Effect of endurance training on plasma free fatty acid turnover and oxidation during exercise

Abstract

Plasma free fatty acid (FFA) levels tend to be lower and the plasma lipolytic hormone response to prolonged exercise of the same intensity is blunted after endurance exercise training. To determine whether training elicits a corresponding decrease in plasma FFA turnover and metabolism during prolonged exercise, we measured plasma [1-13C]palmitate kinetics and oxidation and respiratory gas exchange in 13 subjects during the latter portion of a 90- to 120-min bout of cycle ergometer work performed before and after 12 wk of alternate-day cycling and running. Training increased total fat oxidation during prolonged exercise by 41% (P < 0.005). However, for the final 30-60 min of the cycle ergometer protocol, the rate of 13CO2 production from [1-13C]palmitate oxidation was 27% lower (P < 0.05), the rate of palmitate turnover was 33% less (P < 0.05), and plasma FFA and glycerol concentrations were 32 and 20% lower (P < 0.05), respectively, than in the untrained state. Thus endurance exercise training results in decreased plasma FFA turnover and oxidation during a 90- to 120-min bout of submaximal exercise because of a slower rate of FFA release from adipose tissue.

Acylation-stimulating protein: effect of acute exercise and endurance training

“…Thus, trained subjects have a higher fat oxidative capacity, lower RQ during submaximal exercise and improved fatty acid handling. [15][16][17][18] In a recent study, we showed that a 3-month low-intensity endurance training program in previously untrained, sedentary males improved fat oxidative capacity and lowered plasma triglyceride levels. 18 In the present study, we could not detect any changes in fat oxidative capacity at the whole body level, probably due to the shortterm nature of the present training program.…”

“…Resting days were incorporated on days 4 and 10. After the training session, subjects again followed a standardization period for 3 days (days [15][16][17], with the same standardization diet as on days 1-3 and during which subjects refrained from exercise. In the afternoon of day 17, the subjects again performed a submaximal exercise test at 40% W max , with substrate oxidation being measured and blood being sampled.…”

“…However, regular exercise training improves many aspects of fatty acid metabolism. [15][16][17][18] For example, the increase in plasma FFA levels during acute exercise of a similar intensity is lower in trained subjects, probably due to a blunted sympatho-adrenic-induced lipolysis [19][20][21][22] and an improved fatty acid re-esterification, 23,16 both indicating an improved fatty acid handling. It could therefore be hypothesized that endurance training might lead to a reduction in basal ASP levels, indicating improved ASP sensitivity.…”

An Evaluation of Exercise and Training on Muscle Lipid Metabolism

“…exertion; free fatty acid; glucose; lactate; crossover concept; substrate shuttling EFFECTS OF EXERCISE intensity and training state on muscle lipid metabolism in humans are unclear, as the relatively few studies have utilized different experimental approaches. Some investigations have employed isotopic tracers and indirect calorimetry (25,29,33), whereas others have utilized arteriovenous (a-v) balance methods (17,22,35) and muscle biopsies (18,22 …”

“…isotopic tracers and indirect calorimetry (25,29,33), whereas others have utilized arteriovenous (a-v) balance methods (17,22,35) and muscle biopsies (18,22). In addition, longitudinal and cross-sectional designs have been employed that have tested trained and untrained subjects at either the same absolute or relative exercise intensity, but rarely both.…”