Cooling down after exercise.

If anyone is thinking about starting to exercise, but also wondering about raised blood glucose levels during exercise, I hope this will be of some use.

I’ll start by saying that this rise is a perfectly normal response to the stimulus of the extra activity.

This is because hard exercise will be seen by the body (to a lesser or greater degree) as a fight or flight trigger, with the associated stress hormones circulating. Amongst other things, these hormones trigger glucose release. The harder the exercise, the larger the response.

(If you are just starting to exercise, it doesn’t need to be a hard effort, nor particularly long either, but the points here are still valid).

As the working muscles are demanding fuel, this circulating glucose will be pulled out of the blood and combusted.

As you only want this response while you’re exercising (or being chased by a bear etc), you want to switch it off as soon as you can, so you can get into rest and digest mode and bring blood glucose levels back down again; a thorough cooldown will help out here.

At the end of your session, performing 5 minutes or so (or as much as you need) of very easy activity (slow walking, low rpm/low resistance/gear cycling etc), will bring your heart rate back down close to 100 bpm, which will signal that it’s time to relax and the glucose switch can be turned off.

Follow this with a few cycles of preferably seated or lying face up controlled breathing such as:

4-5 count inhale

4-5 count hold

4-5 count exhale

4-5 count pause

This will further drive your heart rate down and keep moving you into rest and digest.

Finally, if you’re able to find some floor space, go through some easy relaxed mobility movements to help reduce any tension in the working muscles, which again, signals that it’s time to chillax.

Some gentle 90/90 hip switches:


and some thoracic rotations:


for 30 seconds/10 movements each way or so each, not going to extreme ranges, but just so far that you feel better when you finish than when you started.

Spending 10 minutes or so at the end of a session to make sure that the session actually has ended, is time well spent.

To clarify, as stated in the original post, it was an attempt to address the concerns of having rising blood glucose levels during high intensity exercise.

In this context, the muscles are using large amounts of glucose, the fight or flight response kicks in (to cut a long story short), and the liver releases more glucose to deal with the need for the quicker energy supply that high power outputs and higher intensities demand.

So, onto the vexed question of cardio and lowered blood glucose.

Cardio has become a catch all term that most people associate with any form of rhythmic or cyclical endurance exercise. After all, gyms have resistance and cardio sections, and we all know the equipment that is in the cardio section: bikes, treadmills, cross trainers etc. Ergo, using a bike, treadmill or whatever must be cardio exercise.

However, genuine cardiovascular training, perhaps surprisingly, is exercise that creates adaptations in both the heart (cardio) and the blood vessels (vascular), namely an increase in the size of the left ventricle and an increase in capillary density around the muscle fibres (amongst other things).

This is achieved with exercise that is low in intensity, with lower heart rates and lower blood pressure. As energy requirements are more sedate than with higher intensities, it mainly uses fat as a fuel source (with some glucose too, as fat, glucose and creatine phosphate are always in use, it’s the proportion of each that changes as the intensity does).

Basically, the harder you work, the more glucose is used as energy.

What could cause a drop in glucose from “doing cardio” then?

Well, it could be due to exercising in a carb depleted state, if you haven’t got much in store, using what is there will cause that amount to lower further.

It is also likely that exercising in what is known as the grey zone is a factor. This is where exercise is too hard to focus on the aforementioned cardiovascular adaptations, but not hard enough to create the oxygen utilisation benefits that higher power outputs and higher intensities create.

The fuel used for 40 minutes of Zone 2 cycling, should be different to that of doing 6 x 30 second max power bike sprints with full recovery in between, despite both being performed on “cardio” equipment.

Without a heart rate monitor to gauge how hard your system is actually working, it can be very difficult to judge what adaptation you’re working towards, so most people work to the point where they can “feel it”.

This usually means exercise ends up being between 80 & 90% of max heart rate, but at low power outputs/speeds i.e., the grey zone. This will often be due to the speeds/levels most people will need to get the cardiovascular benefits being slower/lower than you’d like/hope: a hard pill for us all to swallow.

This higher heart rate work will cause a drop in blood glucose levels, as you’ll be using up more glucose as a fuel, in order to handle the higher intensities and the need for quicker energy as a result.

The popular Polarised training or 80/20 model is a help here. By making the easy work actually easy (80% of your training), and the hard work actually hard (20% of your training), it gives a different focus to sessions and works towards the adaptations you’re hoping to create. As does using a heart rate monitor to let you know when to back off and when to ramp things up.

In either case, a cool down is still important, you’ll be letting the body know that the “trouble” is all behind it (well, until the next time anyway). It gets you out of the stressed state and you can start to recover; rest and digest, not fight or flight.

If anyone is looking for specific advice for training as a Type 1 diabetes, you could do worse than browsing Tom Allison’s content; he’s an exercise coach who is also Type 1 diabetic. His Instagram profile is type1_tom. Other profiles are available.

In Response said:

@Richard 2024 you do not appear to addressed this question

As this is a forum of people with diabetes, we tend to provide feedback and advice based on personal experience rather than something we just seen on YouTube.
Like @_Steve_ 45 minutes of intensive cycling (for me, this is often in a Spin class) would result in my BG plummeting if I was not able to plan for the exercise by suspending the basal on my pump.
Do you have any experience of this?

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I think that comment was directed to Bobbybrown111 (probably not the singer, but you never know I suppose).

However, I have been in the fitness industry for a quarter of a century.

As for qualifications, I am a Level 3 Personal Trainer and Level 3 Exercise Referral Coach.

In addition, I am Level 4 qualified in Cancer Rehabilitation, Level 4 in Mental Health and Level 4 in Obesity & Diabetes Management.

I also have a fair few other specialised qualifications in Strength and Conditioning, along with recovery and mobility.

None achieved via YouTube College.

I hope this sets your mind at ease.

As for your experience with a Spin class, yep, you'll need to adjust your glucose level to match the glucose output that the class will demand.

Which can be a problem, as you're at the mercy of the instructor and what they've got planned for the session, as opposed to something you've planned out in advance.

Similarly, how you feel on the day, having a different positional set up, or even using a bike than your favourite one will alter how you respond. Just because you attend a class on Tuesday, it doesn't mean that every Tuesday you'll be able to give it both barrels.

A heart rate monitor would give you clues as to how hard you'd be working, and allow you to personalise the session by holding back from super hard efforts etc.

If you use a CGM, then combining it with HRM would give even more data to see how you respond, This would be in technical terms, a bit of a faff though.

In Response said:

@Richard 2024 i think you missed the point that I manage the spin class with my insulin pump.

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I quite possibly did.

I was assuming that you adjusted both carb intake and insulin.