What should runners drink?

Runners should primarily drink water, both in and outside of exercise, to meet their daily hydration needs. However, including other liquids, such as electrolyte-rich sports drinks, can also provide necessary carbohydrates, aid in hydration and improve electrolyte intake and balance. When running, water and electrolytes are lost in sweat so it is important to make sure you replace depleted nutrients with water and/or beverages that contain carbohydrates and electrolytes, namely sodium [1]. The carbohydrates in sports drinks will also help to fuel your body before, during and after a run [2]. 

Runners can also drink caffeinated beverages, as this has been shown to improve performance and increase speed and endurance when consumed before a run. Consuming 3-6 mg caffeine/kg body weight 30-90 minutes before exercise seems to offer benefits to many runners [3].