Increased VLDL-TAG Turnover during and after Acute Moderate-Intensity Exercise

Purpose and Methods: Breakdown rates of very low density lipoprotein triacylglycerols (VLDL-TAG) were quantified before (3 h), during (45 min), and after (3 h) moderate physical exercise at 40% V̇O_2max in young sedentary subjects (four male and four female, age 29.8 ± 1.6 yr, BMI 24.1 ± 0.9 kg·m^-2, V̇O_2max 37.0 ± 1.7 mL·kg^-1·min^-1), using boluses of ²H₅-glycerol (100 μmol·kg^-1) and ²H₂-palmite (6.6 μmol·kg^-1). The catabolic rates of VLDL-TAG were calculated from the decay in the isotopic enrichment using a single-pool model. The results were compared with those obtained during 6 h of rest in five of the same volunteers. Results: VLDL-TAG concentration remained constant throughout the study with exercise (P = NS). The fractional catabolic rate was nearly doubled from rest to exercise (P < 0.05 vs rest) and increased to an even greater extent during the early phase of recovery (P < 0.001 vs rest). During the late recovery phase, the value returned to the preexercise value (P = NS vs rest). The values for the absolute catabolic rate (k_abs) followed the same trend. Conclusion: VLDL-TAG turnover was increased during exercise and during the early phase of recovery.