When we think of respiratory health we often concentrate our thoughts on the lungs and the act of breathing. However, respiratory health also encompasses the heart and our circulatory vessels that pump blood carrying oxygen inhaled through the lungs to all parts of our bodies.
Often the impact of chronic shortness of breath therefore is not just seen in lung function tests but in tests to evaluate the efficiency/health of the heart and circulatory system. One such measure is called heart rate variability (HRV). In simple terms, HRV is the amount of time between heartbeats. In general, if there is a large gap in time between heartbeats the HRV is considered to be good. On the flip side, if there is a short gap in time between heartbeats, the HRV is considered bad.
When physicians evaluate HRV, they are most interested to see whether a person’s heartbeats are getting closer together or farther apart. When they are getting closer together, physicians become concerned as this indicates the heart is working harder than it did before. Poor HRV (meaning shorter and shorter gaps of time between heartbeats) is a significant predictor of cardiovascular events such as heart attacks and strokes.
For COPD patients, heart rate variability tends to be poor which makes sense given that the lungs have to work harder to breathe which places greater stress on the heart and therefore the heart has to beat faster/more often in order to help the rest of body perform normal every day functions. As a result, COPD patients experience a greater incidence of cardiovascular events compared to non-COPD populations.
Exercise has been shown in previous studies in non-COPD populations to improve HRV (meaning exercise helps the heart slow down or said another way it helps the heart beat less frequently). Exercise has also been shown in previous studies to reduce COPD patient shortness of breath. So a group of Brazilian researchers recently decided to evaluate whether exercise could also help COPD patients specifically improve heart rate variability. [1]
The study authors described the purpose of their research project as follows,” Nowadays, exercise training is a well-recognized method to treat symptomatic patients with COPD. Its objective is to improve impaired disease outcomes such as exercise capacity, functional status, health-related quality of life and peripheral muscle force, as well as physical activity in daily life. However, little is known about the effects of exercise training programs on HRV changes in patients with COPD.”
In their study, the research team divided 40 COPD patients into two groups. One group of 20 patients participated in a high intensity exercise program patterned on principles and practices of the COPD treatment pulmonary rehabilitation (high intensity group). The other group of 20 patients engaged in a low intensity exercise program that did not push patients as much as a traditional rehab program does (low intensity group). The researchers desired to see whether either program made a notable difference in heart rate variability and whether one level of intensity was more effective in improving HRV than the other.
The study team discovered that the high intensity exercise group experienced a notable mean improvement in heart rate variability (24% on one particular measure known as the SDNN index, and 27% on another measure known as the rMSDD) while the low intensity group saw their HRV worsen between 12-13% on these same two measures. This led the researchers to conclude that high intensity exercise (ala similar to the intensities practiced in pulmonary rehabilitation programs) not only reduce shortness of breath symptoms but also improves heart rate variability. In the researchers own words, “The present study showed that a 12-week high-intensity exercise training program including endurance and strengthening exercises was able to improve HRV outcomes such as the rMSSD and SDNN variables, whereas a low-intensity program of similar duration was not.”
So what did the two different exercise programs entail? According to the study authors, “In the HI group, circuit training including cycling, walking and strength training was performed based on a protocol previously described. For ergometry cycling, the training intensity was set at 60% of the initial maximal work rate; for treadmill walking, at 75% of the average walking speed during the baseline 6-min walking test (6MWT); and for strength training, at 70% of the baseline 1 repetition maximum test (1RM). Increase in work rates and/or duration was assured on a weekly basis, guided by a predetermined schedule and driven by the patients’ perception of their symptoms (Borg-symptom scores). In the LI group, patients progressively performed 5 different sets of exercises including breathing exercises, strengthening of the abdominal muscles (crunches) and calisthenics. Each set consisted of 12 different exercises which were repeated 15 times each. Every 7 sessions, patients began a new set of exercises with an increment on the intensity. Close supervision was provided during both training protocols, which were attended three times per week, for 12 weeks, with 1-h training sessions.”
As we have discussed in many previous articles, exercise is incredibly beneficial to COPD patients and those who otherwise suffer from chronic shortness of breath regardless of disease severity. We have many times recommended COPD patients seek entry to a pulmonary rehabilitation program in their local area if their pulmonologist will provide a referral.
For those people who cannot access a pulmonary rehab program (and unfortunately that’s about 99% of COPD patients and nearly 100% of an expanded audience of people who suffer from chronic shortness of breath but do not carry a COPD diagnosis), we created our Breathe Better for Life guidebook and CD-ROM, www.breathebetterforlife.com, to put the principles and practices of pulmonary rehabilitation directly in your hands. In the guide we created a 12 week exercise program patterned after the guidelines of the American Thoracic Society, the European Respiratory Society and the American College of Sports Medicine for those with poor respiratory health. Our accompanying CD-ROM provides narrated, pictorial step-by-step instructions for the various strength training, stretching and breathing exercises recommended in the guidebook.
Regardless of what exercise program you follow, it is vitally important for COPD patients to start and maintain an exercise program for the long haul. Many research studies have proven the benefits of a regular exercise program for COPD patients (reduced shortness of breath, fewer hospitalizations, improved quality of life, and improved physical strength and stamina to name a few). This study’s results seem to indicate that following a pulmonary rehabilitation style exercise program can also improve heart rate variability and in so doing lessen the potential for a cardiovascular event.
[1] Camillo CA, et al. Improvement of heart rate variability after exercise training and its predictors in COPD. Respiratory Medicine. 2011 February 20 [Epub ahead of print]
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