Force hydration

Whether you are out in the field, on operations or planning a strenuous workout, hydration is a critical consideration.

Hydration is key to good physical and mental energy across the day. When we are dehydrated, our body has to work harder to pump blood around the body and this makes us more tired than we would otherwise be. In terms of physical energy, we will tire more quickly, during both PT and general activity. We are also more likely to experience brain fog, have trouble concentrating, experience mood problems, and feel lethargic and sleepy, when we don’t have enough fluid on board. There is an abundance of literature and studies done on military personnel, particularly on the higher risk of dehydration seen in military environments. 

Although hydration is important regardless of whether you are in the office or out on the field, inadequate hydration status is more prevalent and concerning during field training and operations. Adopting good habits in the lead up to such activity is important to optimise performance and minimise risk.

So how much do I need to drink?

How much you need to drink each day varies depending on your gender, age, activity levels and environmental conditions. The general recommendation from the Institute of Medicine suggests that men need 13 glasses of fluid each day, and women require 9 glasses each day. While all fluids (and foods with high water content, such as vegetables and fruits) contribute to overall hydration status, your best choice of fluid most of the time is water. Given that our bodies are 60- 70% of water, it makes sense that our goal should be to replace what we lose across the course of the day. Caffeinated drinks don’t dehydrate, but they do increase fluid loss. And any beverage that isn’t water will increase the work our liver and kidneys need to do in order to process it. This isn’t a major, but it is worth being mindful of this as you are deciding what to drink. If in doubt, go for water.

Your operating environment

To ensure hydration, adopt one or more of the following strategies:

  • Start the day with two glasses of water
  • For every cup of coffee, have a glass of water
  • Whenever anyone asks you if you would like a glass of water, say yes
  • Aim to drink 3 glasses of water between breakfast and lunch, and 3 glasses of water between lunch and dinner
  • Have a 750 ml bottle of water for your PT session, and use it
  • For every alcoholic beverage you consume, have a glass of water in between

PT and the field environment

Tactics to put into place for PT sessions and extended field-based work:

Use the formula below to figure out your fluid losses during/after physical activities. This provides an indication of how much you need to drink to replace the loss. Its important to drink up within 2-3 hours of the PT session. 

       0.5          X          1.5 =                    750mL
Weightloss (kg) Rehydration factor Quantity of water to consumed over the 2-3 hrs post exercise.


Hydration planning guide

The table below provides an indication of what fluids you should be refuelling with, depending on the exercise duration.  

Exercise duration Hydration Plan
< 60 mins Water is typically the best option (can add sugar free electrolytes* in if hot or humid conditions).
60 – 90 mins Water is important and electrolytes can be beneficial.
90 mins Water, electrolytes and a small amount of glucose can help maintain energy and focus.

Nuun Sport or Hi 5 are examples of sugar-free electrolytes. You could also add ½ tsp of salt to a litre of water with some lemon juice. Gu energy chews or Cliff Shot blocks are examples of a small amount of carbohydrate that could be used during extended and high intensity PT sessions.