Any exercise is good for expectant mothers and their babies. But recent studies show that resistance exercise is better than aerobic exercise, and a combination of both has the largest positive effects on both mother and baby, particularly when the mother-to-be is obese.
Such were the findings presented by Linda May, PhD, MS, FAHA, Associate Professor in the School of Dental Medicine and Adjunct Faculty Assistant Professor of Exercise Physiology and Obstetrics and Gynecology in the Brody School of Medicine, East Carolina University, on the effects of exercise interventions for preventing gestational diabetes at the 82nd Scientific Sessions.
Dr. May was one of four panelists who spoke during Exercise in Pregnancy — Benefits for Mothers and Offspring on Sunday, June 5. The session was live streamed and can be viewed on-demand by registered meeting attendees at ADA2022.org. If you haven’t registered for the 82nd Scientific Sessions, register today to access the valuable meeting content.
One of the studies that Dr. May cited looked at baseline measurements of pregnant women—some obese, some not—at 16 weeks and then post-intervention measurements at about 36 weeks. The study compared four groups of women: a control group that didn’t change its activity level, a group that did aerobic exercise, a group that did resistance exercise, and a group that did a combination of aerobic and resistance exercise.
Overall, the women who exercised had greater levels of docosahexaenoic acid (DHA) in late pregnancy than the control group, Dr. May noted. DHA helps mothers deliver on time, is good for placentas, helps control the mother’s lipids, and is essential for the baby’s growth and development, especially their nervous systems.
The resistance exercise group also saw the largest decreases in blood glucose levels and body fat and an increase in lean mass, especially in women with gestational diabetes.
But the greatest change from the first to third trimester was in the group that did both resistance and aerobic exercise. The overweight/obese population within this group saw the biggest improvements by decreasing their gestational weight gain and lipid levels, Dr. May said. The lower weight gain decreased the rates of C-sections and the duration of hospital stays.
Researchers also found that the DHA levels of black women who exercise are the same as those of Caucasian women who exercise.
“That’s very exciting, because we’ve also reported that our black women who exercise have less preterm births and less low birth weights, and so that fits with helping to normalize their birth outcomes, or attenuating that racial disparity,” Dr. May said.
Studies of fetal stem cells showed that any exercise by the mother increased the insulin sensitivity and improved the oxidative capacity in infants, she continued. Resistance exercise showed stronger improvements than aerobic exercise, and the two combined were the best.
The benefits of this exercise continued beyond birth. At four weeks, the babies of overweight and obese women who exercised had less body fat, improved motor outcomes, and increased metabolic rates at rest. The babies tracked similarly at six months old, with decreased triglycerides as well as glucose load compared to the other babies.
Samantha Ehrlich, PhD, MPH, Assistant Professor, University of Tennessee at Knoxville, highlighted several studies involving women with gestational diabetes who were given prepackaged meals and then randomized to either walk for 30 minutes or to sit after meals. Using continuous glucose monitoring systems, researchers found a statistically significant reduction in glucose levels in the walking groups during all of the studies, but the time of day of the exercise seems to have varying effects.
Dr. Ehrlich said behavioral counseling interventions should include such key ingredients as setting goals, tracking progress, and getting feedback on those goals from a lifestyle coach.
“Ultimately, we hope to, at some point, have a physical activity prescription that maybe even includes a target for the time of day you should be doing physical activity,” she said. “And we believe that adding these types of targets will help to guide behavior counseling in the clinical setting.”
Ana Barbara Alves Wagner, PhD, Joslin Diabetes Center, spoke about the impact of exercise during pregnancy on offspring programming.
Research has shown that if the mother is obese during pregnancy, there is an increased risk for the offspring to develop obesity during childhood and type 2 diabetes during adulthood. And this detrimental cycle may propagate to future generations.
Dr. Wagner and her colleagues have been studying mouse models to learn if increased physical activity of mothers will improve the metabolic phenotype of those future generations.
They have found that maternal exercise before and during pregnancy improves the metabolic health of male and female offspring and prevents the deleterious effects of maternal high-fat feeding, she said. It also activates protein kinase (AMPK), which plays critical roles in regulating growth and reprogramming metabolism in offspring, leading to epigenetic changes that improve glucose tolerance.
Dr. Ehrlich also explained how exercise stimulates the AMTK signaling in the mother, leading to DNA methylation in offspring.
Sylvia Badon, PhD, Staff Scientist and Perinatal Epidemiologist, Kaiser Permanente Northern California Division of Research, discussed how sedentary behaviors and 24-hour energy expenditure affects diabetes during pregnancy.
She cited a study of 20 women with gestational diabetes who all ate the same breakfast two days in a row, then sat for two hours one day and took a leisurely walk for the hour after eating on the second day. There was a marked decrease in one-hour postprandial glucose levels with light-intensity walking compared to sitting after eating.
Dr. Badon said more studies need to be done looking at normal glucose tolerance during pregnancy and how behavior replacements, such as replacing sedentary time with exercise, may change across pregnancy, as well as whether some replacements may be more impactful for gestational diabetes prevention or management. This should also extend to pre-pregnancy diabetes management, she added.
“There is plenty of additional research that can be done to understand 24-hour movement and behavior replacements on glucose metabolism in pregnancy, both in the context of gestational diabetes and non-gestational diabetes,” she said.