Another important factor for performance, especially in warm conditions, is hydration. Severe dehydration will have a negative impact on performance, causing you to fatigue and slow down. We can generally tolerate a certain level of dehydration (a 2-3% reduction in body weight), but anything greater than this will have a negative impact.


What is the optimal drinking strategy? There is a high level of individual variation in how much we sweat during exercise. We all differ based on training status, hydration status, ambient weather conditions, terrain, clothing etc. The best strategy is to measure your own individual sweat rate. This is relatively easy to do.  For your convenience, I have created a sweat rate and re-hydration calculator on my website at the following link:


To calculate your sweat rate, you will need to measure the following:


  • Weigh yourself (preferably nude) before training/competition.
  • Weigh yourself (preferably nude) after training/competition and after towelling down.
  • Measure the amount of fluid consumed.
  • Estimate any urination between before and after weigh in.
  • Duration of training session or competition.


With this information at hand, you can calculate your sweat rate.  Ideally, you will exercise at race pace for one hour (possibly shorter for swimming). This will allow you to estimate your average sweat loss. You can do this for the three different disciplines, as it is likely you will sweat at different rates depending on the type of activity you’re doing. Ideally, you would perform this test during  a warm-up race to make the figure as realistic as possible.


With this information at hand, you can then calculate your ideal rehydration rate. The calculator allows you to factor in an acceptable level of dehydration. This is set at 2%, which is the maximum accepted weight loss without a negative effect on performance.


If you want to take it to a professional level, determine your sweat rates in different environmental conditions (cold, moderate, hot weather) so that regardless of the weather on the day, you will know what your ideal hydration strategy is for those conditions.


One important consideration with hydration is hyponotraemia , which is a potentially serious medical condition. Hyponotraemia is  caused by consuming too much fluid, resulting in a change in the composition of blood plasma and potentially fatal knock on effects (e.g. swelling of the brain). This generally occurs for beginners or slow competitors who consume excess fluids (i.e. drink more fluid than they lose through sweating) during a triathlon. This is one reason why it is a good idea to measure your sweat rate and have a hydration plan in place. As well as keeping you hydrated, it will prevent you from developing hyponotraemia.


One last thing to mention is caffeine, which has the potential to enhance your performance.  Caffeine works by altering your perception of how hard you’re working. I can testify to the power of caffeine as it has helped me finish a long hard ride on more than one occasion.


Caffeine can be consumed in a number of ways – by taking caffeine tablets in measured doses, by eating a gel which contains caffeine or by drinking coffee or Coke. One point to be aware of is that if you are a habitual coffee drinker than you may not get this performance enhancing effect. The best way to ensure that you get a boost is to stop consuming coffee or caffeine containing products 4-5 days before your event. This “wash-out” period will allow you to get the best effect from caffeine when you take it during an event. As with all nutrition strategies, experiment in training to see if this is right for you.