Glucose uptake by individual skeletal muscles during running using whole-body positron emission tomography

Abstract

The purpose of this study was to examine, by positron emission tomography (PET), the distribution of [18F]fluoro-deoxy-glucose ([18F]FDG) uptake by human muscles during 35 min of running. Thirteen healthy male subjects were studied, seven of whom participated in the exercise study. Running intensity was kept constant such that the subjects' heart rates were maintained at between 140 and 150 beats per minute. [18F]FDG [62.9 (14.8) MBq, mean (SD)] was injected after 15 min of running. PET imaging was started immediately after the running ended. The ratio of [18F]FDG uptake by muscles in runners to that in control subjects (r-c ratio) varied from three to six for the muscles of the foot and leg below the knee joint. The r-c ratio of the medial head of the gastrocnemius (MG) was higher than that of its lateral head (LG). The r-c ratio of the rectus femoris (RF) was lower than that of the other three muscles of the quadriceps femoris (QF). The r-c ratio of inactive muscles located above the waist was approximately 0.7. These results suggest that, during the moderate running of this study: (1) glucose uptake by muscles of the foot and leg below the knee joint clearly increases, (2) the r-c ratio differs significantly among the skeletal muscles, which act synergistically, and (3) glucose uptake by inactive skeletal muscles decreases.

Prospective Evaluation of Physiologic Uptake Detected with True Whole-Body 18F-FDG PET/CT in Healthy Subjects

“…The anterior compartment includes the tibialis anterior and toe extensor muscles. These muscles are active during walking and running (13,15,16) because they decelerate the movement of the foot to the ground after initial heel contact, and they also function concentrically to bring the foot into dorsiflexion during the swing phase of gait. Because all subjects ambulated independently into the clinic for their PET/CT scans, anterior compartment muscle activity occurred in all subjects immediately before the scans.…”

“…No prospective study on the physiologic uptake of 18 F-FDG in healthy subjects has been published. 18 F-FDG PET was used to examine metabolic muscle activity in healthy subjects during running (13)(14)(15), walking (16), and bicycle exercise (17,18). These studies showed that PET can be useful as an alternative technique for evaluating muscle activity on the basis of muscle glucose uptake.…”

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“…While some studies have used PET-FDG for assessing muscular dystrophyrelated cardiomyopathy in patients 21 , it has yet to be assessed in significant studies of skeletal muscle metabolism in DMD patients. There is strong evidence, however, that PET-FDG will be a useful tool for monitoring degeneration in DMD patients since it is a direct indicator of skeletal muscle glucose metabolism [22][23][24][25][26][27] . Areas of myofibre necrosis and subsequent fibrosis can be detected since fibrotic tissue is not metabolically active and thus should not accumulate 18 F-FDG 21 .…”

Functional Imaging of Human Skeletal Muscle During Movement: Implications for Recruitment, Metabolism and Circulation

“…Previous studies of glucose metabolic imaging of skeletal muscle by [ 18 F]FDG PET are categorized into three topics: 1) glucose metabolic imaging during exercise (Fujimoto, et al, 1996, Fujimoto, et al, 2000, Iemitsu, et al, 2000, Kemppainen, et al, 2002, Oi, et al, 2003, Shinozaki, et al, 2003, Tashiro, et al, 1999, 2) comparison between trained and untrained individuals , Takala, et al, 1999, and 3) intramuscular metabolic heterogeneity in exercising muscle (Pappas, et al, 2001 …”

“…To map glucose metabolism and muscle activity, walking (Oi, et al, 2003), running (Fujimoto, et al, 1996, Fujimoto, et al, 2000, Iemitsu, et al, 2000, Oi, et al, 2003, Tashiro, et al, 1999, cycling (Kemppainen, et al, 2002), and shoulder muscle exercise (Shinozaki, et al, 2003) was used in previous studies. Much interesting evidence was gained from these studies.…”