Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology.

The purpose of this study was to examine the effects of acute normobaric (NH, decreased FiO) 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 oxygenated hemoglobin (OHb) decreased, and muscle deoxygenated hemoglobin (HHb) increased environmentally independent from rest to exercise (p < 0.

The Acute Effects of Exercise and Temperature on Regional mtDNA.

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 Arc) are unknown.

Exercise in the heat blunts improvements in aerobic power.

Introduction: PGC-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.

A novel voluntary weightlifting model in mice promotes muscle adaptation and insulin sensitivity with simultaneous enhancement of autophagy and mTOR pathway.

Our understanding of the molecular mechanisms underlying adaptations to resistance exercise remains elusive despite the significant biological and clinical relevance. We developed a novel voluntary mouse weightlifting model, which elicits squat-like activities against adjustable load during feeding, to investigate the resistance exercise-induced contractile and metabolic adaptations. RNAseq analysis revealed that a single bout of weightlifting induced significant transcriptome responses of genes that function in posttranslational modification, metabolism, and muscle differentiation in recruited skeletal muscles, which were confirmed by increased expression of fibroblast growth factor-inducible 14 (Fn14), Down syndrome critical region 1 (Dscr1) and Nuclear receptor subfamily 4, group A, member 3 (Nr4a3) genes.

Effects of 7°C environmental temperature acclimation during a 3-week training period.

Cold environmental temperatures during exercise and recovery alter the acute response to cellular signaling and training adaptations. Approximately 3 wk is required for cold temperature acclimation to occur. To determine the impact of cold environmental temperature on training adaptations, fitness measurements, and aerobic performance, two groups of 12 untrained male subjects completed 1 h of cycling in 16 temperature acclimation sessions in either a 7°C or 20°C environmental temperature.

Effects of exercise in a cold environment on gene expression for mitochondrial biogenesis and mitophagy.

Unlabelled: Cold exposure during cycling and recovery enhances PGC-1α transcription, but aspects of mitophagy and a more intense cold exposure without recovery occurring in the cold have not been explored.

Purpose: Determine the expression of genes related to mitochondrial biogenesis and mitophagy following an acute cycling bout at a temperature below freezing compared to that of room temperature.

Methods: Eleven male participants cycled at 65% W for 1 h at -2 °C and 20 °C and then recovered at room temperature for 6 h.

Skeletal Muscle mRNA Response to Hypobaric and Normobaric Hypoxia After Normoxic Endurance Exercise.

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 proteolysis. Fifteen recreationally trained subjects each cycled for 1 hour before recovering for 4 hours in NN (laboratory atmospheric conditions, 975 m), HH (depressurized to simulate 4420 m), and NH (fraction of O reduced to simulate 4420 m).

Skeletal muscle cold shock and heat shock protein mRNA response to aerobic exercise in different environmental temperatures.

The response of cold shock proteins to exercise and environmental temperature in human skeletal muscle is not known. The purpose of this study was to determine the early mRNA response of human stress proteins to endurance exercise and environmental temperatures. Seven recreationally trained males cycled for 1 hour at 60% VO in 7°C, 20°C, and 33°C with biopsies taken pre- and 3 hours post-exercise.

Effects of exercise in a cold environment on transcriptional control of PGC-1α.

Peroxisome proliferator-activated receptor-α coactivator-1α (PGC-1α) mRNA is increased with both exercise and exposure to cold temperature. However, transcriptional control has yet to be examined during exercise in the cold. Additionally, the need for environmental cold exposure after exercise may not be a practical recovery modality.

Irisin and Fibronectin Type III Domain-Containing 5 Responses to Exercise in Different Environmental Conditions.

Fibronectin type III domain-containing 5 (FNDC5) is a skeletal muscle membrane-bound precursor to the myokine irisin. Irisin is involved in stimulating adipose tissue to become more metabolically active in order to produce heat. The purpose of this study was to determine the effects of exercise in a hot (33 °C), cold (7 °C), and room temperature (RT, 20 °C) environment on the skeletal muscle gene expression of FNDC5 and the plasma concentrations of irisin.

The effect of environmental temperature on exercise-dependent release of brain-derived neurotrophic factor.

Brain-derived neurotrophic factor (BDNF) is a biomarker of cognitive function that is released into the blood stream following exercise, and cognitive function is impaired by environmental temperatures that are hot and cold. To evaluate the exercise-dependent release of BDNF in different environmental temperatures. Recreationally trained males each completed three trials consisting of cycling for 1 h at 60% W at three different temperatures: 33°C (hot), 7°C (cold), and 20°C (moderate room temperature).

Leptin, adiponectin, and ghrelin responses to endurance exercise in different ambient conditions.

Unlabelled: Excessive positive energy balance is a major factor leading to obesity. The ability to alter the appetite-regulating hormones leptin, adiponectin, and ghrelin may help decrease excessive energy intake. Exercise and exposure to extreme temperatures can independently affect these appetite-regulating hormones.

Local muscle cooling does not impact expression of mitochondrial-related genes.

Unlabelled: Recovery that takes place in a cold environment after endurance exercise elevates PGC-1α mRNA whereas ERRα and NRF2 mRNA expression are inhibited. However, the effect of local skeletal muscle cooling on mitochondrial-related gene expression is unknown.

Purpose: To determine the impact of local skeletal muscle cooling during recovery from an acute bout of exercise on mitochondrial-related gene expression.

Demands of Simulated Commuting Using an Electrically Assisted Bicycle.

The American College of Sports Medicine (ACSM) recommends adults participate in weekly aerobic activity for a minimum of 30 minutes moderate intensity exercise 5 days per week or 20 minutes of vigorous activity 3 days per week. The electrically assisted bicycle may help individuals achieve the ACSM's aerobic recommendations and introduce inactive individuals to physical activity. To compare the physiological requirements of riding a bicycle with electric pedal assist versus non-assist among healthy active young adults.

Impact of hot and cold exposure on human skeletal muscle gene expression.

Many human diseases lead to a loss of skeletal muscle metabolic function and mass. Local and environmental temperature can modulate the exercise-stimulated response of several genes involved in mitochondrial biogenesis and skeletal muscle function in a human model. However, the impact of environmental temperature, independent of exercise, has not been addressed in a human model.

Transcriptional control, but not subcellular location, of PGC-1α is altered following exercise in a hot environment.

The purpose of this study was to determine mitochondrial biogenesis-related mRNA expression, binding of transcription factors to the peroxisome proliferator-activated receptor-γ coactivator 1-α (PGC-1α) promoter, and subcellular location of PGC-1α protein in human skeletal muscle following exercise in a hot environment compared with a room temperature environment. Recreationally trained males (n = 11) completed two trials in a temperature- and humidity-controlled environmental chamber. Each trial consisted of cycling in either a hot (H) or room temperature (C) environment (33 and 20°C, respectively) for 1 h at 60% of maximum wattage (Wmax) followed by 3 h of supine recovery at room temperature.