Clinical Research Directory

Energy Dense Fueling for Cold-Weather Operations

High daily energy expenditures without compensatory increases in energy intakes results in severe energy deficits during cold-weather military operations. Observational and experimental data from our laboratory suggests that consuming higher-fat, energy dense products can increase energy intake and attenuate energy deficits, however, laboratory analysis is needed to understand the impact of macronutrient manipulation on substrate oxidation and aerobic performance. This proof of concept, randomized crossover study will examine the effects of consuming an isocaloric bar (approximately 350 kcal) that is higher in carbohydrate (CHO: 50% carbohydrate, 30% fat, 20% protein) or higher in fat (FAT: 30% carbohydrate, 50% fat, 20% protein) on substrate oxidation and aerobic performance (time trial) during acute cold (5°C) exposure. Volunteers will wear shorts and a t-shirt during cold exposure, with continuous monitoring of core and skin temperatures. Baseline data will be collected on volunteer height, weight, body composition, and V̇O2peak. To ensure volunteers are familiar with exercise protocols, they will complete practice sessions of all exercise before the start of data collection. Exercise and diet will be controlled throughout data collection. 24 hours prior to data collection, volunteers will consume a lead-in study diet and will abstain from exercise. After 24 hours, volunteers will return to the laboratory for assessment of substrate oxidation and aerobic performance. Volunteers will consume the CHO or FAT treatment bars under cold conditions, followed by 60 minutes of rest prior to the start of exercise. Volunteers will then complete 90 minutes of load carriage steady-state (55 ± 5% VO2peak) treadmill exercise, wearing a ruck with weighing 30% of their total body mass. After steady-state exercise, aerobic performance will be assessed by having volunteers complete a 2-mile time trial. Indirect calorimetry will be used to determine substrate oxidation during steady-state exercise. Serial blood draws will be collected during each trial to assess circulating substrate/hormone responses. Protocol days will be separated by a minimum washout period of 6 days.

Effect of Caffeine on Cold-stimulated Brown Adipose Tissue Activity

The purpose of the study is to asses brown adipose tissue activity after a cold mild stimulus, preceded by 200mg caffeine or placebo administration.

The Influence of Race and MitoQ Supplementation on Skin Blood Flow in the Cold

Individuals who operate in cold weather are at risk of developing cold injuries, for example, frostbite. They also often experience a loss of hand function and joint mobility due to a decrease in skin temperature and blood flow. In addition, the risk of getting a cold injury is higher in the Black population compared to other racial and ethnic groups. Increases in oxidant compounds can cause the blood vessels in the skin to narrow and decrease skin temperature in the cold. However, it is unknown whether the higher risk of cold injury in Black individuals is because of a greater amount of oxidant compounds in the blood vessels. The purpose of this research is to see if an antioxidant supplement called MitoQ can help to improve skin temperature and blood flow in the cold and if the improvement is greater in Black individuals.

Winter-Swimming and Brown Adipose Tissue Activity in Middel-aged Obese Subjects (WinterBAT).

This study investigates repetitive cold-water exposure on brown fat activity assessed by PET/CT scanning. Furthermore we will assess glucose control upon winter-swimming. Obese prediabetic men and women will be randomized to winter-swimming or control conditions for 4 months.

Intermittent Cold Exposure and Brown Adipose Tissue Hyperplasia

This clinical trial explores how repeated short-term cold exposure impacts the molecular and physiological function of brown adipose tissue (BAT), a thermogenic organ associated with improved cardiometabolic health. While intermittent cold exposure has been shown to increase BAT activity and mass, as measured by fluorodeoxyglucose (18F-FDG) uptake on positron emission tomography/computed tomography (PET/CT) scans, the molecular adaptations within BAT and other thermogenic tissues including skeletal muscle and white adipose tissue (WAT) remain poorly understood. Healthy adults aged 18 to 40 years (6 males and 6 females) will participate in a 10-day cold acclimation protocol (2 hours per day using water-perfused cooling blankets). The primary objective is to determine how cold exposure alters cellular heterogeneity and gene expression in BAT, WAT, and skeletal muscle. Participants will undergo baseline assessments, including measurements of energy expenditure, core and skin temperature, muscle activity, and blood sampling, each performed in both warm and cold conditions. These assessments will be followed by dynamic total-body PET/CT imaging during cold exposure and tissue biopsies from BAT, subcutaneous WAT, and skeletal muscle. These procedures will be repeated after the cold acclimation protocol to evaluate physiological and molecular changes. Additional outcomes include changes in energy expenditure, cold tolerance, and immune cell responses induced by cold exposure.

Omega-3 Fatty Acids as Regulators of Brown Adipose Tissue During Cold Exposure

This clinical trial will assess the whether fish oil supplementation can modulate brown fat activation, shivering, thermal comfort and skin blood flow during cold exposure.

Thermogenic Silencer Regulatory Factors in Humans

A promising approach to correct the metabolic dysfunction associated with obesity is to activate brown fat non-shivering thermogenesis (NST). A critical limitation with NST as a therapeutic option, however, is that this beneficial process is silenced under human physiological temperature conditions and the mechanisms of how this occurs is unknown. This study will be the first to identify human NST silencing factors that may be targeted for the treatment of obesity and metabolic disorders.

Cold Water Exposure's Effects on Physical and Mental Health

An interest in cold-water immersion (CWI) to elicit diverse physiological effects has been prevalent for centuries. CWI typically consists of bodily exposure to water at temperatures ranging from 5-10º C for various durations. CWI has profound cultural significance in different areas of the world, such as in Scandinavian countries, and has emerged as a popular modality for its purported health-promoting effects. Individuals on social media have repeatedly advocated for CWI as a method to improve muscular recovery, enhance sleep, and increase immune and cognitive function. Because of this, companies that specialize in cold tub production have become popularized; however, individuals who are seeking a more cost-effective option are drawn toward cold showers for their preferred method of cold exposure. Despite the scarcity of rigorous research investigating the difference in effects of cold tub versus cold shower CWI, individuals on social media promoting CWI via a shower continue to praise its comparable benefits to that of a tub. Therefore, investigations of chronic CWI (utilizing both a cold tub and a cold shower) is vital. Thus, the purpose of the proposed study is to explore the varying effects of chronic CWI on neural and cognitive function using a cold tub and a cold shower. Further, the study aims to investigate performance measures and immune measures to create a comprehensive understanding of CWI's implications on human physiology over time. The investigators hypothesize measures relating to mental performance and health will improve after 4-weeks of CWI, and there will be no difference between tub and shower immersion groups.