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.

But can you get away with using machines only? It depends. Here are four areas to consider:

How much space you have

Hotel gyms of the early 1990s typically offered only a treadmill, an outdated stationary bike, and some sort of multi-exercise machine, like either a Nautilus or one of its competitors. The fitness manufacturers sold hotel owners on the notion that these expensive machines could replace a rack of dumbbells, thus saving space.

A machine offering multiple options bench, cable rows, tricep pushdowns, and perhaps a pull-up bar—is an effective use of real estate. But hotels realized that guests wanted the options of free weights. So out went the machines. These days, you’ll still find the treadmill and bike in the hotel gym, but you’re more likely to find a rack of dumbbells and more room to spread out.

Bottom line: If you’re stuck in a tiny, throwback hotel gym with only a machine, you can get a good workout. But if you’re shopping for a gym to use regularly, it should include lots of free weights.

How much you train for function

The boom in functional fitness, and in training for movements that mimic those of sports and everyday life, has convinced more guys to embrace free weights, which provide more options than machines, which typically allow for only two-dimensional movements. A typical CrossFit box, for instance, will have no workout machines except for maybe a stationary bike and plenty of rowers (which aren't typically considered machines in the vein of, say, a Bowflex).

With free weights, you’re less likely to rely on the machine. Most anything that can be done with free weights can be duplicated with bodyweight training in a pinch outdoors, in a hotel room, or when there’s no equipment available. And no matter how high you set the machine’s resistance, there’s something more gratifying about throwing a couple of heavy dumbbells around.

Bottom line: There’s nothing wrong with machine exercises. But if you’re looking to train for sport-specific or everyday movement, you’re going to want to grab the free weights more often than not.

Your range of motion

To be fair, if you're a rank beginner, then it can be a little intimidating to show up to the gym on your first day without knowing exactly what you're doing. In cases like that, machines can seem like they offer a friendly guide, helping you get through a workout without looking like you have no idea what you're doing.

But because machines often control your path of movement through an exercise, they can force your body to move slightly unnaturally, especially if your build is unusual or if you have limited mobility. In those cases, free weights will be exactly that—free—and training with them can actually reduce your risk of injury by challenging your smaller supporting muscles to work.

Bottom line: If you're really unsure about your form, then a machine can help in a pinch. But free weights will enable your body to move more naturally (as long as they're not too heavy, of course)—and if you're in need of a trainer, then it's probably just a better idea to hire one and have him or her talk you through the basics.

How long you're willing to wait at the gym

If you’ve spent time in the gym, you’ve dealt with “Cable Flye Guy,” the dude who spends 15 minutes on his three sets on the cable flye machine—three minutes for the actual movements and 12 minutes preening, resting, and checking his phone between sets. Sure, a polite “may I work in?” is proper gym etiquette, but rarely does someone have to wait to use a pair of dumbbells.

Nothing breaks the momentum of a good workout more than waiting for Cable Flye Guy—or at least working in with him.

Of course, the bench station is likely to be crowded on Monday, and the squat racks will probably be popular with your fellow gym clientele. But you'll always have more versatility with an adjustable bench than you will with the Pec Deck.

Bottom line: Unless a spotter is not available—in which case a machine bench press is definitely a safer option—you’re more likely to get a faster, more effective workout avoiding the lines at the machines.

The 'man over machine' factor

If you canoe, kayak, or stand-up paddleboard, you’ve inevitably experienced some fat slob speed by you in a boat: gradually draining his bank account while contributing to his sedentary lifestyle, all the while holding a beer in one hand and his phone in the other.

You, on the other hand, are getting a challenging workout on the water, hitting nearly every muscle in your body, with low-maintenance, environmentally friendly equipment that better holds its resale value.

This same mentality applies to the gym. The guy who relies on machines will be less likely to train when they’re not available. But the guy who embraces free weights knows that he can design a workout anywhere with dumbbells or even his bodyweight.

Bottom line: Like a boat, weight machines will get you where you want to go. But free weights will provide a better workout, sometimes with less aggravation.

Pete Williams is a NASM-certified personal trainer and the author or co-author of a number of books on performance and training.