ALBANY, NY. (The New York Times News Service) -- Giving birth may be the mother of all workouts, and you can train for it, the same as you would a marathon or other extraordinary physical feat.

Having a baby taxes a woman's endurance, and it can have long-term physical repercussions. The right prenatal workout can help make your body birth-ready, leading to an easier labor and a speedier postpartum recovery.

Research shows that pregnant women who exercise don't just have healthier pregnancies, they may enjoy smoother deliveries.

According to the American College of Obstetricians and Gynecologists, exercise during pregnancy can help prepare women for labor and childbirth, and may even improve your ability to cope with labor pains.

First-time moms typically spend at least 18 to 24 hours in labor, with an average of two hours spent pushing. "It makes sense that the fitter you are, the better you'll be able to endure that workout," says Debra Goodman, physical therapist and instructor of "The Pregnancy Workout," a prenatal exercise program in Albany.

Her workout focuses on strength and cardio training and flexibility.

Goodman says women who have taken her class report they spent less time during their labor pushing than the national average.

This is because Goodman teaches women how to safely strengthen their core muscles, including the diaphragm, transversus abdominis, the pelvic floor and deep spinal muscles, which can help them push more productively during labor.

"When you push correctly, you're using the strength of your abdominal muscles," Goodman says. "It's more effective."

Strong abdominals can also help you avoid the physical damage that routinely occurs during labor; during delivery, the outer muscles of the abdomen open and separate, Goodman says. This condition is called diastasis recti. Strong abdominal control can prevent this area from opening too widely, which can put a strain on the back, and can eventually lead to hernias, she says.

Goodman teaches students the importance of Kegel exercises, which strengthen the muscles of your pelvic floor and support your uterus, bowels and bladder.

Goodman also advocates that pregnant women exercise vigorously during pregnancy. She says the idea that women have to sit around and take it easy during pregnancy is outdated. "It doesn't have to be that way," she says. "Women can do vigorous exercise; they just have to choose the right kind."

ACOG recommends at least 30 minutes of exercise a day on most, if not all days. Regular moderate exercise, including walking, swimming, cycling and aerobics can reduce your risk of backaches, constipation, bloating and swelling, and it can improve your energy level, mood and posture, the institution says.

Stretching is also a critical component of prenatal exercise.

"During pregnancy, women get super tight," Goodman says.

Stretching regularly can help control pain and promote flexibility.

Goodman recommends about 20 minutes twice a day.

Prenatal yoga can be a great way for women to stay strong, limber and relaxed throughout pregnancy and birth. "Yoga is an excellent way to train for the marathon of labor and delivery," explains Linda Hill, a yoga teacher who leads a prenatal yoga class in Latham, N.Y.

Hill's classes focus on breath work, strengthening the body, improving balance and relaxation techniques, which can help the muscles release, resulting in a more peaceful labor and delivery, she says. Her students work through a range of poses, including the cat stretch and cobbler's pose, concentrating all the while on their deep and even breaths.

Labor is an endurance event, Hill says. "Practicing prenatal yoga helps to build a strong, flexible body that will be able to go the distance."

Here are some other tips for working out safely during pregnancy:

-- Don't overdo it: It was once thought that women should keep their heart rate under 140 during exercise, but these days, the target heart rate varies widely. Goodman suggests pregnant women use the talk test to keep track of their heart rate and make sure they're not overdoing it. Women should be able to hold a conversation while they're working out. They can also use the rate of perceived exertion, and aim for a moderate level of activity, where you are sweating, and you can still talk.

-- Activities to avoid: Pregnant women can run, but if you weren't a runner before you got pregnant, now is not the time to take it up, Goodman says. She also cautions women to stay away from activities that require balance, because the pregnant body is a little off-center, and activities that put a strain on joints, because during pregnancy, your joints are lax and more vulnerable to damage.

-- Consult your doctor: Before beginning any fitness routine, pregnant women should consult their doctors, says Hill.

Copyright 2009 The New York Times News Service. All rights reserved.