Summaries of key studies on yoga, Pilates, qigong and other mind-body topics.
Recently, as co-chair of a medical conference on the metabolic syndrome and dyslipidemia, I seized the chance to slip a short discussion of yoga-based lifestyle research into a long day of clinical trial expositions that mostly focused on lipid-lowering drug studies. I felt somewhat meek describing a number of relatively small studies, all done on small budgets, while most clinical trials being discussed were 50- to 200-million-dollar studies sponsored by the pharmaceutical industry or the National Institutes of Health [NIH]. However, I was able with reasonable evidence to profess that yoga-based lifestyle changes could compare with the clinical outcomes of pharmacotherapy. The discussion was very well received, and nearly all of the 300 attendees at the meeting—mostly physicians, pharmacists and nurses—reflected that there were valuable lessons to be gleaned from such holistic lifestyle changes. Nonetheless, I don’t think the discussion I led was likely to change any prescribing habits among the clinicians who were present.
Since 2000, European and American journals have published approximately 300 studies on mind-body exercise, 95% of them on qigong, tai chi and yoga; another 800 trials have focused on meditation. Literally hundreds of other studies have appeared elsewhere. But the vast majority of papers published on mindful exercise are from trials that were underpowered, fraught with subject bias and lacking in adequate controls—at least in part because statistically powered, well-controlled studies are very expensive to conduct. Still, when one considers the many smaller trials collectively, there is a clear trend of mostly positive outcomes demonstrating favorable effects. Here is a select group of studies that will be of practical interest to mind-body professionals.
Perhaps the most comprehensive meta-analytic review of all mind-body practices, including mindful exercise, was executed and prepared by Ospina and colleagues (2007) for the Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services. This review included more than 1,100 studies. For anyone wanting a purely objective synthesis of the state of research into mind-body practices—including study-by-study methods and outcomes—this is the most extensive report to date.
The Research Review. Five broad categories of meditation practices were identified: mantra meditation, mindfulness meditation, yoga, tai chi and qigong. Pilates was not included, ostensibly because it generally lacks a central and consistent mindful component. Evidence of the state of research into meditation practices was provided by 813 predominantly poor-quality studies. The three most studied conditions were hypertension, other cardiovascular diseases and substance abuse. Sixty-five intervention studies examined the therapeutic effects of meditation practices on these conditions.
Findings. Meta-analyses showed that Transcendental Meditation, qigong and Zen Buddhist meditation significantly reduced blood pressure. Yoga helped reduce stress. Yoga was no better than a mindfulness-based stress reduction program (developed in the early 1980s by Jon Kabat-Zinn, MD) at reducing anxiety in patients with cardiovascular diseases. Results from 55 studies indicated that some meditation practices produced significant changes in healthy participants. Overall, clear trends showed that mind-body practices reduced blood pressure, decreased stress-related outcomes, lessened pain and curbed disease symptoms.
The reviewers concluded that many uncertainties still surround the practice of meditation (including meditative movement forms like yoga, tai chi and qigong). They added that scientific research on meditation practices appears to have no common theoretical perspective and is characterized by poor methodological quality. Firm conclusions on the effects of meditation practices in health care could not be drawn from the available evidence. More rigorous studies are needed.
Commentary. This report, which runs several hundred pages long, is helpful in the sense that it encapsulates a very large body of research. It confirms that while most mind-body research is poorly designed and controlled, when all of the studies are collectively analyzed, we see a clear trend of positive outcomes.
Unavoidably, the question remains as to how these outcomes compare with those from more conventional therapies. For example, would 2 years of ardent restorative or Iyengar yoga practice reduce the incidence of type 2 diabetes as much as, or more than, pioglitizone or metformin—two popular insulin- sensitizing drugs? Such questions call for further research. The one exclusive and universal asset that mindful therapies can lay claim to is a contemplative-meditative component, which is clearly central to the management and prevention of stress- related disease states, such as cardiovascular disease.
In recent years there has been much interest in yoga and the reversal of heart disease—probably stemming from the early work of the esteemed cardiologist Dean Ornish, MD (Ornish 1998), who was the first to show how a yoga-based lifestyle—principally low-fat dietary therapy, in that case—could slow the progression of heart disease. More recently, Yogendra and colleagues (2004) have shown that a more traditional yoga-based lifestyle therapy approach can also slow the progression of coronary artery disease (CAD) and even induce regression of atherosclerosis in some coronary blood vessels. Assessment techniques used in this study included quantitative coronary angiography (in which a very small catheter is placed into a coronary blood vessel and radiographic contrast material is injected, allowing the arteries to be filmed) and myocardial perfusion imaging, or MPI (a less invasive technique, not involving a catheter, in which a radioactive isotope is specifically taken up by the heart, producing two-dimensional images of the heart and the perfusion of blood it receives).
The Study. Yogendra and associates evaluated the role of lifestyle modification—through yoga techniques, stress management and dietary changes—in slowing CAD. Subjects in this prospective, controlled trial were all angiographically proven CAD patients (71 in the study group and 42 in the control group). The researchers completed a full clinical assessment at baseline, obtaining chest X-rays, electrocardiograms, biochemical parameters (blood counts, fasting and postprandial sugars, lipid profiles, and kidney and liver functions), coronary angiograms and MPI readings for all patients. A psychiatrist evaluated baseline levels of anxiety and depression.
The study group was assigned to a family-based yoga lifestyle program for 1 year. They ate a low-fat, high-fiber vegetarian diet; received guidance on good sleep habits, personal relationships and other topics; learned relaxation techniques; and participated in a walking program and basic yoga asanas. The patients were reassessed at frequent intervals during the program and when it was over.
Findings. At the end of 1 year of yoga lifestyle training, statistically significant changes (p < 0.05) were found in serum total cholesterol (down by 23.3% in study group patients versus 4.4% in control subjects); serum LDL cholesterol (down by 26% in study group patients versus 2.6% in controls); disease regression (found in 43.7% of study group patients versus 31% of controls, using MPI; and in 70.4% of study group patients versus 28% of controls, using angiography); arrest of disease progression (found in 46.5% of study group patients versus 33.3% of controls, using MPI); and progression of disease (found in 9.9% of study group patients versus 35.7% of controls, using MPI; and in 29.6% of study group patients versus 60.0% of controls, using angiography). The study authors concluded that yoga-based lifestyle modifications helped to regress coronary lesions and improve myocardial perfusion. These effects translated into clinical benefits and symptomatic improvement.
Commentary. It is important to understand that hatha yoga itself has very little impact on the atherosclerotic disease process. However, yoga-based lifestyles—daily asana practice, walking, low-fat diet and meditation—do influence this disease process. Manchanda and associates (2000) also reached this conclusion, noting moreover that program compliance was excellent and no side effects were observed.
The Yogendra and Manchanda studies clearly show that in order for a yoga program to either cause regression or at least stop progression of CAD, there must be a significant reduction in blood lipids and lipoproteins (i.e., LDL cholesterol), primarily by dietary means. In the final analysis, yogic lifestyle intervention—rather than hatha yoga per se—is the stimulus needed to generate significant clinical outcomes, as evidenced in these and other trials.
A small but groundbreaking study by Xin and colleagues (2008) at the University of Queensland in Australia is offering promise that the practice of tai chi and qigong can significantly improve risk factors for the metabolic syndrome. Reported on in general terms in the April 2006 issue of IDEA Fitness Journal and published last year in the peer-reviewed, online version of British Medical Journal, the trial evaluated the feasibility, acceptability and effects of a tai chi and qigong exercise program in adults with elevated blood glucose (i.e., prediabetes).
The Study. Eleven participants (8 women, 3 men) 42–65 years of age with elevated blood glucose attended tai chi and qigong exercise training for 1–1.5 hours 3 times per week for 12 weeks and were encouraged to practice the exercises at home. The researchers measured the subjects’ metabolic syndrome risk factors—body mass index (BMI), waist circumference, blood pressure, fasting blood glucose, triglycerides and HDL cholesterol—as well as glucose control indicators (glycated hemoglobin [HbA1c], fasting insulin levels and insulin resistance), health- related quality of life, and stress and depression symptoms.
Findings. There were significant improvements in four of the seven indicators of the metabolic syndrome: BMI (mean difference –1.05, p < 0.001); waist circumference (–2.80 centimeters, p < 0.05); systolic blood pressure (–11.64 millimeters of mercury [mm Hg], p < 0.01); and diastolic blood pressure (–9.73 mm Hg , p < 0.001). There were also significant improvements in HbA1c (–0.32%, p < 0.01); insulin resistance (–0.53, p < 0.05); stress (–2.27, p < 0.05); depressive symptoms (–3.60, p < 0.05); and the SF-36 mental-health summary score (+5.13, p < 0.05), as well as the subscales for general health (+19.00, p < 0.01), mental health (+0.55, p < 0.01) and vitality (+23.18, p < 0.05). Noting these improvements, Xin and colleagues concluded that this type of program was feasible and acceptable for subjects with elevated blood glucose. They noted that a larger controlled trial is needed to confirm these preliminary findings.
Commentary. These are amazing results, albeit from a small trial, considering the modest amount of time (3–4.5 hours per week) invested in the exercise. The reductions of approximately 12 and 10 mm Hg in systolic and diastolic blood pressure, respectively, alone rival the efficacy of many blood pressure medicines (e.g., ACE inhibitors and angiotensin II receptor blockers). For most metabolic syndrome risk factors (blood glucose, triglycerides, HDL cholesterol, waist circumference and blood pressure), significant positive change generally requires at least 1,200–1,500 kilocalories (kcal) of physical activity expenditure per week (equivalent to 12–15+ miles of walking).
Training in mindfulness-based stress reduction (MBSR) is very popular throughout the field of integrated medicine in the United States. MBSR programs vary in their specifics, but generally they use a combination of yoga and meditation to cultivate awareness of body and mind. A key mindfulness skill is taking thoughts, feelings, images and other sensory phenomena and approaching them in an open, nonjudgmental and accepting way. This basic tenet of mindfulness is rooted in the core Buddhist notion that all psychological suffering stems from the judgmental mind’s habit of dividing life into good and bad experiences that should be either strived for or avoided—inevitably leading to some level of frustration, distress, anxiety or depression.
The Study. In a randomized controlled trial, Nyklícek and Kuijpers in the department of psychology and health at Tilburg University in the Netherlands sought to identify the degree to which MBSR’s effects can be attributed to increases in mindfulness skills induced by the training. The researchers compared the results of the MBSR group with those of a waiting-list control condition, while examining whether mindfulness could be identified as the mechanism responsible for any improvements.
Forty women and 20 men from the community, all with symptoms of distress (mean age 43.6 years), were randomized into a group receiving MBSR or a waiting-list control group. Before and after the intervention period, standardized questionnaires were completed on psychological well-being, quality of life and mindfulness.
Findings. Compared with the control group, the MBSR group showed significantly greater reductions in perceived stress (p = 0.016) and vital exhaustion (p = 0.001) and stronger elevations of positive affect (p = 0.006), quality of life (p = 0.009) and mindfulness (p = 0.001). Nyklícek and Kuijpers concluded that improved mindfulness skills might, at least partially, have been responsible for the positive effects of MBSR training. Learning to experience without judgment and observe mainly sensory phenomena could not be identified as mechanisms of change, but an increased capacity to experience life without judgment did correlate with improvement in quality of life over time. Whether participants were practicing at home or in the scheduled sessions did not affect outcomes.
Commentary. In this relatively small study, Nyklícek and Kuijpers point to mindfulness as a mechanism for improving stress perception, enhancing quality of life and reducing vital exhaustion. Readers who wish a single tool for measuring mindfulness might consider an instrument that was used in this study and has been repeatedly validated through other trials: the Mindful Attention Awareness Scale (MAAS), developed by K.W. Brown and others at the University of Rochester. The MAAS is a 15-item scale designed to assess a core characteristic of dispositional mindfulness—namely, open or receptive awareness of, and attention to, what is taking place in the present. This scale can be downloaded at www.ppc.sas.upenn.edu/ppquestionnaires.htm.
Despite the burgeoning growth of mind-body practices and research over the last decade, there have been very few attempts to define mind-body exercise and offer at least a minimum set of characteristics common to its many forms. Reviewing several scores of tai chi and qigong exercise trials, Linda Larkey at Arizona State University with collaborators from other institutions (2009) set out to identify common characteristics and reach a working definition of “meditative movement.” Larkey’s analysis, although focused solely on tai and qigong, is important for future scientific analysis of mind-body exercise programs.
The Study. The researchers began with a working definition of meditative movement (MM) as a category of exercise defined by (a) some form of movement or body positioning, (b) a focus on breathing and (c) a cleared or calm state of mind, with a goal of (d) deep states of relaxation. They reviewed 54 reasonably well controlled studies on tai chi and qigong, both of which met this definition. The aims were to examine health benefits found in the research literature; identify criteria for MM research; and suggest where aspects of MM intersect with, and are distinct from, conventional forms of exercise. Key study elements reviewed were frequency and duration of participation, type of movement, degree of exertion, description of breathing and a clear description of the achievement of relaxed state.
Findings. Based on their analysis, Larkey and colleagues recommended that future MM research should describe and measure the following elements: (a) type and degree of meditative focus; (b) type of movement (relaxed and flowing, static postures, spontaneous/shaking, isometric, stretching or squeezing); (c) degree of focus on breathing, and type of breathing; and (d) achievement of deep relaxation.
Commentary. Although this paper is unquestionably academic in its approach to defining mind-body exercise, it is a bold and pioneering work that in effect characterizes the central qualities of mind-body practices. These qualities should be considered standard criteria for what is and is not mind-body exercise.
Serenity, a fundamental dimension of spirituality, is perhaps best defined as a state of sustained inner peace. Historically, several methods have been used to assess the state of serenity, in particular the 40-item Serenity Scale. Mary Jo Kreitzer and co-workers (2009) at the University of Minnesota recently attempted to develop a shortened, 22-item version of this scale, using the psychometric analysis of Boyd-Wilson, Walkey & McClure (2004) as a guide when selecting which items to include. (Boyd-Wilson and colleagues identified faith, humility and gladness as three major components of serenity.) A sample of 87 participants completed the abbreviated instrument; they were enrolled in an NIH-funded clinical trial examining the impact of MBSR on symptom management following an organ transplant.
Findings. Kreitzer and colleagues’ analysis yielded three serenity subscales: acceptance, inner haven and trust. Their Serenity Scale was positively associated with positive affect and mindful awareness and inversely related to negative affect, anxiety, depression, health distress and transplant-related stress. The researchers concluded that serenity, a dimension of spirituality that is secular and distinct from religious orientation or religiosity, showed promise as a tool for measuring outcomes of nursing interventions designed to improve health and well-being. Although more work (e.g., larger subject numbers) is needed to further validate this shorter scale, it appeared to capture a dimension of spirituality—consisting of acceptance, inner haven and trust—distinct from aspects identified by other spirituality instruments.
Commentary. While this study was performed from a nursing perspective and was aimed at improving patient health and well-being and preventing and managing disease symptoms, it is highly relevant to mind-body fitness professionals. Spirituality, but more specifically serenity, is an important outcome measure of mindful exercise programs, such as restorative yoga, and meditation. The 22-item Serenity Scale could be a helpful tool for querying clients before and after mind-body programs in order to assess changes in serenity measures (specifically acceptance, inner haven and trust). Those interested are referred to the full-text version of this paper (see the reference list); if you have questions, you can contact the author at firstname.lastname@example.org.