Final calendar year, even though reporting this post on the rising pattern of stamina athletes applying constant glucose monitors (CGMs), I tried it myself for two months. The original short article centered on the science (sparse even though it is) behind promises that realizing what your blood sugar is carrying out at any provided instant can enable you gas much more effectively and perform better. But I figured it would be enjoyable to share some of my true CGM data—so what follows are 5 consultant samples that illustrate some of my activities.
To aid me interpret this facts, I known as Kevin Sprouse, a sports activities medicine physician in Knoxville who also serves as head of medication for the EF Instruction-Nippo pro cycling team. Sprouse works by using CGMs with his Tour de France cyclists (although not during competitors), as well as with recreational athletes in cycling and other athletics.
To start, I emailed him some workout data—which, it turns out, is absolutely the incorrect method. “It’s truly essential to search at the 24-hour interval all-around the work out,” he spelled out when we talked. “Looking at just the exercise is a miscalculation. It is myopic.” Reduced blood sugar in the course of a workout could be the consequence of a negative evening meal the evening before. Higher blood sugar may well merely suggest that you did not get ample slumber. Without the need of people contextual clues, the work out details by yourself won’t inform you much.
With that caveat, here’s some information, with glucose measurements on the left axis and managing pace (calculated with a Wahoo GPS check out) on the right axis:
March 28: Uncomplicated 7.5-Mile Operate
This was an uncomplicated operate with a pal at about 8:00/mile speed, and the details is really normal of what I noticed in the very first thirty day period or so of putting on a CGM. But there is a issue with the info. You can see the moment-by-minute updates when I’m taking in my pre-operate banana. But as soon as the run commences, I’m only getting readings each 15 minutes. That’s mainly because I remaining my telephone guiding, and the CGM alone only information readings each and every 15 minutes, which are then uploaded to your mobile phone subsequent time you hook up. So this pattern might be lacking some vital fluctuations through the run.
Supersapiens has given that introduced a devoted wrist reader for men and women like me who loathe operating with their telephones. But when I understood the difficulty, I borrowed a pink narwhal fanny pack from my daughter and started off getting my telephone together.
April 8: Interval Exercise
With my cellular phone in my pocket, I now see a good deal more motion in the details. This exercise routine consisted of a 15-moment heat-up 4 sets of (about) 1:00 hard, 1:00 straightforward, 3:00 challenging, 1:30 effortless 15-minute great-down. Through the tricky part of the exercise routine, you can see my glucose ranges climbing like a staircase.
This was interesting to me, for the reason that the simplistic way of considering about a CGM is that it is a gasoline gauge, telling you how much juice you’ve received remaining in the tank. That is evidently not the circumstance in this context: the more challenging I go, the better my glucose climbs, generating a wonderful staircase sample. As my muscle tissue begin burning by means of gasoline more quickly, excess electrical power from reserve tanks like the carbohydrate stored in my liver is currently being launched into the bloodstream to continue to keep me sprinting.
Then, when I finish my intervals and start off jogging little by little property, my blood sugar stays sky-substantial (anything above 140 is thought of unusually high) because I have ramped up my gas system but am no longer working as really hard.
These readings of 170 at the conclusion of my workout are undoubtedly significant, but likely practically nothing to be concerned about, Sprouse claims. 1 excellent indicator: as shortly as the exercise finishes, they fall really swiftly into a extra usual variety. That probably indicates that my body didn’t have to have to develop a spike of insulin to provide my blood sugar back again down. If I’d taken a gel or other gas in the course of that exercise session (which I didn’t), Sprouse would have counseled me not to bother, as my glucose amounts were currently substantial more than enough.
May possibly 18: Zoom Presentation
On this individual day, I gave an on-line presentation to a non-gain group. It was just 15 minutes extensive, for a tiny and pleasant audience. But hey, I still get nervous. It was interesting to see how life functions, and mental state more frequently, influenced my blood sugar amounts. In the context of physical exercise, assume about the difference involving an straightforward operate, a difficult exercise session, and an significant race. Your speed is unique, but so are your worry levels. In the interval exercise session higher than, how considerably of that staircase outcome was responses (my muscle mass require much more glucose) and how substantially was feedforward (my mind is on high alert, mobilizing bodily sources in anticipation of demands)?
It is also exciting to see the crash later on. I normally come to feel like a squeezed-out sponge soon after providing a talk here’s the physiological correlate. Concentrations under 70 are deemed unusually reduced. How did I react? In all probability by ingesting anything sweet, as a result the subsequent spike at close to 3 P.M. (For the very first month or so of wearing a CGM, I dutifully entered each food and snack into the Supersapiens application, but by this level the novelty had worn off and I was typically only recording pre-work out foods.)
May 20: 42-Mile Bike Trip
I’m not substantially of a cyclist, but one of the scenarios I desired to exam with the CGM was an extended exercise routine in which I may conceivably bonk. Would the emotion of hitting the wall basically correspond with an unusually minimal blood sugar reading? It doesn’t always, Sprouse informed me: “We’ve all thought we had been bonking and actually we just weren’t really match.”
I organized to go for a four-hour journey with a mate, primarily at a relaxed tempo. The exception was the first 20 minutes or so, when I rode tricky mainly because I was late for our conference, and the final half hour, when I rode tricky just for the heck of it. In this graph, the proper-hand axis is my coronary heart fee instead of pace.
The general image is around what you’d assume, Sprouse says. Glucose levels are relatively secure all through the primary component of the ride, but gradually start off to edge downwards immediately after about 1.5 to 2 hours. I deliberately didn’t gasoline at all during this part of the experience, to see how low I’d go. When we finally stopped for a shorter split right after around a few several hours of driving, my glucose stages dipped all the way down down below 70. Then I strike them with a gel and a Larabar, totaling 50 grams of carbs, and you can see my blood sugar quickly react with a big spike.
About 50 % an hour right after the fuel surge, I break up off from my mate and started out hammering home. A person unanswered concern is whether my blood sugar was heading to plunge subsequent the spike no make a difference what, or irrespective of whether the plunge was precipitated in part by the simple fact that my muscles all of a sudden begun burning gas far more promptly. My suspicion is that the primary lower is a response to the sugar-fueled spike—but then, with about 10 minutes remaining in the journey, I begun heading uphill for the final stretch. At that position, you can see my heart fee spike, and the blood sugar concentrations briefly increase all over again, just as they did throughout the most difficult elements of my interval exercise routine.
Sprouse’s get, phrased additional politely, was that I’d fueled like an idiot for this journey: nothing at all for three hours, and then mainlining a huge bolus of sugar. (He recognized, when I spelled out, that I was making an attempt to produce extreme values with the CGM.) If I essentially needed to improve functionality, he reported, the graph proposed that I would not have needed any gasoline for a trip like this long lasting up to most likely two hrs. For the extended journey, I would reward from smaller sized, far more regular doses of fuel—perhaps half a banana in this article, a number of sips of sporting activities drink there, and so on.
Might 23: 7-Mile Easy Operate
This was a further Sunday early morning effortless operate, really similar to the 1 from March 28 except that I brought my cell phone with me to get correct facts. But this time, my blood sugar amounts are swinging all over wildly. As with the bicycle experience, this was partly by style. Commonly I eat tiny or practically nothing before heading out for a early morning operate. This time, I had a peanut-butter-and-honey sandwich—because I realized it would mess with my blood sugar.
For as very long as I can don’t forget, I have knowledgeable one thing identified as rebound hypoglycemia. If I take in a little something, notably if it is carb-significant, 30 to 60 minutes just before a early morning operate, then 15 minutes into the run I’ll begin feeling mild-headed. It’ll previous five to 10 minutes, then disappear. What is taking place, I have gathered, is that my breakfast or snack triggers a delayed insulin response that kicks in approximately when I’m starting up my run. Equally insulin and physical exercise are then trying to reduce my blood sugar, and it overshoots prior to having well balanced out.
I required to see this in action, as a result the sandwich. You can see that my degrees are rising sharply ahead of I even begin functioning. Then soon after about 10 minutes of working, they begin dropping. On this distinct run, I didn’t get the entire light-weight-headedness, but did feel quite sluggish for a although. Then the ranges ultimately stabilize at a suitably elevated level for the rest of the operate.
Sprouse’s information for this circumstance caught me off-guard: he prompt throwing in a transient dash. Just as in the course of my interval workout (or even my on the net converse), ramping up the work and adrenaline will jolt your blood sugar upward. Curiously, he claimed that all through the Tour de France, he tells riders not to have a closing pre-race meal in the few of hrs right before phases that commence with an uphill, because they may want to be completely ready to go tricky proper from the gun. For initially flat stages, which normally start by noodling about gently, they can go forward with the further food two to a few hours before—but then continue to keep gels prepared in circumstance they require a raise early in the stage.
So what is the over-all takeaway from all this? To be straightforward, I didn’t get a prospect to place the machine by its good paces. This was mid-pandemic, when races had been canceled and my four- and six-year-olds were being the two finding out from dwelling. I had problems slipping absent to coach for extra than 50 % an hour at a time, and when I did I wasn’t placing the earth on hearth. You can see the blood sugar spikes from when I was waking up in the middle of the evening and worrying about the point out of the world.
Nevertheless, there are some glimmers of the CGM’s prospective: for dialing in the fueling on very long rides, for figuring out how to stay away from rebound hypoglycemia, and for looking at the way my entire body reacts to strain. That claimed, as Sprouse pointed out, you seriously will need to zoom out from particular person workout routines to see the 24-hour context, and the each day or weekly patterns. That’s a large amount of details to sift by, and Supersapiens’ big challenge (which they’ve been chipping away at considering the fact that my trial run ended in June) is to translate it into digestible and actionable advice—even for those of us who really don’t have a person like Sprouse on speed dial.
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The post 5 Insights from Training with a Ongoing Glucose Monitor appeared to start with on Outdoors Online.