While treadmills are a great alternative to real running and complicated exercises, however, they are not without their downsides.
To start off with, treadmills can be very expensive, especially if you buy one with all the luxurious special features. By the time you add in sales taxes, delivery charges and all the rest, you're looking at a pretty significant chunk of change. Of course, there's nothing saying that you need to get one with absolutely every feature around - if it's your first treadmill, you'll be absolutely fine with a more basic model, whatever the salesman might tell you.
The next problem is that treadmills can be very large, and there might not be space in your house. Again, this problem is quite easily solved, as long as you keep your wits about you and realise exactly how big the treadmill you're buying is, instead of just blindly choosing one that takes your fancy and hoping for the best. There are surprisingly small treadmills on the market for smaller homes - all you have to do is look for them.
Some people complain of loud motors on some cheaper treadmills, and it can be annoying if you're not used to it. A good solution is to put on the TV or listen to some music, which also helps with the boredom that many people experience when they just run on a treadmill and do nothing else at the same time.
The final point is one that is important to people who are training for actual races. As treadmills have no wind resistance, they are quite unsuitable for training for real outdoor running - you should be getting out there and doing it on a track instead. While a treadmill can come close to simulating wind resistance if you adjust its slope gradient, it's not good enough for serious training, and you might injure yourself if you run a race after only training on a treadmill.
