Not only was I privileged enough to meet 4-time World Ironman Champion Chrissie Wellington, but I also got to put her through her paces live on air at the BBC’s 80th birthday event for the World Service down at Bush House in London. For info, the Ironman is a 3.9 km swim, a 180 km bike ride followed by a marathon. During the live 1 hour show with Claudia Hammond on Health Check Alan Ruddock and I did four experiments live on air; with multiple rehearsals we were confident everything would go well. However, as time to go live approached, a crucial machine (a gas analyser) was still not working correctly. We restarted the computer time after time, recalibrated the analyser and checked the mouthpiece. With 30 seconds to go, Alan noticed that the mouthpiece was connected back to front and we were saved (oops – that was me).
The main affair for us was a VO2max test on Chrissie and a ‘Mrs Normal’ (BBC Producer Pam Rutherford) about 30 minutes into the show. The test requires a breath analyser (the one we nearly didn’t get working) to measure the gases breathed in and then expired. The difference between the two can be used to work out how much oxygen is being used by the body: push the body to the limit and you get a measure of the maximum amount of oxygen the body can consume.
To create the intensity of exercise needed to push Chrissie to the max, she ran on a treadmill at 16 km/h and we increased the gradient 1% after every minute (starting at 1%). The graph below shows a typical oxygen uptake curve (mine) for the same protocol. VO2 is the rate of oxygen uptake in litres per minute, normalised by body mass (to give units of ml/min/kg). You can see that VO2 rises pretty sharply to 2% and then continues increasing until a plateau is reached. At 7% your legs are burning, the blood is pumping in your ears and you feel like your eyes are going to pop (well, that’s how I felt anyway).
The value at the plateau is taken as your “VO2max” and in the units shown can be used to compare you to other athletes. On air we shouted out Chrissie’s value as around 60 ml/min/kg and our Mrs Normal as around 30 ml/min/kg. The chaotic nature of the show means that I wouldn’t put too much faith in Chrissie’s value as she didn’t actually reached maximum in the time we had available.
How does this compare to others? Paula Radcliffe has been reported to have a VO2max of around 70 ml/min/kg while Espen Harald Bjerke, a Finnish cross-country skier was reported to have a value of over 90 ml/min/kg. The magnitude of VO2max is not the only thing to be aware of, however. What I didn’t mention above was that our Mrs Normal was running at only 13 km/h so not only did Chrissie have a higher value, but it occurred at a higher running speed.
So, what did I learn from the experience? Well, doing experiments live on air is scary and no matter how many times you practice, technology always goes wrong when you are desperate for it to go right. How the space shuttle ever got off the ground I’ll never know. I was interested to hear that Chrissie had never done a VO2max test and had never worn a heart rate monitor: she didn’t see the need, she said, as Ironman was really all about mental toughness. And, I might just have to go and buy her book A Life Without Limits.
Thanks to Helena Selby and Fiona, the Producers of the show. If you are interested, it can be heard here.