Hydration

Water is the largest component of our bodies, making up about 60% of adult body weight. When we fail to consume enough water, or replenish adequately during and after exercise, dehydration can occur. This can affect our athletic performance, but it can also be detrimental to our overall health, resulting in muscle cramps, heat exhaustion and in severe cases – health stroke, which can be life threatening.

Being well-hydrated allows multiple processes in our body to function optimally, such as removal of waste products, distribution of molecules to cells and also temperature regulation. Loss of fluid can lead to changes in body temperature and imbalances in electrolytes (such as sodium and potassium), which has been linked to causing fatigue, light-headedness and muscle cramps. Dehydration can also affect mental performance, as chemicals in the brain become altered and may result in mood changes and confusion depending on severity. Athletes need to be particularly careful regarding their hydration, as a decrease in blood volume from fluid loss will result in decreased oxygen delivery to the tissue, negatively impacting performance.

Most people would be familiar with the recommendation of drinking 2L (8 glasses) of water per day to stay hydrated. This is a good general guide, however the amount of water required does depend on other factors such as body weight, composition and any concurrent medical conditions. The Nutrient Reference Values for Australia and New Zealand recommend that adult females aim for 2.1L of fluid per day, whereas adult males should aim higher at 2.6L of fluid per day. Pregnant and lactating women should aim for more, and children and adolescents should aim for slightly less.

Athletes need to take into consideration how much fluid they have lost during and after exercise through both sweat and urine output. According to the Sports Dieticians Australia organisation, to ensure adequate re-hydration, the amount of fluid lost should be replaced by 1.5x the amount. For example, if 1kg (representing 1L of fluid) is lost during the bout of exercise, then it should be replaced by 1.5L of fluid. Other strategies for athletes that can help prevent dehydration include being adequately hydrated before exercise, ensuring small fluid volumes are regularly consumed during exercise and pairing post-exercise fluids with recovery food.

Whatever your current levels of exercise, it is important to ensure adequate hydration on a day-to-day basis for optimal general health, as well as for athletic performance.

Author: Nikki Rathbone
M Physio (Sports) B Physio (Hons)
APA Sports & Exercise Physiotherapist

Updated: 9/2/26

Nikki is an APA Titled Sports and Exercise Physiotherapist with 13 years’ experience across elite and recreational sport, women’s health, headaches and migraines, chronic pain, and workplace ergonomics, with a strong focus on identifying root causes and long-term solutions. She holds a Masters of Sports Physiotherapy, is a Level 3 Watson Headache Certified Practitioner, leads dry needling education, and has extensive experience working with high-performance sporting teams while actively contributing to physiotherapy education and mentorship.