Exercise and Later Lows

I’ve heard about this time and time again. You take up exercising or have a particularly busy and active day, and you fight off lows the rest of the night. How can you avoid this? Why does this happen? Why does it seem to happen at some times more aggressively than others?

I have to admit that I really haven’t had a whole heck of a lot of problems with later lows post-exercise. The only times I’ve really noticed that I’ll be dropping a few hours after a run is if I run six miles or farther. The farther I run, the more sensitive to insulin I will become approximately 4 to 6 hours post-run. My lack of experience with this could be attributed to the fact that I exercise daily, generally around the same time, so my later lows actually happen every day and my basals accommodate for them.

The first time I really noticed later lows was after a seven or eight mile afternoon run. I ran between 3:30pm to around 4:40 pm. I went home, corrected my usual correction for the ridiculous post-exercise spike, then sat down for dinner. I was bewildered when I got slammed with a low in the 30’s at around 9pm. I had some juice and had an additional snack which I bolussed for (don’t want to spike too high!) and then an hour later, I’m back in the 30’s with half of my insulin still on board. YIKES!

Throughout the weeks of my training, I only noticed these severe later lows on days that I ran farther than six miles, or in other terms, longer than one hour. What I usually would do in these instances is just eat more. If you are running 35-45 miles per week, eating more is just fine! I can imagine though, that if you are having later lows as you are introducing yourself back into an exercise regimen that you probably aren’t burning the amount of calories that would making snacking a little more a suitable option (unless you want to gain weight!)

My doctor advised me to not correct my post-exercise spike, to help prepare for the later lows. Since I never noticed the corresponding drop in sugars until at least four hours after exercise, that really didn’t seem like a suitable option. After my longer runs it was not uncommon to spike up into the 200’s, and I did NOT want to wait four hours to come back down to normal, assuming I had a later low in the first place. I believe that had I adjusted my basals down 25 – 30 % I probably could have avoided my most serious lows.

After my long runs on weekends, I would always set my daytime basals beginning 2 hours after my run at 70% of my basals for 8 hours and that seemed to help eliminate lows after runs where I was out for longer than two hours. I also noted I would have more serious lows more often after longer and more intense workouts. I had a basic schedule set up for evenings in which I ran greater than six miles where I would not bolus for my night time snack and not adjust my basals at all. I think whatever you do to help manage the later lows, whether you cut back basals, eat more food, or cut back boluses on meals that fall into the time period you are expecting a later low, should help. Just being aware as you are entering into an exercise regimen that you may have the later lows is a great first step.
One curious thing I did note as I became more thoroughly entrenched in my running lifestyle and aggressive amounts of exercise, was that over the past year or so, my basals have universally gone down. A year and 3 months after I began running I have shaved approximately 10 units of insulin per DAY off of my TDD WITHOUT cutting calories. Be aware that sometimes your later lows could actually be decreased basal needs.

Another curious thing I’ve noted through my running journey surrounds insulin needs at the specific time of day that I routinely exercise. For the first year of running, I routinely ran between 3:30pm – 6pm on weekdays (3-4 times weekly) and then ran in the mornings on weekends between 7am and 10am. For the time period between 3:30pm-6:30pm, my basal needs on days that I didn’t run very quickly decreased. It was almost as though my body has a memory of when I work out most often and the metabolism revs up at that time of day whether I work out or not. I’ve recently switched my main workout time from the afternoon to 5:30am – 6:30am and after around two months of this, I have begun to notice AGAIN a decreased basal insulin need during this time even when I don’t work out. Strange how our bodies work!