Q: Does a high school athlete need a sports drink for practice?

A: Maybe! Sports drinks definitely have a role in hydrating athletes. The general guideline is that when activity is continuous for longer than one hour, then a sports drink can help to maintain energy levels. 

When it comes to selecting sports drinks for prolonged activity, it makes sense to choose a sports drink that contains carbohydrates like: Gatorade, Powerade, etc. The reason for this is that during each hour of exercise about 30 - 60 grams of carbohydrates* are metabolized. Having a sports drink will help to maintain fluid levels, blood sugar levels, and energy during prolonged activity.

*Note - athletes working out longer than 2 - 3 hours (e.g. triathletes, ultra-endurance athletes) will burn up even more carbohdyrates per hour. 

When focusing on your hydration, arriving to games and practices in a hydrated state is so important. Research shows that about 76% - 89% of athletes arrive to practice under-hydrated, which then makes it difficult to bring the body to a hydrated state and play at your peak. See the Hydration Overview handout for more recommendations on fluid intake. 

References:
Arnaoutis, et al. FLUID BALANCE DURING TRAINING IN ELITE YOUNG ATHLETES OF DIFFERENT SPORTS. J Strength Cond Res. 2015 Dec; 29(12): 3447–3452.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4515206/

Exercise and Fluid Replacement. Medicine & Science in Sports & Exercise. February 2007 - Volume 39 - Issue 2 - pp 377-390
http://journals.lww.com/acsm-msse/fulltext/2007/02000/Exercise_and_Fluid_Replacement.22.aspx