Exercise and Strength Training in Postmenopausal Women at Risk for Cardiovascular Disease: Need for Strategies to Improve Adherence

The focus on sex and gender research on cardiovascular disease (CVD) has resulted in a 30% decline in the number of women dying from CVD. The decreased mortality rate, specifically due to ischemic heart disease (IHD), which is due to coronary atherosclerotic disease (CAD), has been attributed to an increase in awareness, greater focus on women and their cardiovascular (CV) risk, and the application of evidence-based treatments for the prevention and management of established IHD. ^1,2

An expanded view of the multifactorial epidemiology of IHD in women has identified important risk factors with an adverse effect on CAD, including race, culture, ethnicity, lifestyle influences, and age. ² In women, menopause marks an important biological transition, with the evidence demonstrating a significant increase in the risk for IHD in women older than 55 equaling those of men over the age of 45. ^{2 –4} Estrogen loss at the time of menopause has consistently been shown to have a negative impact on arterial function, prothrombotic factors in the blood ³ adversely alter cholesterol levels with increasing low-density lipoprotein (LDL) and triglycerides, decreasing high-density lipoprotein (HDL), and elevated levels of apolipoprotein B. Higher prevalence of the metabolic syndrome has also been shown in women who are postmenopausal, with increasing truncal obesity and abnormal response to glucose. ^4,5 Early menopause—whether natural or surgically induced—has been shown to significantly increase a woman's risk for IHD and stroke. ⁴

Our understanding of the biological changes and increased risk for IHD with menopause mandates a call to action for clinicians to foster and promote the implementation of prevention strategies for women at risk. Along these lines, the evidence supports a focus on the modifiable risk factors for IHD, including the promotion of behavioral factors of smoking cessation, weight control, healthy diet, and physical activity. Chronic inactivity has been shown to reduce aerobic or cardiorespiratory fitness, which in turn has been shown to be an important and distinct measure of CV risk. ^6,7 Physical activity has been consistently demonstrated to reduce risk for CVD with benefits of weight reduction, improvement in blood pressure, lowered LDL, increased HDL, and improved insulin sensitivity. ⁸ In a study involving 1.1 million women without prior vascular disease, who were followed over an average of 9 years, those who reported moderate activity were found to be at lower risk of CAD and CV events. ⁹

The benefits of exercise and strength training also include the non- CV effects of improved cognitive function, reduced risk of certain cancers, and decreased rates of anxiety and depression. ^8,10,11

Given the documented CV benefits of physical activity and strength training, it is critical to determine the rate of adherence among women at risk for IHD to the AHA guideline recommendations of a minimum of 150 minutes of activity and two sessions of strength training weekly for the improvement of CVD risk factors and outcomes? ¹²

In this month's issue of this journal, Ball et al. provide insight into the exercise habits and barriers to physical activity over a 5-year period in a cohort of 216 menopausal women at low–intermediate risk for CVD as determined by the Framingham Risk Score (FRS). ¹³ The cohort (62% hypertensive, 15% diabetic, and 52% prior or current smokers) were enrolled in the SMART (stress echocardiography in menopausal women at risk for coronary artery disease trial) and followed from 2004 to 2007. This prospective substudy evaluated the self-reporting physical activity in peri- or postmenopausal women with chest pain or CV risk factors based on body mass index (BMI). In the three groups of women (obese, overweight, and normal), the SMART investigators hypothesized that women with known risk for CAD and an elevated BMI at baseline may be more motivated to include aerobic exercise on a regular basis. Contrary to their expectations, at 5-year follow-up, there was no significant relationship between women's BMI and their inclination to change their self-reported physical activity habits over a 5-year period without intervention. Of note, risk of CV did not translate into increased physical activity, as women with a low FRS at baseline were more likely than their intermediate risk peers to increase their physical activity over 5 years (34.3% vs. 7.1%, p = 0.0601). The women in the cohort cited lack of time and lack of motivation as barriers to achieving or maintaining an adequate level of physical activity. An additional important finding was the overall low participation in strength training among all women, regardless of baseline BMI. ¹³

This study provides a real-world view of adherence to an exercise and strength training routine in a relatively homogeneous cohort of women (91% white) at low–intermediate risk for CAD. ¹³ We agree with the SMART investigators that there is an urgent need for clinicians to issue an exercise prescription and education for all women, especially those at risk for CVD about the important benefits of physical activity irrespective of their baseline BMI.

A recent publication on exercise adherence and associated health outcomes from a cohort from the Training Interventions and Genetics of Exercise Response (TIGER) study ¹⁴ highlights a few methods to enhance adherence to exercise programs. In the study, the participants who used a heart rate monitoring device demonstrated improvements adherence to physical activity that resulted in significant improvement in several CV parameters. ¹⁴ As heart rate monitoring is an objective, practical measure of physical activity and presents low interference with normal activities, it can be used to teach individuals how to exercise at a level most likely to elicit physiological change. ¹⁴ This finding raises the importance of exploring the use of a “physical activity prescription” using fitness trackers for the self-evaluation of daily physical activity in women at risk for IHD.

The CV health benefits associated with physical activity and strength training are well established. ¹⁵ The importance of education on the CV benefits of physical activity and strength training including a discussion on methods to increase frequency of aerobic activity and weight training is key to improve adherence and reduce the risk of IHD in women. Focused research is needed in this area and must include the identification of the unique barriers and best practices to minimize these barriers, so as to establish customized prescriptions for the improvement in the frequency of aerobic activity and strength training in the primary and secondary prevention of IHD in women. ¹⁶