scholarly journals Does cerebral oxygen delivery limit incremental exercise performance?

2011 ◽  
Vol 111 (6) ◽  
pp. 1727-1734 ◽  
Author(s):  
Andrew W. Subudhi ◽  
J. Tod Olin ◽  
Andrew C. Dimmen ◽  
David M. Polaner ◽  
Bengt Kayser ◽  
...  
Keyword(s):  
Exercise Performance ◽  
Oxygen Delivery ◽  
Respiratory Acidosis ◽  
Barometric Pressure ◽  
Incremental Exercise ◽  
Peak Oxygen Consumption ◽  
Peak Power Output ◽  
Cerebral Oxygen ◽  
Exercise Tests ◽  
Hemoglobin Oxygenation

Previous studies have suggested that a reduction in cerebral oxygen delivery may limit motor drive, particularly in hypoxic conditions, where oxygen transport is impaired. We hypothesized that raising end-tidal Pco2 (PetCO2) during incremental exercise would increase cerebral blood flow (CBF) and oxygen delivery, thereby improving peak power output (Wpeak). Amateur cyclists performed two ramped exercise tests (25 W/min) in a counterbalanced order to compare the normal, poikilocapnic response against a clamped condition, in which PetCO2 was held at 50 Torr throughout exercise. Tests were performed in normoxia (barometric pressure = 630 mmHg, 1,650 m) and hypoxia (barometric pressure = 425 mmHg, 4,875 m) in a hypobaric chamber. An additional trial in hypoxia investigated effects of clamping at a lower PetCO2 (40 Torr) from ∼75 to 100% Wpeak to reduce potential influences of respiratory acidosis and muscle fatigue imposed by clamping PetCO2 at 50 Torr. Metabolic gases, ventilation, middle cerebral artery CBF velocity (transcranial Doppler), forehead pulse oximetry, and cerebral (prefrontal) and muscle (vastus lateralis) hemoglobin oxygenation (near infrared spectroscopy) were monitored across trials. Clamping PetCO2 at 50 Torr in both normoxia ( n = 9) and hypoxia ( n = 11) elevated CBF velocity (∼40%) and improved cerebral hemoglobin oxygenation (∼15%), but decreased Wpeak (6%) and peak oxygen consumption (11%). Clamping at 40 Torr near maximal effort in hypoxia ( n = 6) also improved cerebral oxygenation (∼15%), but again limited Wpeak (5%). These findings demonstrate that increasing mass cerebral oxygen delivery via CO2-mediated vasodilation does not improve incremental exercise performance, at least when accompanied by respiratory acidosis.

A Prediction Model for Peak Power Output From Different Incremental Exercise Tests

2006 ◽  
Vol 1 (2) ◽  
pp. 122-136 ◽  
Author(s):  
Hans Luttikholt ◽  
Lars R. McNaughton ◽  
Adrian W. Midgley ◽  
David J. Bentley
Keyword(s):  
Power Output ◽  
Peak Power ◽  
Cycle Ergometer ◽  
Incremental Exercise ◽  
Peak Power Output ◽  
Exercise Tests ◽  
Male Athletes ◽  
Power Profile ◽  
Wide Range ◽  
Level Of Agreement

Context:There is currently no model that predicts peak power output (PPO) thereby allowing comparison between different incremental exercise test (EXT) protocols. In this study we have used the critical power profile to develop a mathematical model for predicting PPO from the results of different EXTs.Purpose:The purpose of this study was to examine the level of agreement between actual PPO values and those predicted from the new model.Methods:Eleven male athletes (age 25 ± 5 years, VO2max 62 ± 8 mL · kg–1 · min–1) completed 3 laboratory tests on a cycle ergometer. Each test comprised an EXT consisting of 1-minute workload increments of 30 W (EXT30/1) and 3-minute (EXT25/3) and 5-minute workload increments (EXT25/5) of 25 W. The PPO determined from each test was used to predict the PPO from the remaining 2 EXTs.Results:The differences between actual and predicted PPO values were statistically insignificant (P > .05). The random error components of the limits of agreement of ≤30 W also indicated acceptable levels of agreement between actual and predicted PPO values.Conclusions:Further data collection is necessary to confirm whether the model is able to predict PPO over a wide range of EXT protocols in athletes of different aerobic and anaerobic capacities.

scholarly journals Exercise Performance and Thermoregulatory Responses of Elite Athletes Exercising in the Heat: Outcomes of the Thermo Tokyo Study

2021 ◽  
Author(s):  
Johannus Q. de Korte ◽  
Coen C. W. G. Bongers ◽  
Maria T. E. Hopman ◽  
Thijs M. H. Eijsvogels
Keyword(s):  
Exercise Performance ◽  
Elite Athletes ◽  
Interindividual Variation ◽  
Peak Power Output ◽  
Time To Exhaustion ◽  
Thermal Perception ◽  
Exercise Tests ◽  
Thermoregulatory Responses ◽  
Exercise Induced ◽  
The Impact

Abstract Objective We examined the impact of simulated Tokyo 2020 environmental condition on exercise performance, thermoregulatory responses and thermal perception among Dutch elite athletes. Methods 105 elite athletes from different sport disciplines performed two exercise tests in simulated control (15.9 ± 1.2 °C, relative humidity (RH) 55 ± 6%) and Tokyo (31.6 ± 1.0 °C, RH 74 ± 5%) environmental conditions. Exercise tests consisted of a 20-min warm-up (70% HRmax), followed by an incremental phase until volitional exhaustion (5% workload increase every 3 min). Gastrointestinal temperature (Tgi), heart rate, exercise performance and thermal perception were measured. Results Time to exhaustion was 16 ± 8 min shorter in the Tokyo versus the control condition (− 26 ± 11%, whereas peak power output decreased with 0.5 ± 0.3 W/kg (16 ± 7%). Greater exercise-induced increases in Tgi (1.8 ± 0.6 °C vs. 1.5 ± 0.5 °C, p < 0.001) and higher peak Tgi (38.9 ± 0.6 °C vs. 38.7 ± 0.4 °C, p < 0.001) were found in the Tokyo versus control condition. Large interindividual variations in exercise-induced increase in Tgi (range 0.7–3.5 °C) and peak Tgi (range 37.6–40.4 °C) were found in the Tokyo condition, with greater Tgi responses in endurance versus mixed- and skill-trained athletes. Peak thermal sensation and thermal comfort scores deteriorated in the Tokyo condition, with aggravated responses for power versus endurance- and mixed-trained athletes. Conclusion Large performance losses and Tgi increases were found among elite athletes exercising in simulated Tokyo conditions, with a substantial interindividual variation and significantly different responses across sport disciplines. These findings highlight the importance of an individual approach to optimally prepare athletes for safe and maximal exercise performance during the Tokyo Olympics.

scholarly journals Effects of face masks on performance and cardiorespiratory response in well-trained athletes

2021 ◽  
Author(s):  
Florian Egger ◽  
Dominic Blumenauer ◽  
Patrick Fischer ◽  
Andreas Venhorst ◽  
Saarraaken Kulenthiran ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Minute Ventilation ◽  
Anaerobic Exercise ◽  
Peak Oxygen Consumption ◽  
Exercise Tests ◽  
Maximum Performance ◽  
Outdoor Sports ◽  
Cardiorespiratory Response ◽  
Individual Anaerobic Threshold ◽  
The Individual

Abstract Background During the COVID-19 pandemic, compulsory masks became an integral part of outdoor sports such as jogging in crowded areas (e.g. city parks) as well as indoor sports in gyms and sports centers. This study, therefore, aimed to investigate the effects of medical face masks on performance and cardiorespiratory parameters in athletes. Methods In a randomized, cross-over design, 16 well-trained athletes (age 27 ± 7 years, peak oxygen consumption 56.2 ± 5.6 ml kg−1 min−1, maximum performance 5.1 ± 0.5 Watt kg−1) underwent three stepwise incremental exercise tests to exhaustion without mask (NM), with surgical mask (SM) and FFP2 mask (FFP2). Cardiorespiratory and metabolic responses were monitored by spiroergometry and blood lactate (BLa) testing throughout the tests. Results There was a large effect of masks on performance with a significant reduction of maximum performance with SM (355 ± 41 Watt) and FFP2 (364 ± 43 Watt) compared to NM (377 ± 40 Watt), respectively (p < 0.001; ηp2 = 0.50). A large interaction effect with a reduction of both oxygen consumption (p < 0.001; ηp2 = 0.34) and minute ventilation (p < 0.001; ηp2 = 0.39) was observed. At the termination of the test with SM 11 of 16 subjects reported acute dyspnea from the suction of the wet and deformed mask. No difference in performance was observed at the individual anaerobic threshold (p = 0.90). Conclusion Both SM and to a lesser extent FFP2 were associated with reduced maximum performance, minute ventilation, and oxygen consumption. For strenuous anaerobic exercise, an FFP2 mask may be preferred over an SM.

Cardiopulmonary bypass temperature, hematocrit, and cerebral oxygen delivery in humans

1995 ◽  
Vol 60 (6) ◽  
pp. 1671-1677 ◽  
Author(s):  
David J. Cook ◽  
William C. Oliver ◽  
Thomas A. Orszulak ◽  
Richard C. Daly ◽  
Rex D. Bryce
Keyword(s):  
Cardiopulmonary Bypass ◽  
Oxygen Delivery ◽  
Cerebral Oxygen

scholarly journals Moderate-Intensity Physical Exercise Affects the Exercise Performance and Gut Microbiota of Mice

2021 ◽  
Vol 11 ◽  
Author(s):  
Wenqian Yang ◽  
Yuqian Liu ◽  
Guang Yang ◽  
Binglin Meng ◽  
Zhicheng Yi ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Exercise Performance ◽  
Exercise Intervention ◽  
Time Series Data ◽  
Shannon Index ◽  
Series Data ◽  
Moderate Intensity ◽  
Rrna Gene ◽  
Exercise Tests ◽  
Significant Difference

The gut microbiota is closely associated with the health of the host and is affected by many factors, including exercise. In this study, we compared the gut microbial changes and exercise performance over a 14-week period in mice that performed exercise (NE; n = 15) and mice that did not perform exercise (NC; n = 15). Mice were subjected to stool collection and exercise tests one week prior to adaptive training and after 2, 6, 10, and 14 weeks of exercise. Bacteria associated with the stool samples were assessed via Illumina-based 16S rRNA gene sequencing. While there was no significant difference in body weight between the groups (p &gt; 0.05), the NE group had a significantly higher exercise performance from weeks 2–14 (p &lt; 0.01) and lower fat coefficient (p &lt; 0.01) compared with the NC group. The Shannon index of the gut microbiota in the NC group was higher than that in the NE group at weeks 6 and 10, and the Chao1 index was higher than that in the NE group at week 14. Exercise performance positively correlated with the relative abundance of Phascolarctobacterium. Grouped time series data analysis demonstrated that Bifidobacteria, Coprococcus, and one unnamed genus in the Clostridiales order were significantly increased in the NE group, which correlated with increased glucose, flavonoid, arginine, and proline metabolism. In conclusion, moderate-intensity treadmill exercise significantly increased the exercise performance of mice and changed the core bacteria and bacterial metabolic activity. These results provide a reference for studying the effects of exercise intervention and exercise performance on the gut microbiota of mice.

scholarly journals Ventilatory compensation during the incremental exercise test is inversely correlated with air trapping in COPD

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1661
Author(s):  
Rottem Kuint ◽  
Neville Berkman ◽  
Samir Nusair
Keyword(s):  
Gas Exchange ◽  
Exercise Testing ◽  
Exercise Test ◽  
Cardiopulmonary Exercise Testing ◽  
Incremental Exercise ◽  
Peak Oxygen Consumption ◽  
Air Trapping ◽  
Incremental Exercise Test ◽  
Cardiopulmonary Exercise ◽  
Copd Patients

Background: Air trapping and gas exchange abnormalities are major causes of exercise limitation in chronic obstructive pulmonary disease (COPD). During incremental cardiopulmonary exercise testing, ventilatory equivalents for carbon dioxide (VE/VCO2) and oxygen (VE/VO2) may be difficult to identify in COPD patients because of limited ventilatory compensation capacity. Therefore, we aimed to detect a possible correlation between the magnitude of ventilation augmentation, as manifested by increments in ventilatory equivalents from nadir to peak effort values and air trapping, detected with static testing.    Methods: In this observational study, we studied data obtained previously from 20 COPD patients who, during routine follow-up, underwent a symptom-limited incremental exercise test and in whom a plethysmography was obtained concurrently. Air trapping at rest was assessed by measurement of the residual volume (RV) to total lung capacity (TLC) ratio (RV/TLC). Gas exchange data collected during the symptom-limited incremental cardiopulmonary exercise test allowed determination of the nadir and peak effort values of VE/VCO2 and VE/VO2, thus enabling calculation of the difference between peak effort value and nadir values of  VE/VCO2 and VE/VO2, designated ΔVE/VCO2 and ΔVE/VO2, respectively. Results: We found a statistically significant inverse correlation between both ΔVE/VCO2 (r = -0. 5058, 95% CI -0.7750 to -0.08149, p = 0.0234) and ΔVE/VO2 (r = -0.5588, 95% CI -0.8029 to -0.1545, p = 0.0104) and the degree of air trapping (RV/TLC). There was no correlation between                ΔVE/VCO2 and peak oxygen consumption, forced expiratory volume in the first second, or body mass index.  Conclusions: The ventilatory equivalents increment to compensate for acidosis during incremental exercise testing was inversely correlated with air trapping (RV/TLC) and may be a candidate prognostic biomarker.

Adaptations to High-Altitude Hypoxia

2021 ◽  
Author(s):  
Cynthia M. Beall ◽  
Kingman P. Strohl
Keyword(s):  
High Altitude ◽  
Oxygen Delivery ◽  
Hemoglobin Concentration ◽  
Barometric Pressure ◽  
Ambient Air ◽  
Extreme Environment ◽  
Indigenous Populations ◽  
East African ◽  
Short Term

Biological anthropologists aim to explain the hows and whys of human biological variation using the concepts of evolution and adaptation. High-altitude environments provide informative natural laboratories with the unique stress of hypobaric hypoxia, which is less than usual oxygen in the ambient air arising from lower barometric pressure. Indigenous populations have adapted biologically to their extreme environment with acclimatization, developmental adaptation, and genetic adaptation. People have used the East African and Tibetan Plateaus above 3,000 m for at least 30,000 years and the Andean Plateau for at least 12,000 years. Ancient DNA shows evidence that the ancestors of modern highlanders have used all three high-altitude areas for at least 3,000 years. It is necessary to examine the differences in biological processes involved in oxygen exchange, transport, and use among these populations. Such an approach compares oxygen delivery traits reported for East African Amhara, Tibetans, and Andean highlanders with one another and with short-term visitors and long-term upward migrants in the early or later stages of acclimatization to hypoxia. Tibetan and Andean highlanders provide most of the data and differ quantitatively in biological characteristics. The best supported difference is the unelevated hemoglobin concentration of Tibetans and Amhara compared with Andean highlanders as well as short- and long-term upward migrants. Moreover, among Tibetans, several features of oxygen transfer and oxygen delivery resemble those of short-term acclimatization, while several features of Andean highlanders resemble the long-term responses. Genes and molecules of the oxygen homeostasis pathways contribute to some of the differences.

Abstract 339: Relationship Between Post-arrest Care Hemodynamics and Cerebral Oxygen Saturation in Comatose Survivors of Out-of-hospital Cardiac Arrest: Insights From the CAPITAL-RETURN Trial

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_4) ◽  
Author(s):  
Juan J Russo ◽  
Paul Boland ◽  
Simon Parlow ◽  
Jordan Bernick ◽  
Rebecca Mathew ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Cardiac Arrest ◽  
Intensive Care ◽  
Intensive Care Unit Admission ◽  
Oxygen Delivery ◽  
Cerebral Oxygen ◽  
Shockable Rhythm ◽  
The Mean ◽  
The Relationship ◽  
Capital Return

Introduction: Comatose survivors of OHCA develop a post cardiac arrest syndrome (PCAS) characterized by myocardial dysfunction and cerebrovascular dysregulation. Hemodynamic derangements related to PCAS can jeopardize cerebral oxygen delivery and therefore impair neurologic recovery. However, optimal hemodynamic targets to ensure adequate cerebral oxygen delivery following OHCA remain undefined. Accordingly, we examined the relationship between cardiac index (CI), mean arterial pressure (MAP), and regional cerebral oxygen saturation (rO 2 %) following OHCA. Methods: CAPITAL-RETURN was a prospective, single-center observational study examining hemodynamics in comatose survivors of OHCA undergoing targeted temperature management after an initial shockable rhythm. Between August 2016 and December 2017, comatose survivors of OHCA underwent continuous, blinded, non-invasive monitoring of CI and rO 2 % using bioimpedance (Cheetah Medical, Portland, OR, USA) and near-infrared spectroscopy (Covidien, Boulder, CO, USA), respectively, for 96 hours after intensive care unit admission. In the present study, we examined the relationship between CI, MAP, and rO 2 % using multivariable linear regression. Results: In 56 patients in this analysis, the mean CI and MAP during the first 96 hours of intensive care unit admission were 3.2±0.5 L/min/m 2 and 76±6 mmHg, respectively (Figure). The mean rO 2 % was 63±9% and increased over time (+0.1% per hour; p<0.001). Higher CI was associated with improved rO 2 % (+3.2% per L/min/m2 increase in CI; p<0.0001). There was no association between MAP and rO 2 % (p=0.42). After adjustment for MAP, the association between CI and rO 2 % remained significant (+3.1% per L/min/m2 increase in CI; p<0.0001). Conclusion: In comatose survivors of OHCA with an initial shockable rhythm, a higher CI is associated with improved rO 2 %. Further studies are needed to determine whether CI targets improve rO2% and neurologic outcomes following OHCA.

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