualized patient care is ideal for treating and rehabilitating patients with athletic illnesses and injuries. Exertional heat stroke (EHS) treatment best-practice recommendations state that all patients should undergo identical cold-water immersion (CWI) treatment for ideal outcomes. It is unknown, however, whether CWI can be optimized with individualized treatment plans, encouraging personalized medicine.

Effects of hyperbaric oxygen therapy on exercise-induced muscle damage.

Purpose: To perform a literature review on hyperbaric oxygen (HBO2) therapy as a treatment for exercise-induced muscle damage (EIMD).

Methods: PubMed, Web of Science and Google Scholar were searched for articles related to HBO2 therapy as a treatment for exercise-induced muscle damage. Inclusion criteria included HBO2 therapy as the primary intervention to treat EIMD.

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.

Eliciting an offence narrative: what types of questions do forensic mental health practitioners ask?

Maximising the accuracy and detail of information elicited through a clinical-forensic interview may increase the reliability and validity of an individual's assessment. Despite this, there is little empirical research on what questions forensic mental health practitioners employ, and whether these correspond with empirically established interviewing strategies. In this study, 22 forensic mental health practitioners participated in a mock interview of a young person referred for a sexual risk assessment.

Exercise during hot-water immersion in divers habituated to hot-dry and hot-wet conditions.

Purpose: Diving in warm water increases thermal risk during exercise compared to thermoneutral waters. The purpose of this study was to evaluate exercise endurance in warm- and hot-water conditions in divers habituated to wet or dry heat.

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

Modeling the Metabolic Costs of Heavy Military Backpacking.

Introduction: Existing predictive equations underestimate the metabolic costs of heavy military load carriage. Metabolic costs are specific to each type of military equipment, and backpack loads often impose the most sustained burden on the dismounted warfighter.

Purpose: This study aimed to develop and validate an equation for estimating metabolic rates during heavy backpacking for the US Army Load Carriage Decision Aid (LCDA), an integrated software mission planning tool.

Verification of Maximal Oxygen Uptake in Active Military Personnel During Treadmill Running.

Figueiredo, PS, Looney, DP, Pryor, JL, Doughty, EM, McClung, HL, Vangala, SV, Santee, WR, Beidleman, BA, and Potter, AW. Verification of maximal oxygen uptake in active military personnel during treadmill running. J Strength Cond Res 36(4): 1053-1058, 2022-It is unclear whether verification tests are required to confirm "true" maximal oxygen uptake (V̇o2max) in modern warfighter populations.

Short term heat acclimation reduces heat strain during a first, but not second, consecutive exercise-heat exposure.

Objectives: Determine whether five days of heat acclimation reduces cardiovascular and thermoregulatory strain during consecutive exercise-heat exposures on the sixth day in the heat.

Design: Pair-matched randomized control trial.

Methods: Twenty-four males completed two, 120min exercise sessions (Session 1, Session 2) in a single day before (Day 1) and after (Day 6) four additional days of exercise in either hot (HOT: 40°C, 40% relative humidity, n=16) or temperate (CON: 23°C, 25% relative humidity, n=8) environments.

Effects of modern military backpack loads on walking speed and cardiometabolic responses of US Army Soldiers.

Introduction: Military leaders must understand how modern military equipment loads affect trade-offs between movement speed and physiological strain to optimize pacing strategies.

Purpose: To evaluate the effects of load carried in a recently developed military backpack on the walking speed and cardiometabolic responses of dismounted warfighters.

Methods: Fifteen soldiers (1 woman, 14 men; age, 22 ± 2 years; height, 173 ± 7 cm; body mass (BM), 73 ± 10 kg) completed incremental walking tests with four external load conditions (0, 22, 44, or 66% BM) using the US Army's newest backpack: the Modular Lightweight Load-Carrying Equipment 4000 (MOLLE 4000).

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.

CHANGES IN INFRASPINATUS AND LOWER TRAPEZIUS ACTIVATION IN VOLLEYBALL PLAYERS FOLLOWING REPETITIVE SERVES.

Background: Prolonged and repetitive overhead use of the arm, such as during the volleyball serve, has been linked to overuse injuries.

Purpose: To examine changes in activation of the infraspinatus and lower trapezius following performance of repetitive jump-float serves.

Study Design: Descriptive Cohort study.

Movement Technique During Jump-Landing Differs Between Sex Among Athletic Playing Surfaces.

Pryor, JL, Burbulys, ER, Root, HJ, and Pryor, RR. Movement technique during jump-landing differs between sex among athletic playing surfaces. J Strength Cond Res 36(3): 661-666, 2022-Whether athletic surface type affects movement technique, a causal factor for lower extremity injury, is unclear.

Acute Kidney Injury Biomarker Responses to Short-Term Heat Acclimation.

The combination of hyperthermia, dehydration, and strenuous exercise can result in severe reductions in kidney function, potentially leading to acute kidney injury (AKI). We sought to determine whether six days of heat acclimation (HA) mitigates the rise in clinical biomarkers of AKI during strenuous exercise in the heat. Twenty men completed two consecutive 2 h bouts of high-intensity exercise in either hot ( = 12, 40 °C, 40% relative humidity) or mild ( = 8, 24 °C, 21% relative humidity) environments before (PreHA) and after (PostHA) 4 days of 90-120 min of exercise per day in a hot or mild environment.

Exacerbated heat strain during consecutive days of repeated exercise sessions in heat.

Objectives: An exercise session in a hot environment may increase thermal strain during subsequent exercise sessions on the same and consecutive days. Therefore, this study was conducted to determine lasting physiological strain from moderate-high intensity, intermittent exercise in heat on subsequent exercise.

Design: Repeated measures laboratory study.

Metabolic Demands of Yoga at Varying Tempos and Compared With Walking.

Background: Yoga is a popular alternative to walking, but the tempo at which asanas must be performed to elicit comparable metabolic and cardiorespiratory demands is unknown. Therefore, the authors aim to compare the metabolic demands of moderate-intensity walking to Surya Namaskar yoga performed at varying tempos.

Methods: Inactive obese adults with limited prior yoga experience (n = 10) completed 10 minutes of treadmill walking at a self-selected pace (rating of perceived exertion = 12-13) and three, 10-minute bouts of yoga at a low (6 s/pose; LSUN), medium (4 s/pose; MSUN), and high (3 s/pose; HSUN) tempo with 10-minutes rest between exercise bouts.

Application of evidence-based recommendations for heat acclimation: Individual and team sport perspectives.

Heat acclimation or acclimatization (HA) occurs with repeated exposure to heat inducing adaptations that enhance thermoregulatory mechanisms and heat tolerance leading to improved exercise performance in warm-to-hot conditions. HA is an essential heat safety and performance enhancement strategy in preparation for competitions in warm-to-hot conditions for both individual and team sports. Yet, some data indicate HA is an underutilized pre-competition intervention in athletes despite the well-known benefits; possibly due to a lack of practical information provided to athletes and coaches.