You study the brain under pressure, including the pressure of high-end performance exercise. What got you into this line of work?
I’ve always had a keen interest in exercise and in a previous life, and about 16 kilograms ago, I played football internationally and also ran as a long distance runner for Wales. But while I pushed myself super hard, my body wouldn’t go where my brain wanted to take it. It just irritated me and made me wonder, "what determines exercise performance?" So my genetic inadequacies led me to find a way, at least scientifically, to identify the factors that regulate exercise performance. The big question was "what is the brain’s role in this?"
You’re looking at the brains of high performance athletes like high-altitude mountaineers and free divers, who are able to get unusual levels of oxygen to their brains in low/no oxygen environments. You’re also looking at the brains of people with dementia and stroke. What’s the link?
What unifies my research is our fundamental need to get oxygen to our brain. The brain is the “neuronal governor” taking charge over every other organ in the human body. But paradoxically the brain has evolved to be so reliant on this precious supply of oxygen, rendering it especially vulnerable to failure, as with the clinical complications associated with stroke
So we’re looking at the role of oxygen in top end athletes, who have the best adaptations of all, and comparing them to diseased patients, who have blood trickling into their brain, and who are prone to dementia and stroke as a result. This helps define the limits of brain oxygen delivery across the spectrum of health and disease, from the super-fit Olympian to the super-sick patient.
Free divers provide a fascinating alternative. The current world record for a single breath hold is 11.5 minutes which is staggering … Free divers can double the blood flow to the brain, which is phenomenal, especially when you consider how sensitive the brain is to blood flowing too hard. Free divers and high-altitude mountaineers are setting the upper limits of performance, which allows us to study the mechanisms that we think underpin disease, and identify ways to get this important molecule to organ that defines us.
You do free diving yourself. What’s the appeal?
I’m fascinated by how free divers can achieve what they do, and there’s a competitive side of me too, that wants to push myself as hard as I can go.
We’ve done some studies in diving mammals, looking at what allows some to survive in very low levels of oxygen, such as the fresh water turtles and crucian carp. What they do is slow their metabolism down, so oxygen consumption by the brain also decreases, something we’ve also recently shown in human free divers. Remember the turtles in Finding Nemo? They’re super chilled out. Similarly, free diving forces me to work on eliminating every anxious thought and becoming very relaxed. I find that quite liberating.
You’re also looking at the benefits of exercise on the aging brain?
Yes. As we get older, and especially with inactivity, blood flow and as a consequence, oxygen delivery to the brain decreases, and this has been linked to an impairment in our ability to think, remember and formulate ideas, collectively known as cognition. Long-term physical activity is a potent countermeasure, likely because it can attenuate these changes and improve cognitive function in older life – a form of brain-train as opposed to brain drain.
What are the mechanisms involved?
The first is that exercise stimulates neurogenesis, which is when the brain makes more neurons, or brain cells. That occurs in the hippocampus, in the dentate gyrus, which is especially vulnerable to ageing and which, among other functions, is thought to help in the formation of memories.
The second is that it seems that exercise can help break down or slow the accumulation of a really nasty protein called beta-amyloid, a sticky protein that forms and sets in the brain and blocks our synapses. Exercise can also help reduce inflammation in the brain, and lessen the build up of free radicals that can cause damage. It can also increase production of an important protein, brain derived neurotrophic factor, which allows cells to grow and speak to one other. It also seems that exercise can improve proprioceptive adaptation – that is, the motor skills that allows us to, for instance, touch our nose with our hands.
Are there any particular exercises that are most likely to optimize the beneficial effects of exercise on the brain?
One of the reasons I think exercise works is that it helps our blood vessels get more blood into the brain, and therefore oxygen. When we’re young, our blood vessels are floppy, but as we get older they get really stiff and furred up from the junk of life (like fish and chips causing atherosclerosis). The reason we think exercise is protective is that as blood rushes across the inner lining of those blood vessels, something we call the vascular endothelium, it triggers all sorts of chemicals to be released, especially nitric oxide, which helps the brain’s blood vessels to relax and open up, getting more oxygen to the parts of the brain that need it the most.
And there are certain exercises, for example repeated squat stands, which swing blood flow up to and down to the brain, that really helps drive this response, selectively targeting brain adaptation over the long-term. We’re searching for the “optimal” train-your-brain exercises that work both for athletes and patients.
Likewise, thermal stress, such as hot yoga and sauna all help get (more) blood to the brain. So do exercises involving hydrostatic stress, like aqua aerobics, because the pressure of the water pushes more blood up and into the brain. It also seems that exercise combined with cognitive activity helps, such as reading or trying to work out the Rubik’s cube on the treadmill. But diet also has a huge role; our research has shown that we spend a large proportion of our lives “recovering” from a meal, so if you eat a fat bomb it has a hugely negative impact on the brain.
High-intensity interval training is getting a lot of attention – what might the benefits of HIIT be for the brain?
The brain is reliant on oxygen, and we need to get more blood flowing into the brain as we get older, and exercise is a great way to do that. The question is, [what is] the best way to optimize the beneficial effects of exercise? So one of my colleagues, did some original work with patients [who were] complaining, “I’m not fit, I haven’t got an hour a day, what I want to do is limited time, and compress all of this down into a packet of exercise, so instead of going long, I’m going hard.” Out of this came the HIIT paradigm – a lot of work looking at HIIT is focused on cardiovascular circulation, and it’s actually demonstrated that the intensity of the effort is the key factor that drives protection. We are showing benefits with HIIT that are occurring in the brain. But we’re still playing catch-up, we’re trying to stimulate more research in this field.
Damian Bailey is Professor of Physiology and Biochemistry at the University of South Wales where he is Research Unit Leader and Director of the Research Institute of Health & Wellbeing. His research group (Neurovascular Research Laboratory) is interested in how free radicals (for good or bad) impact upon the cerebral circulation across the spectrum of health and atherosclerotic disease.