Exercises that focus on building muscle and burning glycogen cause predictable increases in blood sugar both during and after exercise.
Contrary to popular belief, your intensive weightlifting workout probably isn’t invoking the same “flight or fight” response that might occur in a car accident, soccer match or Cross Fit competition. In fact, it’s unlikely that adrenaline is the cause of your blood sugar surge while lifting weights.
Even though you may have had a very challenging gym session, the reason why your blood sugar keeps rising both during and after is due to a different (but perfectly typical) physiological response to anaerobic exercise.
Why weightlifting causes a spike in blood sugar
Your body actually breaks down muscle, which includes the breakdown of glycogen, when you lift weights or perform other “anaerobic” or “strength-training” sorts of activities.
In your muscles, glycogen is essentially stored glucose. Particularly when you’re doing out or when you’re not eating, your muscles need that glycogen to fuel and sustain themselves.
Dr. Soumya, head consultant at DRC Clinics, adds that when this glycogen breaks down into lactate and pyruvate, it is cycled to produce ATP and energy for muscular action.
When you strength train, your body produces hormones like glucagon (and occasionally adrenaline), which instruct your liver to release its own glycogen stores for later conversion to glucose.
Dr Soumya continues, “It may also be affected by any continuing meal digestion and whatever degree of insulin resistance is active at that time of day.
This would be accompanied by more pancreatic insulin in a body without diabetes.
You have to manually administer the additional insulin to your body. Some people accomplish this by ingesting 1 unit before or during their workout. (I myself did that when I was powerlifting training.)
You are probably experiencing this standard physiological reaction to anaerobic exercise if you notice a steady rise in your blood sugar during your weightlifting workout, where you start out, for example, with a blood sugar of 100 mg/dL and are 220 mg/dL by the end of it, and you cannot attribute that spike to food.
The same effect may occur with anaerobic exercise such as sprinting and spinning, which are both anaerobic (not aerobic) forms of exercise because they induce rapid increases in heart rate followed by rapid drops in heart rate. Repeat after me.
Why blood sugar levels increase after weight training
Okay, your workout is complete. Because your body transformed that glycogen into glucose for your muscles to use as fuel throughout your workout, your glycogen stores have been depleted.
What’s this? Your body needs to instantly refill those glycogen reserves! Your muscles will start to “eat” themselves without glycogen, or go into “catabolic” mode, meaning that there won’t be enough energy to keep them alive.
You’ve probably heard that while you’re resting, muscle burns more calories to maintain itself than fat does. But if you aren’t ingesting enough calories and giving your muscles the fuel they need to rebuild and sustain themselves, your body will opt to burn muscle first.
Post-workout liver emptying
After a strenuous workout, if you don’t eat a high-quality supply of carbohydrates and protein, your liver will release its own glycogen reserves, break them down into glucose, and then cycle it to your muscles to refill those depleted glycogen stores.
This would be accompanied by more pancreatic insulin in a body without diabetes.
You have to manually provide that insulin to your body.
Consider your alternatives.
What happens if you decide not to consume any carbohydrates after working out? Okay, that’s fine, but after a rigorous weightlifting workout, your body still needs sustenance.
- A substantial amount of the protein in a meal that is heavy in protein and/or fat will likely be turned into glucose, assisting in the replenishment of your glycogen stores.
- You may need to take a tiny bolus of insulin to make up for the glucose your liver produces if you don’t want to eat anything in the few hours following your workout.
- You must assist those muscles in obtaining the fuel they require to survive if you want them to recharge their energy supply and get stronger.
Although it seems complicated, it’s really just fundamental human physiology. The more you can explore and use this knowledge to your workouts as a diabetic, the better your chances are of controlling your blood sugar while working out.
