ArticleDynamic medicine : DM2008
The oxygen delivery response to acute hypoxia during incremental knee extension exercise differs in active and trained males.
Article in Dynamic medicine : DM, 2008. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.
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Who cites it
3 citing papers in PubMed, 2 citations in OpenAlex.
- Article
- The Effect of Breathing Patterns Common to Competitive Swimming on Gas Exchange and Muscle Deoxygenation During Heavy-Intensity Fartlek Exercise.Frontiers in physiology · 2021Article
- Heart rate recovery after maximal exercise is impaired in healthy young adults born preterm.European journal of applied physiology · 2019Article
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Authors and funding
6 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundIt is well known that hypoxic exercise in healthy individuals increases limb blood flow, leg oxygen extraction and limb vascular conductance during knee extension exercise. However, the effect of hypoxia on cardiac output, and total vascular conductance is less clear. Furthermore, the oxygen delivery response to hypoxic exercise in well trained individuals is not well known. Therefore our aim was to determine the cardiac output (Doppler echocardiography), vascular conductance, limb blood flow (Doppler echocardiography) and muscle oxygenation response during hypoxic knee extension in normally active and endurance-trained males.
methodsTen normally active and nine endurance-trained males (VO2max = 46.1 and 65.5 mL/kg/min, respectively) performed 2 leg knee extension at 25, 50, 75 and 100% of their maximum intensity in both normoxic and hypoxic conditions (FIO2 = 15%; randomized order). Results were analyzed with a 2-way mixed model ANOVA (group x intensity).
resultsThe main finding was that in normally active individuals hypoxic sub-maximal exercise (25 - 75% of maximum intensity) brought about a 3 fold increase in limb blood flow but decreased stroke volume compared to normoxia. In the trained group there were no significant changes in stroke volume, cardiac output and limb blood flow at sub-maximal intensities (compared to normoxia). During maximal intensity hypoxic exercise limb blood flow increased approximately 300 mL/min compared to maximal intensity normoxic exercise.
conclusionCardiorespiratory fitness likely influences the oxygen delivery response to hypoxic exercise both at a systemic and limb level. The increase in limb blood flow during maximal exercise in hypoxia (both active and trained individuals) suggests a hypoxic stimulus that is not present in normoxic conditions.
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