When am i dehydrated?

Knowing how much fluids you might lose. When are we dehydrated and when aren’t we? For any sport you need to pay close attention to the amounts of fluid you are losing and taking in. This applies especially so to endurance sports, distance running or sports in a warm climate.

It is widely reported that your performance will start to suffer when you lose just 2-3% of your body weight. However as you stray higher than that the symptoms become more obvious and you start to put yourself in danger. Fluid loss in excess of 10% of body weight and you are likely to require medical assistance. Don’t forget severe dehydration can be fatal if not treated.

So how on earth do you know you are becoming dehydrated while out running? Well it can be hard to tell until the symptoms become obvious, by which time it will have impacted your performance and set in for the duration of the event.

The best way is to see how much fluid you tend to lose while running. Weigh yourself naked, run for 1hr and weight yourself again. The loss will is your fluid loss. 1kg = 1ltr. So this is the amount your pre race hydration and drinking during the race needs to compensate for. You should also do a few test runs in different conditions to see how you much you lose on a mild day and a hot day. The difference can be very significant.