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

People with obesity have high circulating bile acids (BA). Although aerobic fitness favors low circulating BAs, the effect of training intensity prior to clinically meaningful weight loss on BA is unclear. Test the hypothesis that 2-wks of interval (INT) versus continuous (CONT) exercise would lower plasma BAs in relation to insulin sensitivity. Twenty-three older adults with prediabetes (ADA criteria) were randomized to 12 work-matched bouts of INT (n = 11; 60.3 ± 2.4y; 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 ± 2.4y; 34.0 ± 1.7 kg/m 2 ) at 70% HRpeak cycling training for 60 min/d over 2 wks. A 180 min 75-g OGTT was performed to assess glucose tolerance (tAUC), insulin sensitivity (Siis) and metabolic flexibility (RER post-prandial - RER fast ; indirect calorimetry). BA (n = 8 conjugated and 7 unconjugated) were analyzed at 0, 30, and 60 min of the OGTT. Anthropometrics and fitness (VO 2 peak) were also assessed. INT and CONT comparably reduced BMI ( P < 0.001) and fasting RER ( P < 0.001), but raised insulin sensitivity ( P = 0.03). INT increased VO 2 peak as compared to CONT ( P = 0.01). Exercise decreased the unconjugated BAs CDCA iAUC 60min ( P < 0.001), DCA iAUC 60min ( P < 0.001), LCA iAUC 60min ( P < 0.001), and GCDCA iAUC 60min ( P < 0.001). Comparable reductions were also seen in the conjugated BAs HDCA iAUC 60min ( P = 0.01) and TLCA iAUC 60min ( P = 0.007). Increased VO 2 peak associated with lowered UDCA 0min (r = -0.56, P = 0.02) and CA iAUC 60min (r = -0.60, P = 0.005), while reduced BMI related to higher GDCA 0min (r = 0.60, P = 0.005) and GCDCA 0min (r = 0.53, P = 0.01). Improved insulin sensitivity correlated with lower GCDCA iAUC 60min (r = -0.45, P = 0.03) and GDCA iAUC 60min (r = -0.48, P = 0.02), while increased metabolic flexibility related to DCA iAUC 60min (r = 0.64, P = 0.004) and GCDCA iAUC 60min (r = 0.43, P = 0.05). Short-term training lowers some BA in relation to insulin sensitivity independent of intensity.

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Conflict of Interest and Funding Source: Funding for this project was supported by UVA Launchpad Award (SKM), Diabetes Action Research and Education Award (SKM) and National Institutes of Health RO1-HL130296 (SKM). The authors have no conflicts of interest to disclose.