Muscle oxygen extraction and perfusion heterogeneity during continuous and intermittent static exercise

Abstract

The purpose of this study was to compare the effects of intermittent and continuous static exercise on muscle perfusion, perfusion heterogeneity, and oxygen extraction. Perfusion and oxygen uptake of quadriceps femoris muscle were measured in 10 healthy men by using positron emission tomography and [(15)O]H(2)O and [(15)O]O(2) first during intermittent static exercise [10% of maximal static force (MSF)] and thereafter during continuous static exercise at the same tension-time level (5% static; 5% of MSF). In 4 of these subjects, perfusion was measured during continuous static exercise with 10% of MSF (10% continuous) instead of the second [(15)O]O(2) measurement. Muscle oxygen consumption was similar during intermittent and 5% continuous, but muscle perfusion was significantly higher during 5% continuous. Consequently, muscle oxygen extraction fraction was lower during 5% continuous. Perfusion was also more heterogeneous during 5% continuous. When exercise intensity was doubled during continuous static exercise (from 5% continuous to 10% continuous), muscle perfusion increased markedly. These results suggest that continuous, low-intensity static exercise decreases muscle oxygen extraction and increases muscle perfusion and its heterogeneity compared with intermittent static exercise at the same relative exercise intensity.

Blood flow and muscle oxygenation during low, moderate, and maximal sustained isometric contractions

“…We observed exercise-induced increases in blood flow at the level of the conduit artery, but measurement of gross flow at this site does not indicate how much of the added blood actually perfused the contracting muscle. The concurrent examination of muscle oxygenation allowed us to speculate on perfusion, but the combination of Doppler ultrasound and NIRS does not approach the precision of PET, which can show the distribution of blood in a muscle during a sustained isometric contraction (14,20,21).…”

“…In contrast, the latter two methods can provide direct measures of exerciseinduced changes in muscle blood flow. PET measures perfusion directly from the muscle tissue (e.g., 14,21), whereas Doppler ultrasound tracks changes in arterial size and mean blood velocity (MBV) to provide a direct measure of blood flow into a muscle compartment (e.g., 10,19). The combination of Doppler ultrasound and NIRS allows for the assessment of concurrent associations between flow and oxygenation of muscle (see Ref.…”

Calf muscle perfusion at peak exercise in peripheral arterial disease: Measurement by first‐pass contrast‐enhanced magnetic resonance imaging

“…A variety of noninvasive techniques have been employed for the direct assessment of human skeletal muscle blood flow including Doppler ultrasound (3,17,18), scintigraphy (19,20), and plethysmography (21)(22)(23). The most widely accepted clinical standard for noninvasively measuring limb perfusion is venous occlusion strain gauge plethysmography.…”

Peripheral Arterial Disease Assessment

“…[44][45][46] The most widely accepted clinical standard for noninvasively measuring limb perfusion is venous occlusion strain gauge plethysmography. Aside from its inability to provide spatial localization of flow, plethysmography may underestimate perfusion and can be sensitive to changes in both body position and temperature.…”