Pregnancy Fitness: Bonnie Berk

Last Editorial Review: 3/24/2004

By Bonnie Berk
WebMD Live Events Transcript

Get tips for staying fit from Bonnie Berk, founder of the Motherwell pregnancy fitness program. She visited WebMD to discuss feeling and looking your best during your pregnancy, and offered some safe and helpful workout ideas.

The opinions expressed in this transcript are those of the health professional and have not been reviewed by a WebMD physician. If you have questions about your health, you should consult your personal physician.

Moderator: Welcome to WebMD Live. Our guest today is Bonnie Berk, CES, CPFT, founder of the Motherwell pregnancy fitness program.

Member: Is walking on a treadmill safe during pregnancy or not? If safe, please advise the maximum time to use it and how many times during the week. Should I start at five minutes, then 10, then 15?

Berk: The first thing I would ask is are you currently walking on the treadmill? If you are currently walking at a certain intensity and duration, you can continue that pace for that duration as long as you feel you are able. However, if you feel out of breathe or excessively tired at the end of your session, then it would be appropriate to either decrease intensity or decrease duration. As far as frequency, I recommend most pregnant women walk at least 20 minutes on most days of the week, unless advised otherwise by their healthcare provider.

Moderator: So if this person has never used a treadmill before, is during pregnancy a good or bad time to begin? And overall, what should sedentary women do who feel the need to get fit during pregnancy?

Berk: Walking is a great way to exercise whether or not you are pregnant. If somebody is just starting a walking program during pregnancy, I recommend that they start out slowly and go at an intensity that they're able to talk easily. As far as the duration, it is an individual choice and according to your own fitness level. A good way to begin would be to walk for 10 minutes, see how you feel, and maybe later in the day walk another 10 minutes. And then decide for yourself whether you want to continue doing two 10-minute walks or sticking with 20 minutes at a time.

Moderator: Does the Motherwell fitness program target women who are already in shape and want to keep going during pregnancy?

Berk: Actually, the Motherwell program is good for women of all ages and all fitness levels. Each exercise component is designed to be adjusted according to individual comfort and tolerance levels.

Member: I do cardio[vascular] exercise on a cross-trainer three days a week for 35 minutes. Before pregnancy I also worked out on weight machines for 20 minutes afterwards. Is this still safe provided I do not overdo it on the weights? I have read that muscles and joints somehow weaken or elongate during pregnancy, so I wonder if I should strain them with weights at all.

Berk: Good question. It is always good to break up your exercise sessions so that days you exercise aerobically are separated from days you lift weights. I always recommend that any weight-training session begin with at least a 5- to 10-minute warm-up. This is at a much lower intensity than doing a 35-minute aerobic session. And, of course, stretching should be done every day. As far as weight machines are concerned, you need to be aware of stress on the joints during pregnancy. So I recommend that you do lighter weights and more repetitions and be sure to follow the safety guidelines of the American College of Obstetricians and Gynecologists listed on my website.

Member: Is it safe to do crunches while pregnant?

Berk: Actually, the state of the art guidelines recommend women not exercise while lying flat on their backs after the first trimester of pregnancy. I recommend that instead of crunches, pregnant women exercise and strengthen the transverse abdominal muscles with a simple breathing exercise. While sitting comfortably, take a deep breath and as you exhale, pull your belly button toward your spine and then as you inhale release and with each exhale pull the belly button back in. If you start this exercise early in pregnancy, practice at least 20 every day, by the time you deliver, your muscles should be in good shape.

Member: Do abdominal exercises when you are pregnant make for an easier delivery?

Berk: Some people believe the better toned your abdominal muscles are, the easier it is to push out the baby. More important, however, toned abdominal muscles help to prevent low-back problems during pregnancy as well as after delivery.

Member: What are some safe ways to work the abs when you're pregnant?

Berk: Another way to work the abdominal muscles without lying on your back is to get into a position of all fours on your hands and knees, take a deep breathe and as you exhale once again pulling the belly button toward the spine, round the spine and bring your chin on to your chest. And then during inhalation come back to a flat back. This is the rounded cat stretch found on my maternity yoga video.

Member: Yoga is really taking off in popularity lately. Is it good during pregnancy in general, or do you need specific pregnancy yoga classes?

Berk: Good question. Because women are advised to not exercise on their backs during pregnancy, a regular yoga class might not be appropriate. The other issues include inverted poses, which I believe pregnant women should avoid. However, yoga is a perfect way to exercise during your pregnancy. It strengthens muscles that are affected by the pregnancy as well as improving flexibility, calming the nervous system, and relaxing the body. This is important because we know that stress in pregnancy can cause complications and it also prepares a pregnant woman for the childbirth experience in positive ways.

Member: I know it's so important to exercise while pregnant, but I'm just so very tired! Should I just buckle down and take that walk? Or take that nap that seems so desirable?

Berk: Rest is an important part of having a healthy pregnancy. And it is also important to continue to move your body to prevent complications during pregnancy. So I advise that you try to take at least two 10-minute walks per day, after you feel well rested and after you have eaten a meal. Sometimes, if our bodies are not fueled properly, we feel tired. So be sure to take in enough calories to support the pregnancy, eat frequently throughout the day, and drink at least eight to 10 glasses of water to help improve your energy level. The ironic part of exercising is that if you exercise appropriately, afterwards you should feel you have more energy than when you began.

Member: I get quite hot and sweaty when I exercise (mountain biking, hiking, swimming). Is that a problem for the baby?

Berk: It is only a problem if your internal body temperature rises above a 101 degrees F and the only way to determine that would be to take your temperature. Realistically though, most people don't exercise with a thermometer, so I suggest you exercise at a pace that you can talk comfortably and be sure to adequately hydrate yourself throughout the exercise session.

The issue of high temperatures in pregnancy is most important in the first two months when the baby's nervous system is developing. There is a belief that continued high internal body temperatures in early pregnancy could cause failure of the spine to close. In most cases, however, this is usually not a problem but you need to keep it in mind. In the latter months of pregnancy, high internal body temperatures -- especially associated with dehydration -- are believed to contribute to premature labor. So it is always good to exercise moderately and drink plenty of water.

I also want to mention that to avoid over-heating the body, it is best to exercise in the early morning or late evening on hot days. And layer clothing so that when you do get hot you are able to cool the body by stripping the layers off.

Member: Are there exercises you feel are fine for the first trimester, but should be avoided as the pregnancy progresses?

Berk: The biggest is any exercises that you do flat on your back. And if you are exercising properly you also should never be holding your breath. But other than that, you can continue exercising throughout your pregnancy as long as you follow the safety guidelines.

Member: Does exercise help reduce the chances of gestational diabetes?

Berk: Actually, there is some evidence that exercise helps to utilize sugar in the blood stream and in that way reduces the incidence of gestational diabetes. We know in the general population of diabetics that exercise is included in the therapeutic regime, so it is suspected that this is also the case with women prone to gestational diabetes.

Member: Any other high-risk problems or complications that exercise helps you avoid or diminish?

Berk: From a research standpoint, it is hard to prove one way or another if exercise helps to prevent certain complications. Just because of the nature of pregnancy and the demands of a good research study. However, experts believe that exercise reduces musculoskeletal problems such as low-back problems, joint problems, and also helps to reduce the incidence of both gestational diabetes and hypertension [high blood pressure].

Exercise also improves circulation so helps any problems that may develop from slowed circulation such as phlebitis, which is an irritation of the veins usually in the legs. It would also help prevent blood clots. And many symptoms that are typically associated with pregnancy such as fatigue, ankle swelling, leg cramps, and depression -- which, by the way, has been shown to be more of an issue during pregnancy than in the postpartum period.

Member: I would like to know how to get rid of stretch marks. I am in my ninth month. I have been using olive oil regularly on my tummy. In spite of that I have ended up with lots of stretch marks. Can exercise help?

Berk: You can blame your stretch marks on your parents because whether you develop them or not has more to do with genetics than it does with anything you could have done or avoided. The good news is the further you get from the delivery of your baby the less noticeable your stretch marks will become. There are many products advertised as helpful for stretch marks, but none to my knowledge has been proved successful.

Member: If you are six months pregnant and have very bad lower-back pain, what is the best relief method?

Berk: With acute back problems it is always best to see a healthcare provider or a chiropractor who specializes in prenatal clients. Assuming you have the OK, water fitness exercises would be the ideal way to exercise. You want to keep moving and water helps decrease the weight of the pregnancy on the spine. I also recommend, if you can afford it, to receive frequent back massages from a practitioner who has training in pregnancy massage. Mother's Day is coming up, you might want to ask for that as a present.

Member: I'm a group fitness instructor and five and a half weeks pregnant. Due to fatigue and being pregnant, I need to tone down my intensity level while teaching. Any suggestions on how to tone down my intensity level and still maintain a higher impact atmosphere for my students?

Berk: That is a good question. Being a group fitness instructor myself, I understand how you want to continue teaching your class without negatively affecting your pregnancy. Studies have shown that when aerobic instructors teach a class their heart rates go a lot higher than their students' for various reasons. So what you might want to do is talk more and move less intensely. I would avoid any jumping and show your class how they can modify different exercises -- you being the example. So, you're making it a positive experience rather than focusing on the fact that you need to slow down while keeping them hyped up.

Moderator: We talked about not doing sit-ups or exercises on the back, but can you do lunges to keep the stomach and thighs toned? What other thigh exercises can be done?

Berk: One of my favorite exercises that tones both abdominal muscles and thighs is to lean against a wall and bring your hips down to the level of your knees. Take some deep breaths and as you exhale pull the belly button toward your spine. And keep doing that until you can no longer support your body on the wall. Usually after a minute or so, your thighs will tire. So take a rest and you can do this exercise several times. Lunges are fine during pregnancy. As with all exercises, just remember to use your abdominal muscles to support the spine.

One thing I haven't mentioned is the pelvic floor muscles. When you are doing lunges or doing the wall sit exercise I described, there may be a tendency for increased pressure on the pelvic floor muscles. So each time you lunge, or each time you pull the belly button toward your spine, think about pulling the opening to your birth canal up towards your belly button. That is a lot to think about, which is why I recommend pregnant women either attend pregnancy exercise classes or exercise with a pregnancy exercise video so that the instructor is reminding them of things most people may forget.

Member: I haven't been very physically active, but feel as though I need to exercise now because I've been told it makes labor easier (is this true?). One friend says to do Pilates. Another says not to start Pilates when pregnant. I don't know what it is! Can you explain Pilates and is it safe to do when pregnant?

Berk: Pilates is an excellent way to tone and strengthen the entire body after delivery and some exercises can also be done during pregnancy. However, for someone who has never done Pilates before, there are safer, less strenuous ways to accomplish the same goals during pregnancy. On the Motherwell Yoga Video we include balancing exercises on a fitness ball, which strengthen the same muscles you use in Pilates, but it is less rigorous. Also, we include many stretching and strengthening exercises on the yoga video, which Pilates had adapted for his own exercise program. So I would avoid going into a Pilates class if you are pregnant and never have done Pilates before, because it can actually cause more problems than it will help.

Member: How do I get the video you are talking about?

Berk: You can either visit our website or call 1-800-MOMWELL. If you are out of the country, you would need to dial 717-258-4641.

Member: How soon after delivery can I start doing Pilates or any other exercise program?

Berk: How soon you start exercising after delivery depends on what kind of delivery you experienced. If you have an uneventful vaginal delivery, in most cases you can start exercising two to four weeks after delivery, assuming you are no longer bleeding and you have permission to exercise from your healthcare provider. Typically, if you have had a cesarean, most physicians recommend waiting to take any formalized exercise program until the stitches have healed -- which in some cases takes four to six weeks. So it is individual and I always refer women back to their healthcare provider for getting the go ahead.

Member: I am trying to get pregnant at the moment. And I am very active. I run or bike or swim at least five to seven times a week. Are there any exercises that may not be as good or beneficial while you are trying to conceive?

Berk: Good question. In order for pregnancy to occur you need to have enough body fat -- at least 12% -- to store estrogen to support a pregnancy. So while exercise is good, more is not necessarily better, I would recommend that you exercise moderately and avoid strenuous exercise at this time so that your body is functioning in a relatively healthy state. Yoga has been shown to have a significant effect on fertility, so I would include yoga practice at least three times per week in your fitness regime.

Moderator: How do you determine your body fat percentage?

Berk: You would need to go to either a personal trainer or exercise physiologist who will take certain measurements of your body to determine your percent body fat. There are also many sophisticated machines that use water to determine body fat. But without going through extensive testing you probably know if you are underweight or not. If you tend to be underweight and you continue to exercise for long periods of time, you might want to look at your diet, make sure that it is balanced, and cut back on your exercise sessions so that your total exercise time does not exceed one hour per day. But again not knowing your individual situation, I am just making general recommendations. The best person to talk to would be your family physician, who can better determine your nutritional status and whether you need to gain more weight.

Moderator: Would you say that as long as you are menstruating and ovulating regularly, that your exercise has not caused you to be underweight to the point of affecting fertility?

Berk: Yes, if it is regular, that's correct.

Member: I love to swim. How do you rate swimming as an exercise during pregnancy? I was thinking that if I kept up with my lap swims and did Kegels, I would be in good shape.

Berk: Actually, swimming is a wonderful way to exercise aerobically. Swimming also helps to strengthen the upper body and the legs and is great for the back, but does very little to strengthen the abdominal muscles or to improve flexibility unless you consciously try to work those muscles in the water. If you love being in the water, I recommend in addition to swimming, you walk forward and backward in the water several times the length of the pool to help strengthen your abdominal muscles as well as stretch out the muscles in the legs.

It is always a good idea to cross train so you might want to swim one day, walk and do some land exercises another day, and go back and forth. This way you are avoiding overuse injuries and giving yourself a balanced exercise program.

Moderator: Before we say goodbye to you, Bonnie, do you have any final comments for us?

Berk: I would like to emphasize my philosophy of exercising during pregnancy: The goal of exercising should never interfere with the goals of a healthy pregnancy. So exercise moderately, eat nutritiously, and have a healthy pregnancy.

Moderator: We are out of time. Thanks to Bonnie Berk, CES, CPFT, for being our guest, and thank you, members, for joining us today. For more information, please visit the Motherwell website at

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