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Yoga may improve CVD risk factors
A new meta-analysis suggests that regular yoga practice may have clinically important effects on risk factors for CVD.
According to previous research, about 14 million US adults have reported that yoga has been recommended to them by a physician or therapist.
“Yoga has been shown to reduce important psychological cardiovascular disease risk factors such as stress and depression. Being a combination of exercise, controlled breathing and relaxation, it is commonly thought to also improve biological cardiovascular disease risk factors,” Holger Cramer, PhD, from the University of Duisburg-Essen, Essen, Germany, and colleagues wrote.
The researchers reviewed and analyzed randomized controlled trials that studied the effects of yoga on modifiable biological CVD risk factors, including BP, heart rate, respiratory rate, abdominal obesity, blood lipid levels, insulin resistance, oxidative stress, inflammatory markers and atherosclerosis.
Cramer and colleagues identified 44 relevant randomized controlled trials covering 3,168 participants. Some were conducted in healthy individuals, some in patients with diabetes, and some in patients with other risk factors for CVD such as hypertension, prehypertension, metabolic syndrome, obesity, dyslipidemia and impaired insulin resistance.
Compared with the usual care or no intervention, yoga was associated with the improvements in the following risk factors:
- Systolic BP: mean difference, –5.85 mm Hg (95% CI, –8.81 to –2.89).
- Diastolic BP: –4.12 mm Hg (95% CI, –6.55 to –1.69).
- Heart rate: –6.59 bpm (95% CI, –12.89 to –0.28).
- Respiratory rate: –0.93 breaths/minute (95% CI, –1.7 to –0.15).
- Waist circumference: –1.95 cm (95% CI, –3.01 to –0.89).
- Waist/hip ratio: –0.02 (95% CI, –0.03 to 0).
- Total cholesterol: –13.09 mg/dL (95% CI, –19.6 to –6.59).
- HDL: 2.94 mg/dL (95% CI, 0.57-5.31).
- Very low-density lipoprotein: –5.7 mg/dL (95% CI, –7.36 to –4.03).
- Triglycerides: –20.97 mg/dL (95% CI, –28.61 to –13.32).
- HbA1c: –0.45% (95% CI, –0.87 to –0.02).
- Insulin resistance: –0.19 (95% CI, –0.3 to –0.08).
In addition, compared with exercise, yoga was associated with improved HDL (mean difference, 3.7 mg/dL; 95% CI, 1.14-6.26).
The trials that reported safety-related information found no serious adverse events for yoga participants, according to the researchers.
However, most studies had high or unclear risk of selection bias. Specifically, the researchers wrote, 30 studies had insufficient reporting of random sequence generation, two reported inadequate methods of random sequence generation, 35 did not report allocation concealment, three reported inadequate allocation concealment, 34 did not report about masking of outcome assessment, and three did not mask outcome assessors.
“Sensitivity analyses revealed that none of the effects found in this meta-analysis can be regarded as robust against all potential methodological biases,” the researchers wrote. “Moreover, the effects on systolic [BP], diastolic [BP], HDL and triglycerides might be distorted by publication bias.”
Nonetheless, they wrote, given the apparent safety and effectiveness of yoga, “it can be considered as an ancillary intervention for healthy participants and for patients with increased risk [for CVD].”
Disclosure: The review was supported by a grant from the Corona-Foundation, Germany. The researchers report no relevant financial disclosures.
Perspective
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This information is additive to what we already know about the benefits of exercise in that it addresses a specific form of exercise which is not traditionally considered aerobic in nature; aerobic exercise has the most abundant data supporting its CV benefits. Importantly, yoga may be more comprehensive in that it focuses on both physical and mental exercises, suggesting benefit beyond the usual physical activities that have been studied.
I think most forms of exercise offer CV health benefits in a variety of ways. It’s been well-shown that both unstructured activities (walking to work, taking the stairs instead of the elevator) and structured activities such as exercise (jogging, biking, yoga) positively affect cardiac risk factors, lower BP, improve lipids and insulin resistance and reduce obesity, through a variety of mechanisms, and it certainly makes sense that yoga would also improve the risk profile. Additionally, an association between psychological stress and CVD has been fairly well demonstrated, and yoga, through meditation and deep breathing, may offer an added benefit. Although, I would suggest that a good, long jog with increased endorphins lowers stress too.
A meta-analysis like this is almost always fraught with risk for bias (like the hormone replacement or vitamin studies — those people that do/take these things do lots of things ‘healthier’) so the data should be interpreted with caution, but it is still worthy information.
I suspect this sort of data will increase the use of yoga as a form as exercise, and this is good. For many healthy individuals and patients, other forms of exercise can be challenging because of orthopedic problems, limited access to equipment and pools, and other reasons. I would certainly recommend it to patients, particularly those that cannot participate in other exercises because of chronic low back pain, knee or hip arthritis, diabetes with neuropathy/foot issues, advanced age, or other reasons, as it is overall a low-impact exercise and may be safer for certain populations than other forms of exercise.
The more reinforcement that physical activity, in any form, benefits overall health, the better.