Margie H. Davenport

Nutrition and exercise prevent excess weight gain in overweight pregnant women.

PURPOSE To determine the effect of a Nutrition and Exercise Lifestyle Intervention Program (NELIP) for overweight (OW) and obese (OB) pregnant women on pregnancy weight gain, birth weight, and maternal weight retention at 2 months postpartum. METHODS This is a single-arm intervention matched by prepregnant body mass index, age, and parity to a historical cohort (4:1). Women with a prepregnancy body mass index of > or = 25.0 kg x m(-2) (N = 65) participated in a NELIP starting at 16-20 wk of pregnancy, continuing until delivery. NELIP consisted of an individualized nutrition plan with total energy intake of approximately 2000 kcal x d(-1) (8360 kJ x d(-1)) and 40%-55% of total energy intake from carbohydrate. Exercise consisted of a walking program (30% HR reserve), three to four times per week, using a pedometer to count steps. Matched historical cohort (MC; N = 260) was from a large local perinatal database. RESULTS Weight gained by women on the NELIP was 6.8 +/- 4.1 kg (0.38 +/- 0.2 kg x wk(-1)), with a total pregnancy weight gain of 12.0 +/- 5.7 kg. Excessive weight gain occurred before NELIP began at 16 wk of gestation. Eighty percent of the women did not exceed recommended pregnancy weight gain on NELIP. Weight retention at 2 months postpartum was 2.2 +/- 5.6 kg with no difference between the OW and the OB women on NELIP. Mean birth weight was not different between NELIP (3.59 +/- 0.5 kg) and MC (3.56 +/- 0.6 kg, P > 0.05). CONCLUSIONS NELIP reduces the risk of excessive pregnancy weight gain with minimal weight retention at 2 months postpartum in OW and OB women. This intervention may assist OW and OB women in successful weight control after childbirth.

A walking intervention improves capillary glucose control in women with gestational diabetes mellitus: a pilot study

Exercise prescriptions that can be translated into clinical recommendations are clearly needed for women with gestational diabetes mellitus (GDM). A pilot project was developed to document the effectiveness of a structured low-intensity walking protocol on capillary glucose control in GDM women. Ten GDM women followed conventional management of diet and insulin therapy, plus a low-intensity walking program (W) from diagnosis to delivery. Capillary glucose concentrations, insulin requirements, and pregnancy outcomes were compared with a matched cohort by body mass index (BMI), age, and insulin usage (20 GDM women who followed conventional management alone (C)). Baseline capillary glucose concentrations were not significantly different between the W and C groups. The W group had an average acute drop in capillary glucose concentration from pre- to post-exercise of 2.0 mmol x L(-1). In addition, the W group had significantly lower mean glucose concentrations in the fasted state and 1 h after meals than the C group in the week prior to delivery. These lower glucose concentrations were achieved while requiring fewer units of insulin per day (C, 0.50 +/- 0.37 U x kg(-1); W, 0.16 +/- 0.13 U x kg(-1); p < 0.05), injected less frequently. These results suggest an effective role in glucose regulation for this structured walking program.

Development and validation of exercise target heart rate zones for overweight and obese pregnant women

Validated target heart rate (THR) zones for exercise prescription for overweight and obese pregnant women have not been developed. The purposes of this study were to determine if heart rate reserve (HRreserve) is best described by aerobic capacity at peak exercise or by aerobic capacity reserve (VO2 reserve) and to develop and validate THR zones for light-intensity exercise (20%-39%VO2 reserve) in sedentary overweight and obese pregnant women. One hundred six women between 16 and 20 weeks gestation with medical clearance performed a progressive treadmill test to volitional fatigue (peak). Data from every 4th subject were used for cross-validation. Two linear regression equations were performed for each subject, then pooled to obtain mean group values (+/- SD): %HRreserve vs. %VO2 peak and %HRreserve vs. %VO2 reserve. THR zones equivalent to 20%-39%VO2 reserve were developed and validated based on the strongest relationship. %HRreserve had a stronger linear relationship with %VO2 reserve (y = 1.046x -7.561; R2 = 0.741) than %VO2 peak (y = 1.259x -28.795; R2 = 0.604). Validated THR ranges for sedentary overweight and obese pregnant women are 102-124 beats.min-1 (20-29 years of age) and 101-120 beats.min-1 (30-39 years of age), representing an exercise intensity of 20%-39%VO2 reserve as recommended by the American College of Sports Medicine for previously sedentary pregnant women. Overweight and obese women who are medically prescreened can exercise during pregnancy within our validated THR zones. The relationship between HR and VO2 remains strong, but the two are not equivalent in this population group.

Timing of excessive pregnancy-related weight gain and offspring adiposity at birth.

OBJECTIVE: To evaluate whether the timing of excessive maternal weight gain in a cohort of women following current guidelines for healthy living during pregnancy affects neonatal adiposity at birth. METHODS: One hundred seventy-two healthy women who were at least 18 years old with body mass indexes (BMIs) of at least 18.5 were recruited between 16 weeks and 20 weeks of gestation. The cohort followed healthy living guidelines during pregnancy and were retrospectively grouped according to 2009 Institute of Medicine guidelines for weight gain in the first and second halves of pregnancy: 1) appropriate gestational weight gain (ie, within Institute of Medicine recommendations) in the first and second halves of pregnancy (“overall appropriate”); 2) appropriate gestational weight gain in the first half of pregnancy and excessive gestational weight gain in the second half of pregnancy (“late excessive”); 3) excessive gestational weight gain in the first half of pregnancy and appropriate gestational weight gain in the second half of pregnancy (“early excessive”); and 4) excessive gestational weight gain throughout pregnancy (“overall excessive”). Primary measures included neonatal weight, length, BMI, and body fat at birth measured 6–18 hours after delivery. Neonatal body fat greater than 14% was considered excessive. RESULTS: Neonates of women who gained excessively in the first half of pregnancy exhibited greater heel-crown length, birth weight, and excessive body fat (“early excessive” 17.5±3.1%, “overall excessive” 18.7±3.3%) compared with those born to women who gained appropriately (“overall appropriate” 13.2±4.1%; “late excessive” 14.7±3.3%; P<.01). Neonates of women who gained excessively in the first half of pregnancy had an increased risk (odds ratio [OR] 2.64, 95% confidence interval [CI] 1.35–5.17) of elevated body fat at birth compared with neonates of women with total excessive weight gain (OR 1.49, 95% CI 0.80–2.79). CONCLUSION: Timing of excessive weight gain is an important factor influencing neonatal morphometrics. Prevention of early excessive weight gain should be encouraged in the period before conception and reinforced early in pregnancy. LEVEL OF EVIDENCE: II

The effect of supervised prenatal exercise on fetal growth: a meta-analysis

OBJECTIVE: To estimate the influence of structured prenatal exercise on newborn birth weight, macrosomia, and growth restriction. DATA SOURCES: A structured search of MEDLINE, EMBASE, CINAHL, Sport Discus, Ovids All EBM Reviews, and ClinicalTrials.gov databases up to January 13, 2015. The search combined keywords and MeSH-like terms including, but not limited, to “physical activity,” “exercise,” “pregnancy,” “gestation,” “neonatal,” and “randomized controlled trial.” METHODS OF STUDY SELECTION: Articles reporting randomized controlled trials comparing standard care with standard care plus supervised prenatal exercise for which birth size was available were included. Supervision was defined as at least one exercise session performed with study personnel every 2 weeks throughout the program. Interventions consisting solely of pelvic floor exercises, stretching, or relaxation were excluded. Our search yielded 1,036 publications of which 79 were assessed for eligibility. Twenty-eight studies reporting on 5,322 pregnancies were subsequently included in the analysis. TABULATION, INTEGRATION, AND RESULTS: Our meta-analysis demonstrated that prenatal exercise reduced the odds of having a large newborn (birth weight greater than 4,000 g or greater than the 90th percentile for gestational age and sex) by 31% (odds ratio [OR] 0.69, 95% confidence interval [CI] 0.55–0.86; I 2 25%) without altering the risk of having a small newborn (birth weight less than 2,500 g or less than the 10th percentile for gestational age and sex) (OR 1.02, 95% CI 0.72–1.46; I 2 0%) or gestational age at delivery (weighted mean difference −0.00 weeks, 95% CI −0.09 to 0.09; I 2 0%). Newborns of mothers assigned to exercise were lighter than those of nonexercising controls (weighted mean difference –31 g, 95% CI –57 to −4; I 2 0%). Maternal gestational weight gain (weighted mean difference −1.1 kg, 95% CI −1.5 to −0.6; I 2 53%) and odds of cesarean delivery (OR 0.80, 95% CI 0.69–0.94; I 2 0%) were also reduced. CONCLUSION: These data demonstrate that structured prenatal exercise reduces the risk of having a large newborn without a change in the risk of having a small newborn.

Effect of exercise intensity and duration on capillary glucose responses in pregnant women at low and high risk for gestational diabetes

Exercise may influence glucose metabolism during pregnancy. We examined the effect of exercise intensity and duration on capillary glucose responses in pregnant women at low and high risk for gestational diabetes mellitus (GDM) who followed a modified GDM meal plan.

Nutrition and Exercise Reduce Excessive Weight Gain in Normal-Weight Pregnant Women

PURPOSE This study aimed to evaluate the effect of an exercise program of two different intensities, with nutritional control, on gestational weight gain (GWG), infant birth weight, and maternal weight retention at 2 months postpartum (2 mopp). METHODS Pregnant women (prepregnancy body mass index = 18.5-24.9 kg·m) were randomized at study entry (16-20 wk of gestation) to a low-intensity (LI, 30% HR reserve (HRR), n = 23) or moderate-intensity (MI, 70% HRR, n = 26) exercise program, with nutritional control. The exercise program consisted of walking sessions three to four times per week, gradually increasing exercise time from 25 to 40 min per session. Forty-five normal-weight women who did not participate in any structured exercise program during pregnancy and had singleton births were used as a historical control group. RESULTS Total GWG was higher in the control group (18.3 ± 5.3 kg) compared with the LI (15.3 ± 2.9 kg, P = 0.01) and MI (14.9 ± 3.8 kg, P = 0.003) groups. During the intervention, GWG was similar in both intervention groups, with weekly rates of weight gain of 0.49 ± 0.1 and 0.47 ± 0.1 kg·wk in the LI and MI groups, respectively. Excessive GWG during the intervention was prevented in 70% of the women in the LI group and 77% of those in the MI group. Excessive GWG occurred before the intervention began. At 2 mopp, 18% and 28% of the women in the LI and MI groups, respectively, retained ≤2.0 kg compared with only 7% of those in the control group. Infant birth weight was not different between the groups. CONCLUSIONS Results suggest that a prenatal nutrition and exercise program regardless of exercise intensity, reduced excessive GWG and decreased weight retention at 2 mopp in women of normal weight before pregnancy.

The brain-in-motion study: effect of a 6-month aerobic exercise intervention on cerebrovascular regulation and cognitive function in older adults

BackgroundAging and physical inactivity are associated with declines in some cognitive domains and cerebrovascular function, as well as an elevated risk of cerebrovascular disease and other morbidities. With the increase in the number of sedentary older Canadians, promoting healthy brain aging is becoming an increasingly important population health issue. Emerging research suggests that higher levels of physical fitness at any age are associated with better cognitive functioning and this may be mediated, at least in part, by improvements in cerebrovascular reserve. We are currently conducting a study to determine: if a structured 6-month aerobic exercise program is associated with improvements or maintenance of both cerebrovascular function and cognitive abilities in older individuals; and, the extent to which any changes seen persist 6 months after the completion of the structured exercise program.Methods/designTwo hundred and fifty men and women aged 55–80 years are being enrolled into an 18-month combined quasi-experimental and prospective cohort study. Participants are eligible for enrollment into the study if they are inactive (i.e., not participating in regular physical activity), non-smokers, have a body mass index <35.0 kg/m2, are free of significant cognitive impairment (defined as a Montreal Cognitive Assessment score of 24 or more), and do not have clinically significant cardiovascular, cerebrovascular disease, or chronic obstructive pulmonary airway disease. Repeated measurements are done during three sequential six-month phases: 1) pre-intervention; 2) aerobic exercise intervention; and 3) post-intervention. These outcomes include: cardiorespiratory fitness, resting cerebral blood flow, cerebrovascular reserve, and cognitive function.DiscussionThis is the first study to our knowledge that will examine contemporaneously the effect of an exercise intervention on both cerebrovascular reserve and cognition in an older population. This study will further our understanding of whether cerebrovascular mechanisms might explain how exercise promotes healthy brain aging. In addition our study will address the potential of increasing physical activity to prevent age-associated cognitive decline.

Postpartum Exercise Regardless of Intensity Improves Chronic Disease Risk Factors

PURPOSE Women who are unable to return to a healthy weight by 6 months postpartum increase their risk factors for the development of chronic disease (CD; including metabolic syndrome, obesity, and cardiovascular disease). In a prospective randomized intervention study, we examined the effect of exercise intensity on risk factors for CD in the postpartum. We hypothesized that women receiving an intervention targeting healthy weight loss would have improved CD risk factors compared with women not receiving the intervention. Further, we hypothesized that nutrition control and moderate-intensity exercise would have the greatest improvement in CD risk factors versus low-intensity exercise. METHODS Women were randomly assigned to a nutrition plus low-intensity (30% HR reserve; n = 20) or moderate-intensity (70% HR reserve; n = 20) exercise intervention group. The program consisted of supervised walking for 45 min, three to four times per week for 16 wk. All women were screened for CD at the beginning (7-8 wk postpartum) and at the end (23-25 wk postpartum) of the study. A historical control group of 20 sedentary postpartum women was matched by body mass index, age, and parity. RESULTS The low- and moderate-intensity groups lost more body mass (-4.2 ± 4.0 and -5.0 ± 2.9 kg, respectively) compared with the control group (-0.1 ± 3.3 kg, P < 0.01). Plasma low-density lipoprotein was reduced for the low- and moderate-intensity groups (-0.29 ± 0.21 and -0.28 ± 0.17 mmol · L) compared with the control group (0.03 ± 0.18 mmol · L, P = 0.015). In addition, glucose concentrations were reduced and adiponectin concentrations increased (P = 0.037), regardless of exercise intensity, although the sedentary controls remained unchanged or at increased risk for CD. CONCLUSIONS Women receiving a postpartum intervention targeting healthy weight loss, regardless of exercise intensity, improved CD risk factors compared with women not receiving the intervention.

Impact of pregnancy and obesity on cardiorespiratory responses during weight-bearing exercise.

The present study is the first to compare the cardiorespiratory responses during progressive weight-bearing treadmill exercise in normal-weight non-pregnant (NP, n=14), normal-weight pregnant (PG, n=20) and obese pregnant (PGOB, n=20) women. Exercise duration and peak treadmill speed were lower in PG (23.9+/-4.9 min; 1.6+/-0.2m/s; P<0.001) compared to NP (33.7+/-4.9 min; 2.0+/-0.2m/s) and were further reduced in PGOB (19.6+/-2.8 min; 1.4+/-0.1m/s; P<0.001) indicating a performance limitation to exercise. Ventilation in response to exercise was increased in PG (49.4+/-6.6L/min) compared to NP (39.8+/-5.4 L/min, at 100W; p<0.05) women, and was further augmented by obesity (56.7+/-9.3 L/min, at 100W; p<0.05 versus PG) secondary to an elevated metabolic cost of exercise as indicated by no further increase in .V(E)/.V(CO2) and .V(E)/.V(O2) in PGOB compared to PG women. The normal augmentation of heart rate observed in PG during exercise was not further increased by obesity at standardized sub-maximal work rates.