Interesting Psychology Team
4. Exercise just the right amount
I am always amazed at the life cycle of wildebeests. They are best known for their spectacular annual migrations in the plains and open woodlands of Tanzania and Kenya, thousands upon thousands in hypnotic, constant motion. They move for two reasons. First and foremost, they are looking for new pastures. But they are also 600-pound steaks on legs; they have to keep moving because they are very popular with predators.
Given this urgency, the most interesting part of their life cycle is their pregnancy and birth. The gestation is nearly as long as a human’s, about 260 days, but the similarities end as soon as labor begins. The mother gives birth quickly. Unless there are complications, she also recovers quickly. So do the calves, typically rising to their feet—well, hooves—an hour after they’re born. They have to. Calves represent the herd’s future, but they are also the herd’s most vulnerable population, liable to become leopard food.
We, too, spent our evolutionary adolescence on these same savannahs, and we share many of the wildebeests same predator/prey problems. There are, you might imagine, major differences in birthing and parenting between wildebeests and humans. Women take a long time to recover from birth (it’s that big, overweight brain again, evolution’s secret weapon, forcing itself through a narrow birth canal), and their kids won’t be walking for almost a year. Nonetheless, evolutionary echoes imply that exercise was very much a part of our lives, including during pregnancy. Anthropologists think we walked as many as 12 miles per day.
Fit women have to push less
Does that mean exercise should be a part of human pregnancies? Evidence suggests the answer is yes. The first benefit is a practical one, having to do with labor. Many women report that giving birth is both the most exhilarating experience of their lives and the most painful. But women who exercise regularly have a much easier time giving birth than obese women.
For fit women, the second stage of labor—that painful phase where you have to do a lot of pushing—lasts an average of 27 minutes. Physically unfit women had to push for almost an hour, some far longer. Not surprisingly, fit women perceived this stage as being far less painful.
And, because the pushing phase was so much shorter, their babies were less likely to experience brain damage from oxygen deprivation. If you are afraid of labor, you owe it yourself to become as fit as possible going into it. And the reasons are argued purely from the Serengeti.
Exercise buffers against stress
Fit mothers also tend to give birth to smarter babies than obese mothers do. There are two reasons for this. One may have to do with direct effects of exercise—especially aerobic exercise—on a baby’s developing brain. This notion needs more research. More powerful are the data linking aerobic exercise and stress reduction.
Certain types of exercise actually buffer a pregnant woman against the negative influence of stress. Remember those toxic glucocorticoids, the ones that invade neural tissue and cause brain damage? Aerobic exercise elevates a molecule in your brain that can specifically block the toxic effects of those nasty glucocorticoids.
This heroic molecule is termed brain-derived neurotrophic factor. More BDNF means less stress, which means fewer glucocorticoids in your womb, which means better baby brain development.
It may sound strange to say, but a fit mom has a much better chance of having a smart baby—or at least one best able to mobilize his or her IQ—than an unfit mom.
Too strenuous, and baby overheats
As usual, though, there’s a balance. A baby can feel and react to the mother’s motion. When her heart rate goes up, so does baby’s. When mom’s breathing rate increases, so does baby’s. But only if the exercise is moderate. During strenuous exercise, especially in the later stages of pregnancy, the baby’s heart rate begins to decline, as does his breathing.
Overly strenuous exercise begins to shut off blood flow to the womb, restricting baby’s oxygen supply—not good for the brain. The womb can overheat, too. Elevations of more than 2 degrees Celsius raise the risk of miscarriage and can affect brain and eye development. Your oxygen reserve levels are pretty low by the third trimester anyway, so it’s a good time to wind down strenuous activities in preparation for labor. Swimming is one of the best forms of exercise in later stages; the water helps dissipate excess heat away from the womb.
What is the proper balance? Four words: moderate, regular aerobic exercise. For most women, that means keeping your heart rate below 70 percent of its maximal rate (which is 220 beats per minute minus your age), then slowing things down as the due date approaches. But you should exercise. As long as you don’t have obstetric or other medical complications, the American College of Obstetricians recommends 30 minutes or more of moderate exercise per day.
Good advice, even though we are not wildebeests.
Every little bit counts
Maybe you’re not in the habit of exercising every day. Maybe you’re feeling guilty enough already for drinking that second cup of coffee while pregnant. If so, perhaps you will appreciate some reassurance from the research world: As a species, Homo sapiens have been successfully making babies for 250,000 years.
We did very well without all this fancy knowledge, thank you, and with such success that we conquered the world. Your best intentions—Morse code belly-tapping notwithstanding—will go a long way toward creating a great environment for your Baby Brain Development.
