Exercise as it relates to Disease/The significance of exercise in reducing postpartum chronic disease

This wiki page is a university assignment in which the article 'Postpartum Exercise Regardless of Intensity Improves Chronic Disease Risk Factors' is critically appraised.

Davenport MH et al. (2011) Postpartum exercise regardless of intensity improves chronic disease risk factors. Med Sci Sports Exerc. 43(6):951-8.

What is the background to this research?

The study aims to find the optimal method for women to reduce their weight postpartum and their risk factor of developing chronic diseases. The study examined the effect of exercise intensity on risk factors for chronic disease postpartum. The research aimed to define whether exercise intensity plays a major role in the reduction of body max index (BMI) postpartum. This gives insight into whether women can reduce their risk of chronic disease postpartum by completing lower intensity exercise weekly or whether training at a high intensity is of higher benefit to reduce the risk of chronic disease.

Where is the research from?

The women were predominantly recruited using physician and midwife referrals and newspaper advertisements. The women recruited were located in London and Ontario. Each of the researchers are qualified in different areas specialising in pregnancy and postpartum health, creating a multidisciplinary approach. The research was funded by the Canadian Institute of Health Doctoral Research Award, which is a government funded program. The funding is independent of the research and provides no element of bias for the completion of the study.

What kind of research was this?

The study was a prospective, randomised intervention study. 40 participants were split at random to the pre-determined group types, exercise at 30% heart rate reserve (HRR) or 70% HRR. 20 participants were in the control group which completed no prescribed exercise. The need for the study came from conclusions drawn from previous research. Clinical research from the American College of Obstetricians and Gynaecologists indicated that levels of exercise participation postpartum significantly decreased. It also highlighted that postpartum exercise boasted many benefits including weight loss, improved mental wellbeing and improved cardiovascular fitness, all of which contribute to decreased risk of chronic disease (1). Other research focused on muscular strengthening including pelvic floor and abdominal training postpartum to reduce abdominal separation, a common occurrence during pregnancy and birth (2). The study in this review recognised a gap in the research related to differing exercise intensities and the impact this can have on improving health status and reducing chronic disease risk postpartum.

What did the research involve?

The participants were randomised into groups, either exercising at 30% of HRR or 70% HRR or a control group in which participants remained sedentary from delivery to 6 months postpartum. All participants completed a consent form and the study was approved by the Human Ethics Committee of The University of Western Ontario. Responses on exercise frequency and intensity was reported through a questionnaire given to each participant at 2 and 6 months postpartum. An assessment for chronic disease risk was completed to define a baseline at 7-9 weeks postpartum, and was than reevaluated at 23-25 weeks postpartum. The risk assessment included the following measurements.

• BMI
• Waist to hip ratio
• Fasted plasma lipid profile
• Total cholesterol & triglyceride
• Fasted blood biomarkers
• Plasminogen activator inhibitor
• Fasted glucose and insulin test
• Blood pressure

The two intervention groups completed a DEXA body composition assessment and a progressive treadmill test to determine baseline aerobic capacity. Infant gender, weight, length and breastfeeding status was recorded. The intervention groups were given a walking program corresponding with their given HRR. This program was completed 3-4 times per week for 16 weeks. In order to achieve the required HR participants walked, used a stroller, double stroller or carried weights. The first week comprised of 25 minutes of exercise, including a 5 minute warm-up and cool-down. Participants were required to increase session length by 5 minutes each week until they reached 45 minutes. The participants were also required to complete a researcher monitored session once weekly to record body mass, food intake and exercise intensity. Each participant was provided a pedometer to record daily and session steps. The intervention groups were also given individualised nutritional programs by a dietitian, whilst the control group were given 'Eating Well with Canada’s Food Guide' and 'Canada’s Guide to Physical Activity'.

Limitations that are evident in the measurement collections include:

• pedometers can be manipulated to increase steps taken or can be inaccurate depending on body placement
• body mass can fluctuate depending on hydration, time of day and food intake
• food intake records are often underreported

What were the basic results?

83% of the women exercised at least three times per week and completed at least 8 food intake records with a balanced caloric approach were considered to have 100% adherence to the program. Those who had been deemed adherent in the exercise groups were found to have a significantly reduced BMI, minimised weight retention, reduced waist circumference and as such a lower risk for chronic disease after 16 weeks. There was no significant difference in the results between the 2 exercise intensities. The control group which was provided with the aforementioned education materials did not reduce their chronic disease risk and remained inactive. Testing revealed that glucose tolerance levels deteriorated and body mass remained high at 6 months postpartum for the control group.

What conclusions can we take from this research?

The study concluded that postpartum women benefit from structured exercise and nutrition programs which encourage adherence and allow women to remain with their child. Reducing barriers for women to exercise is crucial in increasing levels of adherence and hence increased benefit. An article in the Journal of Women's Health also highlighted barriers such as time, structure and separation were the most common reasons women did not exercise postpartum, however once provided with a way to avoid these were more likely to be less susceptible to disease (3). The findings highlight the importance for women to commence exercise as soon as medically safe, to assist with reduced weight retention, higher levels of mental wellbeing and a lower chronic disease risk factor. In relation to the differing intensities, although there was no variance in weight loss between the two groups, other factors included a slightly reduced heart rate for the 70% HRR group which would also reduce the chances of certain chronic conditions including high blood pressure. In support of these conclusions, a study published by the European Journal of Clinical Nutrition also determined a significant correlation between postpartum exercise, reduced weight retention and reduced levels of chronic disease (4).

Practical advice

The study was clear in how women should exercise postpartum and that it should be medically supported before commencing. This is essential to implicate in real world situations, to protect women postpartum and also ensure that proper execution of any exercise is monitored. Suggestions are that women aim for 10,000 steps at least 3 times per week, ensuring consistent tracking method such as a pedometer or smart watch. Exercise should be combined with a balanced diet with a sufficient caloric intake. Combined, this advice has been proven to reduce the risk of chronic disease in postpartum women whilst also promoting higher levels of mental wellbeing.

Further information/resources

Further resources which may be of interest:

• https://hikeitbaby.com/blog/alternative-ways-to-battle-postpartum-depression/
• http://www.thepregnancycentre.com.au/post-pregnancy/exercise/the-benefits-of-exercise-after-giving-birth
• https://www.healthline.com/health/postpartum-diet

References

1. Birsner M. et al (2020) 'Physical Activity and Exercise During Pregnancy and the Postpartum Period'. The American College of Obstetricians and Gynaecologists. 804.
2. Mottola M. (2003) 'Exercise in the postpartum period: Practical applications', Current Sports Medicine Reports 1(6): 362-368
3. Evenson K et al. (2010) 'Physical Activity Beliefs, Barriers, and Enablers among Postpartum Women' Journal of Women's Health 18(12).
4. Ferrari N et al. (2021) 'Impact of physical activity on course and outcome of pregnancy from pre- to postnatal' European Journal of Clinical Nutrition