Your hydration status can make or break your performance goals. It is essential that you are optimally hydrated before, during and after physical activity to achieve your maximal physical performance.
As an active person, what are your fluid requirements?
General fluid requirements for adults range between 2.2 to 3 L (9 to 12 cups) of fluids every day. However, physical activity increases fluid requirements substantially due to the fluids lost through sweat. Individual sweat rates vary from 0.3 to 2.4 L (about 1 ¼ to 10 cup) of sweat per hour. Sweat rates depend on a number of factors including exercise intensity, fitness level, heat and humidity, altitude and acclimatization.
What are the consequences of being under hydrated?
A loss of sweat of 2% of body weight can compromise physical and mental performance and can make exercise seem harder. You may notice a decrease in energy, a decline in coordination and muscle fatigue and cramping. In addition, fluid losses increase the risk of nausea, diarrhea, vomiting and gastrointestinal problems. If you are dehydrated you are less likely to be able to stay cool during exercise and are at greater risk of developing heat illness.
How can you monitor your hydration status?
In general, plenty of pale coloured urine means you are well hydrated. Find out if you are drinking enough to replace fluid losses during exercise by weighing yourself before and immediately after you exercise. If you lose more than 2% of your body weight during exercise, it means that you need to drink more.
Let’s look at an example:
Martin weighs 70 kg (154 lbs) before soccer practice
He weighs 68 kg (150 lbs) after soccer practice
He has lost 2 kg (4.4 lbs) which is 2.9% of his body weight.
Martin is not drinking enough during exercise and will need to rehydrate by drinking 1 L of fluid for every kg lost. If Martin plans to exercise again in less than 12 hours he should replace fluid loss by 150%. This means he should drink 1.5 L of fluid per kg of weight loss. Since he lost 2 kg, he will need to drink 3 L of fluid. This extra fluid will compensate for increased urine production caused by drinking fluid quickly.
What is the best way to stay hydrated?
- Drink throughout the day. Make water your drink of choice. Milk, tea, coffee (in moderation), and sports drinks also provide fluids. High water containing foods like fruit, vegetables and yogurt are also good choices.
- Pay attention to your thirst. Your thirst mechanism is an important signal that lets you know you need more fluid.
- Choose water or sports drinks during exercise. Sports drinks are necessary for intense exercise lasting longer than one hour. Sports drinks may also be required for exercise that takes place in hot or humid conditions or for sports requiring heavy equipment such as football or hockey.
- Limit or avoid alcohol.
- Follow these guidelines for fluid intake before, during and after exercise:
At least 4 hours before exercise: 5-10 mL per kg of body weight (350-700 mL fluid for a 70 kg person)
2 hours or less before exercise: 3-5 mL per kg of body weight (210-350 mL fluid for a 70 kg person)
During exercise: Sip fluid throughout. Avoid gulping or drinking too quickly as this can lead to over-hydration
Immediately after exercise: Drink 1-1.5 L of fluid per kg of weight lost.
Try these strategies to help you stay hydrated
- Carry a reusable water bottle with you throughout the day. You are more likely to drink when fluids are readily accessible.
- Flavoured beverages may encourage you to drink more often. To keep sugar intake to a minimum, try juice mixed with sparkling water or water flavoured with lemon, orange or cucumber slices.
- Choose foods like grapefruit, watermelon, strawberries and cantaloupe as pre- workout or training snacks.
- Take regular fluid breaks during exercise. Aim for 125 mL fluid every 15-20 minutes. Chilled fluids can help reduce core temperature when exercising in the heat.
Note: If you have concerns about your hydration or nutrition status consider booking a nutrition assessment appointment with our registered dietitian. Movement Performance Centre offers a variety of nutrition services aimed at helping clients set goals that are realistic and focused on indicators of health. Contact us for more information.
Nicola Day, BASC, RD, MS