Abstract
Developing an exercise model that resembles a traditional form of aerobic exercise and facilitates a complete simultaneous assessment of multiple parameters within the oxygen cascade is critically for understanding exercise intolerances in diseased populations. Measurement of muscle blood flow is a crucial component of such a model and previous studies have used invasive procedures to determine blood flow kinetics; however, this may not be appropriate in certain populations. Furthermore, current models utilizing Doppler ultrasound use isolated limb exercise and while these studies have provided useful data, the exercise model does not mimic the whole‐body physiological response to continuous dynamic exercise. Therefore, we aimed to measure common femoral artery blood flow using Doppler ultrasound during continuous dynamic stepping exercise performed at three independent workloads to assess the within day and between‐day reliability for such an exercise modality. We report a within‐session coefficient of variation of 5.8% from three combined workloads and a between‐day coefficient of variation of 12.7%. These values demonstrate acceptable measurement accuracy and support our intention of utilizing this noninvasive exercise model for an integrative assessment of the whole‐body physiological response to exercise in a range of populations.
Highlights
The oxygen cascade refers to the diffusion and transport of oxygen through the pulmonary and systemic circulations culminating in mitochondrial respiration at the level of the skeletal muscle
What is the central question of this study? Determine reliability of measuring skeletal muscle blood flow during dynamic continuous exercise using Doppler ultrasound
What is the main finding and its importance? We demonstrated that muscle blood flow could be reliably measured within and between days to acceptable standards using Doppler ultrasound at three different workloads during continuous dynamic stepping exercise
Summary
The oxygen cascade refers to the diffusion and transport of oxygen through the pulmonary and systemic circulations culminating in mitochondrial respiration at the level of the skeletal muscle. The primary exercise modality has been varying forms of the isolated rhythmic forearm (Amundsen et al, 2002; Shoemaker et al, 1996) or knee extensor contractions (Rådegran, 1997; Shoemaker et al, 1994; Walther et al, 2006). These exercise modalities have several advantages in demonstrating the time course of hyperemia post contraction, identifying blood flow kinetics during periods of muscle contraction and /or relaxation (Tschakovsky et al, 2004) and due to the small, activated muscle mass, vasodilator capacity largely independent of central cardiac limitations (Magnusson et al, 1997)
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