Every exercise machine you'll find in the gym is a little different. But most of them -- especially the cardio machines, and some of the weight machines -- operate on the same basic principles. As long as you're oriented as to those principles, you can jump right in and use most of the machines right away, with nothing more than a glance at the machine's instructional placard for quick reference.
No matter which cardio machine you select, almost all of them will have a "Start" or "Quick Start" button you can press to get started immediately. This sets you up for a manual program -- in other words, controlling the machine's resistance or speed manually. You might also need to enter your age and weight to help the machine estimate your calorie burn.
If you'd rather use a preprogrammed workout, look for an "Enter" or "Program" button, then follow the machine's prompts to select a program. On some machines, you have to start pedaling before you hit the button.
Setting Up a Weight Machine
Although they might all look different and be build to target different muscles, gym strength-training machines also follow a few basic principles. Start by selecting the proper resistance -- you either slide a pin into a weight stack or load weight plates onto the machine. In a few limited cases, you might push buttons to increase and decrease hydraulic or electronic resistance. If you're not sure how much resistance to use, start with the least weight possible and then work your way up.
Next, adjust the machine's seat, backrest or chest pad so that your joints line up with the machine's joints -- that is, the axes upon which its levers move. On the rare occasion that guideline does not apply, adjust the seat so you can grasp the machine's handles comfortably.
Using a Weight Machine
Once you've set up the weight machine to fit your body, sit down and grasp the handles. Pull or push them -- whichever motion raises the weight stack or weight plates -- in a smooth, controlled motion. If any of your body parts started out in contact with the machine's padding -- say, a chest pad or backrest -- maintain that contact as you lift and lower the weights. As long as you maintain a steady pace you will, in most cases, naturally restrict yourself to an appropriate range of motion. A count of two as you lift the weight, then three to four as your lower it, works well.
Exceptions to the Rule
There are only a few exceptions to these basic principles. In terms of cardio machines, most rowing machines won't fire up until you sit down and start rowing. Then you can either continue rowing -- many rowing machines still let you adjust resistance by moving a lever -- or, in a few cases, program the rowing machine to play a game, like racing against another nearby rower or against a previously recorded time.
In terms of weights, free weights -- and to a lesser degree, cable machines -- are different animals entirely. Working with weight machines can prepare you for the weight room, somewhat, by familiarizing you with the proper body mechanics. But as a general rule, it's best to get help from a trainer, gym staff or an experienced lifter before you move on to free weights.