SICK NOTES

Norman knows how to nip nausea in the bud

Nausea caused by exercise is not uncommon, especially in endurance events. In one 161km ultradistance run, for example, it was found that 60 per cent of surveyed athletes reported nausea at some point during the race, and a quarter reported vomiting at some juncture.

The feeling of wanting to throw up – or actually doing so – during exercise can be brought about by a number of factors, whether it’s simply illness or the intensity of the exercise, coupled with your ingestion of food and drink that interfere with your gastrointestinal tract. It’s debilitating, and if doesn’t totally curtail your ride, it will certainly slow your progress.

With the amount of audax riding that I’ve done in the past, these events totalling many hundreds of kilometres at a time and all the stress that puts on the body, it should come as no surprise for you to learn that I’m no stranger to nausea. Let’s rewind to when I was 70, and undertaking a mere 300km audax. To this point I had done around 30 or so of these rides and had no problems with nausea, let alone other problems of riding such long distances. My favourite distance was 400km, which meant having to ride through the day and night in order to finish. I liked the symmetry of this.

When I was still sufficiently crazy to ride 300km, I would finish in 15 hours. I estimate, roughly, that I use about 400 calories per hour at my audax pace. I hardly ever exceed 70 per cent of my maximum power when cycling. I aim to finish, rather than trying to be the first rider home.

Over the ride I would need approximately 15 x 400 = 6,000 calories. About 60 per cent of the calories come from glucose, the rest from fat, which means glucose usage is 6,000 x 60 per cent: 3,600 calories. I have in my body about 600g of glycogen which, at four calories a gramme, works out at 2,400 calories. I am aware there is a deficit of about 1,000 calories, more or less. I am also very aware of the need to maintain glucose and would do so by eating at designated control points. I am trying to show you that as an experienced ultra-cyclist, I watch both calorie and fluid intake like a hawk.

Back to this 300km ride. I was feeling great and kept to my usual regimes of snacking and drinking water to keep hydrated. At about 10 hours into the ride at 6pm, nausea struck me hard. There was no way I could carry on eating, which is precisely the thing you need to do on these rides.

What was causing it? Known causes of nausea and vomiting include: hypohydration (a water deficit in the body); low sodium; altitude exposure; excessive fluid/food consumption; hypertonic (high salt and sugar) beverage intake; and pre-exercise consumption of fatty- or proteinrich foods. However, nothing on this list immediately caught my eye. Something else was at work. Apparently, joints, muscles, the vestibular apparatus in the ear that controls balance, as well as input from the eyes and from postural sensors in the legs and spine, can cause nausea.

I decided that the only way out of this dilemma was to go to sleep. I had time to play with. But where to lie down? There are certain parts of the country where the local authorities pay close attention to the state of their bus stops. Luckily the area I happened to find myself in had a bus-stop shelter that had recently been renovated. It had a nice new bench and thatched roof. This was luxury. Many times on long rides I have had to nap under a bush. I wrapped myself in my spare top and as soon as I hit the bench I was asleep. About an hour later I awoke feeling human and refreshed. Obviously something had equilibrated. But what in the list above had equilibrated I cannot guess. I had lost an hour of time but knew that I still had sufficient hours to finish the ride within time. I was not hungry but just to be sure I had a drink and a snack and went on to complete the ride. I am still unsure about the underlying physiology and the mysterious interaction between muscles and other tissues with the vomiting centre during endurance exercise.

My advice, when on an endurance ride and nausea hits, is to stop and rest, and let whatever is going on settle down. It might not feel like it at the time, but it’s more economical to have a total time-out than continuing haphazardly and putting your whole ride in jeopardy.