Some of the oddest machines in the gym are the rowing machines and, although they are somewhat rare, it is not uncommon to see a skiing machine, too. Many people wonder why these sports have been singled out as being such great exercise - why is there no tennis machine, or swimming machine, for example? The answer is that both rowing and skiing exercise your body in a way that other sports don't.

If you've ever met a rower, you'll know that they have huge amounts of upper-body strength, and there's a reason for that. Rowing is, in many ways, the ultimate upper-body exercise, comprehensively exercising your arm and chest muscles.

The situation is much the same with skiing and your legs. Because of all the leaning and balancing that is needed to ski successfully, almost all of your leg muscles get a workout from skiing.

While rowing and skiing machines are no match for the real thing, either in terms of how much fun they are or how effective they are as exercise, they serve a useful purpose, because we can't all go rowing and skiing every day. If you use both the rowing and skiing machines in one day, you will get an all-over body workout to more than rival the one you might get on the various weight machines, and the chances are that it will be quicker for you too.

However, with rowing machines especially, you need to be careful about overdoing it. Because rowing tends to feel easier on your muscles than it actually is, it's tempting to set too-ambitious targets and tire yourself out completely, perhaps even pulling a muscle. For the sake of your health, take it steady, keeping track of how many repetitions you do on the machine on each visit, and gradually increasing, instead of going all-out one day and doing hundreds more than normal.