Physiological and cognitive responses to hyperoxic exercise in full water submersion.

The positive effects of combined hyperoxia and physical exercise on physiological parameters and cognitive functioning are established for normobaric laboratory contexts. Still, increased practicability exists in hyperbaric settings like underwater activities and SCUBA diving, where environmental and sport-specific factors might moderate effects. Improved cognition, reduced ventilation (V̇), and lower blood lactate concentrations [Lac] are highly relevant, especially during high-stress and rescue scenarios.

Short-term isolation effects on the brain, cognitive performance, and sleep-The role of exercise.

Isolation is stressful and negatively affects sleep and mood and might also affect the structure and function of the brain. Physical exercise improves brain function. We investigated the influence of physical exercise during isolation on sleep, affect, and neurobehavioral function.

Cardiovascular Regulation During Acute Gravitational Changes with Exhaling on Exertion.

During gravitational changes or changes in the direction of action in relation to the body, fluid displacements can be observed. In special cases different breathing maneuvers (e. g.

Cardiorespiratory kinetics in exercise physiology: estimates and predictions using randomized changes in work rate.

Purpose: Kinetics of cardiorespiratory parameters (CRP) in response to work rate (WR) changes are evaluated by pseudo-random binary sequences (PRBS testing). In this study, two algorithms were applied to convert responses from PRBS testing into appropriate impulse responses to predict steady states values and responses to incremental increases in exercise intensity.

Methods: 13 individuals (age: 41 ± 9 years, BMI: 23.

Oxygen-enriched Air Decreases Ventilation during High-intensity Fin-swimming Underwater.

Oxygen-enriched air is commonly used in the sport of SCUBA-diving and might affect ventilation and heart rate, but little work exists for applied diving settings. We hypothesized that ventilation is decreased especially during strenuous underwater fin-swimming when using oxygen-enriched air as breathing gas. Ten physically-fit divers (age: 25±4; 5 females; 67±113 open-water dives) performed incremental underwater fin-swimming until exhaustion at 4 m water depth with either normal air or oxygen-enriched air (40% O) in a double-blind, randomized within-subject design.

Exercise-Related Effects on Executive Functions During a Simulated Underwater Extravehicular Activity.

Objective: Investigation of cognitive performance during extravehicular activities (EVAs) in a space-analog setting.

Background: EVAs performed by humans in microgravity on the International Space Station (ISS) call for high cognitive performance during upper-body workload. Higher cardiovascular demands interact with cognitive performance, but no knowledge exists about EVA's special requirements.

Confinement, partial sleep deprivation and defined physical activity-influence on cardiorespiratory regulation and capacity.

Introduction: Adequate cardiorespiratory fitness is of utmost importance during spaceflight and should be assessable via moderate work rate intensities, e.g., using kinetics parameters.

Relationship between maximal aerobic power with aerobic fitness as a function of signal-to-noise ratio.

Efforts to better understand cardiorespiratory health are relevant for the future development of optimized physical activity programs. We aimed to explore the impact of the signal quality on the expected associations between the ability of the aerobic system in supplying energy as fast as possible during moderate exercise transitions with its maximum capacity to supply energy during maximal exertion. It was hypothesized that a slower aerobic system response during moderate exercise transitions is associated with a lower maximal aerobic power; however, this relationship relies on the quality of the oxygen uptake data set.

Physical Exercise Intensity During Submersion Selectively Affects Executive Functions.

Objective: The intact cognitive processing capacity in highly demanding and dynamically changing situations (e.g., in extreme environmental conditions) is of central relevance for personal safety.

Breath-by-breath oxygen uptake during running: Effects of different calculation algorithms.

New Findings: What is the central question of this study? Breath-by-breath gas exchange analysis during treadmill exercise can be disturbed by different breathing patterns depending on cadence, and the flow sensor might be subjected to variable mechanical stress. It is still unclear whether the outcomes of the gas exchange algorithms can be affected by running at different speeds. What is the main finding and its importance? Practically, the three investigated breath-by-breath algorithms ('Wessel', 'expiration-only' and 'independent breath') provided similar average gas exchange values for steady-state conditions.

Adaptation of Systemic and Pulmonary Circulation to Acute Changes in Gravity and Body Position.

Changes in gravity or body position provoke changes in hydrostatic pressure in the arterial system and in venous return. Potential asymmetries between left (Q) and right ventricular (Q) cardiac output during transient gravity changes were investigated. It was hypothesized that blood volume is temporarily stored in the pulmonary vessels, with amount and duration depending on the level and directions of gravity.

Cardiorespiratory kinetics: comparisons between athletes with different training habits.

Purpose: Fast muscular oxygen uptake ([Formula: see text]) kinetics are limiting factors for high exercise capacities. It is hypothesized that [Formula: see text] and heart rate (HR) kinetics would be faster in individuals, performing long-distance endurance training (CONT) compared with athletes performing predominantly interval-based sports (INT).

Methods: 17 subjects (INT: n = 7, 24 ± 5 years, 183 ± 7 cm, 85 ± 10 kg, 6 ± 3 h of training per week, CONT: n = 10, 37 ± 7 years, 175 ± 9 cm, 69 ± 10 kg, 6 ± 3 h of training per week) completed a treadmill work rate (WR) protocol with pseudo-randomized WR changes with velocities of 6.

Comparison of different breath-by-breath gas exchange algorithms using a gas exchange simulation system.

Background: Mechanical Gas Exchange Simulation Systems (GESS) have never been used to compare different breath-by-breath oxygen uptake calculation algorithms.

Methods: Oxygen uptakes were calculated for each GESS cycle by the "Expiration-only" algorithm (estimating inspiratory volume from the expiratory one), and by two "alveolar" algorithms (both processing inspiratory and expiratory flows and designed to account for the changes in lung gas stores). The volume of oxygen stored in the GESS from one cycle to the subsequent one was either maintained constant or increased/decreased by changing the pumped gas volumes.

Bubble Formation in Children and Adolescents after Two Standardised Shallow Dives.

Circulating venous bubbles after dives are associated with symptoms of decompression sickness in adults. Up to now it is not known to what extent children and adolescents are subjected to a bubble formation during their shallow dives and if there are possible indications for that. The aim of this pilot study is to investigate whether bubbles and/or symptoms occur after standardised repeated dives performed by young divers.

Effect of acute ambient temperature exposure on cardio-pulmonary and respiratory kinetics in men.

Aim: The goal of the study was to compare the kinetic responses of heart rate (HR) and pulmonary (V̇Opulm) and muscular (V̇Omusc) oxygen uptake during dynamic leg exercise across different acute ambient temperature conditions in a climatic chamber.

Methods: Thirteen physically healthy, active, male volunteers demonstrated pseudorandom binary sequence (PRBS) work rate (WR) changes between 30 and 80 W at 15 °C, 25 °C and 35 °C, respectively. HR was measured beat-to-beat using an echocardiogram and V̇Opulm by breath-by-breath gas exchange; V̇Omusc estimations were assessed by applying a circulatory model and cross-correlation functions.

Heart Rate and Oxygen Uptake Kinetics in Type 2 Diabetes Patients - A Pilot Study on the Influence of Cardiovascular Medication on Regulatory Processes.

The aim of this pilot study was to investigate whether there are differences in heart rate and oxygen uptake kinetics in type 2 diabetes patients, considering their cardiovascular medication. It was hypothesized that cardiovascular medication would affect heart rate and oxygen uptake kinetics and that this could be detected using a standardized exercise test. 18 subjects were tested for maximal oxygen uptake.

Validity of Postexercise Measurements to Estimate Peak VO2 in 200-m and 400-m Maximal Swims.

To assess the validity of postexercise measurements to estimate oxygen uptake (V˙O) during swimming, we compared V˙O measured directly during an all-out 200-m swim with measurements estimated during 200-m and 400-m maximal tests using several methods, including a recent heart rate (HR)/V˙O modelling procedure. 25 elite swimmers performed a 200-m maximal swim where V˙O was measured using a swimming snorkel connected to a gas analyzer. The criterion variable was V˙O in the last 20 s of effort, which was compared with the following V˙O estimates: 1) first 20-s average; 2) linear backward extrapolation (BE) of the first 20 and 30 s, 3×20-s, 4×20-s, and 3×20-s or 4×20-s averages; 3) semilogarithmic BE at the same intervals; and 4) predicted V˙O using mathematical modelling of 0-20 s and 5-20 s during recovery.

Faster heart rate and muscular oxygen uptake kinetics in type 2 diabetes patients following endurance training.

Cardiorespiratory kinetics were analyzed in type 2 diabetes patients before and after a 12-week endurance exercise-training intervention. It was hypothesized that muscular oxygen uptake and heart rate (HR) kinetics would be faster after the training intervention and that this would be detectable using a standardized work rate protocol with pseudo-random binary sequences. The cardiorespiratory kinetics of 13 male sedentary, middle-aged, overweight type 2 diabetes patients (age, 60 ± 8 years; body mass index, 33 ± 4 kg·m) were tested before and after the 12-week exercise intervention.

Influence of Apnea-induced Hypoxia on Catecholamine Release and Cardiovascular Dynamics.

Prolonged breath-hold causes complex compensatory mechanisms such as increase in blood pressure, redistribution of blood flow, and bradycardia. We tested whether apnea induces an elevation of catecholamine-concentrations in well-trained apneic divers.11 apneic divers performed maximal dry apnea in a horizontal position.

Estimating peak oxygen uptake based on postexercise measurements in swimming.

To assess the validity of postexercise measurements in estimating peak oxygen uptake (V̇O2peak) in swimming, we compared oxygen uptake (V̇O2) measurements during supramaximal exercise with various commonly adopted methods, including a recently developed heart rate - V̇O2 modelling procedure. Thirty-one elite swimmers performed a 200-m maximal swim where V̇O2 was measured breath-by-breath using a portable gas analyzer connected to a respiratory snorkel, 1 min before, during, and 3 min postexercise. V̇O2peak(-20-0) was the average of the last 20 s of effort.

Spectra Transfer Between a Fourier Transform Near-Infrared Laboratory and a Miniaturized Handheld Near-Infrared Spectrometer.

The aim of this contribution is to demonstrate the transfer of spectra that have been measured on two different laboratory Fourier transform near-infrared (FT-NIR) spectrometers to the format of a handheld instrument by measuring only a few samples with both spectrometer types. Thus, despite the extreme differences in spectral range and resolution, spectral data sets that have been collected and quantitative as well as qualitative calibrations that have been developed thereof, respectively, over a long period on a laboratory instrument can be conveniently transferred to the handheld system. Thus, the necessity to prepare completely new calibration samples and the effort required to develop calibration models when changing hardware platforms is minimized.

A New Model for Estimating Peak Oxygen Uptake Based on Postexercise Measurements in Swimming.

Purpose: Assessing cardiopulmonary function during swimming is a complex and cumbersome procedure. Backward extrapolation is often used to predict peak oxygen uptake (VO2peak) during unimpeded swimming, but error can derive from a delay at the onset of VO2 recovery. The authors assessed the validity of a mathematical model based on heart rate (HR) and postexercise VO2 kinetics for the estimation of VO2peak during exercise.

Inverse relationship between task complexity and performance deficit in 5 m water immersion.

Previous research on cognitive deficits during shallow water immersion led to inconsistent results: some authors observed deficits at 5 m, but others only at depths well beyond 5 m. The present study evaluates whether this discrepancy could be related to different levels of difficulty. Forty-eight subjects participated in a mental rotation task and in a color-word task, both having multiple levels of difficulty.

Changes in cerebral oxygenation during parabolic flight.

Assessing changes in brain activity under extreme conditions like weightlessness is a desirable, but difficult undertaking. Results from previous studies report specific changes in brain activity connected to an increase or decrease in gravity forces. Nevertheless, so far it remains unclear (1) whether this is connected to a redistribution of blood volume during micro- or hypergravity and (2) whether this redistribution might account for neurocognitive alterations.