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. This study simulates EVA-training underwater to investigate its effects on the executive functions inhibition and switching. METHOD: In a counterbalanced crossover design, 16 divers (age: 28 ± 2.4 years; eight females) performed two conditions (i.e., EVA vs. Inactivity [INACT]) in 3-5 m submersion (diving gear; not in a space-suit). EVA included 30 min of moderate-, followed by 30 min of high-intensity upper-body exercise intervals, paired with EVA-specific cognitive-motor tasks. INACT included no exercise in submersion and neutral buoyancy. Both conditions included cognitive testing at pre, mid (after the first 30 min), and post (after the second 30 min) on a tablet computer. Reaction times (RTs) and response accuracy (ACC) were calculated for both tasks. RESULTS: ACC was significantly lower during EVA compared with INACT for inhibition (post: p = .009) and switching (mid: p = .019) at post (p = .005). RTs for inhibition were significantly faster during EVA (p = .022; ηp2 = 0.320). CONCLUSION: Specific physical exercise, intensity, duration, and tasks performed during the EVA might differently affect the exercise-cognition interaction and need further investigation, especially for future long-term space travel. APPLICATION: Future research might serve to improve mission success and safety for EVAs and long-term space travel.

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: 23.8 ± 3.7 kg m-2), completing an exercise test protocol, comprising a section of randomized changes of 30 W and 80 W (PRBS), two phases of constant WR at 30 W and 80 W and incremental WR until subjective fatigue, were included in the analysis. Ventilation ([Formula: see text]), O2 uptake ([Formula: see text]), CO2 output ([Formula: see text]) and heart rate (HR) were monitored. Impulse responses were calculated in the time domain and in the frequency domain from the cross-correlations of WR and the respective CRP. RESULTS: The algorithm in the time domain allows better prediction for [Formula: see text] and [Formula: see text], whereas for [Formula: see text] and HR the results were similar for both algorithms. Best predictions were found for [Formula: see text] and HR with higher (3-4%) 30 W steady states and lower (1-4%) values for 80 W. Tendencies were found in the residuals between predicted and measured data. CONCLUSION: The CRP kinetics, resulting from PRBS testing, are qualified to assess steady states within the applied WR range. Below the ventilatory threshold, [Formula: see text] and HR responses to incrementally increasing exercise intensities can be sufficiently predicted.

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., exhaling on exertion; Ex-Ex) are used to counteract acute fluid shifts. Both factors have a significant impact on cardiovascular regulation. Eight healthy male subjects were tested on a tilt seat, long arm human centrifuge, and parabolic flight. The work aims to investigate the effect of exhaling on exertion on the cardiovascular regulation during acute gravitational changes compared to normal breathing. Possible interactions and differences between conditions (Ex-Ex, normal breathing) for the parameters V'O 2 , V' E , HR, and SV were analysed over a 40 s period by a three-way ANOVA. Significant (p≤0.05) effects for all main factors and interactions between condition and time as well as maneuver and time were found for all variables. The exhaling on exertion maneuver had a significant influence on the cardiovascular response during acute gravitational and positional changes. For example, the significant increase of V'O2 at the end of the exhalation on exertion maneuver indicates an increased lung circulation as a result of the maneuver.

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% O2) in a double-blind, randomized within-subject design. Heart rate and ventilation were measured throughout the dive and maximum whole blood lactate samples were determined post-exercise. ANOVAs showed a significant effect for the factor breathing gas (F(1, 9)=7.52; P=0.023; η2 p=0.455), with a lower ventilation for oxygen-enriched air during fin-swimming velocities of 0.6 m·s-1 (P=0.032) and 0.8 m·s-1 (P=0.037). Heart rate, lactate, and time to exhaustion showed no significant differences. These findings indicate decreased ventilation by an elevated oxygen fraction in the breathing gas when fin-swimming in shallow-water submersion with high velocity (>0.5 m·s-1). Applications are within involuntary underwater exercise or rescue scenarios for all dives with limited gas supply.

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. The combination of restricted sleep, and defined physical exercise during a 45-day simulated space mission is expected to slow heart rate (HR) kinetics without changes in oxygen uptake ([Formula: see text]) kinetics. METHODS: Overall, 14 crew members (9 males, 5 females, 37 ± 7 yrs, 23.4 ± 3.5 kg m-2) simulated a 45-d-mission to an asteroid. During the mission, the sleep schedule included 5 nights of 5 h and 2 nights of 8 h sleep. The crew members were tested on a cycle ergometer, using pseudo-random binary sequences, changing between 30 and 80 W on day 8 before (MD-8), day 22 (MD22) and 42 (MD42) after the beginning and day 4 (MD + 4) following the end of the mission. Kinetics information was assessed using the maxima of cross-correlation functions (CCFmax). Higher CCFmax indicates faster responses. RESULTS: CCFmax(HR) was significantly (p = 0.008) slower at MD-8 (0.30 ± 0.06) compared with MD22 (0.36 ± 0.06), MD42 (0.38 ± 0.06) and MD + 4 (0.35 ± 0.06). Mean HR values during the different work rate steps were higher at MD-8 and MD + 4 compared to MD22 and MD42 (p < 0.001). DISCUSSION: The physical training during the mission accelerated HR kinetics, but had no impact on mean HR values post mission. Thus, HR kinetics seem to be sensitive to changes in cardiorespiratory fitness and may be a valuable parameter to monitor fitness. Kinetics and capacities adapt independently in response to confinement in combination with defined physical activity and sleep.

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. This study therefore investigated whether underwater physical exercise (PE) affected cognitive performance by comparing these effects during underwater fin-swimming as opposed to inactivity under normal environmental conditions. BACKGROUND: Although acute bouts of PE can modulate cognitive performance under highly controlled and standardized laboratory conditions, no previous study has determined whether PE acutely modulates cognitive performance in non-laboratory testing conditions involving extreme environments (e.g., underwater). METHOD: A total of 27 healthy volunteers (16 males and 11 females; 28.9 ± 7.4 years of age) participated in two experiments involving either moderate or high PE intensity. A PRE/POST crossover design was employed among participants while performing cognitive tests in a counterbalanced order (i.e., before and after 20 min of PE in submersion [WET] and once before and after inactivity [DRY] while in the laboratory). Cognitive performance was measured as a combination of executive functions through the Eriksen Flanker (inhibition) and Two-Back (working memory) Tasks using an underwater tablet computer. RESULTS: ANOVAs revealed enhanced reaction times only in the Flanker test after moderate PE for the WET condition. No other effects were detected. CONCLUSION: These findings indicate that cognitive performance is exercise-intensity-dependent with enhanced effects during moderate PE, even in extreme environments (i.e., underwater). APPLICATION: These results should be relevant in recreational and occupational contexts involving underwater activity and may also apply to microgravity (e.g., during extra-vehicular activities). DESCRIPTION: This study compared the acute effects of physical exercise (PE) on cognitive performance in an underwater environment while participants fin-swam with SCUBA (self-contained underwater breathing apparatus) gear. Findings revealed that 20 min of moderate PE positively affected cognitive performance (i.e., inhibitory control ability). However, no changes were observed after high-intensity exercise.

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. The 'independent breath' algorithm showed the lowest breath-by-breath fluctuations in the gas exchange data compared with the other investigated algorithms, both at steady state and during incremental exercise. ABSTRACT: Recently, a new breath-by-breath gas exchange calculation algorithm (called 'independent breath') was proposed. In the present work, we aimed to compare the breath-by-breath O2 uptake ( V̇O2 ) values assessed in healthy subjects undergoing a running protocol, as calculated applying the 'independent breath' algorithm or two other commonly used algorithms. The traces of respiratory flow, O2 and CO2 fractions, used by the calculation algorithms, were acquired at the mouth on 17 volunteers at rest, during running on a treadmill at 6.5 and 9.5 km h-1 , and thereafter up to volitional fatigue. Within-subject averages and standard deviations of breath-by-breath V̇O2 were calculated for steady-state conditions; the V̇O2 data of the incremental phase were analysed by means of linear regression, and their root mean square was assumed to be an index of the breath-by-breath fluctuations. The average values obtained with the different algorithms were significantly different (P < 0.001); nevertheless, from a practical point of view the difference could be considered 'small' in all the investigated conditions (effect size <0.3). The standard deviations were significantly lower for the 'independent breath' algorithm (post hoc contrasts, P < 0.001), and the slopes of the relationships with the corresponding data yielded by the other algorithms were <0.70. The root mean squares of the linear regressions calculated for the incremental phase were also significantly lower for the 'independent breath' algorithm, and the slopes of the regression lines with the corresponding values obtained with the other algorithms were <0.84. In conclusion, the 'independent breath' algorithm yielded the least breath-by-breath O2 uptake fluctuation, both during steady-state exercise and during incremental running.

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 6.5 and 9.5 km h-1. [Formula: see text]O2musc and the respective kinetics were estimated from the measured pulmonary oxygen uptake and HR combined with a circulatory model. Kinetics information were calculated using time series analysis. Higher maxima of the cross-correlation function (CCF) of WR and the respective parameter ([Formula: see text], HR) indicate faster kinetics responses. RESULTS: The kinetics of HR (INT: 0.23 ± 0.04 vs. CONT: 0.42 ± 0.18; P = 0.001), [Formula: see text]O2pulm (0.30 ± 0.05 vs. 0.53 ± 0.20; P = 0.005) and [Formula: see text]O2musc (0.31 ± 0.06 vs. 0.53 ± 0.16; P = 0.005) were significantly slower in INT compared with the CONT athletes. CONCLUSIONS: It seems that at least in the long-term CONT exercise, training without the need of changing intensities is favorable for fast [Formula: see text]O2 and HR kinetics compared with INT exercise including frequently changing intensities.

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. 28 children and adolescents (13.5±1.1 years) carried out two 25 min dives to a depth of 10 m with a 90 min surface interval. Before and after, echocardiographic data were recorded and evaluated with regard to circulating bubbles with an extended Eftedal-Brubakk-Scale by 2 different examiners. Bubbles were observed for a total of 6 subjects, Grade I (n=5) and Grade III (n=1). None of them showed any symptoms of decompression sickness. No differences were established regarding potential influencing factors on bubble formation between the groups with and without bubbles. The results indicate that even relatively shallow and short dives can generate venous bubbles in children and adolescents. To what extent this relates to the decompression sickness or clinical symptoms cannot be validated at this point.

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 (V̇O2pulm) and muscular (V̇O2musc) 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 V̇O2pulm by breath-by-breath gas exchange; V̇O2musc estimations were assessed by applying a circulatory model and cross-correlation functions. RESULTS: No significant differences were observed across the various temperature conditions in each case for HR, V̇O2pulm or V̇O2musc kinetics (p > 0.05). Baroreflex regulation based on HR kinetics does not seem to be influenced between ambient temperatures of 15 °C and 35 °C during dynamic exercise. CONCLUSIONS: The results imply that ambient temperatures of 15 °C, 25 °C and 35 °C have no effect on HR, V̇O2pulm or V̇O2musc kinetics during dynamic moderate exercise. The applied approach may be of interest for assessments of the cardio-pulmonary and respiratory health statuses of individuals working or performing sports in extreme temperature environments. Furthermore, differentiation between systemic (e.g. cardio-dynamic: HR) and specific (e.g. exercising tissues: V̇O2musc) determinants of the relevant physiological systems may improve the evaluation of an individual's health status.

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˙O2) during swimming, we compared V˙O2 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˙O2 modelling procedure. 25 elite swimmers performed a 200-m maximal swim where V˙O2 was measured using a swimming snorkel connected to a gas analyzer. The criterion variable was V˙O2 in the last 20 s of effort, which was compared with the following V˙O2peak 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˙O2peak using mathematical modelling of 0-20 s and 5-20 s during recovery. In 2 series of experiments, both of the HR/V˙O2 modelled values most accurately predicted the V˙O2peak (mean ∆=0.1-1.6%). The BE methods overestimated the criterion values by 4-14%, and the single 20-s measurement technique yielded an underestimation of 3.4%. Our results confirm that the HR/V˙O2 modelling technique, used over a maximal 200-m or 400-m swim, is a valid and accurate procedure for assessing cardiorespiratory and metabolic fitness in competitive swimmers.

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. Parameters measured during apnea included blood pressure, ECG, and central, in addition to peripheral hemoglobin oxygenation. Peripheral arterial hemoglobin oxygenation was detected by pulse oximetry, whereas peripheral (abdominal) and central (cerebral) tissue oxygenation was measured by Near Infrared Spectroscopy (NIRS). Exhaled O2 and CO2, plasma norepinephrine and epinephrine concentrations were measured before and after apnea.Averaged apnea time was 247±76 s. Systolic blood pressure increased from 135±13 to 185±25 mmHg. End-expiratory CO2 increased from 29±4 mmHg to 49±6 mmHg. Norepinephrine increased from 623±307 to 1 826±984 pg ml-1 and epinephrine from 78±22 to 143±65 pg ml-1 during apnea. Heart rate reduction was inversely correlated with increased norepinephrine (correlation coefficient -0.844, p=0.001). Central (cerebral) O2 desaturation was time-delayed compared to peripheral O2 desaturation as measured by NIRSabdominal and SpO2.Increased norepinephrine caused by apnea may contribute to blood shift from peripheral tissues to the CNS and thus help to preserve cerebral tissue O2 saturation longer than that of peripheral tissue.

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. The two tasks were administered once 5 m below the water's surface and once on dry land. Compared to land, subjects' reaction time increased in 5 m depth when task difficulty was low, but it did not increase when task difficulty was high. Thus, performance deficits in 5 m depth were inversely related to task complexity. We interpret this counter-intuitive finding within the framework of a multiple-channel parallel processing model, with channels that are differentially sensitive to immersion. This model correctly predicts performance deficits on simple, but not on complex skills at smaller depths, and deficits on simple as well as complex skills at larger depths, in accordance with the present findings and data from literature.

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. This study aimed to display changes in brain oxygenation caused by altered gravity conditions during parabolic flight. It was hypothesized that an increase in gravity would be accompanied by a decrease in brain oxygenation, whereas microgravity would lead to an increase in brain oxygenation. Oxygenized and deoxygenized haemoglobin were measured using two near infrared spectroscopy (NIRS) probes on the left and right prefrontal cortex throughout ten parabolas in nine subjects. Results show a decrease of 1.44 µmol/l in oxygenized haemoglobin with the onset of hypergravity, followed by a considerable increase during microgravity (up to 5.34 µmol/l). In contrast, deoxygenized haemoglobin was not altered during the first but only during the second hypergravity phase and showed only minor changes during microgravity. Changes in oxygenized and deoxygenized haemoglobin indicate an increase in arterial flow to the brain and a decrease in venous outflow during microgravity.

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 (V̇E), and lower blood lactate concentrations [Lac-] are highly relevant, especially during high-stress and rescue scenarios. Fifteen participants performed 3 × 8 min of continuous underwater fin-swimming at 25 % (low), 45 % (moderate), and 75 % (vigorous) heart rate reserve (HRR) in each test. Three separate test days differed solely by the inspiratory oxygen partial pressure (PIO2: 29 kPa, 56 kPa, and 140 kPa). V̇E was measured continuously, whereas breathing gas analysis, blood sampling, and Eriksen Flanker tasks for inhibitory control (100 stimuli) were performed post-exercise. Two-way ANOVAs with repeated measures on the factors PIO2 and exercise intensity analyzed physiological outcome variables and reactions times (RT) and accuracy (ACC) of inhibitory control. V̇E was significantly reduced for 140 kPa during moderate and vigorous and for 56 kPa during vigorous compared to 29 kPa. 56 kPa and 140 kPa showed no differences. [Lac-], post-exercise V̇CO2, and velocity were unaffected by PIO2. Faster RTs but lower ACC of inhibitory control were observed following exercise at 75 % HRR compared to rest, 25 %, and 45 % HRR, while PIO2 produced no effects. Underwater performance in hyperoxia presents reduced V̇E, possible by dampened chemoreceptor sensitivity, and effects on cognition that differ from laboratory results and emphasise the moderating role of sport-specific factors.

Hyperoxia-induced reductions in V̇_E with 56 and 140 kPa P_IO₂ during constant submaximal fin-swimming intensity compared to air might be prominently caused by peripheral chemoreceptor suppression.No difference between 56 and 140 kPa was detected, indicating a P_IO₂ threshold limiting further hyperoxic influence on V̇_E. O₂ supply might sufficiently cover metabolic demands of submaximal exercise with 56 kPa, while further reductions in V̇_E could be observed only by severely higher P_IO₂.Cognitive performance by inhibitory control was unaffected by P_IO₂. Faster RTs but lower ACC were observed following vigorous exercise (75 % HRR) compared to rest, low, and moderate exercise.

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. N = 16 were isolated for 30 days with daily exercise routines (ISO100) and n = 16 isolated for 45 days with every second day exercise (ISO50). N = 27 were non-isolated controls who either exercised on a daily basis (CTRLEx) or refused exercise (CTRLNonEx) for 30 days. At the beginning and the end of each intervention, intravenous morning cortisol, melatonin, brain-derived neurotrophic factor and IGF-1, positive and negative affect scales, electroencephalography, cognitive function, and sleep patterns (actigraphy) were assessed. High levels of cortisol were observed for the isolated groups (p < .05) without negative effects on the brain, cognitive function, sleep, and mood after 4 to 6 weeks of isolation, where physical exercise was performed regularly. An increase in cortisol and impairments of sleep quality, mood, cognitive function, and neurotrophic factors (p < .05) were observed after 4 weeks of absence of physical exercise in the CTRLNonEx group. These findings raise the assumption that regular physical exercise routines are a key component during isolation to maintain brain health and function.

Secondary prevention through cardiac rehabilitation: physical activity counselling and exercise training: key components of the position paper from the Cardiac Rehabilitation Section of the European Association of Cardiovascular Prevention and Rehabilitation.

Cardiac patients after an acute event and/or with chronic heart disease deserve special attention to restore their quality of life and to maintain or improve functional capacity. They require counselling to avoid recurrence through a combination of adherence to a medication plan and adoption of a healthy lifestyle. These secondary prevention targets are included in the overall goal of cardiac rehabilitation (CR). Cardiac rehabilitation can be viewed as the clinical application of preventive care by means of a professional multi-disciplinary integrated approach for comprehensive risk reduction and global long-term care of cardiac patients. The CR approach is delivered in tandem with a flexible follow-up strategy and easy access to a specialized team. To promote implementation of cardiac prevention and rehabilitation, the CR Section of the EACPR (European Association of Cardiovascular Prevention and Rehabilitation) has recently completed a Position Paper, entitled 'Secondary prevention through cardiac rehabilitation: A condition-oriented approach'. Components of multidisciplinary CR for seven clinical presentations have been addressed. Components include patient assessment, physical activity counselling, exercise training, diet/nutritional counselling, weight control management, lipid management, blood pressure monitoring, smoking cessation, and psychosocial management. Cardiac rehabilitation services are by definition multi-factorial and comprehensive, with physical activity counselling and exercise training as central components in all rehabilitation and preventive interventions. Many of the risk factor improvements occurring in CR can be mediated through exercise training programmes. This call-for-action paper presents the key components of a CR programme: physical activity counselling and exercise training. It summarizes current evidence-based best practice for the wide range of patient presentations of interest to the general cardiology community.

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. Forty-three apparently healthy participants performed a moderate constant work rate (CWR) followed by a pseudorandom binary sequence (PRBS) exercise protocol on a cycle ergometer. Participants also performed a maximum incremental cardiopulmonary exercise testing (CPET). The maximal aerobic power was evaluated by the peak oxygen uptake during the CPET, and the aerobic fitness was estimated from different approaches for oxygen uptake dynamics analysis during the CWR and PRBS protocols at different levels of signal-to-noise ratio. The product moment correlation coefficient was used to evaluate the correlation level between variables. Aerobic fitness was correlated with maximum aerobic power, but this correlation increased as a function of the signal-to-noise ratio. Aerobic fitness is related to maximal aerobic power; however, this association appeared to be highly dependent on the data quality and analysis for aerobic fitness evaluation. Our results show that simpler moderate exercise protocols might be as good as maximal exertion exercise protocols to obtain indexes related to cardiorespiratory health.NEW & NOTEWORTHY Optimized methods for cardiorespiratory health evaluation are of great interest for public health. Moderate exercise protocols might be as good as maximum exertion exercise protocols to evaluate cardiorespiratory health. Pseudorandom or constant workload moderate exercise can be used to evaluate cardiorespiratory health.

Influence of combined exercise and gravity transients and apnea on hemodynamics.

Hemodynamic responses to combined heavy dynamic leg exercise (hiP), breath holding (BH) and gravity-induced blood volume shifts direction were studied. Thirteen subjects were studied at normal gravity and 12 during parabolic flight, performing 20 s hiP or combined hiP&BH (stimulus period) from a baseline of 30 W at normal gravity (1 G(z+)). Heart rate and mean arterial pressure responses to BH were similar between gravity conditions, but stroke volume (SV) differed markedly between gravity conditions: at 1 G(z+) SV was higher [112 +/- 16 ml (mean +/- SD)] during BH, than during eupnea [101 +/- 17 ml (P < 0.05, N = 13)]. In weightlessness the corresponding SV values were 105 +/- 16 and 127 +/- 20 ml, respectively (P < 0.05, N = 6). Transthoracic electrical conductance (TTC) was used as index for intrathoracic volume. TTC fell significantly during BH. This decrease was attenuated in weightlessness. It is concluded that the transient microgravity temporarily reduces the efficiency of the muscle pump so that the deep inspiration at the onset of the high-intensity exercise and breath-hold period cannot augment venous return as it could during identical manoeuvres at normal gravity.