Journal of Applied Physiology

There is evidence across species and across many traits that males display greater between-individual variance. In contrast, (premenopausal) females display large within-individual variance in sex hormone concentrations, which can increase within-individual variance in many other parameters. The latter may contribute to the lower representation of females in metabolic research. This study is a pooled secondary analysis of data from 7 crossover studies to investigate the between-individual and the within-individual variance in fasting plasma metabolites, resting metabolic rate (RMR) and body mass...

Chronic testosterone (T) substitution and short-term T administration positively affect protein metabolism, however, data on acute effects in humans are sparse. This study aimed to investigate T's acute effects on whole-body protein metabolism in hypogonadal and eugonadal conditions. We designed a randomized, double-blind, placebo-controlled, crossover study, including twelve healthy young males. Whole-body protein metabolism was evaluated during 1) eugonadism, and after medically-induced hypogonadism, with application of a gel on each trial day containing either 2) placebo, 3) T 50 mg, or 4) T 150 mg; under basal (5h basal period) and insulin-stimulated conditions (3h clamp)...

Data on static compliance of the chest wall ( C cw ) in preterm infants are scarce. We characterised the static compliance of the lung ( CL ) and C cw to determine their relative contribution to static compliance of the respiratory system ( C rs ) in very preterm infants at 36 weeks' postmenstrual age (PMA). We also aimed to investigate how these compliances were influenced by the presence of bronchopulmonary dysplasia (BPD) and impacted breathing variables. Airway opening pressure, esophageal pressure, and tidal volume ( V T ) were measured simultaneously during a short apnea evoked by the Hering-Breuer reflex...

No abstract text is available yet for this article.

Physical activity, including structured exercise, is associated with favorable health-related chronic disease outcomes. While there is evidence of various molecular pathways that affect these responses, a comprehensive molecular map of these molecular responses to exercise has not been developed. The Molecular Transducers of Physical Activity Consortium (MoTrPAC) is a multi-center study designed to isolate the effects of structured exercise training on the molecular mechanisms underlying the health benefits of exercise and physical activity...

Breathing effort is important to quantify to understand mechanisms underlying central and obstructive sleep apnea, respiratory-related arousals, and the timing and effectiveness of invasive or non-invasive mechanically assisted ventilation. Current quantitative methods to evaluate breathing effort rely on inspiratory esophageal or epiglottic pressure swings or changes in diaphragm electromyographic (EMG) activity, where units are problematic to interpret and compare between individuals and to measured ventilation...

In patients with chronic obstructive pulmonary disease (COPD), pulmonary vascular dysfunction and destruction are observable before the onset of detectable emphysema, but it is unknown whether this is associated with central hypovolemia. We investigated if COPD patients have reduced pulmonary blood volume (PBV) evaluated by 82 Rb-positron emission tomography(PET) at rest and during adenosine-induced hyperemia. This single-center retrospective cohort study assessed 6301 82 Rb-PET myocardial perfusion imaging (MPI) examinations performed over a 6-year period...

BACKGROUND: Understanding post-stroke changes in skeletal muscle oxidative metabolism and microvascular reactivity could help create therapeutic targets that optimize rehabilitative interventions. Due to disuse atrophy, we hypothesized that basal muscle oxygen consumption rate and microvascular endothelial function would be impaired in the tibialis anterior (TA) muscle of the affected leg of chronic stroke survivors compared to the non-affected leg and vs. matched controls. METHODS: Fifteen chronic stroke survivors (10 female) and 15 matched controls (9 female) completed this study...

Mechanisms behind the protective effects of aerobic exercise on brain health remain elusive but may be vascular in origin and relate to cerebral pulsatility. This pilot study investigated the effects of 12 wks aerobic exercise training on cerebral pulsatility and its vascular contributors (large artery stiffness, characteristic impedance) in at-risk middle-aged adults. 28 inactive middle-aged adults with elevated blood pressure or stage 1 hypertension were assigned to either moderate/vigorous aerobic exercise training (AET) for 3 d/wk or no-exercise control (CON) group...

No abstract text is available yet for this article.

Acute exposure to hypoxia increases postural sway, but the underlying neurophysiological factors are unclear. Golgi tendon organs (GTOs), located within the musculotendinous junction (MTJ), provide inhibitory signals to plantar flexor muscles that are important for balance control; however, it is uncertain if GTO function is influenced by hypoxia. The aim of this study was to determine how normobaric hypoxia influences lower limb tendon-evoked inhibitory reflexes during upright stance. We hypothesized that tendon-evoked reflex area and duration would decrease during hypoxia, indicating less inhibition of postural muscles compared to normoxia...

Blood flow regulation within the microvasculature reflects a complex interaction of regulatory mechanisms and varies spatially and temporally according to conditions such as metabolism, growth, injury, and disease. Understanding the role of microvascular flow distributions across conditions is of interest to investigators spanning multiple disciplines; however, data collection within networks can be labour-intensive and challenging due to limited resolution. To overcome these experimental challenges, computational network models which can accurately simulate vascular behavior are highly beneficial...

While existing literature supports associations between cerebrovascular dysfunction and the emergence of depression and depressive symptoms, relatively little is known about underlying mechanistic pathways that may explain potential relationships. As such, an integrated understanding of these relationships in pre-clinical models could provide insight into the nature of the relationship, basic mechanistic linkages and areas in which additional investment should be targeted. This scoping review was conducted in MEDLINE, EMBASE and Scopus to outline the relationship between depressive symptoms and cerebrovascular dysfunction in pre-clinical animal models with additional focus on the areas above...

Cold exposure increases blood pressure (BP) and salivary flow rate (SFR). Increased cold-induced SFR would be hypothesised to enhance oral nitrate delivery for reduction to nitrite by oral anaerobes and to subsequently elevate plasma [nitrite] and nitric oxide bioavailability. We tested the hypothesis that dietary nitrate supplementation would increase plasma [nitrite] and lower BP to a greater extent in cool compared to normothermic conditions. Twelve males attended the laboratory on four occasions. Baseline measurements were completed at 28°C...

Hypertensive postmenopausal women are more likely to develop adverse cardiac remodelling and respond less effectively to drug treatment than men. High intensity interval exercise (HIIE) is a non-pharmacological strategy for the treatment of hypertension, however, the effectiveness in women remains uncertain. This study was designed to evaluate (1) effects of HIIE training upon morphological and functional markers of cardiovascular health in female SHR and (2) to determine whether the hormonal shift induced by ovariectomy could influence cardiovascular responses to HIIE...

Despite the prognostic effect of physical activity, acute bouts of high-volume endurance exercise can induce cardiac stress and post-exercise hypercoagulation associated with increased thrombotic risk. The aim of this study was to explore the effect of high-volume endurance exercise on coagulation and thrombotic activity in recreational cyclists. Thirty-four recreational cyclists completed 4.8 ± 0.3 hours cycling at 45 ± 5% of maximal power output on a bicycle ergometer. Intravenous blood samples were collected pre-exercise, immediately post-exercise, 24 and 48 hours post-exercise and analysed for brain natriuretic peptide (BNP), cardiac troponin (cTn), C-reactive protein (CRP), D-dimer, thrombin-antithrombin (TAT) complex, tissue factor (TF), tissue factor pathway inhibitor (TFPI) and TF to TFPI ratio (TF:TFPI)...

The metabolic cost of walking (MCOW), or oxygen uptake normalized to distance, provides information on the energy expended during movement. There are conflicting reports as to whether sex differences in MCOW exist, with scarce evidence investigating factors that explain potential sex differences. This study 1) tested the hypothesis that females exhibit a higher MCOW than males, 2) determined whether normalizing to stepping cadence ameliorates the hypothesized sex difference and 3) explored whether more habitual daily steps and time in intensity-related physical activity, and less sedentary time were associated with a decreased MCOW...

Cyclooxygenase (COX) products of arachidonic acid metabolism, specifically prostaglandins, play a role in evoking and transmitting the exercise pressor reflex in health and disease. Individuals with type 2 diabetes mellitus (T2DM) have an exaggerated exercise pressor reflex; however, the mechanisms for this exaggerated reflex are not fully understood. We aimed to determine the role played by COX products in the exaggerated exercise pressor reflex in T2DM rats. The exercise pressor reflex was evoked by static muscle contraction in unanesthetized, decerebrate, male, adult UCD-T2DM (n=8) and healthy Sprague-Dawley (n=8) rats...

Recent evidence indicates that sex-based differences in cardiovascular disease (CVD) begin early in life, particularly when associated with risks factors such as a sedentary lifestyle. CVD is associated with elevated sympathetic nerve activity (SNA), quantified as increased SNA bursting activity in humans. Whether burst characteristics are influenced by sex- and (in)activity at younger ages is unknown. The purpose of our study is to compare SNA bursts in active and sedentary female and male rats at ages including pre-puberty into young adulthood...

Sarcolemmal membrane excitability is often evaluated by considering the peak-to-peak amplitude of the compound muscle action potential (M-wave). However, the first and second M-wave phases represent distinct properties of the muscle action potential, which are differentially affected by sarcolemma properties and other factors such as muscle architecture. Contrasting with previous studies in which voluntary contractions have been used to induce muscle fatigue, we employed repeated electrically-induced tetanic contractions of the adductor pollicis muscle and assessed the kinetics of M-wave properties during the course of the contractions...