Wait until the afternoon to begin breaking up the sidewalk ice. The website Consumer Affairs recommends this for two reasons. First, the ice will begin to melt as the sun emerges and the temperatures rise. Also, back injuries are more likely in the morning before you've had a chance to stretch and move around.
Take five to 10 minutes to stretch and exercise your back muscles, making them less susceptible to injury. Then dress in warm clothing, jacket, scarf and hat. Wear gloves that allow you to get a good grip on a shovel.
Blow away any snow that is resting on top of the ice with a snow blower. You could shovel the snow, but the snow blower will allow you to save your energy and back muscles for working on the layer of ice underneath the snow.
Heat up some sand in a microwave and sprinkle it over the ice on your sidewalk. The ice will begin to melt and become softer, making it easier on your back to break up and remove.
Break apart the ice with a shovel. Use a shovel that has a long, curved handle so that less bending is required. When you do need to bend, do it at your knees. Leaning forward and twisting your body during ice removal is what will put you at risk of hurting your back.
Scoop up small blocks of ice, and take your time removing them. Don't make the activity strenuous. Heavy, quick loads are more likely to cause injury than light, short loads. Remember to lift at the knees and keep your back straight.