Crystal Mackay

It’s well known that exercise is good for your brain. For years, scientists have shown even a single session of heart-pumping activity can sharpen executive function – the mental skills we use to plan, focus attention, remember instructions and juggle tasks. But what happens when movement isn’t an option? Recognizing that age, disability or illness can limit a person’s ability to exercise, Western kinesiology professor Matthew Heath and his team in the Faculty of Health Sciences set out to determine if they could elicit the same exercise-induced brain response in a way that doesn’t require movement. They studied a technique called intermittent hypoxia, a method that temporarily reduces the amount of oxygen a person breathes, then restores it to normal, repeating the cycle over a 60-minute session. The results were recently published in the journal Psychophysiology. “It’s like sending a person up to the top of Everest and back down again several times,” said Heath. “And what we found is that just one bout of intermittent hypoxia led to a marked improvement in executive function.” The research team enrolled 24 healthy young adults in the study. Participants wore a facemask that lowered their oxygen intake to 11 per cent for five minutes, roughly what you’d experience at high altitude, before returning it to the normal 21 per cent found at sea level. Throughout the session, researchers monitored ventilatory and cardiac measures as well as brain blood flow using transcranial Doppler ultrasound and near-infrared spectroscopy. Prior to and following the hypoxia intervals, participants completed an antisaccade task – a standardized test of executive function that requires individuals to look away from a visual stimulus, engaging focused attention and inhibitory control. Unlike previous studies that measured cognitive changes after multiple sessions, this research showed just one round of intermittent hypoxia was enough to produce a measurable brain boost. “When we compare this to exercise, we’re looking at a cardiovascular stimulus rather than a motor one, and we’re still seeing cognitive improvement,” said kinesiology master’s student Denait Haile, who led the study. “We are giving your brain a little sprint challenge and watching it perform better. It was really interesting to see how this positive stress had an impact in such a short amount of time.”  

Reduced oxygen levels lead to increased blood flow

The researchers believe the boost to executive function is tied to physiological changes triggered by the reduced oxygen. When oxygen levels drop, the body responds by increasing blood flow to the brain and enhancing its ability to extract oxygen more efficiently. “For people who can’t exercise, those in the ICU or with a spinal cord injury, for example, this may serve as a way to boost blood flow in the brain and help guard against cognitive decline,” said Heath. Still, the team stresses the technique must be done safely  – under controlled conditions,  and the careful watch of health professionals. “We’re constantly monitoring participants and ensuring their oxygen saturation levels stay within safe limits,” said Haile. As for clinical applications, Heath and Haile agree more research is needed, but the potential is exciting. “In our study, we demonstrated that we were able to safely apply the protocol and see a noticeable benefit,” said Haile. “It’s definitely sparked interest in what might be possible.”