Different Exercise, Different Energy System, Different Blood Sugars

Exercise is commonly broken up into two subcategories- aerobic and anaerobic exercise.  Technically, these terms refer to the presence (aerobic) or absence (anaerobic) of oxygen in cell metabolism, the process by which the cells of the body obtain energy.  

In aerobic work, the body uses oxygen to produce energy.  Often, this means that the heart and lungs are working harder than usual, in order to get enough oxygen into the muscles.  In aerobic activity, the muscles utilize oxygen to convert glucose (often from muscle glycogen stores) into adenosine triphosphate, or ATP, which is essentially a molecular unit of intracellular energy transfer.  If the glucose stores in the body become low, the body begins to use fat as fuel. 

Aerobic exercise is sustainable for longer periods of time; it is usually performed for twenty minutes or longer.  (Examples include running, cycling, cross-country skiing, or walking.)  Aerobic works strengthens the heart and lungs, and, because of the longer duration builds endurance.  It improves the circulation of blood and transportation of oxygen in the body, reduces blood pressure and burns fat.  

As opposed to the moderate intensity of aerobic exercise, anaerobic exercise is short and intense.  (It does not last longer than two minutes).  In anaerobic work, the energy needs are greater, so the body creates energy without oxygen, instead relying on its own chemical process.  Instead of carbohydrates and fat, the main energy source for lower intensity endurance work, adenosine tri phosphate (ATP) and creatine phosphate are the main sources of energy.  Examples or anaerobic exercise include sprinting and weight lifting.  Anaerobic exercise helps build strength and muscle mass, stronger bones and increases speed, power, muscle strength and the metabolic rate as well.  When you perform aerobic exercise, you will notice an increase in the heart beat rate and the rise in your level of respiration.

When moving, we are never totally aerobic or anaerobic.  However, our bodies lean towards one energy pathway; the proportion between these two metabolisms changes directly based on the intensity of the exercise.  It is especially important for diabetic athletes to be of which energy system an exercise is working, so he or she can adjust insulin levels properly.

My body responds relatively predictably to aerobic exercise.  When I go for a run, I can (usually) count on my blood sugar becoming lower.  This is because glucose is the primary fuel source, especially for the first thirty minutes of exercise.  To compensate, I decrease my insulin.  For especially long aerobic activity, such as two hour or longer runs or skis, I also consume a carbohydrate based sports drink, in order to make sure that my body has enough glucose to burn for energy.  Although my blood sugar seems to drop at different rates during different activities, the trend is generally universal.  At a moderate effort, my blood sugar generally falls during aerobic exercise.