March 2016 Issue

Focus on Fitness: Yoga for Heart Health
By Jennifer Van Pelt, MA
Today's Dietitian
Vol. 18 No. 3 P. 60

Research shows yoga can lower blood pressure and heart rate, and improve BMI and cholesterol.

Heart disease is the leading cause of death worldwide and in the United States, according to the Heart Disease and Stroke Statistics — 2016 Update, compiled annually by the American Heart Association (AHA), the Centers for Disease Control and Prevention, the National Institutes of Health, and other government agencies. Annually, one in seven Americans (more than 370,000) die from heart disease—that's about one person every 84 seconds, according to the AHA.1

To prevent cardiovascular disease (CVD), the AHA and other professional organizations recommend daily aerobic exercise. Recommended exercise includes activities generally viewed as traditional, such as walking, running, cycling, swimming, other sports, and aerobic dance. Yoga is categorized as a mind-body exercise or alternative exercise/therapy, depending on how and why it's practiced. Many different styles of yoga exist, from physically intense power styles to gentle, more stationary practices. Yoga can be practiced for its fitness benefits of improved strength, flexibility, and balance, or for therapeutic purposes, such as stress or pain relief. I've covered the different yoga styles, as well as some of yoga's therapeutic benefits (eg, chronic pain relief, mental health, weight loss, diabetes) in previous columns of Today's Dietitian. Yoga typically isn't considered a 'cardio' workout, even though one's heart and breathing rate can be elevated in faster-paced yoga styles. However, a growing body of evidence suggests that practicing yoga also can prevent CVD or improve risk factors for developing it. This month, I'll focus on the science behind yoga's cardiovascular benefits and recent published studies.

So, if heart rate isn't continuously elevated in the target aerobic range (as it is during traditional cardiovascular exercises, like swimming and brisk walking), how does yoga contribute to lowering the risk of CVD? After more than 2,000 published research articles, there's still no firm scientific consensus on the exact mechanisms underlying yoga's cardiovascular benefits. It has been proposed that yoga reduces activation and reactivity of the body's central stress response system—a complex interaction between the central nervous system and endocrine system—thereby promoting relaxation and feelings of well-being. This stress reduction then leads to positive effects on inflammatory and metabolic responses related to heart disease risk. Yoga also may directly stimulate the vagus nerve, which is responsible for the body's fight-or-flight response, by regulating the sympathetic/parasympathetic nervous system. Certain yoga poses and deep diaphragmatic breathing enhance the parasympathetic nervous response (calming) over the sympathetic nervous response (the adrenaline-related fight-or-flight response). The domination of the parasympathetic response has been linked to healthy cardiac function, positive mood, and reduced inflammation. Yoga also may help lower blood pressure, improve arterial function, and stimulate the production of antioxidants in our body's cells, all of which help reduce risk of CVD.2,3

Although the exact mechanism for yoga's cardiovascular benefits isn't yet fully understood, the fact that it does provide benefit has been demonstrated by several recently published studies, including the following:

• In a pilot study of a yoga program for 124 older adults, researchers found that one session of yoga modified for older adult physical limitations and including coordinated breath-body movement, stationary stretching poses, breathing techniques, and relaxation significantly reduced heart rate and blood pressure.4
• In a matched control study of 58 middle-aged individuals, yoga practitioners had significantly better cardiorespiratory performance than those doing traditional aerobic activities. The yoga group practiced yoga for at least one hour per day, and the exercise group performed traditional aerobic activities for at least seven hours weekly over two years. Spiroergometry was used to measure respiratory performance per kilogram of body weight and maximum oxygen consumption per minute.5
• A 2014 systematic review and meta-analysis analyzed 37 randomized controlled trials with more than 2,700 participants that compared yoga with no exercise or traditional aerobic exercise. Yoga significantly improved BMI, body weight, blood pressure, heart rate, cholesterol, and triglycerides compared with no exercise. These positive changes were similar to improvements in participants who did traditional aerobic exercise. Yoga styles included senior yoga, stationary Iyengar yoga, active yoga with breath-synchronized movements, and yoga with chanting.6
• Another 2014 systematic review assessed the effects of yoga on hypertension in 48 randomized, controlled trials and 72 nonrandomized studies (more than 6,600 patients total). The researchers found that yoga significantly reduced blood pressure in patients with normal blood pressure as well as those with high blood pressure. The authors suggested that yoga could be used as an effective adjunct therapy for hypertension.7

These studies are only a small sample of a large body of research on yoga and CVD published over the last 20 years. It's uncertain whether yoga will make its way into professional guidelines for CVD prevention, since so many different yoga styles have been used in published studies and a firm recommendation for a particular yoga style can't be made. From my review of the above studies and others, and my own experience with teaching and practicing yoga, I feel confident offering the
following guidance for your clients:

• To obtain maximum cardiovascular benefit, yoga should be practiced on an ongoing basis for 30 minutes to one hour multiple times per week, whether or not other exercise is performed.
• Yoga can be practiced by anyone, including those with movement limitations and those who have never exercised. Cardiovascular benefits can be achieved even if yoga is your client's only activity.6
• Regardless of the yoga style, each yoga session should consist of poses (asanas), deep breathing techniques (pranayama), and relaxation/meditation (dhyana). Some clients may prefer yoga that also provides spiritual or philosophical teachings, available in many yoga studios or retreats.
• Most importantly, clients should choose a yoga style that's in line with their fitness level, and yoga classes should be taught by trained and experienced yoga teachers. It may take time and many classes (in person or online) or DVDs to find that perfect yoga style. Some clients may require extra encouragement if they believe they're too inflexible, too old, or too busy to start doing yoga.

— Jennifer Van Pelt, MA, is a certified group fitness instructor and health care researcher in the Reading, Pennsylvania, area.

References
1. Mozaffarian D, Benjamin EJ, Go AS, et al. Heart disease and stroke statistics — 2016 update: a report from the American Heart Association. Circulation. 2016;133:e38-e360.

2. McCall MC. How might yoga work? An overview of potential underlying mechanisms. J Yoga Phys Ther. 2013;3(1):130.

3. Manchanda SC. Yoga — a promising technique to control cardiovascular disease. Indian Heart J. 2014;66(5):487-489.

4. Bhavanani AB, Ramanathan M, Madanmohan. Single session of integrated "silver yoga" program improves cardiovascular parameters in senior citizens. J Intercult Ethnopharmacol. 2015;4(2):134-137.

5. Sovová E, Čajka V, Pastucha D, Malinčíková J, Radová L, Sovová M. Positive effect of yoga on cardiorespiratory fitness: a pilot study. Int J Yoga. 2015;8(2):134-138.

6. Chu P, Gotink RA, Yeh GY, Goldie SJ, Hunink MM. The effectiveness of yoga in modifying risk factors for cardiovascular disease and metabolic syndrome: a systematic review and meta-analysis of randomized controlled trials. Eur J Prev Cardiol. 2016;23(3):291-307.

7. Tyagi A, Cohen M. Yoga and hypertension: a systematic review. Altern Ther Health Med. 2014;20(2):32-59.
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