When you need to lift a heavy object, follow these suggestions from the American Academy of Family Physicians:
Don't hurry or try to jerk the object. Lift it slowly and smoothly so you won't strain your back.
Face the object when you lift it. Don't twist.
Hold the object close to you, not at arm's length.
If you can straddle the object, bend your knees before lifting and keep your back straight.
If you can, carry the load so that it lies between your shoulders and your waist.