Lowering Physical Activity Impairs Glycemic Control in Healthy Volunteers

Abstract

Introduction Postprandial glucose (PPG) is an independent predictor of cardiovascular events and death, regardless of diabetes status. While changes in physical activity produce changes in insulin sensitivity, it is not clear whether changes in daily physical activity directly impact PPG in healthy, free-living persons. Methods We utilized continuous glucose monitors to measure PPG and PPG excursions (ΔPPG; post- minus pre-meal blood glucose) at 30-min increments after meals in healthy, habitually active volunteers (n=12, Age 29±1 y, BMI 23.6±0.9 kg•m-2, VO2max 53.6±3.0 mL•kg-1•min-1) during three days of habitual (≥10,000 steps•d-1) and reduced (<5,000 steps•d-1) physical activity. Diets were standardized across monitoring periods, and fasting-state oral glucose tolerance tests (OGTT) were performed on the fourth day of each monitoring period. Results During three days of reduced physical activity (12,956±769 to 4,319±256 steps•d-1), PPG increased at 30 and 60-min post-meal (6.31±0.19 to 6.68±0.23 mmol•L-1 and 5.75±0.16 to 6.26±0.28 mmol•L-1, P<0.05 relative to corresponding ACTIVE time point), and ΔPPG increased by 42%, 97%, and 33% at 30, 60, and 90-min post-meal, respectively (P<0.05). Insulin and C-peptide responses to the OGTT increased after three days of reduced activity (P<0.05), and the glucose response to the OGTT did not change significantly. Conclusions Thus, despite evidence of compensatory increases in plasma insulin during an OGTT, ΔPPG assessed by CGMS increased markedly during three days of reduced physical activity in otherwise healthy, free-living individuals. These data indicate that daily physical activity is an important mediator of glycemic control, even among healthy individuals, and reinforce the utility of physical activity in preventing pathologies associated with elevated PPG.

Blood Glucose Levels of Subelite Athletes During 6 Days of Free Living

“…Lowering physical activity is known to impact the glycemic control of healthy individuals and the increased insulin sensitivity witnessed due to training wanes with 5 days of detraining. 16,[40][41][42] The large amount of time spent out of band by Ath07 and Ath08 is likely to be attributed to these diet and lifestyle choices. This conclusion is supported by Ath07 and Ath08 showing the highest FPI levels and FIS and only achieving average or above average category VO2max levels based on gender and age.…”

Physically active vs. inactive lifestyle, muscle properties, and glucose homeostasis in middle-aged and older twins

“…Regular physical activity maintains glucose homeostasis (Henriksen 2002;Boule et al 2005;Petersen and Shulman 2006;Church et al 2010;Mikus et al 2012). Moderate-intensity exercise decreases the risk for type 2 diabetes mellitus (Henriksen 2002;Jeon et al 2007;PAGAC 2008), even at low levels of activity (<150 min/week) (Waller et al 2010).…”

From signal transduction to signal interpretation: An alternative model for the molecular function of insulin receptor substrates

“…Intervention to change the context should therefore be the most intuitive and straight forward approach to counteract insulin resistance. Indeed, often lifestyle change with concomitant improvement in blood parameters such as adipokines and lipid profile is most successful to improve metabolic control in individuals affected by the metabolic syndrome (Mikus et al, 2011;Roberts et al, 2006). The hypothetical model described in this review can only be correct based on two premises: Both, IRS molecules with context-dependent phosphorylation patterns and correlating protein complexes, must exist.…”