How much should I drink on a long run? Ideally you need to replace what you lose. The amount of fluid you lose while running for one hour varies depending on a number of factors. On average, a person loses approximately 0.5 to 1 liter of fluid per hour of intense exercise such as running.
These factors include your body size, intensity of the exercise, ambient temperature, humidity, and your personal sweat rate. To get a more accurate estimate of your fluid loss, you can weigh yourself before and after a run. The weight difference reflects the amount of fluid lost during exercise. For every 0.45 kg of weight lost, it is generally recommended you consume about 475 to 710 milliliters) of fluid to rehydrate adequately.
It's important to listen to your body's thirst cues and drink fluids regularly during exercise to prevent dehydration. Better still, drink before you feel thirsty because thirst is an indicaiton you have already started to dehydrate.
Also, consider the environmental conditions and adjust your fluid intake accordingly. If you have specific hydration needs or concerns, it's always a good idea to consult with a healthcare professional or a sports nutritionist who can provide personalized advice based on your individual circumstances.
Do I need energy gels?
For most cases if you are running for up to an hour then you probably won't benefit much from taking energy gels or drinks. However for very long runs taking in extra calories may be beneficial.
The number of calories burned while running depends on various factors, including your body weight, running speed, duration of the run, and individual metabolic rate. For example, a 57kg runner at moderate intensity burns approximately 750 calories per hour. Someone weighing 84Kg burns around 1100 calories per hour at a similar intensity.
Energy gels typically contain 100 - 150 calories per serving. So to replace what you might burn on a 3 hour run you have to consume a lot of energy gels. However, unlike water, your body stores energy for running as carbohydrate in muscles and the liver as well as energy in the form of fat.
Taking energy gel helps your natural energy stores last longer. But if you are serious about running or walking very long distances then it is important to eat food in order to get enough energy to maintain performance. It will pay off in the long run (no pun intended).
To get a more accurate estimate of your personal calorie expenditure, you can use fitness trackers, online calculators, or consult with a fitness professional.