The effect of heat on lung diffusing capacity for carbon monoxide (DLCO) during cycling exercise.

Purpose: This study aimed to quantify the combined effects of heat exposure and exercise of increasing intensity on pulmonary blood flow using lung diffusing capacity for carbon monoxide (DLCO) as an indirect measure. We hypothesized that, during exercise in the heat, the well-documented increase in skin blood flow for thermoregulation would lead to alterations in pulmonary blood flow and a subsequent fall in DLCO versus a thermoneutral condition.

Methods: Nine healthy subjects (4 F/5 M, 20-45 years, VOmax 46.

Endurance test selection optimized via sample size predictions.

Selecting the most appropriate performance test is critical in detecting the effect of an intervention. In this investigation we ) used time-trial (TT) performance data to estimate sample size requirements for test selection and ) demonstrated the differences in statistical power between a repeated-measures ANOVA (RM-ANOVA) and analysis of covariance (ANCOVA) for detecting an effect in parallel group design. A retrospective analysis of six altitude studies was completed, totaling 105 volunteers.

Effect of 8 days of exercise-heat acclimation on aerobic exercise performance of men in hypobaric hypoxia.

Exercise-heat acclimation (EHA) induces adaptations that improve tolerance to heat exposure. Whether adaptations from EHA can also alter responses to hypobaric hypoxia (HH) conditions remains unclear. This study assessed whether EHA can alter time-trial performance and/or incidence of acute mountain sickness (AMS) during HH exposure.

Potential for dehydration to impact the athlete biological passport.

In order to inform the Athlete Biological Passport (ABP), this study determined whether the elevation in hemoglobin (Hb) following intracellular or extracellular dehydration would trigger an atypical passport finding (ATPF). Seven male and three female volunteers (age: 23 ± 4 y; height: 170 ± 8 cm; body mass: 78 ± 12 kg) were carefully euhydrated (EUH) to determine baseline Hb levels. Volunteers then completed both an exercise-induced sweating dehydration (SW) protocol and a diuretic-induced dehydration (DI) protocol.

Myocardial adaptability in young and older-aged sea-level habitants sojourning at Mt Kilimanjaro: are cardiac compensatory limits reached in older trekkers?

Introduction: High-altitude ascent induces left (LV) and right (RV) ventricular adaptations secondary to hypoxia-related hemodynamic and myocardial alterations. Since cardiopulmonary decrements observed with aging (e.g.

Aerobic Exercise Performance During Load Carriage and Acute Altitude Exposure.

Coffman, KE, Luippold, AJ, Salgado, RM, Heavens, KR, Caruso, EM, Fulco, CS, and Kenefick, RW. Aerobic exercise performance during load carriage and acute altitude exposure. J Strength Cond Res 34(4): 946-951, 2020-This study quantified the impact of combined load carriage and acute altitude exposure on 5-km running time-trial (TT) performance and self-selected pacing strategy.

Acetazolamide does not alter endurance exercise performance at 3,500-m altitude.

Acetazolamide (AZ) is a medication commonly used to prevent acute mountain sickness (AMS) during rapid ascent to high altitude. However, it is unclear whether AZ use impairs exercise performance; previous literature regarding this topic is equivocal. The purpose of this study was to evaluate the impact of AZ on time-trial (TT) performance during a 30-h exposure to hypobaric hypoxia equivalent to 3,500-m altitude.

Biological variation of resting measures of ventilation and gas exchange in a large healthy cohort.

Purpose: Resting measures of ventilation and gas exchange are impacted by a variety of physiological stressors, such as those resulting from a research intervention or an extreme environment. However, the biological variation of these parameters, an important statistical consideration for identifying a meaningful physiological change, has not been quantified.

Methods: We performed a retrospective analysis of 21 studies completed by the U.

Separate and combined influences of heat and hypobaric hypoxia on self-paced aerobic exercise performance.

Heat and hypobaric hypoxia independently compromise exercise performance; however, their combined impact on exercise performance has yet to be quantified. This study examined the effects of heat, hypobaric hypoxia, and the combination of these environments on self-paced cycling time trial (TT) performance. Twelve subjects [2 female, 10 male; sea level (SL) peak oxygen consumption (V̇o), 41.

Age-dependent effects of thoracic and capillary blood volume distribution on pulmonary artery pressure and lung diffusing capacity.

Aging is associated with pulmonary vascular remodeling and reduced distensibility. We investigated the influence of aging on changes in cardiac output (Q), mean pulmonary artery pressure (mPAP), and lung diffusing capacity in response to alterations in thoracic blood volume. The role of pulmonary smooth muscle tone was also interrogated via pulmonary vasodilation.

Effect of age on the presence of comet tails at high altitude.

Extravascular lung water (EVLW) increases in healthy adults upon exposure to high altitude, likely due to increased pulmonary vascular resistance (PVR). Older individuals experience increased PVR during exercise, which may be exacerbated by trekking at high altitude. This study aimed to determine whether EVLW development is greater in older versus younger adults during graded altitude exposure.

Effects of intrathoracic pressure, inhalation time, and breath hold time on lung diffusing capacity.

The single breath hold maneuver for measuring lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO) incorporates multiple sources of variability. This study examined how changes in intrathoracic pressure, inhalation time, and breath hold time affect DLCO, DLNO, alveolar-capillary membrane conductance (DmCO) and pulmonary capillary blood volume (Vc) at rest and during submaximal exercise. Thirteen healthy subjects (mean ± SD; age = 26 ± 3y) performed duplicate tests at rest and during submaximal exercise.

Exhaled Nitric Oxide Changes During Acclimatization to High Altitude: A Descriptive Study.

Unlabelled: Summerfield, Douglas T., Kirsten E. Coffman, Bryan J.

The influence of pulmonary vascular pressures on lung diffusing capacity during incremental exercise in healthy aging.

Alveolar-capillary surface area for pulmonary gas exchange falls with aging, causing a reduction in lung diffusing capacity for carbon monoxide (DLCO). However, during exercise additional factors may influence DLCO, including pulmonary blood flow and pulmonary vascular pressures. First, we sought to determine the age-dependent effect of incremental exercise on pulmonary vascular pressures and DLCO.

Influence of Thoracic Fluid Compartments on Pulmonary Congestion in Chronic Heart Failure.

Introduction: Pulmonary congestion is a common finding of heart failure (HF), but it remains unclear how pulmonary and heart blood volumes (V and V, respectively) and extravascular lung water (EVLW) change in stable HF and affect lung function.

Methods: Fourteen patients with HF (age 68 ± 11 y, LVEF 33 ± 8%) and 12 control subjects (age 65 ± 9 y) were recruited. A pulmonary function test, thoracic computerized tomographic (CT) scan, and contrast perfusion scan were performed.

The effect of aging and cardiorespiratory fitness on the lung diffusing capacity response to exercise in healthy humans.

Aging is associated with deterioration in the structure and function of the pulmonary circulation. We characterized the lung diffusing capacity for carbon monoxide (DL), alveolar-capillary membrane conductance (Dm), and pulmonary-capillary blood volume (Vc) response to discontinuous incremental exercise at 25, 50, 75, and 90% of peak work (W) in four groups: ) Young [27 ± 3 yr, maximal oxygen consumption (V̇o): 110 ± 18% age predicted]; 2) Young Highly Fit (27 ± 3 yr, V̇o: 147 ± 8% age predicted); ) Old (69 ± 5 yr, V̇o: 116 ± 13% age predicted); and ) Old Highly Fit (65 ± 5 yr, V̇o: 162 ± 18% age predicted). At rest and at 90% W, DL, Dm, and Vc were decreased with age.

The blood transfer conductance for nitric oxide: Infinite vs. finite θ.

Whether the specific blood transfer conductance for nitric oxide (NO) with hemoglobin (θ) is finite or infinite is controversial but important in the calculation of alveolar capillary membrane conductance (Dm) and pulmonary capillary blood volume (V) from values of lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO). In this review, we discuss the background associated with θ, explore the resulting values of Dm and V when applying either assumption, and investigate the mathematical underpinnings of Dm and V calculations. In general, both assumptions yield reasonable rest and exercise Dm and V values.

Pulmonary capillary reserve and exercise capacity at high altitude in healthy humans.

Purpose: We determined whether well-acclimatized humans have a reserve to recruit pulmonary capillaries in response to exercise at high altitude.

Methods: At sea level, lung diffusing capacity for carbon monoxide (DLCO), alveolar-capillary membrane conductance (DmCO), and pulmonary capillary blood volume (V c) were measured at rest before maximal oxygen consumption ([Formula: see text]) was determined in seven adults. Then, DLCO, DmCO and V c were measured pre- and post-exhaustive incremental exercise at 5150 m after ~40 days of acclimatization.

Optimizing the calculation of DM,CO and VC via the single breath single oxygen tension DLCO/NO method.

Alveolar-capillary membrane conductance (D(M,CO)) and pulmonary-capillary blood volume (V(C)) are calculated via lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) using the single breath, single oxygen tension (single-FiO2) method. However, two calculation parameters, the reaction rate of carbon monoxide with blood (θ(CO)) and the D(M,NO)/D(M,CO) ratio (α-ratio), are controversial. This study systematically determined optimal θ(CO) and α-ratio values to be used in the single-FiO2 method that yielded the most similar D(M,CO) and V(C) values compared to the 'gold-standard' multiple-FiO2 method.

Women-specific factors to consider in risk, diagnosis and treatment of cardiovascular disease.

In the era of individualized medicine, gaps in knowledge remain about sex-specific risk factors, diagnostic and treatment options that might reduce mortality from cardiovascular disease (CVD) and improve outcomes for both women and men. In this review, contributions of biological mechanisms involving the sex chromosomes and the sex hormones on the cardiovascular system will be discussed in relationship to the female-specific risk factors for CVD: hypertensive disorders of pregnancy, menopause and use of hormonal therapies for contraception and menopausal symptoms. Additionally, sex-specific factors to consider in the differential diagnosis and treatment of four prevalent CVDs (hypertension, stroke, coronary artery disease and congestive heart failure) will be reviewed with emphasis on areas where additional research is needed.