Stimulants and training zones

Physiology
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TLDR: How to deal with training zones and an elevated heart rate due to stimulants?

Hi all,

First time poster here. I’m looking forward to both learning and contributing on this forum.

I’m a former rower turned coach who still likes to be competitive himself (rowing, road cycling and XC MTB)

About two weeks ago I started taking prescription stimulants to deal with ADHD.

One of the side effects is an elevated heart rate, both in rest and during exercise. Underlying and dangerous heart conditions are ruled out.

It’s a time released (12-14h) medicine taken at breakfast. Due to working life and potential trouble sleeping both exercise before taking and taking later are generally out of the question.

That raises several questions.

In what way is this going to influence my training zones?

Should I adjust my heart rate zones according to the new distribution, or (since the muscles and metabolism haven’t changed in any way) stick to the power zones as I established them before (and accept the higher heart rate as a fact)?

I haven’t really tried to reach my maximum heart rate but literature suggests my HRmax hasn’t changed. Does that mean I will produce lower power at HRmax?

And íf I adjust my training zones according to the new heart rate distribution (and as a result will lower my output significantly in the lower zones) won’t that basically make me slower because the muscles aren’t stimulated the way they used to?

I’m aware you can’t give me medical advise, but if you could weigh in from a sports physiology point of view that would be greatly appreciated.

1 Like
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Hi @thijs010 ,
Welcome to the forum.

I would ask your doctor how the medicine works (*). That is: does it influence your oxygen uptake, heart rate (as in: directly), oxygen transportation and indirect heart rate effects (what is happening in your body causing the heart rate to rise).

From this information you can conclude what should happen to your training zones.

  • if oxygen transport is normal and so are your working muscles → test your zones after about a week of taking the medication (and make sure you are rested like with every test)
  • if oxygen transport is down, increase your zones through a test, to ensure you can properly gauge your intensity for a given power output
  • if muscles performance is down, be careful to not overload your muscles.

Final thoughts:

  • something else is requiring more blood, causing the heart rate to rise. Training with power would give you a better way to target a specific muscle intensity.
  • A higher heart rate means you have more stress → a workout may cause more central fatigue then you would expect as ‘something else is eating your energy too’
  • your capacity to deliver blood to your working muscles is reduced, if something else is taking oxygen too → expect your maximum aerobic capacity to be a little down.
  • sprint performance, both power and heart rate, is probably not affected if the medication is not directly impacting heart rate.

(*) you may get a more detailed answer from the manufacturer. Also, you might be a great case study for them as you have more HR reference data available than the average patient.

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oh, and please let us know what you discovered, with or without the help of a doctor.

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Thanks for the reply, very helpful pointers as to where to look.

Makes a lot of sense to look at oxygen uptake as well, instead of only using the heart rate versus power ratio. Kinda should have thought about it myself.

Haven’t talked to any real experts and unfortunately my doctor wasn’t really helpful although he tried his best.

I’ve found a few interesting articles, so I will definitely get back!

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As promised I will share a few of my findings after a few weeks on and off medications.

  • Literature suggests no raise in HRmax
  • Literature suggests no other changes on metabolic and ventilatory level

Most of my training was done in the lower zones, so that’s where my focus was when comparing it to earlier data of 2022.

  • Power/HR (in lower zones) has decreased significantly as expected
  • Cardiac drift appears to be not out of the ordinary (again, in lower zones)
  • During occasional high intensity work I got a few times pretty close to an all time HRmax, which was very rare before. Could be due to little time spent in higher zones though.
  • DFA alpha 1 HRV pretty much useless (difference between power at 0.75 on and off meds was insane) where former tests resulted in expected values (DFA alpha 1 of 0.75 right upper limit of Z2 in 7 zone model)
  • Although body temperature was not measured this appears to be higher (as is suggested is some literature)

When taking the conversations (cardiologist, physiologist, psychiatrist and trainers) all together the general conclusion seems to be that new testing needs te be conducted to establish new HR zones in relation to the power zones, but that the power zones itself shouldn’t have changed that much.

Since I’m more into training than into testing, my practical application is to stick to the power zones as I’m used to for low intensity work. Although I try to stay in the lower power range or the zones opposed to creeping up as I’m used to, to keep the heart rate in check.

Next up is increase intensity through VO2max work and some Zwift racing and see what happens.

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Thanks for reporting back!