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Abstract Background Inadequate energy intake induces changes in endogenous glucose production (GP) to preserve muscle mass. Whether addition provision of dietary protein modulates GP response to energy deficit is unclear. The objective was to determine whether exercise-induced energy deficit effects on glucose metabolism are mitigated by increased dietary protein. Methods Nineteen men ([mean ± SD] 23 ± 2 y, VO2peak 59 ± 5 ml·kg-1·min-1) were divided into three groups, two consuming moderate (MP; 0.9 g protein kg-1 d-1), and one high (HP; 1.8 g protein kg-1 d-1) protein diets (55% energy from carbohydrate) for 11 days. Following 4 days of energy balance (D1-4), energy expenditure was increased for 7 days (D5-12) in all groups. Energy intake was unchanged in two, creating a 1000 kcal d-1 deficit (DEF-MP, DEF-HP; n = 6, both groups), whereas energy balance was maintained in the third (BAL-MP, n = 7). Biochemical markers of substrate metabolism were measured during fasting rest on D4 and D12, as were GP and contribution of gluconeogenesis to endogenous glucose production (fgng) using 4-h primed, continuous infusions of [6,6-2H2]glucose (dilution-method) and [2-13C]glycerol (MIDA technique). Glycogen breakdown (GB) was derived from GP and fgng. Results Plasma β-hydroxybutyrate levels increased, and plasma glucose and insulin declined from D4 to D12, regardless of group. DEF-MP experienced decreased plasma GP from D4 to D12 ([mean change ± SD] 0.24 ± 0.24 mg·kg-1·min-1), due to reduced GB from D4 (1.40 ± 0.28 mg·kg-1·min-1) to D12 (1.16 ± 0.17 mg·kg-1·min-1), P < 0.05. Conversely, BAL-MP and DEF-HP sustained GP from D4 to D12 ([mean change ± SD] 0.1 ± 0.5 and 0.0 ± 0.2 mg·kg-1·min-1, respectively) by maintaining GB. Conclusion Exercise-induced energy deficit decreased GP and additional dietary protein mitigated that effect.

Abstract Background A sudden increase in exercise and energy expenditure is associated with an increase in protein turnover and nitrogen excretion. This study examined how a sudden increase in exercise-induced energy expenditure affected whole body protein metabolism and nitrogen balance in people of differing levels of aerobic fitness. We hypothesized that alterations in whole-body protein turnover would be attenuated, and nitrogen balance would be preserved, in individual with higher levels of aerobic fitness. Methods Eleven men, categorized as either having a lower (LOW-FIT; n = 5) or higher (FIT; n = 6) aerobic fitness level, completed a 4-d baseline period (BL) of an energy balance diet while maintaining usual physical activity level, followed by a 7-d intervention consisting of 1,000 kcal·d-1 increased energy expenditure via exercise (50–65% VO2peak). All volunteers consumed 0.9 g protein·kg-1·d-1 and total energy intake was adjusted to maintain energy balance throughout the 11-d study. Mean nitrogen balance (NBAL) was determined for BL, days 5–8 (EX1), and days 9–11 (EX2). Whole-body protein turnover was derived from phenylalanine and tyrosine kinetics assessed while fasting at rest on days 4, 7, and 12 using a priming dose of L-[ring-15N]tyrosine and a 4-h primed, continuous infusion of L-[15N]phenylalanine and L-[ring-2H4]tyrosine. Results A significant main effect of time indicated that NBAL increased over the course of the intervention; however, a group-by-time interaction was not observed. Although FIT demonstrated a lower net protein oxidation and higher net protein balance compared to LOW-FIT, neither the effect of time nor a group-by-time interaction was significant for Phe flux, net protein oxidation, or derived whole-body protein synthesis and net protein balance. Conclusion The absence of significant group-by-time interactions in protein metabolism (i.e., NBAL and whole-body protein turnover) between LOW-FIT and FIT males suggest that aerobic fitness level does not modulate protein "sparing" in response to an unaccustomed increase in energy expenditure.

The purpose of this study was to evaluate the effects of aerobic exercise in the heat on circulating concentrations of tumor necrosis factor (TNF)-α, soluble TNF receptors (STNFR1&2), and surface expression of TNFR1&2 on monocyte subpopulations. Twelve recreationally active Caucasian men (24.4 ± 3.4 yrs.; 180.0 ± 6.8 cm; 81.5 ± 8.0 kg; 47.2 ± 4.8 mL·kg -1 ·min -1 ) completed an exercise protocol in three environmental conditions: high temperature/low humidity [HTLH; 35 °C, 20% relative humidity (RH)]; high temperature/moderate humidity (HTMH; 35 °C, 45%RH); and moderate temperature/moderate humidity (MTMH; 22 °C, 45%RH). Each protocol consisted of a 60-minute cycling trial at 60% VO 2 max, a 15-minute rest, and a time-to-exhaustion trial at 90% VO 2 max (TTE). Blood was sampled before (PRE), immediately after (POST) the 60-minute trial, immediately post-TTE (PTTE), and one-hour post-TTE (REC). Circulating TNF-α and STNFR1&2 were assayed. TNFR1&2 expression on monocyte subsets was measured by flow cytometry on a subset of participants (n = 8). TNF-α area under the curve with respect to increase (AUCi) was greater during HTMH compared to MTMH and HTLH. STNFR1 concentration was greater during HTMH compared to MTMH. With all trials combined, STNFR1 concentration increased from PRE to POST, PTTE, and REC. TNFR1 expression on non-classical monocytes was greater during HTMH compared to HTLH while TNFR2 expression was lower during HTLH compared to both MTMH and HTMH. Data suggest that exercise in the heat increases circulating TNF-α and STNFR1 concentration concomitantly. Furthermore, non-classical monocyte expression of TNFRs are impacted by temperature and humidity during exercise., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Authors.)

This study investigated the effect of cold-water hand immersion on selective attention as measured by the Stroop Color Word Test in nomorbaric normoxia and hypoxia. Ten healthy men rested for 60 min, after which they immersed their non-dominant hand into 5 °C water for 15 min. The interference score of the Stroop Color Word Test and thermal sensation were measured at baseline in the final 5 min of resting and in the final 5 min of cold water hand immersion. The interference score was not influenced by hypoxia but was found to be significantly improved compared to resting in both conditions during cold water hand immersion. Selective attention improved during 15 min of cold-water hand immersion, with increased thermal sensations rated as "very cool" of the immersed arm. Cold-water hand immersion may be helpful in improving cognitive function in normoxia and normobaric hypoxia.

Purpose: Cold-induced vasodilation (CIVD) is known to protect humans against local cold injuries and improve manual dexterity. The current study examined the effects of metabolic heat production on cold-induced vasodilation responses in normobaric hypoxia and normoxia., Methods: Ten participants immersed their non-dominant hand into 5 °C water for 15 min. Minimum finger temperature (T min ), maximum finger temperature (T max ), onset time, amplitude, and peak time were measured before and after exercise under normoxia (21% O 2 ) and two levels of normobaric hypoxia (17% O 2 and 13% O 2 )., Results: Neither T min nor amplitude was affected by hypoxia. However, T max was significantly decreased by hypoxia while reduction in onset time and peak time trended towards significance. T min , T max, and amplitude were significantly higher during post-exercise CIVD than pre-exercise CIVD., Conclusion: The CIVD response may be negatively affected by the introduction of hypoxia whereas metabolic heat production via exercise may counteract adverse effects of hypoxia and improve CIVD responses.

Background & Aims: Caffeine intake in a convenience sample of U.S. college students (N = 1248) was surveyed at five geographically-dispersed United States (U.S.) universities., Methods: Intake from coffee, tea, soft drinks, energy drinks, gums, and medications was assessed. Associations between caffeine intake and demographic variables including sex, age, race/ethnicity, family income, general health, exercise, weight variables and tobacco use were examined. Reasons for use of caffeine-containing products were assessed., Results: Caffeine, in any form, was consumed by 92% of students in the past year. Mean daily caffeine consumption for all students, including non-consumers, was 159 mg/d with a mean intake of 173 mg/d among caffeine users. Coffee was the main source of caffeine intake in male (120 mg/d) and female (111 mg/d) consumers. Male and female students consumed 53 vs. 30 mg/d of caffeine in energy drinks, respectively, and 28% consumed energy drinks with alcohol on at least one occasion. Students provided multiple reasons for caffeine use including: to feel awake (79%); enjoy the taste (68%); the social aspects of consumption (39%); improve concentration (31%); increase physical energy (27%); improve mood (18%); and alleviate stress (9%)., Conclusions: As in the general U.S. population, coffee is the primary source of caffeine intake among the college students surveyed. Energy drinks provide less than half of total daily caffeine intake but more than among the general population. Students, especially women, consume somewhat more caffeine than the general population of individuals aged 19-30 y but less than individuals aged 31-50 y., (Published by Elsevier Ltd.)

Objective: To determine whether 2 days of staging at 2500-3500 m, combined with either high or low physical activity, reduces acute mountain sickness (AMS) during subsequent ascent to 4300 m., Methods: Three independent groups of unacclimatized men and women were staged for 2 days at either 2500 m (n = 18), 3000 m (n = 16), or 3500 m (n = 15) before ascending and living for 2 days at 4300 m and compared with a control group that directly ascended to 4300 m (n = 12). All individuals departed to the staging altitudes or 4300 m after spending one night at 2000 m during which they breathed supplemental oxygen to simulate sea level conditions. Half in each group participated in ∼3 hours of daily physical activity while half were sedentary. Women accounted for ∼25% of each group. AMS incidence was assessed using the Environmental Symptoms Questionnaire. AMS was classified as mild (≥0.7 and <1.5), moderate (≥1.5 and <2.6), and severe (≥2.6)., Results: While staging, the incidence of AMS was lower (p < 0.001) in the 2500 m (0%), 3000 m (13%), and 3500 m (40%) staged groups than the direct ascent control group (83%). After ascent to 4300 m, the incidence of AMS was lower in the 3000 m (43%) and 3500 m (40%) groups than the 2500 m group (67%) and direct ascent control (83%). Neither activity level nor sex influenced the incidence of AMS during further ascent to 4300 m., Conclusions: Two days of staging at either 3000 or 3500 m, with or without physical activity, reduced AMS during subsequent ascent to 4300 m but staging at 3000 m may be recommended because of less incidence of AMS.

Background: To determine the effectiveness of a low-cost 12-week worksite physical activity intervention targeting a goal of 10,000 steps per day on reducing anthropometric indices, blood pressure indices, and plasma biomarkers of cardiovascular disease (CVD) risk among the employees of a major university., Methods: Fifty university employees (n = 43 female, n = 7 male; mean age = 48 ± 10 years) participated in the 12-week physical activity intervention (60 min, 3 day/week). Each session included both aerobic (cardiorespiratory endurance) and muscle-strengthening (resistance) physical activity using existing university facilities and equipment. Anthropometric indices, blood pressure indices, and plasma biomarkers of CVD risk assessed included those for obesity (body mass index), hypertension (systolic blood pressure, SBP; diastolic blood pressure, DBP), dyslipidemia (high-density lipoprotein, HDL; low-density lipoprotein, LDL; total serum cholesterol), and prediabetes (impaired fasting glucose, IFG). Steps per day were assessed using a wrist-worn activity monitor. Participants were given the goal of 10,000 steps per day and categorized as either compliers (≥ 10,000 steps per day on average) or non-compliers (< 10,000 steps per day on average) based on their ability to achieve this goal., Results: Overall, 34% of participants at baseline were already at an elevated risk of CVD due to age. On average, 28% of participants adhered to the goal of 10,000 steps per day. After 12-weeks, participants in both groups (compliers and non-compliers) had lower BMI scores (p < 0.001), lower HDL scores (p < 0.034), and higher IFG scores (p < 0.001). The non-compliers had a greater reduction of BMI scores than the compliers (p = 0.003). Participants at risk for CVD had greater reductions than those not at risk for several risk factors, including SBP (p = 0.020), DBP (p = 0.028), IFG (p = 0.002), LDL (p = 0.006), and total serum cholesterol (p = 0.009)., Conclusion: While the physical activity intervention showed mixed results overall with both favorable changes in anthropometric indices yet unfavorable changes in plasma biomarkers, it was particularly beneficial in regards to both blood pressure indices and plasma biomarkers among those already at risk of CVD. Trial registration ClinicalTrials.gov NCT03385447; retrospectively registered.

Seo, Yongsuk, Jeremiah Vaughan, Tyler D. Quinn, Brittany Followay, Raymond Roberge, Ellen L. Glickman, and Jung-Hyun Kim. The effect of inspiratory resistance on exercise performance and perception in moderate normobaric hypoxia. High Alt Med Biol. 18:417-424, 2017., Purpose: Respirators are simple and efficient in protecting workers against toxic airborne substances; however, their use may limit the physical performance of workers. The purpose of this study was to determine the effect of inspiratory resistance on physical performance and breathing perception in normobaric hypoxia., Method: Nine healthy men wore a tight-fitting respiratory mask outfitted with one of four different inspiratory resistors (R) (0, 1.5, 4.5, 7.5 cm H 2 O/L/Sec) while exercising at normobaric hypoxia (17% O 2 ) at submaximal exercise workloads of 50, 100, and 150 W on a cycle ergometer for 10 minutes each, followed by a maximal oxygen uptake (VO 2 max) test to exhaustion., Results: Maximal power output at R7.5 was significantly lower than R0 (p = 0.016) and R1.5 (p = 0.035). Respiration rate was significantly reduced at R4.5 (p = 0.011) and R7.5 (p ≤ 0.001) compared with R0. Minute ventilation was significantly decreased in R7.5 compared with R0 (p = 0.003), R1.5 (p = 0.010), and R4.5 (p = 0.016), whereas VO 2 was not significantly changed. Breathing comfort (BC) and breathing effort (BE) were significantly impaired in R7.5 (BC: p = 0.025, BE: p = 0.001) and R4.5 (BC: p = 0.007, BE: p = 0.001) compared with R0, but rating of perceived exertion (RPE) remained unchanged., Conclusions: Added inspiratory resistance limited maximal power output and increased perceptions of BC and BE in normobaric hypoxia. However, low-to-moderate inspiratory resistance did not have a deleterious effect on VO 2 or RPE at submaximal or maximal exercise. Perceptual and physiological characteristics of respirators of varying inspiratory resistances should be considered by manufacturers and end users during design and respirator selection processes.

Background: Hypoxia and exercise each exhibit opposing effects on executive function, and the mechanisms for this are not entirely clear. This study examined the influence of cerebral oxygenation and perfusion on executive function during exercise and recovery in normobaric hypoxia (NH) and normoxia (N)., Methods: There were 18 subjects who completed cycling trials in NH (12.5% FIo2) and N (20.93% FIo2). Right prefrontal cortex (PFC) oxyhemoglobin (O2Hb) and middle cerebral artery blood velocity (MCAbv) were collected during executive function challenges [mathematical processing and running memory continuous performance task (RMCPT)] at baseline, following 30 min of acclimation, during 20 min of cycling (60% Vo2max), and at 1, 15, 30, and 45 min following exercise., Results: Results indicated effects of time for Math, RMCPT, and O2Hb; but not for MCAbv. Results also indicated effects of condition for O2Hb. Math scores were improved by 8.0% during exercise and remained elevated at 30 min of recovery (12.5%), RMCPT scores significantly improved at all time points (7.5-11.9%), and O2Hb increased by 662.2% and 440.9% during exercise in N and NH, respectively, and remained elevated through 15 min of recovery in both conditions., Discussion: These results support the influence of PFC oxygenation and perfusion on executive function during exercise and recovery in N and NH.Stavres J, Gerhart HD, Kim J-H, Glickman EL, Seo Y. Cerebral hemodynamics and executive function during exercise and recovery in normobaric hypoxia. Aerosp Med Hum Perform 2017; 88(10):911-917.

To further elucidate physiological and cognitive performance differences between African-American (AA) and Caucasian individuals (CAU) before, during or after hypoxic and normoxic exercise. Twelve college aged (18-25) apparently healthy African-American (six volunteers) and Caucasian (six subjects) males took part in two trials consisting of normobaric normoxia and normobaric hypoxia (12% oxygen). Each subject cycled at 50% of their altitude adjusted VO 2max (-26% of normoxia VO 2max ) for one hour after a two-hour baseline. Subjects were monitored for cerebral and arterial O 2 saturation, as well as the Trail Making Test A and B (TMT) psychomotor performance. Arterial saturation proved to be significantly higher in AA (86.0±4.7) compared to CAU (79.5±4.8) during the first 60 minutes of exposure to hypoxia at rest (p=0.039), but not during exercise. However, cerebral oxygenation to the left frontal lobe was decreased near the conclusion and in 30 minutes after normoxic exercise. TMT B data revealed that CAU (79±12.7) had faster scores than the AA subjects (98±25.1) at all time points and was significantly different at the 115-minute time point of the hypoxic trial (p=0.024). The data suggests that before, during and after normobaric normoxia and hypoxia trial there is a differential response between AA and CAU in regards to arterial and cerebral oxygenation, as well as psychomotor tests.

Background: An acute bout of exercise can improve cognitive function in normoxic and hypoxic conditions. However, limited research supports the improvement of cognitive function and mood state in women. The purpose of this study was to examine the effects of hypoxia and exercise on working memory and mood state in women., Methods: There were 15 healthy women (age = 22 ± 2 yr) who completed the Automated Neuropsychological Assessment Metrics-4th Edition (ANAM), including the Running Memory Continuous Performance Task (RMCPT) and Total Mood Disturbance (TMD) in normoxia (21% O2), at rest in normoxia and hypoxia (12.5% O2), and during cycling exercise at 60% and 40% Vo2max in hypoxia., Results: RMCPT was not significantly impaired at 30 (100.3 ± 17.2) and 60 (96.6 ± 17.3) min rest in hypoxia compared to baseline in normoxia (97.0 ± 17.0). However, RMCPT was significantly improved during exercise (106.7 ± 20.8) at 60% Vo2max compared to 60 min rest in hypoxia. Following 30 (-89.4 ± 48.3) and 60 min of exposure to hypoxia (-79.8 ± 55.9) at rest, TMD was impaired compared with baseline (-107.1 ± 46.2). TMD was significantly improved during exercise (-108.5 ± 42.7) at 40% Vo2max compared with 30 min rest in hypoxia. Also, RMCPT was significantly improved during exercise (104.0 ± 19.1) at 60% Vo2max compared to 60 min rest in hypoxia (96.6 ± 17.3)., Discussion: Hypoxia and an acute bout of exercise partially influence RMCPT and TMD. Furthermore, a moderate-intensity bout of exercise (60%) may be a more potent stimulant for improving cognitive function than low-intensity (40%) exercise. The present data should be considered by aeromedical personnel performing cognitive tasks in hypoxia.Seo Y, Gerhart HD, Stavres J, Fennell C, Draper S, Glickman EL. Normobaric hypoxia and submaximal exercise effects on running memory and mood state in women. Aerosp Med Hum Perform. 2017; 88(7):627-632.

Seo, Yongsuk, Hayden D. Gerhart, Jeremiah Vaughan, Jung-Hyun Kim, and Ellen L. Glickman. Does acute normobaric hypoxia induce anapyrexia in adult humans? High Alt Med Biol. 18:185-190, 2017.-Exposure to hypoxia is known to induce a reduction in core body temperature as a protective mechanism, which has been shown in both animals and humans. The purpose of this study was to test if acute exposure to normobaric hypoxia (NH) induces anapyrexia in adult humans in association with decreased peripheral oxygen saturation (SpO 2 ). Ten healthy male subjects were seated in atmospheres of normobaric normoxia 21% (NN21), NH 17% (NH17), and 13% (NH13) O 2 for 60 minutes in a counterbalanced manner. Rectal temperature (Tre) was continuously monitored together with the quantification of metabolic heat production (MHP) and body heat storage (S). Baseline physiological measurements showed no differences between the three conditions. SpO 2 was significantly decreased in NH17 and NH13 compared with NN21 (p ≤ 0.001). Tre decreased following 60 minutes of resting in all conditions, but, independent of the conditions, showed no association between Tre and levels of hypoxic SpO 2 . There was also no significant difference in either MHP or S between conditions. The present results showed no evidence of hypoxia-induced anapyrexia in adult humans during 1 hour of resting after exposure to NH either at 13% or 17% O 2 .

Objective: To assess self-reported walking and sedentary behavior in young adults before and after downloading "Pokémon Go!"., Materials and Methods: In September 2016, a sample of 358 (19.8 ± 2.1 years old, n = 187 females) college students who had downloaded "Pokémon Go!" on their cellular telephones (i.e., cell phones) were surveyed for weekly walking and sedentary behavior via the International Physical Activity Questionnaire. A single interview was administered to participants who estimated their walking and sedentary behavior at three time points: the week immediately preceding their download of "Pokémon Go!" (Baseline), the first week after downloading the game (Time 1), and the week the survey was completed (Time 2). Differences in self-reported physical activity and sedentary behavior across the three time points and across the two genders were compared via analyses of variance., Results: There was a significant main effect of time (F ≥ 49.3, P ≤ 0.001) for walking and sedentary behavior. Participants reported greater (t ≥ 9.5, P < 0.001) daily walking during Time 1 (218.6 ± 156.3 minutes) and Time 2 (182.7 ± 172.1 minutes) versus the baseline (108.5 ± 110.8 minutes). Walking behavior was also significantly greater (t = 4.1, P < 0.001) at Time 1 versus Time 2. Participants reported greater (t ≥ 6.5, P < 0.001) daily sedentary behavior during baseline (346.6 ± 201.3 minutes) versus both Time 1 (261.7 ± 172.4 minutes) and Time 2 (284.3 ± 175.4 minutes). Sedentary behavior was also significantly greater (t = 2.6, P = 0.03) at Time 2 versus Time 1. There were no effects of gender (F ≤ 1.8, P ≥ 0.17)., Conclusion: Playing "Pokémon Go!" was associated with increased self-reported walking and decreased sedentary behavior. Such games hold promise as technology that may promote physical activity and discourage sedentary behavior.

Background: Hypoxia is a physiological state defined as a reduction in the distribution of oxygen to the tissues of the body. It has been considered a major factor in aviation safety worldwide because of its potential for pilot disorientation. Pilots are able to operate aircrafts up to 3810 m without the use of supplemental oxygen and may exhibit symptoms associated with hypoxia., Objective: To determine the effects of 3810 m on physiology, cognition and performance in pilots during a flight simulation., Methods: Ten healthy male pilots engaged in a counterbalanced experimental protocol comparing a 0-m normoxic condition (NORM) with a 3810-m hypoxic condition (HYP) on pilot physiology, cognition and flight performance., Results: Repeated-measures analysis of variance demonstrated a significant (p ≤ 0.05) time by condition interaction for physiological and cognitive alterations during HYP. A paired-samples t test demonstrated no differences in pilot performance (p ≥ 0.05) between conditions., Conclusion: Pilots exhibited physiological and cognitive impairments; however, pilot performance was not affected by HYP.

Unlabelled: Incentivized exercise program interventions have recently led to mixed findings with regard to increasing physical activity, attendance, and improving healthy lifestyles. However, in this area limited research exists on implementing a combined negative reinforcement strategy, using a "buy-in" and positive reinforcement system., Purpose: To determine the effect of comparing a non-incentivized reward system with an incentivized reward system using combined positive and negative rewards on physical activity, attendance, and health and performance outcomes., Methods: 15 Previously sedentary faculty and staff of a large public research university participated in two separate 12-week exercise interventions and wore a program accelerometer throughout the entire day during the 12weeks. During the first intervention, there were no incentives offered to participants. The second intervention consisted of an incentivized program. Positive reinforcements included various rewards for meeting achievements related to physical activity levels. A program rebate worth $25 for achieving 450miles was used as the negative reinforcement "buy-in" incentive., Results: A two-way repeated measures ANOVA demonstrated a main effect of time for percent body fat (p<0.001) and push-ups (p=0.018). All other variables revealed no differences between conditions or from pre to post testing. There was no difference between conditions with physical activity or attendance., Conclusion: No differences in physical activity or health-related variables were found within the incentivized and non-incentivized conditions., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Exposure to hypoxia is associated with cognitive impairment, mediated by cerebral deoxygenation. This can be problematic for individuals who perform mental tasks at high altitude. Eight healthy men completed two experimental trials consisting of 5h of exposure to normobaric hypoxia (12.5% O2). In one of the experimental trials (Hypoxia) subjects remained resting in a seated position the entire 5h; in the other experimental trial (Hypoxia and Exercise) subjects rested 2h, cycled for 1h at constant wattage (workload equivalent to 50% of altitude adjusted VO2max), then rested the last 2h. Cerebral oxygenation was measured continuously via near-infrared spectroscopy and cognitive performance was assessed by Trail Making Test A and B. Cerebral oxygenation and cognitive performance both were impaired during exposure to hypoxia. In the Hypoxia and Exercise trial, subjects experienced further declinations in cerebral oxygenation without concomitant decreases in cognitive function. These data demonstrate that cognitive function declines during exposure to normobaric hypoxia and this decline is not exacerbated by low intensity exercise., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background & Aims: Dietary supplements (DS) are popular in many countries but little data are available on their use by sub-populations such as college students. Since students share a variety of characteristics and similar lifestyles, their DS use may differ from the general population. This study assessed DS use, factors associated with DS use, and reasons for use among U.S. college students., Methods: College students (N = 1248) at 5 U.S. universities were surveyed. Survey questions included descriptive demographics, types and frequency of DS used, reasons for use and money spent on supplements. Supplements were classified using standard criteria. Logistic regression analyses examined relationships between demographic and lifestyle factors and DS use., Results: Sixty-six percent of college students surveyed used DS at least once a week, while 12% consumed 5 or more supplements a week. Forty-two percent used multivitamins/multiminerals, 18% vitamin C, 17% protein/amino acids and 13% calcium at least once a week. Factors associated with supplement use included dietary patterns, exercise, and tobacco use. Students used supplements to promote general health (73%), provide more energy (29%), increase muscle strength (20%), and enhance performance (19%)., Conclusions: College students appear more likely to use DS than the general population and many use multiple types of supplements weekly. Habits established at a young age persist throughout life. Therefore, longitudinal research should be conducted to determine whether patterns of DS use established early in adulthood are maintained throughout life. Adequate scientific justification for widespread use of DS in healthy, young populations is lacking., (Published by Elsevier Ltd.)

The obesity epidemic has grown in the past decade due to physical inactivity (i.e., having a sedentary job) and an increase in caloric intake. This problem combined with the reluctance of many faculty and staff members exercising in the same environment as student's presents a unique challenge in an academic setting. The purpose of this study was to examine the effectiveness of a 12-week exercise program focused toward the faculty and staff in improving several health-related variables such as curl-ups, push-ups, sit-and-reach, and balance. Fifty-seven faculty and staff participated in the current study. Participants engaged in a variety of exercise classes taught by certified instructors three days a week for 12-weeks. Paired samples t-tests illustrated a significant (p < 0.001) decrease in body mass and significant (p ≤ 0.001) improvements in curl-ups, push-ups, sit-and-reach, and balance. This data demonstrates that a 12-week faculty and staff exercise program has the potential to improve performance in several health-related variables such as curl-ups, push-ups, sit-and-reach, and balance. The ability of this program to improve health-related variables and possibly delay or prevent the development of overweight and/or obesity, sarcopenia, and other chronic diseases is encouraging.

Purpose: The purpose of this study is to determine how cold exposure and lower body negative pressure effected cardiovascular variables., Methods: Eleven males (20.3 years ± 2.7) underwent two 20-minute exposures to LBNP. During the 2 trials, the subjects were exposed to cold air (10°C) (COLD) and to ambient temperature (23°C) (AMB). The trials consisted of a 100-minute pre-LBNP period followed by a 20-minute exposure to LBNP and then a 15-minute recovery period. Cardiovascular variables were recorded every 30 minutes using bioimpedance., Results: When LBNP was applied during the AMB trials, stroke volume immediately decreased. During the COLD trial, there was a five-minute delay before the decrease in stroke volume. Heart rate increased immediately after LBNP initiation during the AMB trials but there was a delay in the increase during the COLD trials. That same pattern was followed with mean arterial blood pressures. Cerebral oxygenation was significantly lower throughout the COLD trial as compared to the AMB trials. Six subjects reported symptoms of syncope or presyncope during the AMB trials but there were no reports of symptoms during the COLD trials., Conclusion: From analysis of this data, cold improved the subject's tolerance to LBNP.

Introduction: Dehydration limits the appropriate delivery of oxygen and substrates to the working muscle. Further, the brain's ability to function may also be compromised whereby thermal sensation and mood state may be altered., Purpose: The purpose of the present investigation was to compare the thermoregulatory, perceptual, and negative mood state profile in glucose (GLU) vs. non-glucose beverage (NON-GLU) condition., Methods: Ten healthy men volunteered and were counterbalanced either a GLU or NON-GLU containing beverage on separate mornings. In each condition, they were exposed to 37°C, 50% relative humidity (RH) for baseline, exercise, rehydration, and recovery periods. The exercise period elicited the desired level of dehydration (mean of 2.6 ± 0.3% body weight losses). Upon completion of the protracted exercise, participants were administered either a GLU or NON-GLU containing electrolyte based sports drink ad libitum for 30 min, followed by a recovery period of 15 min in 37°C, 50% RH. Rectal (Tre) and mean skin temperatures (Tsk) were continuously monitored. Gagge (TS) and heated thermal sensation (HTS), profile of mood state (POMS) were measure at the end of each period., Results: During recovery after rehydration, Tre was not significantly different between conditions (GLU vs. NON-GLU) (37.4 ± 0.8 vs. 37.0 ± 1.2°C); Tsk was also not affected by rehydration in both conditions (36.0 ± 0.5 vs. 36.0 ± 0.6°C) and, TS and HTS did not differ between conditions (0.9 ± 1.3 vs.1.3 ± 0.7) and (1.0 ± 0.8 vs.0.8 ± 0.3). Total mood disturbance (TMD) score for the POMS was utilized for overall negative mood state and demonstrated a main effect for time (p < 0.05). TMD during recovery was decreased compared to before hydration in both conditions., Conclusion: The non-glucose containing beverage maintained plasma volume and was effective at maintaining body temperature homeostasis in a similar fashion compared to the glucose containing beverage. Furthermore, negative mood state was not different between the two conditions. The non-glucose beverages can serve a valuable role in the exercise environment depending upon the sport, the ambient temperature, the individual, duration of the exercise, the age and training states of the individual.

When exposed to a cold environment, a barehanded person experiences pain, cold sensation, and reduced manual dexterity. Both acute (e.g. exercise) and chronic (e.g. cold acclimatization or habituation) processes might lessen these negative effects. The purpose of this experiment was to determine the effect of cold habituation on physiology, perception, and manual dexterity during rest, exercise, and recovery in 5 °C. Six cold weather athletes (CWA) and eight non habituated men (NON) volunteered to participate in a repeated measures cross-over design. The protocol was conducted in 5 °C and was 90 min of resting cold exposure, 30 min of cycle ergometry exercise (50 % VO2 peak), and 60 min of seated recovery. Core and finger skin temperature, metabolic rate, Purdue Pegboard dexterity performance, hand pain, thermal sensation, and mood were quantified. Exercise-induced finger rewarming (EIFRW) was calculated for each hand. During 90 min of resting exposure to 5 °C, the CWA had a smaller reduction in finger temperature, a lower metabolic rate, less hand pain, and less negative mood. Despite this cold habituation, dexterity performance was not different between groups. In response to cycle ergometry, EIFRW was greater in CWA (~12 versus 7 °C) and occurred at lower core temperatures (37.02 versus 37.31 °C) relative to NON but dexterity was not greater during post-exercise recovery. The current data indicate that cold habituated men (i.e., CWA) do not perform better on the Purdue Pegboard during acute cold exposure. Furthermore, despite augmented EIFRW in CWA, dexterity during post-exercise recovery was similar between groups.

Introduction: The physiological effects of immersion hypothermia and afterdrop are well-characterized, but the psychological effects are less clear. The purpose of this study was to quantify changes in cognitive function during and after lower body water immersion., Methods: On separate mornings, nine young healthy men participated in both neutral (35 +/- 1 degree C) and cold (13 +/- 1 degree C) water immersion. Subjects rested in neutral air for 30 min followed by 60 min water immersion to the iliac crest and 15 min of recovery in neutral air. Rectal temperature and mean skin temperature were continuously monitored. Metabolic rate, the Stroop Color Word Test (SCWT), and the Profile of Mood State (POMS) were quantified at predetermined intervals., Results: During immersion in cold water, rectal temperature was reduced, but SCWT and POMS scores were unchanged relative to baseline. Despite the reduced rectal temperature, little to no shivering was observed during immersion and metabolic rate did not change. During recovery from cold immersion, rectal temperature was further reduced by approximately 0.5 degree C, shivering was noted, and metabolic rate increased. Coincident with this acute afterdrop, SCWT Color-Word performance (delta = -4 +/- 8 vs. 7 +/- 6 correct responses) and Interference score (delta = -2 +/- 7 vs. 4 +/- 8) was impaired relative to recovery from neutral immersion (i.e., when core temperature and metabolic rate did not change)., Conclusion: These results suggest that recovery from lower body cold water immersion elicits the afterdrop phenomenon and shivering, which together impair selective attention as measured by the SCWT.

The purpose of this study was to determine the most efficacious time to administer caffeine (CAF) in chewing gum to enhance cycling performance. Eight male cyclists participated in 5 separate laboratory sessions. During the first visit, the subjects underwent a graded exercise test to determine maximal oxygen consumption (V[Combining Dot Above]O(2)max). During the next 4 visits, 3 pieces of chewing gum were administered at 3 time points (120-minute precycling, 60-minute precycling, and 5-minute precycling). In 3 of the 4 visits, at 1 of the time points mentioned previously, 300 mg of CAF was administered. During the fourth visit, placebo gum was administered at all 3 time points. The experimental trials were defined as follows: trial A (-120), trial B (-60), trial C (-5), and trial D (Placebo). After baseline measurements, time allotted for gum administration, and a standard warm-up, the participants cycled at 75% V[Combining Dot Above]O(2)max for 15 minutes then completed a 7-kJ·kg(-1) cycling time trial. Data were analyzed using a repeated measures analysis of variance. Cycling performance was improved in trial C (-5), but not in trial A (-120) or trial B (-60), relative to trial D (Placebo). CAF administered in chewing gum enhanced cycling performance when administered immediately prior, but not when administered 1 or 2 hours before cycling.

It has been repeatedly demonstrated that increasing the variety of available food and purchasing options reliably increases eating and consumer spending behavior, respectively. However, the potential probehavioral effect of increasing the variety of exercise equipment options on the amount of exercise individuals perform is very limited. The purpose of this investigation was to compare the amount, enjoyment (liking), and effort perception of resistance training exercise vs. sedentary alternatives during a high-variety (HV) resistance-exercise equipment condition (10 choices) vs. a low-variety (LV) equipment condition (2 choices). During each condition (HV) and (LV), children (8-12 years), young adults (18-26 years), and older adults (≥60 years) had free-choice access to both resistance-exercise equipment and sedentary activities for a total of 20 minutes. The amount of time allocated to resistance exercise, the total number of repetitions performed, and session liking were measured during each condition. The participants significantly (p ≤ 0.05 for all) increased: repetitions performed (126.4 ± 71.7 vs. 88.0 ± 48.8), the amount of time allocated for exercise (14.3 ± 6.3 vs. 12.1 ± 6.5 minutes) and liking (8.1 ± 1.5 vs. 7.1 ± 2.1 cm) during the HV condition relative to the LV condition. The rating of perceived exertion was not significantly (p = 0.13) different from HV (4.2 ± 2.4) to LV (3.8 ± 2.3). Increasing the variety of exercise equipment available to children, young and older adults increased their exercise participation and enjoyment of that exercise without altering their perceived exertion. The practical application from this research is that increasing the variety of exercise equipment available to one's clients may increase their exercise adherence.

The purpose of the present investigation was to determine the relationship between serum ghrelin concentrations, adiposity, and verbal learning in a group of healthy, fit older adults. Participants were 28 healthy older adults (age: 70.8 ± 9.3 yrs, BMI: 27.3 ± 5.7). Participants reported to the laboratory and basic anthropometric data were collected, followed by a blood draw to quantify serum ghrelin. Participants then underwent cognitive testing that included the revised Hopkins Verbal Learning Test (HVLT), as well as the Mini-Mental Status Exam (MMSE). The results of the MMSE test revealed that the volunteers were cognitively intact (MMSE 27.6 ± 1.8). A significant correlation emerged between serum ghrelin concentrations, 2 trials of the HVLT (Trial 1: r = 0.316, P = 0.05; Trial 2: r = 0.395, P = 0.03), and the sum of three-site skinfold analysis (r = 0.417, P = 0.015). Based upon the aforementioned relationships, it appears that fasting levels of serum ghrelin are related to both verbal learning and adiposity in healthy, fit older adults.

Objective: Sleep deprivation and cold air exposure are both experienced in occupational and military settings but the combined effects of these 2 stressors is unknown. The purpose of this study was to determine the effects of 53 hours of total sleep deprivation on thermoregulation during the rewarming phase (25°C air) after acute cold air exposure (10°C air)., Methods: Eight young men underwent 2 trials in which they either received 7 hours of sleep at night or were totally sleep deprived. On 3 consecutive mornings, the subjects underwent 2 hours of cold air exposure followed by 2 hours of rewarming. Rectal temperature, mean skin temperature, oxygen consumption, and thermal sensation were measured., Results: Rewarming from acute cold air exposure caused a decline in rectal temperature (~0.5°C) each day but this was not different between subjects who were totally sleep deprived and subjects who received 7 hours of sleep at night. During this same period, mean skin temperature increased (from ~22°C to 27°C), oxygen consumption decreased (from ~7 to 4 mL·kg(-1)·min(-1)), and the participants felt warmer., Conclusions: Under the conditions of the present study, sleep-deprived persons are not at a greater risk for a decline in rectal temperature (ie, a hypothermic afterdrop) during rewarming from cold air., (Copyright © 2012 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Lower body water immersion (LBWI) is experienced in the marine industry but the physiological responses to LBWI are unclear. The purpose of the current experiment was to test the effects of water temperature and immersion duration on rectal temperature, heart rate, stroke volume, blood pressure, metabolic rate, and thermal sensation in healthy subjects., Methods: Nine young men underwent two 60-min trials of seated LBWI to the iliac crest in a counterbalanced fashion. On one occasion, the water was 35 degrees C (LBWI-Neutral) and on the other it was 13 degrees C (LBWI-Cold); the upper body remained thermoneutral and dry throughout., Results: As expected, exposure to cold water reduced mean skin temperature and individuals reported cold thermal sensation. Mean arterial pressure was significantly higher at 60 min of LBWI-Cold (86 +/- 7 mmHg) compared to LBWI-Neutral (76 +/- 5 mmHg) while heart rate tended to be lower. The change in rectal temperature from baseline to 30 min of LBWI-Cold (delta = -0.01 +/- 0.21degrees C) was significantly smaller than the change in T(re) from 30 to 60 min of LBWI-Cold (delta = -0.46 +/- 0.16 degrees C). Despite this accelerated drop in core temperature during minutes 30-60, metabolic rate did not increase significantly., Conclusion: LBWI-Cold reduces core temperature and increases arterial blood pressure via an increase in total peripheral resistance. This experimental model may help scientists better understand the body during cold stress. Further, people who are occupationally exposed to cold water (when the torso, hands, and arms remain thermoneutral) may be at increased risk for hypothermia.

Low-dose caffeine administered in chewing gum does not enhance cycling to exhaustion. The purpose of the current investigation was to examine the effect of low-dose caffeine (CAF) administered in chewing gum at 3 different time points during submaximal cycling exercise to exhaustion. Eight college-aged (26 ± 4 years), physically active (45.5 ± 5.7 ml·kg(-1)·min(-1)) volunteers participated in 4 experimental trials. Two pieces of caffeinated chewing gum (100 mg per piece, total quantity of 200 mg) were administered in a double-blind manner at 1 of 3 time points (-35, -5, and +15 minutes) with placebo at the other 2 points and at all 3 points in the control trial. The participants cycled at 85% of maximal oxygen consumption until volitional fatigue and time to exhaustion (TTE) were recorded in minutes. Venous blood samples were obtained at -40, -10, and immediately postexercise and analyzed for serum-free fatty acid and plasma catecholamine concentrations. Oxygen consumption, respiratory exchange ratio, heart rate, glucose, lactate, ratings of perceived exertion, and perceived leg pain measures were obtained at baseline and every 10 minutes during cycling. The results showed that there were no significant differences between the trials for any of the parameters measured including TTE. These findings suggest that low-dose CAF administered in chewing gum has no effect on TTE during cycling in recreational athletes and is, therefore, not recommended.

We sought to determine if cold acclimatized men display higher economy (i.e. lower oxygen consumption at a given workload) during graded cycle ergometry in the cold (5°C). After completing a familiarization trial 1 week prior, five cold weather athletes (CWA) and eight physically active men (NON) underwent graded exercise tests to volitional fatigue in 5°C. The protocol always started at 60 W and increased by 20 W each minute. Oxygen consumption (VO(2)), respiration rate (RR), tidal volume (TV), and respiratory exchange ratio (RER) were determined via open circuit spirometry. Individuals were matched for body size and minutes of weekly physical activity. Repeated measures analyses of variance were conducted across time (workload) and cold acclimatization was entered as a between subjects factor. VO(2) peak was not different between groups but CWA had lower VO(2) at 60 and 240 W. CWA also had lower RR at 180 and 260 W as well as lower RER at 240 and 260 W. At submaximal workloads, cold acclimatized men have higher exercise economy than non-acclimatized men. This could have implications for those who work in this context.

Several industries experience periods of cold exposure and rewarming throughout the workday but mental performance under these conditions is unknown. A better understanding of cognition during the rewarming phase after cold exposure may help reduce accidents and improve performance. Ten young men (wearing ~0.1 clo) underwent three consecutive mornings trials where they were exposed to cold air (10°C) and then subsequently rewarmed (25°C air). A computerised test battery was administered during each stage of the protocol to determine working memory, choice reaction time, executive function and maze navigation. Rectal and skin temperature, oxygen consumption and thermal sensation were also measured throughout and showed a typical response. Relative to baseline performance, working memory, choice reaction time and executive function declined during exposure to 10°C, and these impairments persisted 60 min into the recovery period (i.e. once physiological parameters had returned to baseline). Further work is needed to develop countermeasures to this predicament., Practitioner Summary: This study showed that working memory, choice reaction time and executive function declined during exposure to 10°C air, and these impairments persisted 60 min into the rewarming period (i.e. once measurable physiological parameters had returned to normal). Individuals may be at risk for injury after removal from a cold environment.

Objective: To explore the effect of aspirin on the thermoregulatory responses of men during exposure to 12°C air (acute cold exposure) for a period of 120 minutes and recovery in 25°C air (rewarming) for 120 minutes., Methods: Seven male subjects (26.1 ± 2.4 yr) underwent pre-experimental testing to determine peak VO(2) and body composition. Participants underwent 3 trials in which they ingested the following for 1 week prior to each experimental trial: a capsule filled with cellulose (placebo), 81 mg · day(-1) of aspirin (low-dose aspirin), or 650 mg · day(-1) of aspirin (high-dose aspirin). Each trial consisted of a 30-minute baseline period, 120 minutes of exposure to 12°C air, and 120 minutes of recovery in 25°C air. Mean skin temperature and rectal temperature (T(re)) were measured, and heat production was calculated., Results: During both acute cold exposure and rewarming, analysis of variance revealed a main effect for time (P < .05) with respect to T(re), mean skin temperature, and heat production. However, there were no significant differences between the treatments or treatment by time interactions., Conclusions: These data demonstrate that aspirin had no significant effect on the thermal and metabolic responses during acute cold exposure and rewarming., (Copyright © 2011 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.)

In the cold, Purdue Pegboard (PP) performance declines. The purpose of this study was to determine if this cold-induced impairment is consistent across days (i.e. test-retest reliability) in 5°C. In thermoneutral air (25°C), 14 men were familiarised to the dominant hand (PPa) and bimanual (PPb) PP tasks. They then experienced two 90-min cold exposures (Day 1, Day 2) while wearing ∼1 clo. Bare hands were maintained throughout. Performance on both tasks showed high reliability from day to day (intraclass correlations >0.700) in both thermoneutral and cold conditions. However for both tasks, room temperature performance did not predict performance in the cold (intraclass correlations <0.450). When screening applicants for manual labour in the cold, one must consider that room temperature dexterity does not correlate with dexterity in the cold. It is recommended that a 60-min period of cold exposure be employed to assess manual dexterity in these workers. STATEMENT OF RELEVANCE: This study shows that PP performance in room temperature does not predict performance in the cold but performance in the cold is consistent from day to day. When screening applicants for manual labour in the cold, it is recommended that dexterity tests be conducted in the same ambient conditions.

Both mood and cognitive function are altered in cold environments. Body warming through exercise may improve Stroop interference score and lessen total negative mood. The purpose of this study was to determine the effect of equal caloric bouts of interval (INT) and continuous (CONT) exercise on mood and selective attention in the cold. Eleven young men underwent two experimental trials in 5°C air. Both trials consisted of 90 min acute cold exposure (ACE), 30 min exercise (INT vs. CONT), and 60 min recovery (REC). The Profile of Mood States (POMS) and Stroop Color Word Test (SCWT) were administered at four time points. Mean body temperature decreased during ACE, increased during exercise, and decreased during REC. Repeated measures analysis of variance revealed a main effect for time for several of the POMS sub scores. In particular, negative mood was significantly decreased after exercise relative to ACE and then significantly increased during REC. Further, CONT appears to be more effective than INT at decreasing negative mood. Components of the SCWT supported both the arousal and distraction theories for simple perception, but no significant effects were shown for the interference score. In the cold, exercise decreases negative mood but does not appear to affect selective attention. Further mechanistic studies could determine the best mode and intensity of exercise for improving cognitive function in the cold.

Salt intake may cause conflict for the cardiovascular system as it attempts to simultaneously maintain blood pressure (BP) and temperature homeostasis. Our objective was to determine the effect of a salt and water load vs. a water load upon rectal temperature (Tre) in healthy volunteers. Twenty-two healthy, non-hypertensive Caucasian men enrolled in two trials in which they ingested either salt and body temperature water (SALT), or body temperature water (WATER). BP, Tre, cardiac index, peripheral resistance and urine output were monitored one, 2 and 3 h post-baseline. Changes in the dependent variables were compared between those subjects who were salt sensitive (SS) and those who were salt resistant (SR) at the same time intervals. The percentage change reduction in Tre was greater following SALT compared with WATER at +120 min (-1.1±0.7 vs. -0.6±0.5%, P=0.009) and at +180 min (-1.3±0.8 vs. -0.7±0.6%, P=0.003). The percentage change reduction in Tre was greater in the SR group compared with the SS group at +180 min (-1.6±0.9 vs. -0.9±0.5%, P=0.043). SALT decreased Tre more than WATER. SS individuals maintained temperature homeostasis more effectively than SR individuals following SALT. These results may explain why some individuals are SS while others are SR. If these results are generalizable, it would be possible to account for the role of sodium chloride in the development of SS hypertension.

Military and factory work often involves exposure to cold temperatures. With prolonged exposure, individuals report feeling cold and develop pain in their hands, both of which might be alleviated by endogenous heat production via exercise. The purpose of this study was to evaluate how interval (INT) and continuous (CONT) cycle ergometry alter thermal sensation, hand pain, mean finger temperature, and skin surface temperature gradient (forearm-finger) following immobility in moderate cold. Fourteen young men underwent two trials (each was three total hours in 5°C) consisting of a 90-min period of acute cold exposure (ACE), 30 min of exercise (INT or CONT), and a 60-min recovery period (REC). INT and CONT were isoenergetic, reflecting 50 ± 1% of each individual's VO(2) peak. All perceptual scales were significantly correlated during ACE (i.e., test-retest reliability). As expected, individuals felt colder and reported more hand pain during ACE, as compared to thermoneutral conditions. Relative to ACE, both INT and CONT increased mean finger temperature, which was associated with warmer thermal sensation and less hand pain. During REC in 5°C, individuals felt colder and reported more hand pain than during exercise. Although there were no perceptual differences between INT and CONT, moderate exercise in general can cause subjective feelings of warmth and less hand pain in people acutely exposed to moderate cold.

This double-blind, placebo-controlled, within-subject experiment examined the effects of low-dose caffeine on pain reported during an exhaustive grip task. The grip task consisted of holding a metal block attached to standard Olympic weight plates with the arm at the side until the participants could no longer maintain their grip. Apparently healthy recreationally trained college-aged adults (men, n = 5; women, n = 5) were given either a piece of Stay Alert™ gum that delivered 85% of the effective dose of 100 mg of caffeine in 5 minutes or an identical placebo gum that contained no caffeine. Subsequently, pain perception and ratings of perceived exertion were recorded during an exhaustive grip task every 15 seconds and the overall time to exhaustion. No significant difference was found in time to exhaustion between treatments. A significant main effect of treatment for reported pain (p < 0.001, Φ = 0.377) was observed. Thus, in a population of recreationally trained college-aged adults, low-dose caffeine may attenuate the individual's perception of pain during a grip to exhaustion task.

The present study examined the association between serum insulin like growth factor-1 (IGF-1) concentrations and cognitive function in a sample of healthy, fit older adults (age: 70.8±9.3 years, body mass index (BMI): 27.3±5.7). Participants reported to the laboratory and basic anthropometric data were collected, followed by a fasted blood draw to quantify serum IGF-1. Participants then underwent cognitive testing that included the Mini-Mental Status Exam (MMSE), Trail Making Test A and B, Ruff's 2 and 7 test of selective attention and Letter Number Sequencing. Results showed the participants were generally cognitively intact (MMSE 27.6±1.8). Significant partial correlations (controlled for age, gender and years of education) emerged between serum IGF-1 concentrations and the total (r=0.381, P=0.030) and longest trial (r=0.455, P=0.011) on Letter Number Sequencing. Similar partial correlations yielded significant relationships between serum IGF-1 and Ruff's Automatic Detection Errors (r=-0.495, P=0.006), Controlled Speed Errors (r=-0.598, P=0.002) and errors made on the Trial Making Test part B (r=-0.466, P=0.010). These findings suggest that fasting levels of serum IGF-1 are related to higher levels of cognitive performance in healthy older adults, including working memory, selective attention and executive function. Further work is needed to more clearly determine possible mechanisms., (Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.)

The present study investigated the effects of training combining elastic tension, free weights, and the bench press. Eleven college-aged men (untrained) in the bench press participated in the 13-week study. The participants were first given instructions and then practiced the bench press, followed by a one-repetition maximum (1RM) test of baseline strength. Subjects were then trained in the bench press for 3 weeks to allow for the beginning of neural adaptation. After another 1RM test, participants were assigned to 1 of 2 conditions for the next 3 weeks of training: 85% Free-Weight Tension, 15% Elastic Tension (BAND), or 100% Free-Weight Tension (STAND). After 3 weeks of training and a third 1RM max test, participants switched treatments, under which they completed the final 3 weeks of training and the fourth 1RM test. Analysis via analysis of covariance revealed a significant (p ≤ 0.05) main effect for time and interaction effect for Treatment (BAND vs. STAND). Subsequent analysis via paired-samples t-test revealed the BAND condition was significantly better (p = 0.05) at producing raw gains in 1RM strength. (BAND 9.95 ± 3.7 kg vs. STAND 7.56 ± 2.8 kg). These results suggest that the addition of elastic tension to the bench press may be an effective method of increasing strength.

Cardiac patients with depression have shown altered autonomic nervous system functioning, expressed as reduced heart rate variability. This may be associated with poorer physical fitness and less physical activity among depressed patients. These relationships were explored among patients enrolled in outpatient cardiac rehabilitation. 22 depressed and 22 nondepressed patients, matched for sex and age, were assessed at enrollment. The Beck Depression Inventory and structured interviews were used to measure depression. Patients completed ambulatory monitoring of ECG (i.e., Holter) and physical activity, as well as a treadmill stress test. Depression was associated with several measures of heart rate variability. Activity and fitness were lower among the depressed patients. Although exploratory, accounting for activity and fitness attenuated the relationship between depression and heart rate variability. This suggests that altered fitness and activity may help explain altered autonomic tone that characterizes patients with cardiovascular diseases who are psychologically depressed.

The purpose of this study was to evaluate how interval (INT) and continuous (CONT) exercise alter body temperatures and manual dexterity in the cold (5 degrees C). Fourteen young men underwent two trials consisting of a 90-min period of acute cold exposure (ACE), 30 min of exercise (INT or CONT), and a 60-min recovery period (REC). Participants donned approximately 1 clo but the hands remained bare for the entire protocol so that a steep decline in dexterity performance occurred prior to the initiation of exercise. INT and CONT were isoenergetic, reflecting 50 +/- 1% of each individual's VO(2) peak. Rectal (Tre) and skin temperatures were monitored continuously and dexterity testing was conducted at ten time points throughout each 3-h trial. In addition, oxygen consumption (VO(2)) and torso hemodynamics were assessed via indirect calorimetry and impedance cardiography (ICG), respectively. As expected, finger temperature and dexterity declined during ACE, relative to baseline. Both modes of exercise increased finger temperature and dexterity, relative to ACE. However, CONT was more effective than INT at increasing finger temperature on the dominant hand, which was associated with better dexterity scores during REC. Tre was not different between trials but a significant increase in stroke volume was found following CONT. Perhaps elevated stroke volume during post-exercise REC plays a role in finger rewarming and dexterity performance. Further mechanistic studies are needed to confirm the role of cardiovascular function in the enhancement of manual performance in the cold.

Background: Dietary Approaches to Stop Hypertension (DASH) has been shown to successfully reduce systolic (SBP) and diastolic blood pressure (DBP) when evaluated in clinically controlled environments but there is a lack of information regarding the efficacy of the original DASH diet when it is applied in a free-living environment., Purpose: To provide descriptive data as to the changes in blood pressure individuals could expect to achieve when following the DASH diet in a free-living environment for 4-weeks with no additional behavioral modifications., Methods: Twenty, pre- and stage 1 hypertensive participants were randomly split into 2 groups; DASH (males N = 5, females N = 5, age = 38.5 ± 10.8) and control (males N = 7, females N = 3, age = 38.1 ± 11.1). The DASH group was instructed on how to follow the DASH diet on their own for 4-weeks while the control group continued their normal diet. SBP, DBP, body weight, 3-day food diaries and physical activity recall questionnaire data were collected pre and post intervention using a traditional person-to-person instructional technique., Results: Two-way ANOVA demonstrated that there was a significant group (DASH, control) by time (pre, post) interaction for SBP (P = 0.003) and no significant effects for DBP. The interaction was due to a significant reduction (P < 0.001) in SBP in the DASH group (pre: 141.3 ± 11.3 mmHg vs. post: 130.7 ± 9.1 mmHg) over the course of the intervention with no change in SBP in the control group (pre: 133.5 ± 6.6 mmHg vs. post: 131.9 ± 8.9 mmHg). Pearson's correlation analyses revealed that changes in potential moderators of blood pressure including body weight, BMI, sodium intake and total kilocalories were each not associated with changes in SBP (r ≤ 0.14, P ≥ 0.5) or DBP (r ≤ 0.10, P ≥ 0.6) pre- to post-treatment. Chi-square demonstrated no significant differences in the number of participants per group (n = 4 DASH, n = 1 control) who indicated increasing physical activity during the intervention., Conclusion: DASH diet followed in a free-living environment significantly reduced SBP but not DBP. However, the changes in SBP and DBP were very similar to those noted in controlled clinical feeding evaluations of the DASH diet. Presently, none of the potential moderators of blood pressure that were assessed were independently associated with the observed changes in blood pressure which may be due to our small sample size or the possibility that it is the combined change in multiple factors that lead to reductions in blood pressure when following the DASH diet.

Introduction: It is well documented that cardiovascular alterations occur during acute cold exposure (ACE). Interindividual variability is present, due mainly to body size differences, gender, and age. However, no study has evaluated stroke volume in the same individual twice in the same ambient conditions (i.e., test-retest reliability). Impedance cardiography (ICG) has become a popular method to acquire hemodynamic data in both clinical and applied physiology settings. Further, ICG does not interfere with other dependent variables such as oxygen consumption. Therefore, based on the uniqueness of the methodology, we sought to test reliability in this technology at 5 degrees C for 65 min on two separate occasions., Methods: Nine young men underwent two 65-min trials of resting ACE, separated by at least 72 h. Volunteers were clothed in approximately one layer of clothing. Core and skin temperatures, oxygen consumption, and central hemodynamics were measured., Results: As expected, core and skin temperature decreased while oxygen consumption showed a modest increase over time. In both trials, stroke volume significantly increased over time as heart rate decreased. There was similarity within subjects and between trials for all variables, as assessed via bivariate correlations., Conclusion: Cold increased stroke volume and decreased heart rate when subjects were pooled together, but each subject retained his individuality (minimal interindividual differences). Results suggest that impedance cardiography may be a reliable technique to use during acute cold exposure.

Unlabelled: Enhanced sympathoadrenal activity has been implicated in the pathogenesis of acute mountain sickness (AMS). This study was designed to examine the time course of circulating catecholamines in individuals with and without AMS., Methods: Subjects were low-altitude residents (10 men, 8 women) who had not been exposed to altitude within the previous 2 mo. They breathed 12% O2 (hypoxia equivalent to 4600 m altitude) for 8 h while seated at rest. AMS was evaluated using Lake Louise scores (LLS) at 0, 1, 3, 5, and 7 h of exposure using a threshold of 3 to define AMS. Blood samples were collected to measure arterial blood gases and oxygen saturation as well as arterial and venous epinephrine (A-EPI and V-EPI) and norepinephrine (A-NE and V-NE)., Results: Eight subjects (44%) developed AMS at some time during the experiment. Blood gases showed no significant difference between subjects with or without symptoms (AMS+ and AMS-, respectively). However, AMS+ subjects showed significantly greater concentrations of A-EPI over the 8 h without any between-group difference in V-EPI. Levels of A-NE were significantly higher at baseline and during the first hour of hypoxia in subjects who later developed AMS. V-NE increased significantly over time among all participants with no difference between groups., Conclusions: These findings suggest a possible physiological marker for individuals who may be relatively susceptible to AMS and provide additional insight into the sympathoadrenal response to acute hypoxia.

Background: Associations between obesity and poor iron status have been described in children and adults. Proposed mechanisms for this association implicate a physiologic etiology, suggesting body fat accretion may progressively degrade iron status. However, the relationship between iron status and body composition in non-obese adults remains unclear., Objective: In this study we examined the relationship between body composition, inflammation, and iron status in healthy, non-obese, pre-menopausal females., Methods: Iron status was assessed using red cell distribution width, transferrin saturation, serum ferritin, and soluble transferrin receptor (sTfR). Tumor-necrosis factor-alpha provided a marker of inflammation, and body fat percentage (BF) was calculated from mean skinfold thickness measurements at 3 sites., Results: In this cohort (n = 207), the prevalence of iron deficiency was similar (p > 0.05) between normal and overweight (BMI 25.0-30.0 kg/m(2)), and normal and overfat (BF >or=30.0%) volunteers. There were no differences in individual iron status indicators, including sTfR, between overweight or overfat volunteers as compared to normal weight and normal fat peers. Logistic regression analyses indicated that overfat volunteers had a lower (p < 0.05) risk of iron deficiency, whereas overweight individuals demonstrated no change in relative risk as compared to peers., Conclusion: These findings suggest that, in non-obese adults, decrements in iron status are not associated with increasing adiposity.

Objective: It is well established that a combination of factors, including ethnicity, may influence an individual's response to cold stress. Previous work from our laboratory has demonstrated that when faced with a cold challenge, there is a similar response in heat production between Caucasian (CAU) and African American (AA) individuals that is accompanied by a differential response in core temperature. The objective of this study was to evaluate the influence of ethnicity (CAU vs AA) on the thermoregulatory response after acute cold exposure (ACE-REC, 25 degrees C air)., Methods: Five AA males (20.8 +/- 0.5 years) and 10 CAU males (25.6+/-4.9 years) underwent pre-experimental testing to determine Vo(2max) (AA = 37.2 +/- 0.1 mLxkg(-1)xmin(-1), CAU = 44.3 +/- 8.7 mLxkg(-1)xmin(-1)) and body composition (AA = 14.6 +/- 5.4%, CAU = 19.2 +/- 5.0%). Participants underwent acute cold exposure that consisted of 120 minutes of exposure to 10 degrees C air (ACE) followed by 120 minutes of recovery in 25 degrees C air (ACE-REC). Rectal temperature (T(re)) was measured via a rectal thermistor. Mean skin temperature (T(sk)) was assessed with thermistors. Oxygen consumption (Vo(2)) was assessed via indirect open circuit spirometry. Rectal temperature and T(sk) were measured continuously, and if T(re) < or = 35 degrees C, testing was terminated., Results: Analysis of variance for ACE-REC revealed a significant main effect for T(sk) across time (P < .001), T(re) across time (P < .001), and Vo(2) across time (P < .001). In addition, a significant time x ethnicity interaction was revealed for T(re) (P = .008), T(sk) (P = .042), and Vo(2) (P = .019) during ACE-REC., Conclusions: Based on these data, there is a differential response between CAU and AA across time for Vo(2), T(re), and T(sk) ACE-REC.

Purpose: This study examined how a high-protein diet affected nitrogen balance and protein turnover during an exercise-induced energy deficit., Methods: Twenty-two men completed a 4-d (D1-4) baseline period (BL) of an energy balance diet while maintaining usual physical activity level, followed by 7 d (D5-11) of 1000 kcal.d increased energy expenditure via exercise (50-65% V O2peak). One group consumed 0.9 g of protein per kilogram per day and maintained energy balance throughout the 11-d intervention (BAL, N = 8). The other two groups consumed their BL energy intake throughout the 11 days, resulting in a 7-d, 1000-kcal.d energy deficit. These groups consumed either 0.9 g of protein per kilogram per day (DEF, N = 7) or 1.8 g of protein per kilogram per day (DEF-HP, N = 7). Mean nitrogen balance (NB), calculated per kilogram of fat-free mass (FFM), was determined for BL, days 5-8 (EX1), and days 9-11 (EX2). Whole-body protein turnover was derived from phenylalanine and tyrosine kinetics assessed while fasting at rest on days 4, 7, and 12, using a priming dose of L-[ring-N]tyrosine and a 4-h, primed, continuous infusion of L-[N]phenylalanine and L-[ring-H4]tyrosine., Results: DEF experienced a decrease in NB from BL to EX 1 that was maintained in EX 2. No changes in NB occurred for BAL or DEF-HP over time. No within- or between-group differences were found over time for Phe flux (Qp), conversion rate of Phe to Tyr (Qpt), or the derived protein synthesis value (Sp)., Conclusion: Increased dietary protein maintained NB during exercise-induced energy deficit, but this did not impact resting whole-body protein turnover.