Nora Isaacs

IT is 5 p.m. on a Tuesday and Victor Cal and Suliman Sharif, both 14, have already taken Overtime Fitness in Mountain View, Calif., by storm. They hopped wildly on the flashing lighted squares of an In the Groove dance pad, rode stationary bikes, shared cellphone pictures, chatted with a personal trainer and played a rousing game of table tennis. The pair, friends since seventh grade, once spen…