Toolbox: Going High and the Brain Revolution
I just came back from my annual one week working holiday, consisting of me jetting from the far Eastern end of the country (St. John’s, Newfoundland) to Banff, Alberta for the annual Canadian Society for Exercise Physiology conference. In between the stunning scenery and warnings about coyotes and bears, let’s take a look at some of the latest topics in scientific debate…
The fall is one of the busiest times for an academic. On top of all the usual trappings of academia, October is also prime time for students past and present knocking on my door for reference letters for scholarships and applications. At the same time, this is also usually the time of year where many of the major granting agencies have their deadlines. Couple that with students invading my door worrying about the midterm exam I’m brewing up, and October becomes prime time to make myself scarce!
So even if it means putting in hours in preparation and in catching up, it’s always a nice break to take a week away during the fall for the annual Canadian Society for Exercise Physiology (CSEP) conference. CSEP is the largest organization in Canada devoted to exercise and sports science, and serves as an annual family reunion of sorts for us sport science geeks. The fact that the conference was deep in the Canadian Rockies, in Banff, made it an even nicer working holiday!
We have devoted the past 5 weeks on Toolbox to various ideas around the off-season. And just as many of us are looking ahead to plans for making 2009 the best season yet, conferences like CSEP are the perfect chance to look ahead to emerging ideas in sport science. Therefore, here are my random thoughts on a number of sessions that I attended, and some ideas that they generated.
Altitude and Hypoxic Training
An excellent symposium was organized on the issues and practicalities surrounding altitude training and the use of hypoxic tents. The speakers were top-notch researchers and practitioners, including Dr. Randy Wilber, chief physiologist for the US Olympic Committee, and Dr. David Smith of the University of Calgary and one of the chief physiologists for the Canadian Olympic Committee. The session was led off by Dr. Juha Peltonen, one member of the Finnish group that has pioneered much of the initial research into hypoxic facilities and athletic performance.
Some key ideas and thoughts:
• Remember that altitude training is NOT as simple as the altitude stress causing you to respond by naturally producing more erythropoietin and therefore red blood cells, ultimately increasing oxygen carrying capacity and aerobic performance. The actual mechanism(s) underlying benefits from hypoxic training is still largely unclear. While this red blood cell (hematopoietic) pathway is one strong possibility, many studies have demonstrated improvement following hypoxic training despite no changes in blood parameters, such that other pathways, yet unknown, must contribute.
• Remember also that every one of us is an individual, with our own peculiar responses to any exercise or stress stimulus. Therefore, just as we all respond differently to an identical training stimulus, there is a high degree of individual variability in response to hypoxic training. One often-overlooked study (1), by the main folks who first proposed the “live high train low” paradigm, found that nearly 50% of their subjects did not respond to altitude training with any improvement in aerobic capacity or 5 km run times at all.
• When is the best time in a periodized training program to incorporate altitude training? David Smith is a proponent of keeping it away from the main competitive and peak phases of a training year. Often, there’s too much at stake at this time. Rather, his ideas revolve using altitude training during the phases equivalent to late Base and early Build segments. In this way, altitude training, rather than putting the finishing touches to peak form, is used to optimize the body for the prime training phases instead. This idea makes a lot of sense, because it may also help to minimize the risk of over-training during highly stressful periods. Anecdotally, we saw David Millar come off the Giro and straight into an extended altitude camp, with the end result that he was essentially invisible and in poor form throughout the Tour and afterwards.
Brain or Body?
Another highly interesting symposium was a debate format on one of the most befuddling problems facing exercise scientist. The question is simplicity itself: Why do we fatigue during exercise? Seemingly simple, yet it’s a question whose answers have eluded us after centuries of investigation.
The bulk of research has thus far focused on specific potential mechanisms, such as the inability of the heart to keep up with oxygen demands, limits to metabolism and its ability to convert sufficient energy from food, or the muscles to contract at sufficient capacity. To make a grossly simplistic analogy, this thrust of research is essentially looking at the design characteristics and limits of the bike.
The alternative theory that was first advanced by Professor Tim Noakes of the University of Cape Town in South Africa seeks to put the brain back into prominence. Noakes feels that too much of physiological research has treated the body as an automaton, reflexively responding to stimulus (e.g. temperature, lactic acid buildup, heart rate, deepness of breathing) by shutting down the body at the point of catastrophic collapse without much conscious control.
In Noakes’s “Central Governor” model, the human organisim is a complex and intelligent system. The brain acts as the primary controller, adjusting our intensity of effort in real-time, based on physiological sensors throughout the body and also on motivation and prior experience. For example, you would never start out running a marathon at a 100 m sprint pace, because you intuitively know the approximate effort and intensity required for a marathon. You also rapidly make adjustment to your self-selected work output (aka wattage) based on internal (e.g. sensors in your muscles) and external (e.g. environmental temperature) cues.
Ultimately, the body and brain are aiming to intelligently adjust its effort in order to perform the task (10 km run, 16 km time trial) in as efficient a manner as possible, all the while avoiding overcooking itself and reaching a point of catastrophic collapse (e.g. heat stroke). To put it very simply, Noakes’s model has the analogy that you may have the highest-zoot bike and equipment available, but it’s still the rider that wins the race!
Unfortunately, from the time the Central Governor model was first proposed in the late 1990s, exercise physiologists split into two distinct “pro” and “con” camps, and the debate has been quite divisive and exclusive. I have always been of the opinion that both models can be completely consistent with each other, with much of the schism caused by the simple fact that the choice of exercise tests used in research studies almost be default forces the results of that study to be interpreted in only one possible direction.
Call me a fence sitter extra-ordinaire, but I think it perfectly logical that we are always aiming to avoid catastrophic collapse in the first place, but also have “safety fuses” built into our body to stop when we reach those danger points. Therefore, current work in my lab is aiming at developing exercise tests that can test both models at the same time.
So summing up, while the human body does not evolve that rapidly, ideas about how it works certainly do! Given Professor Noakes’s status in the field of exercise science (among many things, Noakes wrote the classic book “Lore of Running” that drove much of the running boom in the early 1980s), we’re guaranteed to continue this debate in the coming years.
Chapman, R.F., J. Stray-Gundersen, and B.D. Levine. 1998. Individual variation in response to altitude training. Journal of Applied Physiology 85: 1448-1456.
Stephen Cheung is a Canada Research Chair at Brock University, with a research specialization in the effects of thermal stress on human physiology and performance. He can be reached for comments at [email protected] .