Exercise: The Missing Link to Insulin Resistance

     CDC:Lifestyle Change Program

By: Virginia Pearson

 “Exercise is a celebration of what our body can do. Not a punishment for what we eat”

Anonymous

Exercise is an important factor in metabolic health. During physical activity, our muscle cells can easily take in glucose in response to insulin from the food we eat (1), which helps maintain blood glucose at normal level. Choosing not to be active throughout the day triggers our muscles to become insulin resistant, which decreases the ability for our body to use the food we eat as fuel (2,1). Over time, insulin resistance slowly causes metabolic health complications to emerge. In order to prevent chronic diseases, such as obesity and type 2 diabetes, we should engage in daily healthy eating behaviors along with regular physical activity to support our overall health (3,4).  

Exercise

There are many different ways to be physically active: leisure activities like walking, cycling, sports, and other active forms of recreation, such as dance, yoga, tai chi. Physical activity can also be a form of transportation, such as walking and cycling, and can be done at work and at home. All forms of physical activity can provide health benefits if undertaken regularly and of sufficient duration and intensity (3). The beauty of it all is that we have a choice on how to implement movement throughout our day to suit our individual needs and abilities. 

Unfortunately, our society has replaced physical activity throughout the day with passive work-related and leisure activities (1,3).  As a result of physical inactivity, the nutrients we consume don’t get used and promote our cells to become insulin resistant, which is the underlying factor of metabolic dysfunction throughout our body (5,6). 

What are the recommendations for physical activity? 

The US Department of Health and Human Services, HHS, recommends adults to engage in 150 minutes (2 ½ hours) of planned physical activity and 2 days of muscle-strengthening activity per week (7). 

 HHS: Move Your Way (7) 

Not getting the recommended time for physical activity? 

You are not alone. 

Despite a self-reported increase in physical activity, in both urban and rural communities, an average of 86% of adults are still not getting enough physical activity throughout the week (8).  

       CDC:Trends (8)

Why is this a problem?  

Physical inactivity leads to insulin resistance, which has been associated as a common factor within chronic diseases, such as obesity, type 2 diabetes, and metabolic syndrome (2). 

Insulin is a hormone that is made by the pancreas to allow our cells to take in and use glucose for energy from the food we consume (5). In order to meet the energy demand during physical activity, our muscle cells consume 60-80% of glucose in response to insulin (1). On the contrary, during physical inactivity, our muscle cells do not want or need as much glucose. Over time, the excess glucose triggers the cells to become insulin resistant, preventing the cells from responding to insulin. 

Studies have suggested that insulin resistance may have developed as a protective mechanism for our body to cope with the presence of excess nutrients (1), but we don’t realize that until it is too late. 

What is the solution?

Exercise may be the missing link to decreasing and preventing insulin resistance. 

If we engage in daily physical activity, we will support our muscles to take in and use glucose properly. Adults that engage in physical activity show metabolic flexibility, which is influenced by insulin sensitivity (2). Their bodies are able to use different sources of energy based on their needs, while still allowing their muscles to preserve glucose reserves for later use (2). As a result, metabolic flexibility supports their metabolic health by effectively using and controlling glucose (2). 

Even without an increase of muscle mass or weight loss, engaging in physical activity has shown to increase muscle insulin sensitivity. This improves blood glucose levels (9,6) and could prevent the progression of metabolic dysfunction, indicating that we should focus on implementing movement throughout our day to focus on increasing insulin sensitivity for our metabolic health.

In adults with type 2 diabetes, an increase of physical activity of more than 150 minutes per week, has shown an improvement in blood glucose control, while an aerobic exercise routine for 3-months has shown improvements in pancreatic function (9), all which improve metabolic health. In addition, the combination of supervised aerobic and resistance training, as suggested by the HHS, has shown a prolonged improvement in long-term blood glucose control (10), which can decrease our risk of developing type 2 diabetes. 

What’s next? 

We can start supporting our metabolic health by simply moving more throughout the day and sitting less. Implementing physical activity throughout the day has shown to support our metabolic health by decreasing insulin resistance and allowing our body to effectively use and control glucose. The combination of healthy eating behaviors along with the recommended 150 minutes per week and 2 days of strength training is still the best method to maintain overall health. 

 “If we don’t make time for physical activity today, we will make time for illness in the future.”

Anonymous

References:

1.Rynders C.A., Blanc S., DeJong N., Bessesen D.H., Bergouignan A. Sedentary behaviour is key determinant of metabolic inflexibility. The Journal of Physiology. 2018;596.8;1319-1330.

2.Sparks L.M., Goodpaster B.H. Metabolic Flexibility in Health and Disease. Cell Metabolism. 2017;25;1027-1036.  

3.World Health Organization. Global Action Plan on Physical Activity 2018-2030: more active people for a healthier world. Geneva.2018;14. License: CC BY-NC-SA 3.0 IGO.

4.National Heart, Lung, and Blood Institute. Healthy Eating Plan. Retrieved 9/21/2020. https://www.nhlbi.nih.gov/health/educational/lose_wt/eat/index.htm.

5.Peterson M.C., Shulman G.I. Mechanisms of Insulin Action and Insulin Resistance. Physiological Reviews. American Physiological Society. 2018;98;2133-2223.

6. Meex R.C.R., Blaak E.E., Van Loon L.J.C. Lipotoxicity plays a key role in the development of both insulin resistance and muscle atrophy in patient with type 2 diabetes. Obesity Reviews. 2019;20;1205-1217.

7.US Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd Edition. Washington, DC: U.S. 2018;8,11.

8.Whitfield G.P. et al. Trends in Meeting Physical Activity Guidelines Among Urban and Rural Dwelling Adults-United States, 2008-2017. Morbidity and Mortality Weekly Report. Center for Disease Control and Prevention. 2019;weekly;vol.68;No.23;513-518.

9.Kumar A.S. et al. Exercise and insulin resistance in type 2 diabetes mellitus: A systematic review and meta-analysis. Annals of Physical and Rehabilitation Medicine. 2019;62;98-103.

10.Pan B. et al. Exercise training modalities in patients with type 2 diabetes mellitus: systematic review and network meta-analysis. International Journal of Behavior Nutrition and Physical Activity. 2018;15;72.

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