The optimal timing between meal ingestion and simple physical activity for improving blood glucose control is unknown. This study compared the effects of physical activity on postprandial interstitial glucose responses when the activity was conducted either immediately before, immediately after, or 30 min after breakfast. Forty-eight adults were randomized to three separate physical activity interventions: standing still (for 30 min), walking (for 30 min), and bodyweight exercises (3 sets of 10 squats, 10 push-ups, 10 lunges, 10 sit-ups). In each intervention, 16 participants completed four trials (A to D) during which a 500 kcal mixed nutrient liquid breakfast meal was consumed. Interstitial glucose responses were recorded using continuous glucose monitoring for 2 h after the meal. The activity was completed either after the glucose monitoring period (trial A; control) or immediately before (trial B), immediately after (trial C), or 30 min after (trial D) the breakfast. Mean, coefficient of variance (CV), and area under the curve (AUC) for glucose were calculated and compared between the four trials. Walking and bodyweight exercises immediately after the meal improved mean, CV, and AUC glucose (P ≤ 0.05 vs. control), while standing immediately after the meal only improved AUC glucose (P ≤ 0.05 vs. control) and nearly improved mean glucose (P = 0.06). Mean, CV, and AUC glucose were not affected by standing, walking, or bodyweight exercise conducted immediately before, or 30 min after the meal (all P > 0.05 vs. control). Energy intake (diet records) and energy expenditure (Actigraph) were consistent throughout the studies and did not influence the findings. Low-to moderate-intensity activity should be implemented soon after eating to improve glucose control following breakfast. The type of activity appears less important than the timing. These findings will help optimize exercise-meal timing in general health guidelines. ClinicalTrials.gov Identifier: NCT03730727Open Access This article is distributed under the terms of the Creative Comm ons Attribution 4.0 International License (http:// creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Purposeful and deliberate exercise improves postprandial glucose control. However, there is less information concerning the effects of simple physical activities (standing, walking, circuit exercise) that can easily be integrated into a person’s day. Furthermore, the optimal timing between such an activity and a meal that elicits the most optimal glucose control is completely unknown. Three groups of 16 healthy adults volunteered to participate in three separate interventions: Stand (30-minutes standing still; RPE = 6±1), Walk (30-min treadmill walk at a self-selected brisk pace; RPE = 11±2, 5.6±0.8 kph), and Circuit (three sets of 10 squats, 10 push-ups, 10 lunges, 10 sit-ups; RPE = 11±2, 7.1±1.8 minutes to complete). In each intervention, participants completed four trials during which they drank a mixed-nutrient breakfast shake containing 500 kcals. Interstitial glucose responses were measured by continuous glucose monitoring (Dexcom G5). Postprandial glucose tolerance was quantified during the 2-hours period after meal ingestion. In each trial, the physical activity was completed either 2-hours after (trial A; control), immediately before (trial B), immediate after (trial C), or 30-minutes after (trial D) the meal. While trials B and D showed some improvement in postprandial glucose control compared to trial A, this was not statistically significant. Trial C, however, showed a significant improvement in mean glucose, standard deviation for glucose, and the area under the glucose curve in all three interventions (P<0.05), when compared to trial A. Energy intake (diet records) and energy expenditure (Actigraph) were consistent throughout the studies and did not influence the findings. In conclusion, low to moderate-intensity physical activity (either standing, walking, or body-weight circuit exercise) is best implemented soon after a meal to induce the greatest improvement in blood glucose control, in young healthy adults. Disclosure T.P. Solomon: None. E. Tarry: None. C.O. Hudson: None. A.I. Fitt: None. M. Laye: None. Funding Physiological Society