Interindividual Differences in Oxygen Delivery Demand Matching and its Impact on Exercise Fatigability
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Background: At the start of exercise, the energy demand of the muscle increases. To meet this demand, energy production using oxygen increases. More oxygen is brought to the muscle mainly by a widening of the blood vessels. In small muscle mass exercise, it is generally accepted that oxygen delivery is tightly coupled to the demand of the muscle (Wagner, 2012, Wajner & Goodman, 2011). Recently however, individual differences in oxygen delivery demand matching have been revealed, and these differences predict performance. (Kellawan et al., 2014; Bentley et al., 2014; Bentley et al., 2017). Objectives: 1) Quantify an individual’s oxygen delivery (O2D) to oxygen consumption (V̇ O2) ratio using a range of exercise intensities 2) Quantify the association between the oxygen delivery to oxygen consumption ratio and exercise fatigability. Methods: 10 participants performed multiple incremental rhythmic forearm handgrip exercise tests until exhaustion to quantify individual oxygen delivery to oxygen consumption ratio. These participants were divided into high and low responder groups, where ‘high responders’ were defined as having higher oxygen delivery relative to oxygen consumption and ‘low responders’ had lower oxygen delivery relative to oxygen consumption. A fatiguing exercise test, using intermittent maximal contractions, was used to quantify fatigability. Oxygen delivery was determined by measuring forearm blood flow with ultrasound and by estimating the oxygen content of the blood through venous blood sampling. Forearm oxygen consumption was calculated as the product of forearm blood flow and arterial-venous oxygen content difference. Results: High responders experienced less fatigability than the low responders. High responders had greater absolute change in O2D (p < 0.01), forearm blood flow (FBF) (p<0.05) and in forearm vascular conductance (FVC) (p<0.05), reflecting a greater widening of the blood vessels. Conclusions: In forearm handgrip exercise, the high responders demonstrated less exercise fatigability. High responders had greater widening of the blood vessels, suggesting the potential for relative enhancement of the blood vessel response to the same exercise demand.
URI for this recordhttp://hdl.handle.net/1974/23954
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