Physician, Wheel Thyself!

Pedaling the Cure

Voices

Given the increasing clinical and epidemiological evidence of the benefits of regular exercise, it is strange that so many doctors still waste so much time crawling around inner cities imprisoned in their cars. This does no good to them nor to the environment, and if they tell their patients to exercise, they could well attract the fair retort, “Physician, wheel thyself.”

I can attest to the immense advantage of a bicycle to a general practioner needing to visit patients in central London. In my first three years of bicycling 12.8 km (8 miles) per working day, I covered 9,656 km (6,000 miles). Now, 23 years and three bicycles later [1998], the mileage is over 100,000 km (62,000 mi), which is nearly 2.5 times around the Earth or a quarter of the way to the moon.

These innumerable short journeys have added up to a small urban odyssey, which has been not only highly efficient but enjoyable. Once I had experienced the freedom of movement and saving of time provided by my bicycle, it became increasingly unthinkable to return to the frustrating torpor of trying to use my car for the job.

The early euphoria of overtaking Jaguars and BMWs has fortunately worn off – although it remains an agreeable, if rather repetitive, experience.

Cars consume 50 times more oxygen than cyclists per unit of distance covered, producing carbon dioxide at a similar ratio. They also have a greater cooling problem, since they explode their fuel combined with air at 2,000-2,250 C (3,632-4,082 F), which is more than one-third of the surface temperature of the sun.

Cyclists operate at only 37 C (98.6 F), and, from the standpoint of physics, are not heat engines but constant-temperature energy converters that are more analogous to fuel cells.

We, too, have to keep cool, and our main system of heat dispersal takes up no extra space and is functionally – if not socially – most elegant. In short, we evaporate.

We cyclists are, so far as is known, the most efficient movers in the solar system, for two main reasons: Unlike the birds and the bees and all limbed land animals (including ants and pedestrians), we use almost no muscular energy in supporting our body weight. Like frogs and toads, we convert chemical energy into mechanical work at about 25 percent efficiency, whereas cars achieve only 20 percent efficiency.

We have the advantage over cars of using biochemical and neuronal systems that have developed over 500 million years and been tested (often to destruction) under the most rigorous conditions.

We move silently and cleanly about our towns or countryside at almost no risk to anyone else, and (this puts us even more on the side of the angels) we leave the air cleaner than we find it, thanks to the trapping of airborne particulate debris by the mucous sheet covering our bronchial and bronchiolar epithelium.

We do not fume in traffic jams or add to them, and while that sluggish primate Homo urbanus vehiculo constrictus will no doubt be with us for some time yet, his days of dominance may well be numbered.

We are seeing already in our towns the re-emergence of that earlier and more active subgroup of the species Homo se propellens and Puella se propellens, who steer towards a sustainable future and overtake on their bikes.

R.E. Williams, M.D., is a British general practitioner based in London. A longer version of this article first appeared in the British Medical Journal [www.bmj.com].