Rudroff, Thorsten, authorKindred, John H., authorBenson, John-Michael, authorTracy, Brian L., authorKalliokoski, Kari K., authorFrontiers Media S. A., publisher2007-01-032007-01-032014-05Rudroff, Thorsten, John H. Kindred, John-Michael Benson, Brian L. Tracy, and Kari K. Kalliokoski, Greater Glucose Uptake Heterogeneity in Knee Muscles of Old Compared to Young Men During Isometric Contractions Detected by [18F]-FDG PET/CT. Frontiers in Physiology 5, article 198 (May 2014): 1-8. http://dx.doi.org/10.3389/fphys.2014.00198http://hdl.handle.net/10217/83371We used positron emission tomography/computed tomography (PET/CT) and [18F]-FDG to test the hypothesis that glucose uptake (GU) heterogeneity in skeletal muscles as a measure of heterogeneity in muscle activity is greater in old than young men when they perform isometric contractions. Six young (26 ± 6 years) and six old (77 ± 6 years) men performed two types of submaximal isometric contractions that required either force or position control. [18F]-FDG was injected during the task and PET/CT scans were performed immediately after the task. Within-muscle heterogeneity of knee muscles was determined by calculating the coefficient of variation (CV) of GU in PET image voxels within the muscles of interest. The average GU heterogeneity (mean ± SD) for knee extensors and flexors was greater for the old (35.3 ± 3.3%) than the young (28.6 ± 2.4%) (P = 0.006). Muscle volume of the knee extensors were greater for the young compared to the old men (1016 ± 163 vs. 598 ± 70 cm3, P = 0.004). In a multiple regression model, knee extensor muscle volume was a predictor (partial r = −0.87; P = 0.001) of GU heterogeneity for old men (R2 = 0.78; P < 0.001), and MVC force predicted GU heterogeneity for young men (partial r = −0.95, P < 0.001). The findings demonstrate that GU is more spatially variable for old than young men and especially so for old men who exhibit greater muscle atrophy.born digitalarticlesenghttps://creativecommons.org/licenses/by/4.0/glucoseagingpositron emission tomographymuscle volumecomputed tomographyTextThis article is open access and distributed under the terms and conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0).https://dx.doi.org/10.3389/fphys.2014.00198