Summer Training: Overhydration – Hyperhydration – Dehydration. Know your stuff and be prepared.
Hot weather can make it difficult to maintain optimal hydration; dehydration is not healthy, but neither is overconsuming (overhydrating) fluids during exercise. Drinking too much water without electrolytes during exercise can cause (the sometimes fatal condition) hyponatremia. Hyponatremia literally ‘low sodium’ often known as water intoxication is the condition where your sodium levels are very low due to excessive sweating in addition to only replacing the lost fluids with water without replacing the lost electrolytes. Basically you have diluted your bodily fluids to a dangerous level.
One of the adaptations to training is a reduction in the amount of sodium lost in sweat. However, as sweat rates increase the sweat gland has less time to recover sodium so if you are sweating a lot more than usual you may need to increase consumption.
Getting hot and moderately dehydrated during some sessions can have beneficial effects. The body adapts by increasing plasma volume, this reduces haematocrit level and EPO is produced to bring the level back up. The net result is an increase in red cell volume. NB Chronic dehydration is not healthy and will have a negative impact on health, performance and adaptation;- ensure you rehydrate properly after exercise.
Hyperhydrating prior to tough sessions by drinking 400-800ml of strong electrolyte solution -double up on electrolyte fizz tabs could be a useful strategy and the same after exercise in addition to a good protein recovery drink. REMEMBER water alone will just increase urine volume after exercise, this is one situation where you really benefit from sodium.
During exercise, it is important to balance hydration and energy needs. If hydration needs are high and energy needs low then superhydration drink mix is optimised to deliver more hydration to the right body compartment.
For most sessions Training Mix can maintain energy levels without fear of compromising fat burning. The special slow-release sugar used in Training Mix has been shown to work well in hydration drinks (Amano, 2019), making it a good choice for most zwift sessions. OK, if you want to race for several hours it may be beneficial to switch to a regular energy drink like Energy Mix but for sessions less than 90 minutes Training Mix can be a great option.