Subcutaneous abdominal adipose tissue lipolysis during exercise determined by arteriovenous measurements in older women.

Abstract

To characterize the lipolytic response in the subcutaneous abdominal adipose tissue in older women to endurance exercise. Cross-sectional exercise study. Exercise laboratory, Copenhagen, Denmark. Seven healthy, older women (mean age +/- standard error = 75 +/- 2 years); weight: 67.8 +/- 4.9 kg; body fat: 40 +/- 3; maximal oxygen uptake (VO2max): 1.43 +/- 0.07 L.min 1). Body composition (dual energy x-ray absorptiometry (DEXA)), maximal oxygen uptake (VO2max, maximal cycling test), lipolytic response to exercise (arterial and adipose tissue venous catheterization at rest and during 60 minutes of continuous cycling at a load corresponding to 60 of VO2max), adipose tissue blood flow (ATBF) (133Xenon (133Xe) washout), oxygen consumption and respiratory exchange ratio during exercise (indirect calorimetry), whole blood glycerol, plasma nonesterified fatty acids (NEFA), lactate, glucose, epinephrine, norepinephrine, insulin, serum growth hormone, and hematocrit. Glycerol and NEFA mobilization rates increased by 250 and 180, respectively, from rest to exercise. This was achieved primarily by an increase in veno-arterial differences, because ATBF did not increase significantly. NEFA:glycerol mobilization ratio was about two at rest and remained at that level during exercise, indicating significant local reesterification in both conditions. After an initial decrease, arterial plasma NEFA concentration increased significantly, by 26, indicating that NEFA delivery exceeded muscle uptake. Older women are capable of prompt and substantial increase in subcutaneous abdominal adipose tissue glycerol and NEFA mobilization rates in response to moderate acute endurance exercise. The lipolytic response matches skeletal muscle NEFA uptake, and decreased ability to mobilize fat during exercise is therefore not likely to cause increased fat mass with advancing age.