Spring Fitness in Full Effect ... Sweat It Out With the Stars!

Fitness in spring is heating up as stars hit the gym! Check out Max Ehrich flexing his bulk mode, alongside A-listers like Mark Wahlberg, Jason Derulo, and Alex Rodriguez showing off their muscles. Meanwhile, hottest women are hitting the weights too—Kate Upton and Khloe Kardashian among them. Get a closer look at these fit faces as they prepare for their next big lifts!