Tommy Sutor, MS, CSCS

Acute Intermittent Hypoxia: A Scientific and Personal Odyssey

Take home messages (do them first so we can follow along!)

  • Acute intermittent hypoxia shows great promise to improve many motor functions in chronic sci.
  • Everybody has a role in making this happen.

I’m a physical activity guy who was looking for a dream job when I heard about Push to Walk, where they were doing activity based training for people with SCI. This was in 2011 .. I came to Working 2 Walk for the first time a couple of months later.

A scientist asked the audience what would a cure be, and someone replied that it would be getting back everything you take for granted every day.

From 2011 to 2015 I worked at Push to Walk, but what I saw was that only some people made fantastic functional gains. How could we make it better for everyone? I was close to people like Wise Young. At Working 2 Walk in 2012 I spent a long time talking to Ravi Bellamkonda, and what I learned was that people were taking things and combining them with activity-based training.

So one day I was training a client in the gym whom I’d known for a few years. I asked how her weekend had been, and she told me about being at the beach with her family. She said, “I want to run in the sand. I want to play in the ocean with my kids.”

Gut punch.

In two years of working with her, I hadn’t been able to really help her. It was experiences like that that pushed me into science. I no longer wanted to make SCI better. I needed to.

So in 2015 I went to the University of Florida Rehab Science program to work with Dr Emily Fox, and she told me to go talk to Dr Andrew Mitchell about acute intermittent hypoxia

What’s that? It’s an 8 to 15 cycle of very short (60 to 120 seconds) hypoxic intervals. You remove oxygen for a minute or two, then have it for a minute or two. Then remove it, then have it. Over and over, for 8 to 15 cycles.

Double blind studies show that doing this improves ankle strength, hand function, and ventilation. It improves walking outcomes better than locomotor training alone.

How does this work? Since 1980, many animal studies showed that it leads to plasticity in motor function. Reducing oxygen releases serotonin, which makes motor neurons more sensitive to incoming information.

That’s just one way we think it works, but know that there are decades of research that back this up. All those animal studies gave us confidence to do this. This isn’t something you can do at home, by for example, holding your breath. The breathing has to be in a normal pattern.

They’ve done new work with a man who had a  severe C5 complete injury who needed a pacemaker diaphragm to breathe, alto’ he was able to breathe alone for long enough periods to see if the animal findings translated to humans.

He tolerated the testing well. What we saw was that his diaphragm was able to the same amount of work in a shorter time frame. We also saw that after the hypoxia treatment, he was able to breathe in more strongly due to the neuronal activation. This was the first time we’d tried this on a person, and not only did he tolerate it well, he gained some function.

So, our hypothesis was that one session of AIH improves breathing and trunk function in humans with chronic sci. (This is going to be his PhD thesis.)

There are 3 participants enrolled right now. None of them responded to the sham protocol. All three of them improved in some measure, including inspiratory and expiratory pressure.

Emily Fox is going to build on this this fall.


  • One’s role in the cure movement may not be obvious, but it exists. (Tommy couldn’t have predicted he’d become a person studying the controlled management of oxygen to the bodies of people with SCI when he began looking for that dream job!)
  • Acute intermittent hypoxia shows great promise to improve many motor functions in chronic spinal cord injury.

(Tommy’s kind of amazing here, friends. Just sayin’.)

Question: Do these benefits persist?

They fade after a few hours, but we hypothesize that if we could combine it with activity based training, we expect that could be extended.

Question: why not do this for longer than 12 minutes?

That comes from the animal literature. The dose could be detrimental over longer time frames.

Question: What advice would you give people right now?

Physical activity, and generally the more the better. It’s pretty hard to approach the point where you get too much.

Question: At what point does the brain start to release the serotonin?

All mammals have this thing called the carotid body, which detects a change in your inhaled oxygen. When it gets that notice, it starts releasing the serotonin.

Question: (missed it, sorry)

Answer: technical info about serotonin receptors

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