A Basic Guide to Fluid Intake for Marathons
A fluid strategy is important not only for performance but also for safety and enjoyment. Without a good fluid plan you won’t be able to make the most of your training. A loss of only 2% of your body weight will decrease your performance. If you want to achieve your personal goals in the marathon. you need a good fluid strategy, and practicing your plan in training is important. Like many things practice and adjustment is what will get you there.
How much fluid do you need?
Everyone is different plus the conditions make a big difference, if you live in Tasmania and come and race on the Gold Coast then not doubt you will need to drink more than usual. If you practice drinking good amounts of fluids in training, you will be able to drink more in events also. Your body will adapt to what you show it. As a general rule you want about 4-7mls per 1kg body weigh every hour. For example if you weigh 70kg aim for 280mls per hour as a minimum and say 500mls as a maximum on anything over 60min runs. That said the best thing to do is keep track of how much you consume on your runs (or some idea) and then note your weight change by using your scales. For example if in a 2 hour run and you drop 2kg and consumed 500mls means you lost approx 2.5L during the run and will want a bit more in future runs in similar conditions. Measuring Weight change is a very simple and useful thing to check and you can also use that to help your recovery by ensuring you get back to your pre run weight, which helps speed your recovery.
Set up a system for drinking
Most of the modern heart rate monitors and many of the good sports watches have timers that can be set to beep every 15 minutes. Drinking on a regular basis in your training run swill help your body adapt for the event itself. In fact you can improve this by as much as 50% in a 6 week period.
Its also important to monitor how you feel. If you feel nauseous then you may have consumed fluids that are too strong for you, drink some water to help dilute down what is in your stomach. If you feel bloated, your stomach is full. In this situation reduce your drinking as you are consuming more than your body can process. This can also be caused by drinking strong drinks that sit in your stomach.
How do you carry your drinks?
These days there are lots of very good systems to carry drinks in running belts, some even have insulation. For long training sessions, especially in the heat you may need to plan your drink stops or run via drinking fountains. i prefer to carry as I don't have to stop and disrupt my tempo.
There are also a number of great running belts that not only hold water bottles but can also hold your cell phone and or your MP3 player almost essential in this day and age!
Make sure you know how much your bottles do hold so of them are deceptive due to their shape. I need 3x500ml bottles, on a hot day that’s enough fluid for 3 hours when training or 2 ½ hours when racing. You can hide these along your training course or leave at your car and return 1/2 way through your run to pick up.
What about sports drinks?
The general rule is less than one hour and water is fine but once the length of the session starts to increase you will need to take in energy and electrolytes. Sports Drinks are designed to optimise fluid and energy intake. There now is enough research to say that sports drinks improve performance in events as short as one hour, so once you reach this point it is a good idea to start to either eat some food or use a sports drink. In training you will recover faster and this can only help you in your preparation for the marathon.