Continuous vs. interval sports

The best way to describe the different effects is to use two examples.

Continuous endurance exercise

Continuous sports are sports that require relatively constant performance over a longer period of time. This applies to all endurance sports, as well as some other sports. We take cycling as an example here. Cyclists sometimes spend more than seven hours a day in the saddle and have to be able to perform at a certain level for the entire duration.

If you are healthy, this is not a problem. His body registers a drop in blood sugar and reacts by releasing less insulin. As a result, his blood sugar remains relatively constant. When you ride harder, more carbohydrates are used to meet the increased energy needs. These, in turn, can only be channeled into the muscle cells (where they are needed) with the help of insulin. A certain amount of insulin is therefore always required for the energy metabolism to take place.

If the cyclist does not eat anything for a long time or does not consume carbohydrates in liquid form (eg energy gels), even the healthy person runs the risk of going hungry. The body no longer has any carbohydrates to cover the necessary energy. He now falls back on the fat reserves and sometimes even on the protein stores in the body until enough carbohydrates are available again or until something nutritious is eaten.

The problem with diabetics is that their insulin is either already in their body or they have too little insulin in their body. It is regulated externally via a pen, pump, etc. If a diabetic does endurance sports, the need for insulin decreases, just like in healthy people. The insulin pump offers the great advantage that a healthy metabolism can be imitated. In other words, insulin delivery is reduced before exercise, as well as during exercise and after exercise as required. Especially with the new "closed-loop systems" there is a comparable blood sugar profile when comparing a healthy person and a diabetic. When blood sugar falls, the pump delivers little to no insulin; when blood sugar rises, the pump increases insulin delivery. Thus, the blood sugar can be controlled very well. Sounds relatively easy at first, but despite good technology there are still a few pitfalls, which will be discussed below.

Load with varying intensity

First of all: Interval loads are more demanding for a healthy as well as for a diabetic body than even loads. This is why it is often difficult for diabetics to regulate their blood sugar correctly during interval loads.

Ice hockey is used here as an example. A hockey player goes onto the ice, does 2-3 sprints, maybe a check and then leaves the ice again. He is now on a break and will come back 4-5 minutes later for the next brief assignment. So his body always has to go from "0" to 100 and back.

This interval load leads to an increased release of hormones. In particular, the antagonists of insulin, adrenaline and noradrenaline, are released, causing blood sugar to rise. These two hormones inhibit, i.e. weaken, the effect of the existing insulin. In particular, diabetics with a pump system have a lot of trouble with ice hockey. Therefore, it must be ensured that the game starts with the lowest possible sugar value. It is especially helpful if the sugar is falling and not already rising before the game. There are various methods of forcing the sugar to sink beforehand.

Pump wearers can increase their temp basal rate (about 1 hour before the game)
Cover the last meal generously with the pen
In general: eat your last meal no later than 2, better 3 hours before the game

After the game, it is all the more important to be careful if a value that is too high has to be corrected. As a rule of thumb, I always wait 30 minutes after the game before making any corrections at all. Then I correct the current value with half of the actual dose. A glass of milk is recommended before going to bed, as this is broken down very slowly and evenly. In this way, hypoglycemia after ice hockey can be avoided or at least mitigated.

By the way: Blood sugar can also rise during continuous exercise. For example, when someone is very nervous during a race (marathon or bike race) or there is a mass fall, the body also releases masses of adrenaline and norepinephrine. As with the intervals, this leads to an increase in blood sugar.

However, interval training in endurance sports differs from ice hockey. The endurance athlete does not sit on the bench during the breaks, but actively recovers. This somewhat bypasses the Interval effect on blood sugar. Therefore, blood sugar does not rise during interval training.