There are many kinds of strength (力量) training equipment. They do not cost much and     1     (sell) in sporting stores.

Free weights (自由负重器械),     2     (common) used in strength training, are handheld weights. They are not connected to exercise equipment, so we call them “free”. If you do not have free weights, you can use a heavy thing     3     is safe to lift.

Many gyms and health clubs have weightlifting or resistance (阻力) machines. Some people also buy these machines     4     (set) them up at home. But they can cost a lot of money.

However, working with free weights or weightlifting machines can sometimes be     5     (danger). If you are new to weight training, experts suggest working with     6     trainer or physical fitness specialist. This way you will learn the right way to move and avoid injury.

Experts have this warning for those     7     (want) to start weight training. They say you should talk with your doctor before beginning if you are     8     (old) than age 40, and have not been active recently.

If you are suing weights, how much should you use? The right amount (量) should tire your body after 12 to 15     9     (time). You can slowly increase the amount as you get stronger.

Also listen     10     your body. If an exercise causes pain, stop it. Experts say after the pain goes away, you can try the exercise again, but with a lower weight.