A single bout of prolonged aerobic exercise lowers plasma TAG (triacylglycerol) concentrations the next day by increasing the efficiency of VLDL (very-low-density lipoprotein)-TAG removal from the circulation. The effect of resistance exercise on VLDL-TAG metabolism is not known. Therefore we evaluated VLDL-TAG kinetics by using stable isotope-labelled tracers in eight healthy untrained men (age, 25.3 ± 0.8 years; body mass index, 24.5 ± 0.6 kg/m2) in the post-absorptive state in the morning on two separate occasions: once after performing a single 90-min bout of strenuous isokinetic resistance exercise (three sets × ten repetitions, 12 exercises at 80% of maximum peak torque production, with a 2-min rest interval between exercises) on the preceding afternoon and once after an equivalent period of rest. Fasting plasma VLDL-TAG concentrations in the morning after exercise were significantly lower than in the morning after rest (0.23 ± 0.04 compared with 0.33 ± 0.06 mmol/l respectively; P = 0.001). Hepatic VLDL-TAG secretion rate was not different (P = 0.31), but plasma clearance rate of VLDL-TAG was significantly higher (by 26 ± 8%) after exercise than rest (31 ± 3 compared with 25 ± 3 ml/min respectively; P = 0.004), and the mean residence time of VLDL-TAG in the circulation was significantly shorter (113 ± 10 compared with 144 ± 18 min respectively; P = 0.02). Fasting plasma NEFA (non-esterified fatty acid; 'free' fatty acid) and serum β-hydroxybutyrate concentrations were both significantly higher after exercise than rest (P < 0.05), whereas plasma glucose and serum insulin concentrations were not different (P > 0.30). We conclude that, in healthy untrained men, a single bout of whole-body resistance exercise lowers fasting plasma VLDL-TAG concentrations by augmenting VLDL-TAG removal from plasma. The effect appears to be qualitatively and quantitatively similar to that reported previously for aerobic exercise.
- Acute exercise
- Hepatic metabolism
- Lipid kinetics
- Very-low-density lipoprotein (VLDL)
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