ATF6 Regulates Cardiac Hypertrophy by Transcriptional Induction of the mTORC1 Activator, Rheb.

Rationale: Endoplasmic reticulum (ER) stress dysregulates ER proteostasis, which activates the transcription factor, ATF6 (activating transcription factor 6α), an inducer of genes that enhance protein folding and restore ER proteostasis. Because of increased protein synthesis, it is possible that protein folding and ER proteostasis are challenged during cardiac myocyte growth. However, it is not known whether ATF6 is activated, and if so, what its function is during hypertrophic growth of cardiac myocytes.

Increases in core temperature counterbalance effects of haemoconcentration on blood viscosity during prolonged exercise in the heat.

What is the central question of this study? The purpose of the present study was to determine the effects of exercise-induced haemoconcentration and hyperthermia on blood viscosity. What is the main finding and its importance? Exercise-induced haemoconcentration, increased plasma viscosity and increased blood aggregation, all of which increased blood viscosity, were counterbalanced by increased red blood cell (RBC) deformability (e.g.

Acute normobaric hypoxia reduces body temperature in humans.

Anapyrexia is the regulated decrease in body temperature during acute exposure to hypoxia. This study examined resting rectal temperature (Trec) in adult humans during acute normobaric hypoxia (NH). Ten subjects breathed air consisting of 21% (NN), 14% (NH14), and 12% oxygen (NH12) for 30 min each in thermoneutral conditions while Trec and blood oxygen saturation (Spo2) were measured.

Alterations in the rate of limb movement using a lower body positive pressure treadmill do not influence respiratory rate or phase III ventilation.

The purpose of this study was to determine the effect of alterations in rate of limb movement on Phase III ventilation during exercise, independent of metabolic rate, gait style, and treadmill incline. Subjects completed five submaximal exercise bouts on a lower body positive pressure treadmill (AlterG P 200). The percent body weight for the five exercise bouts was 100, 87, 75, 63, and 50% and each was matched for carbon dioxide production (V CO2 ).

Effect of air temperature on the rectal temperature gradient at rest and during exercise.

The purpose of the current study was to determine the effect of air temperature on the rectal temperature gradient at rest and during exercise. It was hypothesized that the rectal temperature gradient would be exacerbated in cold environments and attenuated in warm environments both at rest and during exercise. Each subject completed three exercise bouts on a motor driven treadmill at approximately 55% of their previously determined maximal oxygen uptake.

Specific exercise heat stress protocol for a triathlete's return from exertional heat stroke.

A triathlete collapsed with exertional heatstroke (EHS) during 2 races over 3 months. The American College of Sports Medicine recommends a heat tolerance test (HTT) following EHS if there is a concern with return to play. The classical walking HTT may not be the best test to evaluate elite triathletes' heat tolerance due to race intensity, nor is it suited to evaluate acclimation ability, which may play a role in risk of heat illness.

Skeletal muscle fatigue precedes the slow component of oxygen uptake kinetics during exercise in humans.

The mechanisms determining exercise intolerance are poorly understood. A reduction in work efficiency in the form of an additional energy cost and oxygen requirement occurs during high-intensity exercise and contributes to exercise limitation. Muscle fatigue and subsequent recruitment of poorly efficient muscle fibres has been proposed to mediate this decline.

Evaluation of the ventilatory effects of a restraint chair on human subjects.

Background: Combative individuals often require physical restraint in the prehospital and law enforcement setting. Specialized restraint chairs have been utilized for this purpose in the latter case, but concern has arisen that restrained individuals are at risk for ventilatory compromise and asphyxiation.

Objective: We sought to determine if placement in a restraint chair results in alterations of respiratory or ventilatory function.

ACTN3 and ACE genotypes in elite Jamaican and US sprinters.

Unlabelled: The angiotensin-converting enzyme (ACE) and the alpha-actinin-3 (ACTN3) genes are two of the most studied "performance genes" and both have been associated with sprint/power phenotypes and elite performance.

Purpose: To investigate the association between the ACE and the ACTN3 genotypes and sprint athlete status in elite Jamaican and US African American sprinters.

Methods: The ACTN3 R577X and the ACE I/D and A22982G (rs4363) genotype distributions of elite Jamaican (J-A; N = 116) and US sprinters (US-A; N = 114) were compared with controls from the Jamaican (J-C; N = 311) and US African American (US-C; N = 191) populations.

Is active sweating during heat acclimation required for improvements in peripheral sweat gland function?

We investigated whether the eccrine sweat glands must actively produce sweat during heat acclimation if they are to adapt and increase their capacity to sweat. Eight volunteers received intradermal injections of BOTOX, to prevent neural stimulation and sweat production of the sweat glands during heat acclimation, and saline injections as a control in the contralateral forearm. Subjects performed 90 min of moderate-intensity exercise in the heat (35 degrees C, 40% relative humidity) on 10 consecutive days.

Physiologic effects of the TASER after exercise.

Objectives: Incidents of sudden death following TASER exposure are poorly studied, and substantive links between TASER exposure and sudden death are minimal. The authors studied the effects of a single TASER exposure on markers of physiologic stress in humans.

Methods: This prospective, controlled study evaluated the effects of a TASER exposure on healthy police volunteers after vigorous exercise, compared to a subsequent, identical exercise session that was not followed by TASER exposure.

Translating physical activity recommendations into a pedometer-based step goal: 3000 steps in 30 minutes.

Background: It is a public health recommendation to accumulate at least 150 minutes per week of moderate intensity physical activity. Although pedometers are widely used as a physical activity-monitoring tool, they are unable to measure activity intensity. Translating current physical activity recommendations into a pedometer-based guideline could increase the public health impact of physical activity interventions.

Metabolic demands of simulated firefighting tasks.

Firefighters having higher cardiovascular fitness completed a series of simulated firefighting tasks more quickly than those having lower fitness. These results support the need of a high level of cardiovascular fitness for firefighters to ensure not only their safety, but that of fellow firefighters and rescue victims.

Electromyographic data do not support a progressive recruitment of muscle fibers during exercise exhibiting a VO2 slow component.

The origin of the slow component (SC) of oxygen uptake kinetics, presenting during exercise above the ventilatory threshold (VT), remains unclear. Possible physiologic mechanisms include a progressive recruitment of type II muscle fibers. The purpose of this study was to examine alterations in muscle activity through electromyography (EMG) and mean power frequency (MPF) analysis during heavy cycling exercise.

Fatigue and sleep quality in nurses.

Fatigue is a critical issue for nurses that may lead to medical errors, degradation in performance, decreased mental acuity, and social problems. Poor sleep quality is also a contributing factor in fatigue that nurses experience. Therefore, the purpose of this study was to examine the differences in perceptions of fatigue between night-shift and day-shift nurses, as measured by scores on the Brief Fatigue Inventory (BFI) and to examine differences in sleep quality between the two groups, as measured by responses on the Pittsburgh Sleep Quality Index (PSQI).

Physiological effects of a conducted electrical weapon on human subjects.

Study Objective: Sudden death after a conducted electrical weapon exposure has not been well studied. We examine the effects of a single Taser exposure on markers of physiologic stress in healthy humans.

Methods: This is a prospective trial investigating the effects of a single Taser exposure.

Sodium ion concentration vs. sweat rate relationship in humans.

The purpose of this study was to determine the effect of active heat acclimation on the sweat osmolality and sweat sodium ion concentration vs. sweat rate relationship in humans. Eight healthy male volunteers completed 10 days of exercise in the heat.

Effect of pedaling technique on muscle activity and cycling efficiency.

The purpose of this study was to examine the acute effect of talocrural joint position on muscle activity and gross mechanical efficiency (GE). Eleven trained cyclists participated in three randomized 6-min cycling bouts at approximately 80% of maximal aerobic capacity on an electromagnetically braked cycle ergometer while oxygen consumption and muscle activity (EMG) were monitored during the subject's self-selected pedaling technique (control) and while using a dorsi- and plantarflexed pedaling technique. The mean differences in range of motion of the dorsi- and plantarflexed technique from the control position were 7.

Ventilatory and metabolic demands during aggressive physical restraint in healthy adults.

We investigated ventilatory and metabolic demands in healthy adults when placed in the prone maximal restraint position (PMRP), i.e., hogtie restraint.

Effects of hypoxia on the onset of muscle deoxygenation and the lactate threshold.

Six subjects performed two trials of incremental cycling to exhaustion under normoxic and hypoxic conditions. The lactate threshold and onset of muscle deoxygenation were highly correlated under both conditions, and during the hypoxic condition both variables shifted leftward.

Skin blood flow affects in vivo near-infrared spectroscopy measurements in human skeletal muscle.

Skin blood flow affects NIRS. Leg skin blood flow (SkBF) was increased and decreased following local heating and intradermal epinephrine injection. Epinephrine decreased muscle saturation (StO(2)), and heating the leg increased StO(2).

Effects of sodium bicarbonate on VO2 kinetics during heavy exercise.

Purpose: Sodium bicarbonate was used to investigate the effect of blood pH on VO2 kinetics during heavy exercise.

Methods: On separate days, 10 active subjects performed two 6-min cycling bouts (208 +/- 12 W) at 25 W above their ventilatory threshold. Each subject ingested 0.

Effect of skin temperature on the cholinergic sensitivity of the human eccrine sweat gland.

Unlabelled: Although sweat gland activity is directly controlled by the central nervous system, which detects changes in core body temperature, sweat glands can also be influenced by local cutaneous thermal conditions.

Objective: The present study sought to determine the effect of local skin temperature on pilocarpine-induced sweating within a range of typical skin temperatures.

Methods: Thirteen subjects (30 +/- 6 years; 172 +/- 11 cm; 72.

Effect of acute normobaric hypoxia on peripheral sweat rate.

Peripheral sweat rate was measured to determine if acute normobaric hypoxia exerted a local inhibition on sweat gland function. It was hypothesized that peripheral sweat rate would be reduced during hypoxia, following cholinergic stimulation. Nineteen subjects (24 +/- 3 yr; 177 +/- 9 cm; 75.