期刊
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM
卷 292, 期 1, 页码 E107-E116出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpendo.00148.2006
关键词
crossover concept; free fatty acids; substrate partitioning; exercise; regional metabolism
资金
- NIAMS NIH HHS [AR-042906] Funding Source: Medline
- NATIONAL INSTITUTE OF ARTHRITIS AND MUSCULOSKELETAL AND SKIN DISEASES [R01AR042906] Funding Source: NIH RePORTER
To evaluate the contribution of working muscle to whole body lipid oxidation, we examined the effects of exercise intensity and endurance training ( 9 wk, 5 days/wk, 1 h, 75% V-O2 peak) on whole body and leg free fatty acid ( FFA) kinetics in eight male subjects ( 26 +/- 1 yr, means +/- SE). Two pretraining trials [ 45 and 65% V-O2 (max) ( 45UT, 65UT)] and two posttraining trials [ 65% of pretraining V-O2 peak ( ABT), and 65% of posttraining V-O2 peak ( RLT)] were performed using [ 1-C-13] palmitate infusion and femoral arteriovenous sampling. Training increased V-O2 peak by 15% ( 45.2 +/- 1.2 to 52.0 +/- 1.8 ml . kg(-1) . min(-1), P < 0.05). Muscle FFA fractional extraction was lower during exercise ( EX) compared with rest regardless of workload or training status ( approximate to 20 vs. 48%, P < 0.05). Two-leg net FFA balance increased from net release at rest ( approximate to - 36 mu mol/min) to net uptake during EX for 45UT ( 179 +/- 75), ABT ( 236 +/- 63), and RLT ( 136 +/- 110) ( P < 0.05), but not 65UT ( 51 +/- 127). Leg FFA tracer measured uptake was higher during EX than rest for all trials and greater during posttraining in RLT ( 716 +/- 173 mu mol/min) compared with pretraining ( 45UT 450 +/- 80, 65UT 461 +/- 72, P < 0.05). Leg muscle lipid oxidation increased with training in ABT ( 730 +/- 163 mu mol/min) vs. 65UT ( 187 +/- 94, P < 0.05). Leg muscle lipid oxidation represented similar to 62 and 30% of whole body lipid oxidation at lower and higher relative intensities, respectively. In summary, training can increase working muscle tracer measured FFA uptake and lipid oxidation for a given power output, but both before and after training the association between whole body and leg lipid metabolism is reduced as exercise intensity increases.
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