Altering Physical Activity Influences Insulin Responses to Glucose Ingestion in Healthy Adults

Abstract

This study determined if varying physical activity (PA) the day prior to an oral glucose tolerance test (OGTT) differentially influenced postprandial glucose and insulin kinetics. Fifteen healthy, young adults participated in three OGTT trials the morning after performing 50% (LOW), 100% (HABITUAL), or 150% (HIGH) of their habitual PA (determined by 7-day pedometry). Trials were randomized and separated by at least 1-wk. For each OGTT trial, blood glucose and insulin were measured after an overnight fast and at 30-min intervals for 2 h following ingestion of the glucose beverage. Between-trial differences were analyzed using a general linear model with repeated measures. Subjects successfully achieved the desired percentage of habitual steps prior to each trial: LOW: 51±5%, HABITUAL: 99±6%, and HIGH: 149±9%. Fasting blood glucose and glucose total area under the curve (AUC) did not differ between trials. Serum insulin AUC was lower (p<0.05) following the HIGH (34,158±8,786 pmol·min·L−1) compared to the LOW (40,738±9,276 pmol·min·L−1) trial. No differences were observed when the LOW and HIGH trials were compared to HABITUAL. These data suggest that varying the PA level (from 50 to 150% of habitual PA) the day prior to an OGTT influences the insulin (but not blood glucose) response to an OGTT.

Pathophysiology of Physical Inactivity-Dependent Insulin Resistance: A Theoretical Mechanistic Review Emphasizing Clinical Evidence

“…These lipid molecules are mainly composed of sphingosine and are a significant component of the cellular lipid bilayer membrane by an essential role in maintaining its integrity [ 117 ]. Ceramide synthesis occurs in at least three distinct ways as the de novo pathway, the sphingomyelin hydrolysis (degradation), and the salvage (recycling) pathway [ 8 ]. In addition to structural roles, more recent studies have suggested a causal relationship between ceramide and metabolic complications as well as insulin resistance [ 118 ].…”

“…But substantial changes in modern lifestyle towards lower physical activity have also increased the prevalence of DM in young adults [ 6 , 7 ]. Furthermore, there is a positive relationship between long-term physical inactivity and insulin resistance [ 4 , 8 ]. But the exact linking pathophysiologic pathways are not well understood.…”

Insulin and aging – a disappointing relationship

“…Vegetarian diets are also associated with lower insulin resistance and lower fasting insulin levels, even in comparison with matched lean controls, and appear to improve healthspan and possibly also lifespan ( 74 , 75 ). Another lifestyle parameter associated with better healthspan is physical exercise, which causes lower fasting and post-challenge insulin levels as well as improved insulin sensitivity ( 76 – 78 ).…”