Cheap parts – Watch out for things like plastic versus steel pulleys with bushings instead of ball bearings, small diameter cables and low-end, thin upholstery that likely will tear or wear down quickly. Plastic end caps on frames may come off and leave sharp edges.
Any ability to wiggle the machine – What's critical to a quality home gym is that it feels absolutely solid and stable; if you can shake the machine or see bolts moving, it's a huge red flag. You should even be able to hang on a taller unit and not feel it budge.
Jerky, unnatural motion of exercises – If the exercise doesn't feel smooth and natural in the store, it's not going to in your home either.
Thin padding on seats and seatbacks – See if you can press your thumb through the padding to touch the wooden seat board. Can you? Walk away.
Uncovered handgrips or uncoated frames – Pretty rare these days, but possible if you're shopping really low end equipment. Beware.
No warranty – Yikes! Need we say more?
Variables to consider:
User goals – Make sure you can clearly identify what you want to get from the gym, because your goals should influence the type of machine you select and the variety of exercises it offers. For simple all-over fitness and toning, you can get a basic machine. If you have two or more people who will work out at the same time, you'll need more than one weight stack. If you're looking to beef up, on the other hand, you are probably better off joining a health club that has lots of strength training options – or getting a whole lot of iron plates and bars.
Type of resistance – Moving the mass of weight plates in a stack (where you select the amount using a pin) feels natural to most users, but they do create heavier, louder, and more expensive gyms. If you're on a tight budget, some gyms now feature resistance through elastic bands or rubber/plastic rods and bows. Such systems do provide a decent workout and are quite compact but be warned that bands, rods or bows require far more adjustments through the course of a workout. Know your patience level. Another inexpensive option is a gym that uses free weight plates instead of a selectorized stack, but then you have to buy the plates, have some knowledge about where to put them AND you have to load and unload heavy plates to change exercises. Not for all.
Traditional fixed movement versus newer user-defined path of motion – Basically, that means this: Traditional gyms have fixed arms. You grab and push. Kind of a no-brainer. Newer types have arms that move, hinge or rotate freely so you have to use your abs to stabilize yourself AND you can choose the position and direction in which you move. (Some gyms actually just have cables that offer an even freer motion.) Although a great workout, this can be tougher to master and is best for someone with more experience.
Affordability – With fitness equipment, you get what you pay for. That's not to say a $500 home gym won't get you somewhere, but generally you need to pay about $800 and up for a quality, biomechanically correct, reasonably long-lasting machine with a moderate number of exercise options. Good lower-priced models will range from about $800 to the low $1,500s. Although perhaps without the highest-end construction or bells and whistles, really excellent gyms can be found for $1,500 to $4,000. You can easily pay up to $5,000, or more, if you have no bottom to your budget.
Space available – You'll be surprised how big these can look in a small room. So measure carefully. Space an issue? Consider foldaway benches or a piece designed for a corner.
* Amount of weight – Consider who will be using the machine and ensure that it has adequate resistance levels that start low enough so Grandpa can lift but also that increase to a sufficient load to challenge your high school athlete. Small add-on plates are often available for in-between amounts.
Ability to add options – Some gyms – the more expensive ones usually – will allow added stations for additional prices, such as leg presses or rows. Consider this if you think you may want to expand your gym one day.
Weight of unit – Home gyms with steel stacks can weigh more than 300kg, which may not be an issue if you're putting this in the basement. But for upper floors, find out how many pounds per square foot the floor can support! If the floor is rated to hold less weight, you may need to reinforce it or relocate the gym. Who wants an upstairs gym to end up in the lap of someone trying to watch TV downstairs? Ouch.
Maintenance – The home gym should include complete instructions on things such as lubing guide rods, tightening bolts, checking cables, etc. Be sure to perform the recommended maintenance to keep your investment functioning well.
Add-ons – For interest, you can find various bars and cuffs, instruction books, and even moveable and adjustable benches. Go back to your retailer when you get bored to see what is available to get you motivated again.