Time to add another sports drink to the already crowded space of sports, energy, enhanced water beverages category, and who better to do it than Coca-Cola and Adidas?

Testing in Japan has been underway, with tentative plans for a roll-out based on the trial period taking place. Specifically, the collaboration is an isotonic fitness drink called “Aquarius Pro” that takes its lead from sports-inspired brand Adidas, and manufactured by Coca-Cola.

This may be what Coke needs to gain a foothold in the ever-expanding hydration category of beverages. Gatorade, the formidable leader (which has also taken a hit with the introduction of some 200 beverages in the last 2 years alone), is owned by PepsiCo which has dominated the category for some time. (Coke owns Powerade.)

As our research shows in our North American Youth Culture Studies, there’s also been a shift in the types of beverages young people consider “sports” with enhanced water creeping up such as Vitamin Water, and energy drinks such as Monster and Rockstar capturing youth culture marketshare from former leaders. (See the Spring Study 2010 for top brand listings by gender and age groups.)

To go along with this, Adidas has also announced that it plans to beef-up its brand Reebok, which has taken a hit since Adidas took over ownership. Plans include re-focusing Reebok as a fitness brand and partnering with various top gyms. The end-game may include a Reebok gym as well.