THE DEBATE OVER whether to use free weights or machines has raged in gyms for decades, with passionate supporters on both sides.

In one corner stand the descendants of Arnold Schwarzenegger’s bodybuilding world of the 1970s, firm believers in the notion of pumping barbells, dumbbells, and kettlebells for maximum muscle growth.

In the other corner stand—or sit, or kneel—those who embraced the Nautilus culture of the 1980s and the industry of fitness machines it inspired. For these guys, machines are the safer, more effective, one-stop-shopping option. (Bowflex, anyone?) Plus, you’re less likely, at least in theory, to use bad form on a machine—and it’s less obvious how little you’re lifting.

But just as the lines between those who prefer weights or cardio has blurred, with many athletes combining both, so too has the distinction between free-weight proponents and those who gravitate toward machines. These days, most athletes see the benefits of training with both free weights and machines.