"Probably the best exercise for a pregnant woman is walking, an excellent way to tone muscles, get fresh air, keep your body regular, and help you sleep soundly at night. But remember: never push yourself to the point of exhaustion. It's much better to take several short, pleasant walks spaced throughout the day rather than one long, tiring trek." Guide for Expectant Parents.
How Far and How Often?If you already walk, keep up your regular program. To get started, walk 20 -30 minutes a day three days a week and build from there to 30 - 60 minutes most days of the week. Walking for exercise can continue into your last trimester and right up until birth as long as it is comfortable for you.
How Fast and How Hard?Moderation is the word during pregnancy, don't push yourself to the extreme. The chemical byproducts and raised body temperature of overexertion are bad for the fetus. Your pulse rate should not be above 140 beats per minute at any time during your walk. You may also use the "talk test" -- you should be able to speak in complete sentences without having to huff and puff and gasp out only short phrases. A pulse more than 100 beats per minute five minutes after a workout means you have worked your body too hard. Drink water before, during, and after your walk to help regulate your core body temperature. The fetus cannot get rid of excessive heat, so avoid exercising in hot weather and keep your walking workout moderate. Consider mall walking as an alternative during hot weather.
Posture!A good walking posture is essential and can help prevent backache.
Stand up straight: Think of being a tall and straight, do not arch your back.
Do not lean forward or lean back: Leaning puts strain on the back muscles.
Eyes forward: not looking down but rather 20 feet ahead.
Chin up (parallel to the ground): This reduces strain on neck and back.
Loosen the shoulders: Shrug once and let your shoulders fall and relax, your shoulders slightly back.
Suck in your stomach
Tuck in your behind: Rotate your hips forward slightly. This will keep you from arching your back.