Not many athletes give enough consideration to their hydration status during training in the winter and spring. Well it’s cold so you don’t really sweat that much…or do you?

Just remember that as you sweat, you are losing body fluid (in the very cold weather you also lose body fluid from vapour lost in the breath). Essentially the majority of this fluid is coming from your blood, and the blood volume actually drops (due to a fall in the blood plasma volume) which in turn will cause a rise in your heart rate, circulatory distress, reduced ability to deliver oxygen to the working muscle, and a possible increase in carbohydrate use. Significantly a 2% loss in body mass through sweating will cause a 10-20% drop in performance levels!

So it may be important to assess how much you sweat, in order to calculate how much to drink, for both winter and summer training.

Here’s the easy way:

• Jump on the scales (preferably naked) before you train, remembering to keep a note of your weight (don’t forget to get dressed before you go training or you may get arrested).
• Enjoy your session, and drink as you normally would. Recording your fluid intake (mentally or otherwise) can also be of use to help calculate your sweat rate.
• Weigh yourself as soon after the training session as possible (naked and towelled dry).
• Any difference in body mass is sweat loss that you have not replaced. Every 0.5 kg lost equals 500 ml fluid! (You may be surprised how much you sweat, even in winter.)
• Add the bodymass lost to volume consumed, this equals total sweat loss. To calculate sweat rate, divide total amount by time of training session. This will give you an idea of fluid needed for the intensity, duration and weather conditions in future sessions.
• Finally, chances are you have not fully hydrated during your training session, so in order to fully rehydrate, drink 1.25 times the volume of weight lost.

Hope this helps you stay hydrated, and improve your recovery from your rides

Dr Garry Palmer
Sportstest Ltd