My name is Lisa Lenertz and I am both a scientist and exercise enthusiast. Kevin and I share the same desire to expose others to the value of exercise and good nutrition in hopes that people will lead longer, healthier and more fulfilling lives. Kevin achieves this through personal training and I am a biology professor who wants students who take a biology class from me to learn something about their own health and ways to achieve a lifetime of good health. In my spare time I travel, run, bike, strength train and eat healthy delicious meals prepared by my husband, a fantastic and imaginative cook.
I will be writing articles for Monroe Real Training that provide clients and other fitness enthusiasts with scientific explanations for how good lifestyle choices prevent disease and facilitate healthy living. I was trained as a cell and molecular biologist and thus have a passion for understanding what happens within individual cells and specifically what happens to individual molecules within cells. I will be discussing diverse topics that include but are certainly not limited to nutrition, diabetes, osteoporosis, drug and alcohol use, depression and inflammation. We hope you will find this information useful and that you will become more energized about maintaining a healthy lifestyle, because you will have a better understanding of how finishing a dreaded run or forcing yourself to exercise leads to positive body changes.
The topic of the first article is type 2 diabetes, a topic that I chose completely at random. Type 2 diabetes is a major public health problem that is largely attributed to environmental factors. This disease develops when the body is unable to respond to the hormone insulin, which is produced by a special cell in the pancreas known as the beta cell. Insulin that is circulating in the blood binds to a specific protein located on the outside of certain cells including muscle and fat cells. This protein that the insulin hormone binds to was creatively named the insulin receptor. As a side note, only scientists who study fruit flies or a small worm called C. elegans are creative when naming things. The rest of us lack creativity. Once the insulin meets the insulin receptor, the cell undergoes many changes. A process known as signal transduction begins, which ultimately tells the cell to absorb more glucose, the molecule our bodies use to make energy. I think of signal transduction like a game of connect the dots. One molecule activates another, which activates another, which activates another, leading to diverse cellular changes depending upon what the original signal was and the state of the cell. There are many players involved in signal transduction, and the case of insulin and the insulin receptor is no exception. One key end result of insulin signaling is that a protein known as glucose transporter type 4 (GLUT4) makes its way to the outermost part of the cell, which is referred to as the plasma membrane or cell membrane. It is GLUT4 that allows glucose to be transported into the cell and either is stored or broken down through a fascinating and complex process to produce energy.
So, what does this have to do with exercise? Type 2 diabetes is reversible up to a point in its disease progression. If your doctor tells you that you are prediabetic, you can change that diagnosis and eliminate the diabetes. How is this possible? One of the many mechanisms by which this is achieved is by increasing the amount of GLUT4 your cells produce. If you have more GLUT4, your cells are able to take more glucose from the blood. To explain this, allow me to provide you with a brief lesson about genetics.
Every cell in your body, with the exception of your sperm or eggs, contains the same genetic material, or DNA. Although every cell has the same DNA, cells vary greatly in what parts of the DNA are being used at one time and to what extent. Genes are sections of DNA used to encode proteins. Basically, we have genes to make numerous and vastly diverse proteins. Simplistically, one gene equals one protein. Proteins are used for everything from maintaining cell structure, to helping cells divide, to helping make or destroy other proteins, to serving as neurological signals in the brain, and in this case, allowing glucose to be transported from the blood into the cell. Numerous scientists have demonstrated that the act of exercising increases the amount of GLUT4 produced in a cell. When a cell has more GLUT4, there is more GLUT4 to be located at the plasma membrane to transport glucose from the blood, across the membrane, and into the cell.
Exercise produces gene expression changes. Gene expression changes is a fancy term for saying different proteins will be made in different circumstances. Many volunteers, probably poor college students, have participated in exercise studies looking at gene expression changes in muscle. In these studies, individuals have a small sample of their muscle tissue taken before and after exercise, and a scientist examines the tissue for any changes in the amount of various proteins including GLUT4. I personally would never volunteer to have someone extract a piece of my muscle that I worked very hard to form, but the sacrifices of others have provided us with many useful results. Engaging in exercise changes how much GLUT4 protein is made from the GLUT4 gene. This is significant because diabetics produce less of this protein. There are many other cellular mechanisms by which exercise changes how cells behave to protect us from developing diabetes, but regulating GLUT4 is one of the key mechanisms.
So, what does this mean for our daily lives? Being physically active produces stimuli that cells use to make internal changes. It is possible to develop type 2 diabetes even if you are of normal weight. Exercising plays a key role in keeping us healthy and should not be excluded from people’s routines even once a desired weight is achieved. One of my friend’s father has developed type 2 diabetes even though he is of normal weight. He lives a sedentary lifestyle.
At one of the four marathons I have ran, I talked with a runner who started running after being diagnosed as prediabetic. We were participating in the Zoom! Yah! Yah! indoor marathon, a 150 lap adventure in January in Minnesota with some of the most hardcore runners that have ever existed. When I signed up for the marathon I had no idea that I would be the least experienced runner of the group of approximately 45 runners and that most runners were trying to run 50 marathons in 50 states, and several had run over 200 marathons. When running around the track 150 times, I tried to find someone who was as inexperienced as myself. The closest I came was the gentleman who told me his doctor told him a year ago that he was prediabetic and needed to change his lifestyle. He took his doctor’s advice and ran FIVE marathons in one year although he had never run one before! Zoom! Yah! Yah! was number six. The running took care of the problem and he now does not have to worry about being diabetic.
Although running one marathon approximately every two months is a worthy achievement worth serious bragging points, you do not need to run hundreds of miles a month to protect yourself from type 2 diabetes. Only a medical type doctor can provide you with specific guidelines, but I can tell you that every time you engage in exercise you are telling your cells to make internal changes that keep you healthy. If you know of a friend or family member who has been told he or she is prediabetic, please try to encourage that person to engage in some physical activity as it does amazing things for your body.
Richter E.A. & Hargreaves M. (2013) Exercise, GLUT4, and skeletal muscle glucose uptake. Physiol. Rev. 93:993-1017.