If you’re tracking your glucose using CGM, you might be worried by an apparent glucose rise during high-intensity exercise. You shouldn’t be. Despite the acute rise in glucose, high-intensity training actually improves both fasting glucose and insulin sensitivity in as little as two weeks. Both of these adaptations lead to better metabolic flexibility and glucose control.
If you've linked your Apple Health or Google Fit accounts, we'll automatically import and mark any workouts as strenuous if your heart rate exceeded 150 BPM for over 5 minutes, and you experienced a rise in glucose of more than 20 mg/dl.
If you manually log your workouts, be sure to edit the workout and switch Strenuous to On.
Remember, spikes caused by a strenuous activity don't count against zone scores or metabolic scores for the activity or day.
Example of high-intensity exercise (vs regular exercise) causing a rise in glucose:
Interestingly, circulating glucose tends to rise during brief bouts of intense exercise (>80% VO2max), and even more so for the hour after exercise ends. This is thought to be because high-intensity exercise stimulates the secretion of specific hormones (catecholamines, including “the stress hormone” epinephrine), which stimulate glucose production in the liver to increase up to 8-fold. The muscles, however, only increase their use of glucose by about 3-4 fold, and the result is a supply/demand mismatch where there is excess glucose in the blood. This elevated glucose signals a rise in insulin, at which point muscles take up the excess glucose to replenish stored glucose (glycogen), and we see a concurrent fall in glucose back to baseline values.
Read more in our blog post on exercise https://www.levelshealth.com/blog/glucose-and-exercise