Exercise Training Independent of Intensity Lowers Plasma Bile Acids in Prediabetes.

Introduction: People with obesity have high circulating bile acids (BA). Although aerobic fitness favors low circulating BA, the effect of training intensity before clinically meaningful weight loss on BA is unclear. This study aimed to test the hypothesis that 2 wk of interval (INT) versus continuous (CONT) exercise would lower plasma BA in relation to insulin sensitivity. Methods: Twenty-three older adults with prediabetes (ADA criteria) were randomized to 12 work-matched bouts of INT (n = 11, 60.3 ± 2.4 yr, 32.1 ± 1.2 kg⋅m-2) at 3 min at 50% HRpeak and 3 min at 90% HRpeak or CONT (n = 12, 60.8 ± 2.4 yr, 34.0 ± 1.7 kg⋅m-2) at 70% HRpeak cycling training for 60 min⋅d-1 over 2 wk. A 180-min 75-g oral glucose tolerance test (OGTT) was performed to assess glucose tolerance (tAUC), insulin sensitivity (Siis), and metabolic flexibility (RERpostprandial-RERfast; indirect calorimetry). BA (n = 8 conjugated and 7 unconjugated) were analyzed at 0, 30, and 60 min of the OGTT. Anthropometrics and fitness (...O2peak) were also assessed. Results: INT and CONT comparably reduced body mass index (BMI; P < 0.001) and fasting RER (P < 0.001) but raised insulin sensitivity (P = 0.03). INT increased ...O2peak as compared with CONT (P = 0.01). Exercise decreased the unconjugated BA chenodeoxycholic acid iAUC60min (P < 0.001), deoxycholic acid iAUC60min (P < 0.001), lithocholic acid iAUC60min (P < 0.001), and glycodeoxycholic acid (GCDCA) iAUC60min (P < 0.001). Comparable reductions were also seen in the conjugated BA hyodeoxycholic acid iAUC60min (P = 0.01) and taurolithocholic acid iAUC60min (P = 0.007). Increased ...O2peak was associated with lowered UDCA0min (r = -0.56, P = 0.02) and cholic acid iAUC60min (r = -0.60, P = 0.005), whereas reduced BMI was related to higher GDCA0min (r = 0.60, P = 0.005) and GCDCA0min (r = 0.53, P = 0.01). Improved insulin sensitivity correlated with lower GCDCA iAUC60min (r = -0.45, P = 0.03) and GDCA iAUC60min (r = -0.48, P = 0.02), whereas increased metabolic flexibility was related to deoxycholic acid iAUC60min (r = 0.64, P = 0.004) and GCDCA iAUC60min (r = 0.43, P = 0.05). Conclusions: Short-term training lowers some BA in relation to insulin sensitivity independent of intensity. [ABSTRACT FROM AUTHOR]