Two new trials and an evidence review add encouraging evidence 01/28/2019
Note: This article originally appeared in January 2019
Yoga really has only grown hotter in America — literally so, in steamy Bikram-yoga studios — since its emergence here in the 1960s.
One recent national survey reported that the proportion of Americans who practice yoga rose by one-half from 2012 (9.5%) to 2017 (14.3%).
And, according to the U.S. National Institutes of Health, research ties yoga to a varied range of health benefits — a list that continues to broaden.
Now, three new studies add to the body of evidence indicating that a regular yoga practice can help maintain and enhance human health.
Yoga and meditation boosted energy levels and brain performance
Scientists from Ontario, Canada’s University of Waterloo decided to see whether and how yoga and meditation might affect brain function and overall energy levels.
Specifically, they conducted a trial designed to test the effects of hatha yoga and so-called mindful or mindfulness meditation.
Mindful meditation simply involves judgment-free, moment-to-moment awareness of existence. Practitioners usually just focus on their breathing and allow thoughts, feelings, and bodily sensations to pass without any lingering attention.
The term “hatha” yoga covers all types of yoga that feature physical postures (asanas) and dynamic movements plus breathing techniques (pranayama).
Traditionally, the purpose of yogic body and breathing exercises was to better prepare the mind for meditation, whose goal was inner peace.
However, most Western practitioners — and many educated urbanites in modern India — follow the teachings of 20th-century Indian instructors such as B. K. S. Iyengar and Swami Satchidananda, who came to America and focused on the physical aspects of yoga.
The University of Waterloo team recruited 31 adults, who were asked to complete 25 minutes of hatha yoga, 25 minutes of mindfulness meditation, and 25 minutes of quiet reading — a “control” task — in randomized order (Luu K et al. 2016).
After the yoga and the meditation sessions, the volunteers scored significantly better on brain tests that measure “executive function”, compared to the control reading task.
Both mindful meditation and hatha yoga appeared to boost participants’ energy levels — but hatha yoga produced better results than meditation alone.
Co-author Peter Hall offered a possible — and seemingly plausible — explanation for the observed benefits of meditation and yoga: “Hatha yoga and mindfulness meditation both focus the brain’s conscious processing power on a limited number of targets like breathing and posing, and also reduce processing of nonessential information.”
As Dr. Hall said, “These two functions might have some positive carryover effect in the near-term following the session, such that people are able to focus more easily on what they choose to attend to in everyday life.”
Kimberley Luu, lead author on the paper, offered this perspective on the results of their small, pilot study: “This finding suggests that there may be something special about meditation — as opposed to the physical posing — that carries a lot of the cognitive benefits of yoga.”
And Dr. Luu noted ongoing uncertainty about the reasons for the energy and cognitive benefits of physical exercise: “There are a number of theories about why physical exercises like yoga improve energy levels and cognitive test performance. These include the release of endorphins, increased blood flow to the brain, and reduced focus on ruminative thoughts.”
Yoga and cardio-fitness exercise improved heart disease risk factors
Indian researchers from two hospitals in the city of Jaipur examined the outcomes for heart disease patients who routinely performed aerobic cardio-fitness exercises and/or yoga (Sen N et al. 2018).
Previous research indicated that — especially when combined with conventional medical treatment when needed — aerobic exercise and yoga help reduce the risk of death and heart disease.
For their study, the Indian researchers tested the effects of yoga and aerobic exercise on heart disease risk factors among obese heart-disease patients with type-II (adult-onset) diabetes.
The clinical trial involved 750 recently diagnosed patients, who were assigned to perform one of three different daily workouts for six months:
- Yoga only – 240 patients
- Aerobic exercise only – 225 patients
- Yoga + Aerobic exercise – 285 patients
After the trial ended, the aerobics-only and yoga-only groups showed similar reductions in six key risk factors: blood pressure, triglycerides, total cholesterol, LDL cholesterol, weight, and waist circumference.
And the risk reductions were twice as big in the combined aerobics-plus-yoga group, and they displayed extra heart-function and exercise capacity benefits.
Co-author Naresh Sen, D.M., Ph.D., drew a reasonable conclusion: “Combined Indian yoga and aerobic exercise reduce mental, physical and vascular stress and can lead to decreased cardiovascular mortality and morbidity. Heart disease patients could benefit from learning Indian yoga and making it a routine part of daily life.”
Yoga and tai chi benefit stroke victims and those at risk
Nearly one-third of adults worldwide suffer from high blood pressure, which promotes the risk of stroke, and some 23 million new strokes are projected to occur over the next 12 years.
And rates of diabetes — which is characterized and promoted by unhealthful blood fat and sugar profiles — are soaring, worldwide.
Australian researchers from the universities of Monash, South Australia, and Melbourne reviewed 26 prior studies to seek answers to some key questions (Thayabaranathan T et al 2018).
They wanted to see whether there’s good evidence that yoga and/or tai chi can help prevent stroke and protect those at greatest risk — and if so, how do they do it.
The Australian team also wanted to see whether yoga and/or tai chi could lower blood pressure and improve two risk factors for stroke and diabetes: unhealthful blood fat profiles and high blood sugar levels.
We described yoga as it’s usually practiced in the West, above. Tai chi originated as a form of self-defense and has evolved into a slow and gentle form of exercise, in which standing and crouching postures flow gracefully from one to the other.
The research team selected 26 research papers published between 1985 and 2017 that included possible evidence concerning the effects of yoga and tai chi on stroke risk factors: blood pressure, cholesterol, diabetes, atrial fibrillation, smoking and alcohol consumption, obesity, anxiety, and depression.
And they found significant credible evidence that yoga and tai chi can reduce the biggest single stroke risk factor: high blood pressure.
The Australian team proposed that mind-body interventions (MBIs) such as yoga and tai chi may help lower blood pressure by teaching people to breathe more deeply and slowly, which typically calms the nervous system and lowers your heart rate.
In addition to dropping blood pressure levels, the new review concluded that MBIs can improve diabetics’ health by boosting blood and oxygen supply throughout the body, which promotes better insulin production and aids people’s internal antioxidant capacity.
Finally, the Aussie team noted the obvious fact that mind-body interventions such as tai chi and yoga get relatively sedentary stroke survivors moving in safe, highly healthful ways.
As study co-author Dr. Maarten Immink said, “This is where yoga and tai chi are so helpful. They are gentle, movement-based MBIs which help people focus — a state of mind which stroke survivors often lose — and be active at the same time.”
- Luu K, Hall PA. Examining the Acute Effects of Hatha Yoga and Mindfulness Meditation on Executive Function and Mood. Mindfulness. 2016; 8 (4): 873. DOI: 10.1007/s12671-016-0661-2
- National Center for Integrative and Complementary Health Care. National Survey Reveals Increased Use of Yoga, Meditation, and Chiropractic Care Among U.S. Adults. Accessed at https://nccih.nih.gov/research/results/spotlight/NHIS2017-Adult-Survey
- National Center for Integrative and Complementary Health Care. Yoga for Health. Accessed at https://nccih.nih.gov/health/providers/digest/yoga
- Sen N, Tanwar S, Jain A. Better Cardiovascular Outcomes of Combined Specific Indian yoga and Aerobic Exercise in Obese Coronary Patients with Type 2 Diabetes. Journal of the American College of Cardiology. Mar 2018. 71 (11 Supplement) A2115; DOI: 10.1016/S0735-1097(18)32656-1.
- Thayabaranathan T, Immink MA, Stevens P, Hillier S, Thrift AG, Brodtmann A, Carey L, Kilkenny MF, Cadilhac DA. Understanding the potential for yoga and tai chi interventions to moderate risk factors for stroke – a scoping review. Future Neurology. 27 Sept 2018. Vol. 13. No. 4. https://doi.org/10.2217/fnl-2018-0005.