Acute Moderate Hypoxia Reduces One-Legged Cycling Performance Despite Compensatory Increase in Peak Cardiac Output: A Pilot Study

Gatterer, Hannes; Menz, Verena; Burtscher, Martin

doi:10.3390/ijerph18073732

Cited by 4 publications

(1 citation statement)

References 31 publications

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“…Thus, elevated limb specific blood flow associated with single-leg cycling may also benefit exercise training at altitude. It has previously been reported that blood saturation, VO 2 peak, and peak power are reduced in single-leg cycling in hypoxia [ 28 ], however, it is still unknown if single-leg cycling can be used to at least partially offset the likely greater reduction in blood saturation and subsequent performance normally seen with traditional double-leg cycling. If so, this will allow athletes to exercise at the greater muscle-specific work rates typically associated with sea level training.…”

Section: Introductionmentioning

confidence: 99%

Single Leg Cycling Offsets Reduced Muscle Oxygenation in Hypoxic Environments

Draper

Singer

Dulaney

et al. 2022

IJERPH

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The intensity of large muscle mass exercise declines at altitude due to reduced oxygen delivery to active muscles. The purpose of this investigation was to determine if the greater limb blood flow during single-leg cycling prevents the reduction in tissue oxygenation observed during traditional double-leg cycling in hypoxic conditions. Ten healthy individuals performed bouts of double and single-leg cycling (4, four-minute stages at 50–80% of their peak oxygen consumption) in hypoxic (15% inspired O2) and normoxic conditions. Heart rate, mean arterial pressure, femoral blood flow, lactate, oxygenated hemoglobin, total hemoglobin, and tissue saturation index in the vastus lateralis were recorded during cycling tests. Femoral blood flow (2846 ± 912 mL/min) and oxygenated hemoglobin (−2.98 ± 3.56 au) during single-leg cycling in hypoxia were greater than double-leg cycling in hypoxia (2429 ± 835 mL/min and −6.78 ± 3.22 au respectively, p ≤ 0.01). In addition, tissue saturation index was also reduced in the double-leg hypoxic condition (60.2 ± 3.1%) compared to double-leg normoxic (66.0 ± 2.4%, p = 0.008) and single-leg hypoxic (63.3 ± 3.2, p < 0.001) conditions. These data indicate that while at altitude, use of reduced muscle mass exercise can help offset the reduction in tissue oxygenation observed during larger muscle mass activities allowing athletes to exercise at greater limb/muscle specific intensities.

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Section: Introductionmentioning

confidence: 99%

Single Leg Cycling Offsets Reduced Muscle Oxygenation in Hypoxic Environments

Draper

Singer

Dulaney

et al. 2022

IJERPH

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Multiple N-of-1 trials to investigate hypoxia therapy in Parkinson’s disease: study rationale and protocol

Daalen

Meinders

Giardina³

et al. 2022

BMC Neurol

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Background Parkinson’s disease (PD) is a neurodegenerative disease, for which no disease-modifying therapies exist. Preclinical and clinical evidence suggest that hypoxia-based therapy might have short- and long-term benefits in PD. We present the contours of the first study to assess the safety, feasibility and physiological and symptomatic impact of hypoxia-based therapy in individuals with PD. Methods/Design In 20 individuals with PD, we will investigate the safety, tolerability and short-term symptomatic efficacy of continuous and intermittent hypoxia using individual, double-blind, randomized placebo-controlled N-of-1 trials. This design allows for dose finding and for including more individualized outcomes, as each individual serves as its own control. A wide range of exploratory outcomes is deployed, including the Movement Disorders Society Unified Parkinson’s Disease Rating scale (MDS-UPDRS) part III, Timed Up & Go Test, Mini Balance Evaluation Systems (MiniBES) test and wrist accelerometry. Also, self-reported impression of overall symptoms, motor and non-motor symptoms and urge to take dopaminergic medication will be assessed on a 10-point Likert scale. As part of a hypothesis-generating part of the study, we also deploy several exploratory outcomes to probe possible underlying mechanisms of action, including cortisol, erythropoietin and platelet-derived growth factor β. Efficacy will be assessed primarily by a Bayesian analysis. Discussion This evaluation of hypoxia therapy could provide insight in novel pathways that may be pursued for PD treatment. This trial also serves as a proof of concept for deploying an N-of-1 design and for including individualized outcomes in PD research, as a basis for personalized treatment approaches. Trial registration ClinicalTrials.gov Identifier: NCT05214287 (registered January 28, 2022).

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The relationship between hemoglobin and V˙O2max: A systematic review and meta-analysis

Webb,

Gorman,

Morkeberg

et al. 2023

PLoS ONE

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Objective There is widespread agreement about the key role of hemoglobin for oxygen transport. Both observational and interventional studies have examined the relationship between hemoglobin levels and maximal oxygen uptake (V˙O2max) in humans. However, there exists considerable variability in the scientific literature regarding the potential relationship between hemoglobin and V˙O2max. Thus, we aimed to provide a comprehensive analysis of the diverse literature and examine the relationship between hemoglobin levels (hemoglobin concentration and mass) and V˙O2max (absolute and relative V˙O2max) among both observational and interventional studies. Methods A systematic search was performed on December 6th, 2021. The study procedures and reporting of findings followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Article selection and data abstraction were performed in duplicate by two independent reviewers. Primary outcomes were hemoglobin levels and V˙O2max values (absolute and relative). For observational studies, meta-regression models were performed to examine the relationship between hemoglobin levels and V˙O2max values. For interventional studies, meta-analysis models were performed to determine the change in V˙O2max values (standard paired difference) associated with interventions designed to modify hemoglobin levels or V˙O2max. Meta-regression models were then performed to determine the relationship between a change in hemoglobin levels and the change in V˙O2max values. Results Data from 384 studies (226 observational studies and 158 interventional studies) were examined. For observational data, there was a positive association between absolute V˙O2max and hemoglobin levels (hemoglobin concentration, hemoglobin mass, and hematocrit (P<0.001 for all)). Prespecified subgroup analyses demonstrated no apparent sex-related differences among these relationships. For interventional data, there was a positive association between the change of absolute V˙O2max (standard paired difference) and the change in hemoglobin levels (hemoglobin concentration (P<0.0001) and hemoglobin mass (P = 0.006)). Conclusion These findings suggest that V˙O2max values are closely associated with hemoglobin levels among both observational and interventional studies. Although our findings suggest a lack of sex differences in these relationships, there were limited studies incorporating females or stratifying results by biological sex.

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Acute Moderate Hypoxia Reduces One-Legged Cycling Performance Despite Compensatory Increase in Peak Cardiac Output: A Pilot Study

Cited by 4 publications

References 31 publications

Single Leg Cycling Offsets Reduced Muscle Oxygenation in Hypoxic Environments

Single Leg Cycling Offsets Reduced Muscle Oxygenation in Hypoxic Environments

Multiple N-of-1 trials to investigate hypoxia therapy in Parkinson’s disease: study rationale and protocol

The relationship between hemoglobin and V˙O2max: A systematic review and meta-analysis

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