Brent C Ruby

Brent C Ruby
University of Montana | UMT · Montana Center for Work Physiology and Exercise Metabolism

About

236
Publications
51,601
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3,780
Citations
Citations since 2017
53 Research Items
1768 Citations
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20172018201920202021202220230100200300

Publications

Publications (236)
Article
Full-text available
The purpose of this study was to examine the effects of acute normobaric (NH, decreased FiO2) and hypobaric (HH, 4200 m ascent) hypoxia exposures compared to sea level (normobaric normoxia, NN). Tissue oxygenation, cardiovascular, and body fluid variables measured during rest and a 3-min step-test following 90-min exposures (NH, HH, NN). Muscle oxy...
Article
Our Alaskan Backcountry Expeditionary Hunting (ABEH) paradigm represents an 8-14 day unscripted, remote expedition in the uninhabited Brooks Range. Despite negative energy balance (i.e., -9.7 ± 3.4 MJ/day) and significant weight loss (Δ-1.5 ± 0.7 kg) largely influenced by high levels of energy expenditure (i.e., 17.4 ± 2.6 MJ/day), participants ret...
Poster
Our Alaskan Backcountry Expeditionary Hunting (ABEH) paradigm represents an 8-14 day unscripted, remote expedition in the uninhabited Brooks Range. Despite negative energy balance (i.e., -9.7 ± 3.4 MJ/day) and significant weight loss (Δ-1.5 ± 0.7 kg) largely influenced by high levels of energy expenditure (i.e., 17.4 ± 2.6 MJ/day), participants ret...
Article
Full-text available
Recent aerobic exercise training in the heat has reported blunted aerobic power improvements and reduced mitochondrial-related gene expression in men. It is unclear if this heat-induced blunting of the training response exists in females. The purpose of the present study was to determine the impact of 60 min of cycling in the heat over three weeks...
Article
Full-text available
Objective: Determine serum lipid and general health/fitness alterations following a 5-month wildfire suppression season. Methods: We recruited 100 wildland firefighters (WLFFs) to a 5-month pre- to post-season observational study. Nude body mass, blood pressure (BP), grip strength, and step-test heart rate (HR) were recorded. Blood samples were...
Article
Background: Previous data have demonstrated that Tour de France riders maintain total daily energy expenditure (TDEE) between 3.5 and 5.5 times the basal metabolic rate (×BMR). In contrast, TDEE for healthy male septuagenarians has been reported to average 1.3 to 2.0 ×BMR. Purpose: Measure the TDEE and water efflux during ultraendurance work in...
Article
Full-text available
Wildland firefighters (WLFFs) perform in adverse environments making rapid adjustments to dietary needs. The National Mobile Food Services (NMFS) contract details WLFF dietary provisions on wildfire incidents. Objective: Determine the nutrient content of food and drink provided to and consumed by WLFFs under the NMFS contract. Methods: Individual (...
Chapter
Adaptive Training Protocols (ATP) is a collection of algorithms and software to apply principals of intelligent tutoring to physical fitness training. To obtain norming data for ATP, we examined exercise performance from 34 participants under an adaptive workout regimen lasting 13 weeks. The goal of the regimen was to train to pass the performance...
Article
Slivka, Dustin, Charles Dumke, Walter Hailes, and Brent Ruby. Impact of hypoxic exercise recovery on skeletal muscle glycogen and gene expression. High Alt Med Biol. 22:300-307, 2021. Background: The impact of altitude during recovery from exercise is largely unknown. The purpose of this study was to determine the acute gene response and muscle gly...
Article
Full-text available
A reduced mitochondrial DNA (mtDNA) copy number, the ratio of mitochondrial DNA to genomic DNA (mtDNA:gDNA), has been linked with dysfunctional mitochondria. Exercise can acutely induce mtDNA damage manifested as a reduced copy number. However, the influence of a paired (exercise and temperature) intervention on regional mtDNA (MINor Arc and MAJor...
Article
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Objective: Document wildland firefighters (WLFFs) hydration status during a singular workshift (13.7 ± 1.4 h). Methods: WLFF-researchers documented real-time WLFF (n = 71) urine metrics and fluid consumption. Body weight and blood samples (n = 25) were also collected. Two-tailed dependent t-tests determined statistical significance (p < 0.05)....
Article
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IntroductionPGC-1a has been termed the master regulator of mitochondrial biogenesis. The exercise-induced rise in PGC-1a transcription is blunted when acute exercise takes place in the heat. However, it is unknown if this alteration has functional implications after heat acclimation and exercise training.PurposeTo determine the impact of 3 weeks of...
Article
Full-text available
Introduction The purpose of this study was to evaluate heat stress occurring in wildfire management activities with variable environmental conditions. Methods Direct observation and real-time wireless physiological monitoring allowed for weather and physiological metrics, including heart rate, core temperature (Tc), skin temperature, and physiolog...
Article
Hypobaria and hypoxia exert independent effects on oxidative stress during exercise, while combined effects on the post-exercise recovery period remain unclear.Accordingly, this study examined the recovery period during lab-simulated hypoxic and hypobaric conditions following exercise-induced oxidative stress. Participants (n=13) performed 60-minut...
Article
Introduction Wildfire suppression is characterized by high total energy expenditure and water turnover rates. Hydration position stands outside hourly fluid intake rates. However, dose interval remains ambiguous. We aimed to determine the effects of microdosing and bolus-dosing water and microdosing and bolus-dosing carbohydrate-electrolyte solutio...
Article
Full-text available
We have previously reported negative energy balance and health benefits during an Alaska backcountry expeditionary hunting (ABEH) immersion in two males. The purpose of our present study was to increase the number of participants, include females, and evaluate macronutrient intake and serum lipids. Four men (age: 46 ± 6 year, BMI: 26 ± 1 kg/m 2) an...
Article
Full-text available
Wildland fire suppression presents a working environment that often exceeds an energy expenditure of 20 MJ/day. However maladaptive seasonal responses in adiposity and blood lipid profiles have been noted. PURPOSE: To determine changes in clinical health metrics and serum lipids resulting from 5 months of seasonal wildland fire suppression. METHODS...
Article
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PurposeResearch has elucidated the impact of post-exercise carbohydrate nutrition and environmental conditions on muscle glycogen re-synthesis. However, research has minimally considered the implications of glycogen recovery in females and has mostly focused on commercial sport nutrition products. The purpose of this study was to determine the effe...
Article
Full-text available
Introduction Wildland firefighters (WLFF) work long hours in extreme environments, resulting in high daily total energy expenditure. Increasing work-shift eating episodes and/or providing rations that promote convenient eating has shown augmented self-selected work output, as has regular carbohydrate (CHO) consumption. It remains unclear how curren...
Article
Cold environmental temperatures during exercise and recovery alter the acute response to cellular signaling and training adaptations. Approximately three weeks is required for cold temperature acclimation to occur. Purpose: To determine the impact of cold environmental temperature on training adaptations, fitness measurements, and aerobic perform...
Article
Full-text available
Hiking with a pack is the highest intensity task that wildland firefighters (WLFFs) perform during sustained activities related to wildland fire suppression. Firefighters perform this and other tasks together as a crew; this provides a unique model to evaluate select physical and physiological changes in members of working crews over a fire season...
Conference Paper
Full-text available
Introduction. The dietary and activity patterns of humans during the agricultural, industrial, and digital revolutions has changed drastically from the hunter/gatherer lifestyle pursued for 84,000 generations. Unfortunately, we are now facing an obesity pandemic. Data surrounding dietary intake, energy expenditure, and metabolism of the hunter/gath...
Article
Background: The physiological effects of hypoxia may be influenced by how hypoxia is achieved. The purpose of this study was to determine the effects of recovery in hypobaric hypoxia (HH), normobaric hypoxia (NH), and normobaric normoxia (NN) after endurance exercise on gene expression related to mitochondrial biogenesis, myogenesis, and proteolysi...
Article
Full-text available
Objective: The purpose of this study was to evaluate pre- and postseason measures of body composition, skeletal muscle, and blood parameters/liver lipid in wildland firefighters (WLFF) over the fire season. Methods: Alaskan WLFF (N = 27) crews were evaluated pre- and postwildfire season, which included 63 ± 10 operational days. Body composition,...
Article
Our aim was to examine the effect of a synthetic material undergarment on heat stress during exercise in a hot environment. Ten active males completed two trials of intermittent (50 min walking, 10 min sitting) treadmill walking over 3 h in 35°C and 30% relative humidity. Subjects wore wildland firefighter flame-resistant meta-aramid blend pants an...
Article
Full-text available
The purported healthy aspects of subsistence foods have led to the popularity of the Paleo diet. There has been very little focus, surprisingly, on health benefits derived from the nomadic nature of humans during the Paleolithic era. The purpose of our study was to examine total energy expenditure (TEE), total energy intake (TEI), body composition,...
Poster
Full-text available
The purpose of this study was to evaluate seasonal changes in body composition, intrahepatic lipid, and blood lipids in wildland firefighters.
Article
Heat acclimation lowers physiological strain when exercising in the heat, and may be enhanced by promoting dehydration during acclimation. The purpose was to compare fluid intake during heat acclimation by promoting dehydration (DEH=0.5 mL kg⁻¹ 15 min⁻¹, ~2.4% dehydration per acclimation session) compared to euhydration (EUH=2.0 mL kg⁻¹ 15 min⁻¹, ~...
Article
Full-text available
Introduction: The objective of this study was to document characteristics of hiking during wildland firefighter (WLFF) training and wildfire suppression. For the first time, the overall physical demands during wildland firefighting were evaluated in the field using global positioning systems coupled with wireless physiological monitoring and load...
Article
Full-text available
Epidemiological investigations have supported the healthy benefits of subsistence foods. Surprisingly, the health benefits derived from the nomadic nature of humans during the Paleolithic era have been understudied. Hunting and gathering activity that occurs far from the conveniences of civilization on public land most likely represent the closest...
Article
The purpose of this study was to examine the pattern of urinary protein excretion induced by three consecutive days of wildland firefighting. Eighteen male active duty military personnel were served as the participants. All testing consisting of three consecutive days was conducted at a Northwestern USA fire camp. All participants consumed military...
Article
Full-text available
Objective: This study aimed to determine the physiological and thermoregulatory responses of individuals exercising in the heat (US military red flag conditions, wet-bulb globe temperature 31.5-32.2ºC) while consuming varied volumes of ambient temperature water and ice slurry. Methods: Participants (N = 12) walked on a treadmill for 3 hours at a...
Article
Exercise and oxidative stress research continues to grow as a physiologic sub-discipline. The influence of high altitude on exercise and oxidative stress is among the recent topics of intense study in this area. Early findings indicate that exercise at high altitude has an independent influence on free radical generation and the resultant oxidative...
Article
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Several training strategies such as plyometrics have been shown to improve running economy; however its physiological basis remains elusive. To examine the effect of plyometric training on the energy cost of running (ECR, J[BULLET OPERATOR]kg[BULLET OPERATOR]min), titin and myosin heavy chain (MHC) isoforms. Subjects were randomly assigned to a 6 w...
Article
The purpose of this study was to compare glucose and insulin responses during an oral glucose tolerance test (OGTT) in cold (C), neutral (N), and hot (H) environments. Eleven males completed three 4-hour climate-controlled OGTT trials (C, 7.2°C; N, 22°C; and H, 43°C). Participants remained semireclined for 60 minutes before ingesting a 1.8 g/kg glu...
Article
Full-text available
Altitude exposure and exercise elicit oxidative stress in blood; however, exercise recovery at 5000 m attenuates oxidative stress. The purpose was to determine the altitude threshold at which blood oxidative stress is blunted during exercise recovery. Twelve males 18-28 years performed four-cycle ergometry bouts (60 min, 70% VO2max, at 975 m). In a...
Article
Full-text available
A variety of dietary choices are marketed to enhance glycogen recovery after physical activity. Past research informs recommendations regarding the timing, dose, and nutrient compositions to facilitate glycogen recovery. This study examined the effects of isoenergetic sport supplements (SS) vs. fast food (FF) on glycogen recovery and exercise perfo...
Article
Full-text available
The purpose of this investigation was to characterize the effects of self-selected work activity on energy expenditure, water turnover, and thermal strain during wildland fire suppression. A secondary aim was to contrast current data with data collected 15 years ago using similar methods to determine whether job demands have changed. Participants (...
Article
Full-text available
Abstract The purpose of this study was to determine the effects of repeated bouts of long-duration endurance exercise on both muscle and urinary levels of oxidative DNA damage in moderately trained individuals. Seven moderately trained male cyclists participated in this study. All participants repeated two sessions consisting of a 5-h cycling perio...
Article
Full-text available
It is unclear whether the capabilities of recreationally active modern humans are unique due to present training practices or linked to the selection resulting from migration, escape, scavenging, and hunting and/or endurance running in early Homo. The purpose of this study was to determine upper values for total energy expenditure (TEE) and water t...
Article
The purpose of this study was to investigate the effects of pneumatic compression pants on post-exercise glycogen resynthesis. Active male subjects (n=10) completed two trials consisting of a 90-minute glycogen depleting ride, followed by 4 hours of recovery with either a pneumatic compression device (PCD) or passive recovery (PR) in a random count...
Article
Full-text available
The purpose of this study was to determine changes in physiological markers of heat acclimatization across a 4-month wildland fire season. Wildland firefighters (WLFF) (n=12) and non-WLFF (n=14) were assessed pre and post-season for body mass, percent body fat, and peak VO2. Both groups completed a 60-minute heat stress trial (walking at 50% of pea...
Article
Background: The ability to physically perform at high altitude may require unique strategies to acclimatize before exposure. The effect of acute hypoxic exposure on the metabolic response of the skeletal muscle may provide insight into the value of short-term preacclimatization strategies. Objective: To determine the human skeletal muscle respon...
Article
Full-text available
Hypoxic exercise is characterized by workloads decrements. Because exercise and high altitude independently elicit redox perturbations, the study purpose was to examine hypoxic and normoxic steady-state exercise on blood oxidative stress. Active males (n=11) completed graded cycle ergometry in normoxic (975m) and hypoxic (3000m) simulated environme...
Article
Full-text available
Hypoxia due to altitude diminishes performance and alters exercise oxidative stress responses. While oxidative stress and exercise are well studied, the independent impact of hypoxia on exercise recovery remains unknown. Accordingly, we investigated hypoxic recovery effects on post-exercise oxidative stress. Physically active males (n = 12) perform...
Article
Full-text available
Special Tactics Officer (STO) selection is conducted to select officers to enter the combat controller training pipeline. The aims were to determine physical activity patterns, estimate energy expenditure, and identify whether return and/or unsuccessful candidates demonstrated differences in cortisol responses compared to non-selected and/or first-...
Article
Full-text available
Heat stress down-regulates mitochondrial function, while carbohydrate supplementation attenuates the exercise induced stimulation of mitochondrial biogenesis in humans. The effects of exogenous carbohydrate during exercise in the heat on metabolic mRNA have not been investigated in humans. The purpose of this study was to determine the impact of ex...
Article
Full-text available
To evaluate the previously developed physiological strain index (PSI) model using heart rate and skin temperature to provide further insight into the detection and estimation of thermal and physiological heat strain indices. A secondary aim was to characterize individuals who excel in their performance in the heat. 56 male participants completed 2...
Article
Previous research findings indicate that environmental temperature can influence exercise-induced oxidative-stress responses, although the response to variable temperatures is unknown. The purpose of this study was to investigate the effect of warm, cold, and "neutral," or room, environmental temperatures on the blood oxidative stress associated wi...