Twelve weeks of endurance training increases FFA mobilization and reesterification in postmenopausal women

We examined the effects of exercise intensity and training on rates of lipolysis, plasma free fatty acid (FFA) appearance (Ra), disappearance (Rd), reesterification (Rs), and oxidation (RoxP) in postmenopausal (PM) women. Ten sedentary but healthy women (55 ± 0.6 yr) completed 12 wk of supervised endurance exercise training on a cycle ergometer [5 days/wk, 1 h/day, 65% peak oxygen consumption (V̇o2peak)]. Flux rates were determined by continuous infusion of [1-13C]palmitate and [1,1,2,3,3-2H5]glycerol during 90 min of rest and 60 min of cycle ergometer exercise during one pretraining exercise trial [65% V̇o2peak (PRE)] and two posttraining exercise trials [at power outputs that elicited 65% pretraining V̇o2peak (absolute training; ABT) and 65% posttraining V̇o2peak (relative training; RLT)]. Initial body weights (68.2 ± 4.5 kg) were maintained over the course of study. Training increased V̇o2peak by 16.3 ± 3.9% ( P < 0.05) (Zarins ZA, Wallis GA, Faghihnia N, Johnson ML, Fattor JA, Horning MA and Brooks GA. Metabolism 58: 9: 1338–1346, 2009). Glycerol Ra and Rd were elevated in the RLT trial ( P < 0.05), but not the ABT trial after training. Rates of plasma FFA Ra, Rd, and RoxP were elevated during the ABT compared with PRE trial ( P < 0.05). FFA Rs accounted for most (50–70%) of Rd during exercise; training reduced FFA Rs during ABT, but not RLT compared with PRE. We conclude that, despite the large age-related decrease in metabolic scope in PM women, endurance training increases the capacities for FFA mobilization and oxidation during exercises of a given power output. However, after menopause, total lipid oxidation capacity remains low, with reesterification accounting for most of FFA Rd.