Wednesday, September 21, 2011

ADHD and Exercise: Should You Dial It Back If You Take Stimulants?

A question came up in an ADD Forum thread last week about exercising while on stimulants.  One of the forum members had been told by her pdoc that since she was on Adderall, it was important to keep her heart rate below 160.  If she didn't she might go into cardiac arrest!  On the one hand, she loves to exercise; on the other, she'd prefer to avoid cardiac arrest.  She wondered if any of the other forum members could speak from experience.

I can speak from experience.  Her doctor is talking up his ass.  His advice is based on research that was done in the early seventies on patients with heart disease.  It was never meant to be applied to the general population.

About a year ago, I too was concerned about my max heart rate.  When I ran on the treadmill, I would inevitably hover at 185, and could easily get up to 194 for several seconds at a time.  According to the helpful heart rate chart on the machine, my "maximum" heart rate is 184.  You're familiar with those Helpful Chart, right?  They're the ones that determine your maximum heart rate by subtracting your age from 220.  By subtracting still more numbers, you learn your "target" heart rates for anaerobic and aerobic exercise.

Image credit: Morgoth666, retrieved from on 9/19/11

According to the Helpful Chart, my heart rate was impossible.  I was sustaining my VO2 max for 15 or 20 minutes at a time.  I should have been dead or something, right?

I checked in about this with my own pdoc, who assured me that I'd get tired and have to stop exercising long before I was anywhere close to risking cardiac arrest.  As much as I trust my doctor, I'm someone who prefers to do my own research.  I went home and googled the question.

Lo and behold, I came across this article in the New York Times, which reports that the idea of "maximum heart rates" is being challenged.  Maybe challenged is the wrong word -- Dr. William Haskell, PhD, who invented the formula, has been laughing at its misapplication for years.  Turns out that he derived his formula from patients with heart disease, to be used as a means for testing for heart disease, and even so, maximum heart rates vary between individual.

Who would have thought!  Maximum heart rates, like just about everything else, vary by individual!

If you're interested in the topic, the New York Times article is worth checking out.  If you just want the highlights, here they are:

  • The "max heart rate" concept was misunderstood, popularized, and then misapplied across the entire fitness community.
  • A study of the US Mens' Olympic Rowing Team showed that working heart rates varied dramatically among these elite athletes, from 160 beats per minute to 220 beats per minute
  • Exercise physiologists have known for years that this kind of variability is normal.
  • Heart rate by itself is not an indicator of fitness -- you want to look at recovery time.  Your heart rate should drop by at least 12 beats after one minute of rest.
  • If you underestimate your "maximum" heart rate, you're going to go too easy, and you're not going to improve your fitness.
The NYT article doesn't cover athletes who take stimulants for ADHD.  Stimulants can definitely raise your heart rate.  But unless you have an underlying heart condition (and your pdoc should have had this checked before prescribing them to you) you'll probably wear yourself out before you're remotely close to danger.  Given how important exercise is for controlling ADHD symptoms, it's a mistake to cheat yourself of the exercise you need by underestimating your "maximum" heart rate.

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