Many people believe that the main aim of regular exercise or physical activity is weight loss. As a result, many individuals try to cut corners to lose weight without partaking in regular physical activity. Clinical evidence has suggested (for many years) that lower resting heart rates result of regular physical activity and exercise. However, scientific research has identified and displayed the strong correlation between your resting heart rate and the likelihood of many diseases including heart disease and diabetes. Therefore, it gives credence to the fact that the main focus of regular exercise is to improve fitness which subsequently can protect the body from diseases that weight loss alone cannot achieve.

Defining Resting Heart Rate

Resting heart rate refers to the number of heartbeats per minute, while at rest.
In general, resting heart rate for adults varies between 60 and 100 beats per minute. It’s generally accepted that a lower resting heart rate is a sign of improved fitness levels, elite athletes can often display resting heart rate in the 40s.

Resting Heart Rate & Fitness

Although widely accepted that lower resting heart rates are an indication of improved fitness level, the exact mechanism and pathway are not well known. Put simply, the heart is a muscle that automatically works to contract and propel blood around the body. At rest, we all have a minimum amount of oxygen and nutrients (via the blood) that our body needs to stay alive and the heart works to provide that in an efficient manner. If your heart is strong enough to supply that basic, minimum level in fewer beats it’s reasonable to conclude that the heart muscles are able to propel the blood further in each beat which indicates improved fitness.
There are also other factors at work such as the peripheral tissues becoming more efficient at accepting oxygen and nutrients from the blood which also helps to reduce the amount of work the heart needs to put in.
Although weight loss can reduce resting heart rate by reducing the amount of cells that need blood supply, weight loss alone does not generate sufficient stress to cause an improvement in fitness/heart strength.

The Framingham Study

• Observational Study
• 4052 Subjects Were Followed Over approx. 20 Year Period
• Compared Resting Heart Rate, Diabetes, Blood Pressure, Cholesterol and Smoking Status as well as future cardiovascular disease development.

Results

“Older age, female [gender], higher diastolic BP, higher BMI, diabetes, smoking, and lower HDL cholesterol were all associated with higher resting heart rate”

• “Higher physical activity as measured by the physical activity index was associated with a small but significant decrease in resting heart rate”
• Baseline resting heart rate predicted incident cardiovascular disease
• Each 1-SD (11 bpm) increase in baseline heart rate was associated with a 15% increased risk of cardiovascular disease
• With each 1-SD (11bpm) increase in baseline heart rate associated with a 32% increased risk of future heart failure
• Resting heart rate was associated with higher risk of coronary heart disease and stroke in age- and sex-adjusted analyses
• lower resting heart rate was associated with a 40% increased risk of requiring permanent pacemaker placement (Asymptomatic bradycardia [low heart rate] has been associated with higher rates of pacemaker implantation in older patients)
• Resting heart rate predicted increased risk of all-cause death, with each 1-SD (11 bpm) increase in heart rate associated with a 17% increased risk of all-cause death
• “Interestingly, we found that resting heart rate captured at a single examination was as strong a predictor of cardiovascular outcomes as repeated measurements of heart rate averaged over the course of 8 years. This highlights the potential role of resting heart rate as an easily obtainable measure of cardiovascular prognosis.”

Implications & Application

Those with higher resting heart rates were more likely to have diabetes, be a regular smoker, have higher diastolic blood pressure, higher BMI (body mass index) and higher HDL Cholesterol at baseline.
Additionally, those with higher resting heart rates tended to be at greater risk of developing a cardiac condition later in life. Therefore, it’s reasonable to deduce that lowering resting heart rate (for those without an underlying medical condition) should be a desirable goal for those at risk of heart disease.
Increased physical activity & physical fitness are related to decreased resting heart rate and subsequently could result in prevention of cardiac episode and heart disease.
We need to shift our focus away from weight loss alone as a primary goal but instead focus on improving our physical fitness and heart health.
By measuring resting heart rate, we can monitor the effectiveness of an exercise program in improving overall fitness which if sustained can result in reduced risk of heart disease.

References

Ho, J., Larson, M., Ghorbani, A., Cheng, S., Coglianese, E., Vasan, R., & Wang, T. (2014). Long-term Cardiovascular Risks Associated With an Elevated Heart Rate: The Framingham Heart Study. Journal Of The American Heart Association, 3(3), e000668-e000668. http://dx.doi.org/10.1161/jaha.113.000668