Abstract
Endurance training is associated with skeletal muscle adaptations that regulate the oxidative metabolism during ischemia/reperfusion. The aim of this study was to noninvasively assess in vivo differences in the oxidative metabolism activity during ischemia/reperfusion between trained and untrained individuals, using near infrared spectroscopy (NIRS) combined with a vascular occlusion test (VOT) technique (NIRS‐VOT). Sixteen untrained (26.3 ± 5.1 year) and seventeen trained (29.4 ± 4.9 year) healthy young adult men were submitted to a VOT (2 min baseline, 5 min occlusion, and 8 min reperfusion). Oxygen utilization was estimated from the area under the curve of the NIRS‐derived deoxyhemoglobin [HHb] signal during occlusion (AUCocc). Muscle reperfusion was derived from the area above the curve (AACrep) of the [HHb] signal after cuff release. The AUCocc of the untrained participants (21010 ± 9553 % · s) was significantly larger than the AUCocc of their trained counterparts (12320 ± 3283 % · s); P = 0.001). The AACrep of the untrained participants (5928 ± 3769 % · s) was significantly larger than the AACrep of the trained participants (3745 ± 1900 % · s; P = 0.042). There was a significant correlation between AUCocc and AACrep (r = 0.840; P = 0.001). NIRS assessment of oxidative metabolism showed that trained individuals are more efficient in shifting between oxidative and anaerobic metabolism in response to ischemia and reperfusion.
Highlights
IntroductionAnaerobic metabolism becomes upregulated causing a decrease in cellular pH, reduction in cellular ATP, and an increase in oxidative stress (as hypoxia impairs mitochondrial function) (Zhou et al 1996; Hoppeler et al 2003)
In response to hypoxia, anaerobic metabolism becomes upregulated causing a decrease in cellular pH, reduction in cellular ATP, and an increase in oxidative stress (Zhou et al 1996; Hoppeler et al 2003)
The aim of this study was to noninvasively assess in vivo whether trained individuals were more efficient at acutely modulate the oxidative metabolism activity of the skeletal muscle during ischemia/reperfusion compared with untrained individuals, using near infrared spectroscopy (NIRS) combined with a vascular occlusion tests (VOT) (NIRS-VOT)
Summary
Anaerobic metabolism becomes upregulated causing a decrease in cellular pH, reduction in cellular ATP, and an increase in oxidative stress (as hypoxia impairs mitochondrial function) (Zhou et al 1996; Hoppeler et al 2003). Hypoxia-inducible factors are transcription factors that sense a decrease in oxygen partial pressure and activate genes associated with anaerobic metabolism. This transition away from oxidative metabolism provides a protective effect in response to hypoxia by reducing reactive oxygen species (ROS) production and cell death (Zagorska and Dulak 2004; Lindholm and Rundqvist 2016). Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society
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