Post by Rachel Duffy and Glen Pyle

With the new social distancing practices and most non-essential businesses closed, people are finding creative ways to maintain their cardiovascular health. Challenges on social media are popping up asking people to film a portion of their home workout routine, or to do a specific number of push-ups, all in an attempt to promote staying active while we all work to “flatten the curve”. Throughout all this creativity, a simple and minimalist activity seems to have been overlooked.

Walking. Putting one foot in front of the other not only maintains cardiovascular health: it decreases risk factors associated with cardiovascular disease.

A Simple Step

Even though walking is a simple way to exercise, many people see walking like any other physical activity: no pain, no gain. The World Health Organization recommends that people participate in a moderately intense aerobic exercise program for at least 150 minutes a week. But research suggests that sweating your way through the COVID pandemic may not be necessary to keep the cardiovascular system fit and healthy.

A Stroll in the Park

A 2016 study followed 60 women from Delaware County in New York state to determine if a modest walking program could reduce cardiovascular disease risk factors including blood pressure, serum cholesterol, high-density lipoprotein (HDL) levels, and obesity.

High blood pressure – or “hypertension” – is defined as a blood pressure greater than 130 mmHg/80 mmHg. Hypertension arises from abnormal constriction of the arteries or blockage of blood vessels. Cholesterol is a waxy-like substance that is made by the body and plays a critical role in a number of biological functions. But diets rich in fats can increase cholesterol levels beyond what is needed, and excessive cholesterol sticks to the walls of blood vessels. These cholesterol plaques decrease blood flow and increase the risk of ischemia, stroke, and heart attacks. HDL helps to remove excess cholesterol and is protective against cardiovascular disease. Finally, body mass index (BMI) measures the relationship between height and weight, and is a way to quantify the level of obesity.

Women in the study had an average BMI of 30.8 kg/m2, which is just above the obesity threshold of 30.0 kg/m2. Average blood pressure was 132 mmHg/80 mmHg, while cholesterol levels were 201 mg/dL. Both of these values are above recommended levels. HDL was measured at 56 mg/dL which is within the normal range, but below the desirable threshold of 60 mg/dL. In short, while the cardiovascular risk factors were not dangerously high in this cohort of women, they were all borderline unhealthy and represented real risks for cardiovascular health.

Women were asked to walk briskly for 150 minutes each week for 10 weeks. A “brisk walk” is defined as a pace of >100 steps per minute. At the end of the walking program women showed significant improvements for each risk factor measured. Blood pressure values dropped below the threshold of hypertension to an average of 127 mmHg/79 mmHg, and cholesterol levels dropped an average of 6.22 mg/dL, which also brought values into the normal range. HDL – the “good” cholesterol – increased slightly and women lost an average of 3.1 lbs which significantly decreased BMI. Although the change in each individual parameter was relatively small, together these changes decreased the 10-year cardiovascular risk after just 10 weeks of walking.

Walking through a forest landscape

Walking a Well-Word Path

While the study by Marigliano and colleagues offers some new insight into the ability of a modest walking program to decrease cardiovascular risk factors, it was not the first study to show the health benefits of walking. A review of the scientific literature by Public Health England in 2017 reported that as little as 10 minutes of daily walking had a positive impact on cardiovascular, musculoskeletal, and mental health. A 2018 meta-analysis of 38 studies found that even modest amounts of regular walking reduced cardiovascular risk factors. However, unlike the study by Marigliano, the meta-analysis found no significant impact on cholesterol or HDL levels. Overall these studies show that modest levels of regular walking have positive impacts on cardiovascular health.

The Power of Walking

Modest levels of walking reduce cardiovascular disease risk, but can this simple and low intensity intervention benefit people who are already at high risk for cardiovascular disease? Lee et al examined the impact of physical activity on 39,372 women, including some who were smokers, overweight, or had high levels of serum cholesterol. The study found that light to moderate walking for as little as 1 hour a week decreased coronary heart disease rates even in women with high cardiovascular disease risks. Interestingly, they found that the duration of walking was more important than intensity.

A Big Return on a Small Investment

Regardless of what the threshold is for maximum effect, studies agree that light to moderate exercise has benefits for cardiovascular health. Some people with cardiovascular disease have physical limitations that limit their participation in exercise programs. However, walking is a widely accessible activity that acts as a low intensity entry point into exercise. It causes few musculoskeletal or orthopedic problems, requires no special equipment, and it offers mental health benefits as well as physical ones. Even in the COVID19 pandemic walking outside is encouraged for everyone, as long as social distancing guidelines are followed.

Woman walking her dog.

The Heart of a Pandemic

Cardiovascular health is always important, but it is particularly significant during the COVID19 pandemic. Mortality rates among people with pre-existing cardiovascular disease are higher than average, and 50% higher than even those with chronic respiratory conditions. Several studies have reported that the virus is associated with heart damage, which may explain why people with heart disease are more likely to experience severe cases and higher rates of mortality. The link between viral infection, cardiovascular disease, and high mortality is not new or unique to COVID19: a 1932 study of influenza outbreaks in the United States between 1917 and 1932 found that up to half of the deaths attributed to the outbreaks were linked to cardiovascular disease.

Take the Next Step Towards a Healthy Heart

During this historic but isolating time, do yourself a favour: turn off Netflix, get off the couch, and get outside for a refreshing walk. Not only will it clear your mind and rid yourself of the stuffy indoor air, but you will also be walking yourself to a healthier heart. Just remember that during your outdoor walk, if you run into other pedestrians, try to remain a safe 6 feet (2 meters) away to do your part to flatten the curve.