There are two parallel agendas in a brand new paper from the science workforce at Supersapiens, the corporate selling steady glucose screens for endurance athletes. The apparent one is to unravel among the mysteries surrounding rebound hypoglycemia, a plunge in blood sugar that afflicts some individuals once they eat too near a exercise. The underlying one is to indicate that sticking CGMs, which had been initially developed as medical units for managing diabetes, on hundreds of completely wholesome athletes yields some helpful insights that we wouldn’t be capable of receive in any other case. Each targets are attention-grabbing—at the very least to me, provided that I’ve skilled occasional bouts of rebound hypoglycemia for so long as I can bear in mind.
The preliminary pitch from Supersapiens was {that a} CGM may operate as a “real-time gasoline gauge” to trace ranges of glucose (i.e. sugar) within the bloodstream. I dug into the small print of this declare on this 2021 article, however the important thing level is that glucose ranges are far more difficult than the fuel dial in your automotive. Train burns glucose, however triggers the liver to dump extra into circulation. Consuming carbs raises glucose ranges, however triggers insulin that strikes glucose again out of the bloodstream and into muscle and fats cells for storage. There are a complete bunch of alerts and countersignals trying to maintain roughly a teaspoon of glucose in circulation always.
Generally these alerts get crossed. Should you eat a bowl of oatmeal within the morning, your blood sugar will doubtless rise. In response, you’ll secrete insulin to get the degrees again to regular. However the insulin spike doesn’t take impact instantly; it received’t peak for 45 to 60 minutes. In the meantime, in the event you head out for a run, your muscle tissues will begin burning by way of glucose as a lot as 100 instances quicker than they do at relaxation. Should you time it badly, the insulin will kick in simply as your muscle tissues begin demanding extra glucose, and the 2 results collectively will trigger your ranges to overshoot and produce a blood-sugar low. That rebound hypoglycemia (or reactive hypoglycemia, because it’s additionally identified) could make you are feeling dizzy, light-headed, and weak.
The everyday recommendation for coping with rebound hypoglycemia is to keep away from consuming between about 30 and 90 minutes earlier than train, and significantly to keep away from high-carb and high-glycemic-index meals. Supersapiens makes the app used with Abbott’s Libre Sense Glucose Sport Biosensor, so it has entry to a giant database of anonymized information collected by its customers. This can be a fairly uncommon trove, as a result of scientists within the pre-CGM period didn’t spend lots of time measuring glucose ranges in individuals with out diabetes. After I spoke to a few of Supersapiens’ scientists again in 2021, they had been struggling to outline what kinds of glucose readings must be thought-about crimson flags, as a result of nobody was completely positive what was regular for endurance athletes. The brand new research, revealed in the European Journal of Sport Science by a workforce led by Andrea Zignoli of Supersapiens and the College of Trento in Italy, is principally a proof of precept exhibiting that this large database has some worthwhile classes to show us.
The research itself is pretty easy. They analyzed nearly 49,000 occasions from 6,700 customers through which somebody ate one thing after which exercised. The important thing variables had been how lengthy earlier than train they ate, and whether or not their glucose ranges dipped under 70 mg/dL through the first half-hour of train. That is an arbitrary threshold for rebound hypoglycemia, and in reality there doesn’t appear to be a constant threshold that produces unfavourable signs in numerous individuals. Scientists aren’t even positive whether or not it’s absolutely the degree of glucose that issues, or the speed at which it’s dropping, or another mixture. However 70 mg/dL is an affordable benchmark that signifies that your blood sugar ranges dropped considerably greater than you’d count on.
The primary query they thought-about is how prevalent rebound hypoglycemia is. This can be a tough one to quantify, as a result of nearly everybody will get low blood sugar throughout exercises sometimes (even when they don’t expertise signs), and nobody will get it each time they work out. Should you expertise it in additional than 20 % of your exercises, it’s in all probability honest to say that you simply’re inclined to it. About 15 % of the Supersapiens customers met this threshold.
As for meal timing, right here’s a graph that reveals what quantity of exercises produced a blood-sugar low (on the vertical axis), as a operate of time for the reason that final meal (on the horizontal axis):
There’s a fairly apparent bump there, peaking at about 50 minutes earlier than the exercise. That’s while you’re most probably to provide your self rebound hypoglycemia, and the chance is increased for all the interval between about 30 and 90 minutes prior.
So there it’s! Massive information from a complete bunch of CGM customers reveals us what we already form of knew. To be honest, they do some additional data-crunching. By their calculations, round 86 % of individuals aren’t inclined to rebound hypoglycemia in any respect. Eight % are inclined, however can reduce their threat by adjusting the timing of their pre-workout meal. And the final six % are inclined, however meal timing doesn’t appear to make a distinction for them. That’s a helpful, if miserable, new perception for individuals who occur to fall into the final group.
As for the larger image—the concept that we’ll be taught helpful issues by having endurance athletes put on CGMs—it’s removed from a slam dunk, however I feel it is a good begin. There’s a protracted, lengthy record of sports activities science devices that may plausibly declare that they may give us helpful data. However only a few of them comply with by way of with the arduous slogging required to validate these claims. Confirming that there’s a pre-workout meal-timing window for rebound hypoglycemia doesn’t actually transfer the needle, and to get deeper insights Supersapiens goes to should persuade a subset of its customers to maintain actually correct meal and exercise information. It received’t be simple, however I’m already curious to see what they’ll provide you with subsequent.
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