Substrate Source Use in Older, Trained Males after Decades of Endurance Training

• DOI: 10.1249/mss.0b013e3181572ace
• Publication Date: 2009-03-05T02:46:01Z
• Authors: HANNEKE BOON; RICHARD A. M. JON...; RENE KOOPMAN; ELLEN E. BLAAK; WIM H. M. SARIS; ANTON J. M. WAGEN...; LUC J. C. VAN LOON
• Keywords: Endurance Training; Lipid Oxidation; Exercise physiology; Aerobic Exercise

The purpose of this study was to compare substrate source use in older, long-term exercising, endurance-trained males with sedentary controls.[U-C]palmitate and [6,6-H2]glucose tracers were applied assess plasma free fatty acid (FFA) glucose oxidation rates, estimate muscle- and/or lipoprotein-derived triacylglycerol (TG) muscle glycogen use. Subjects 10 controls (age 57 +/- 1 60 2 yr, respectively). Muscle biopsy samples collected before after exercise fiber type-specific intramyocellular lipid content.During exercise, palmitate Ra, Rd, Rox significantly greater the trained subjects compared (Ra: 0.36 0.02 0.25 0.02; Rd: 0.03 0.24 Rox: 0.31 0.20 mmol.min, respectively, P < 0.01). This resulted FFA total fat rates versus (P 0.001). Muscle- TG contributed 11 3% control groups, respectively (NS). No significant net changes content observed.Older, oxidize more during moderate-intensity than do controls. rate is attributed a higher release, uptake, rate. In contrast, does not seem represent major h older or men.