Toronto-born Michael Woods is competing in the 2022 Tour de France. With the race nearing its halfway point, writer Bruce Grierson chats with KPE experts Robert Bentley, assistant professor, cardiovascular physiology; Jack Goodman, professor emeritus, cardiac health and exercise and Ira Jacobs, professor, exercise physiology about the athlete and the physiology behind his performance.
Bruce Grierson (moderator): Nearing the halfway point of the Tour de France, Canada’s big hope, Toronto-born Mike Woods, is, let’s be honest, a long shot to win. But Woods is such a unique package, in ways we’ll talk about, that you can’t entirely rule him out. Before we dig into Mike’s chances let me ask you this: is the Tour de France the most demanding endurance test there is?
Robert Bentley: Well, it’s definitely demanding, and the overall winner of this team sport needs to be an ideal combination of various cycling sub-specialties. But I’d suggest there are some individual endurance runs that may top it. Like the Marathon des Sables — a six-day, 251km ultramarathon in the Sahara Desert. Or the notorious Barkley Marathon — a 160km trail race held in a state park in Tennessee. Since 1995, only 15 racers have finished in the allotted 60 hours. (This year no one did!)
Ira Jacobs: I think it’s important to define what we mean by “most demanding.” Tour de France competitors have amazing aerobic fitness in general (as measured by their high maximal aerobic power (i,e. VO2max). But aerobic power is only one variable in endurance. There’s also aerobic capacity —that is, the ability to sustain a high rate of oxygen consumption for a long time. And on that score, indeed, there are sports like ultramarathons, or long cross-country skiing competitions, where the aerobic capacity of successful competitors exceeds that of Tour de France cyclists.
(Also, consider that aerobic fitness alone — however you measure it — won’t win you the Tour de France. There are times when anaerobic capacity contributes significantly to competitors’ ability to distance themselves from the pack.)
BG: As you know, Michael Woods is a bit of a unicorn, in this respect: he was a serious professional runner before he took up cycling. In fact, he is the only human to have run a sub-four-minute mile (3:57 at age 18!) and completed the Tour de France. That’s a unique story. In what ways might it give him an advantage?
IJ: Undoubtedly the running provided a much smoother on-ramp for Mike than if he’d just come to cycling cold in his twenties. The physiological adaptations to training at the required intensity were already highly developed.
This is contentious among exercise physiologists, but there’s a large body of research demonstrating the importance of the central nervous system in regulating the onset of fatigue in response to physiological strain. I am among those who think the evidence supports that the “central regulator” is trainable. The repeated exposure to intense physiological stress and strain as a runner is likely transferable to almost any form of exercise. The high-performance athlete “learns” to delay the onset of fatigue. Mike likely already had that adaptation at the time he commenced serious cycling training.
RB: Cyclists and runners have a lot of similarities from a cardiovascular perspective. They need large, powerful hearts to pump oxygenated blood to the working muscles. How large and powerful? Over to you, Jack. [Prof. Jack Goodman completed a CIHR funded project exploring cardiac remodeling in middle-aged, long standing, sub-elite runners, cyclists and triathletes.]
Jack Goodman: The hearts of these athletes are indeed bigger, more efficient pumps, which not only deliver oxygen but also flush metabolic waste from the muscles very efficiently —that’s an important part of superior muscular endurance. The maximal output of these hearts is much higher, so they can maintain higher and higher work rates at a lower relative intensity, well below their upper capacity. Many of our study participants were actually runners who switched to cycling in mid-life, and their strong base of endurance fitness from years of running allowed for a rapid and successful transition to cycling.
RB: A sub-four-minute mile is a very impressive feat, not just from a physical standpoint but a mental one —the drive it takes to push yourself to that level of performance. Mike is definitely “comfortable being uncomfortable” during a race.
JG: His speed may also translate into greater hill climbing power, since that may be in part, a function of his skeletal muscle make-up. But regardless, he clearly has excellent cardiorespiratory “power,” which reflects both heart and circulatory prowess and skeletal muscle efficiency. Meanwhile, sport performance can be highly specific, and success in one sport may not translate exactly the same way to another.
BG: What are the relative aerobic demands of distance running vs distance cycling?
JG: Both cycling and running can impose very high oxygen demands, but each has unique characteristics. One thing is common to both: speed and terrain will impose different oxygen demands. Running is completely weight-bearing, so there is no opportunity to glide, and minimal drafting: so there’s no free lunch, ever. A key aspect to riding success is the watt/weight ratio — the higher the better. Whereas an efficient runner is typically lighter, which is advantageous for weight-bearing exercise.
BG: The runaway race favourite, Tadej Pogacar of Slovenia, is 23 years old. The average age of the winner of the Tour is 28. Mike’s 35. How much does that matter? And, just generally, when do athletes peak cardiovascularly?
JG: World best times for sprinters are generally held by younger athletes, while endurance record holders tend to be older. For example, Carlos Lopes of Portugal won the 1984 Olympic marathon in 2:09.21 at the age of 37. The late, great Ed Whitlock ran the marathon in under 2:55 at age 73! Endurance athletes can maintain peak performance later in age than most sprinters or power athletes.
BG: One stat I saw: pro cyclists tend to start declining after around 10 years of high-level competition – that’s late-twenties for most of these guys, who started as teenagers. But Mike didn’t turn pro till 2013, at age 26. So by that measure he’s kinda still … in his prime!
RB: I guess this could be considered his prime. But Father Time is a factor, no matter when an athlete took up the sport.
As we age, our bodies change. For example, testosterone levels peak around 18-19 years of age, and decline thereafter. Testosterone plays an important role in muscular strength and endurance, and also in red blood cell production – the cells that carry oxygen in the blood. Both are clearly important for cycling.
And while Mike may have started cycling later – thereby sparing himself a few years in the saddle — with the high impact of those running miles, it’s probably a wash. There are still a lot of miles on those legs (and knees).
BG: Professor Jacobs, what can we say about the heat? At some point it’s likely to be a factor. Is there anything about Mike — his age, his running background, his upbringing in the chilly climes of Canada – that might bear on how he handles it?
IJ: I don’t think so. All high-performance aerobic athletes have a high degree of heat acclimatization “built-in” to the physiological mechanisms that help regulate body temperature by virtue of their aerobic fitness. As for exposure to Canada’s winter temperatures … it’s unlikely to be a factor, since being exposed to cold does not mean that one actually gets cold — particularly for athletes who are generating so much heat during their training.
BG: Thank, all, for your thoughts. May the road rise to meet you.