Race Day
Sonnet is out the door by 7AM while I and the kids have a more leisurely morning. After bagels, we drive to the train station, train to Waterloo, underground to Canary Warf and Docklands Lite Rail to Cutty Sark - pictured. Phew! We arrive just in time to see the elite men race past. They are thin and lite on foot - the surface area of their lungs the size of a basketball court. This is true actually. According to my very old "Running A Marathon:" gas diffusion is directly related to surface area (Fick's equation). Normal lung space is 50 to 100 square meters in an adult and perhaps twice that for a marathoner. At rest, only 30 to 40 m2 is employed for gas exchange, with as few as one-third of lung capillaries perfused. With exercise, however, both pulmonary blood flow and tidal volume increase to enlarge surface area for gas exchange. By perfusing more capillaries and ventilating additional alveoli, the surface area for gas exchange is increased and diffusion increases proportionately. So there it is.
Both kids are troopers and stay close by my side as everywhere is jammed with spectators. We connect with Nat and Justin at the Cutty or Mile-Six. It's a good meeting point as it allows us to hustle underneath the Thames via the Greenwich footpath to Canary Wharf to see Miles 16 and 19.
Madeleine on the Marathon: "Do they have to do that?"
