Impact of pre- and post-meal exercise on 24-H glucose profiles in young adults who are overweight and obese.

Objective: This study investigated the long-term effects of pre-meal exercise (PRE) versus post-meal exercise (POST) on glucose homeostasis in young adults who are overweight and obese using continuous glucose monitoring (CGM). Methods: In this randomized controlled trial, 34 adults (18-35 years) completed a 10-week intervention. The PRE group performed ≥30 min of moderate-intensity aerobic exercise (65 % HRmax) within 60 min before meals, whereas the POST group exercised within 0-90 min after meals, five times weekly. Participants completed two supervised sessions and three self-directed sessions weekly, monitored via heart rate belts. Habitual diets were maintained throughout the study, and physical activity was monitored using ActiGraph 3X accelerometers. Primary outcomes were 24-h CGM metrics; secondary outcomes included physical activity and metabolic indicators. Two-way ANOVA were used. Results: There is no group × time interactions reached significance for any glucose variability metric, blood biomarker, or cardiovascular parameter (all p > 0.05), confirming comparable efficacy between regimens. Significant time-effect improvements emerged in continuous glucose monitoring metrics (time in range: F = 4.85, p = 0.035) and cardiometabolic parameters (fasting glucose: F = 4.74, p = 0.038; insulin: F = 5.22, p = 0.030; triglyceride: F = 7.41, p = 0.011, systolic blood pressure: F = 4.45, p = 0.043; diastolic blood pressure: F = 15.04, p = 0.001) following the 10-week intervention. There is lower hypoglycemic exposure in the pre-meal group than the post-meal group (time below range, group effect: F = 4.54, p = 0.041), with triglycerides decreasing exclusively in pre-meal group (Δ = -.22 ± .37 mmol/L, p = 0.005). Post-meal exercise showed marginal insulin reduction (Δ = -1.92 μU/mL, p = 0.069). Conclusions: The 10-week exercise intervention significantly improved continuous glucose monitoring metrics (notably increased time in range) and cardiometabolic parameters (fasting glucose, insulin, blood pressure, triglycerides) without significant group × time interactions. The pre-meal group maintained consistently lower hypoglycemic exposure than the post-meal group. Triglyceride reduction occurred exclusively with pre-meal exercise, while insulin showed a marginal decrease only with post-meal exercise. These findings demonstrate comparable overall efficacy between timing protocols despite selective benefits for specific parameters.