01.07.2016
Benefits seen for endothelial function and arterial stiffness in RA
by Pauline Anderson
Contributing Writer, MedPage Today
Practicing tai chi significantly improved endothelial function and arterial stiffness in a trial involving older women with rheumatoid arthritis (RA), according to Jeong-Hun Shin, MD, PhD, of Hayang University, Republic of Korea, and colleagues.
“To the best of our knowledge, this study is the first evidence of a possible reduction of cardiovascular risk through tai chi exercise by improving endothelial dysfunction and arterial stiffness in patients with RA,” wrote the study authors in Arthritis Research & Therapy.
Research shows that atherosclerosis, the underlying process of cardiovascular disease, is increased in RA. A pivotal early step in atherosclerosis is endothelial dysfunction, measured by brachial artery flow-mediated dilation (FMD). Arterial stiffness, assessed by brachial ankle pulse wave velocity (baPWV), is also an important indicator of vascular disease.
It’s widely assumed that, in RA, disease-related inflammation and traditional risk factors such as hypertension, diabetes, dyslipidemia, and smoking contribute to the elevated cardiovascular disease (CVD) risk. Physical inactivity is likely another risk factor in RA.
Tai chi combines meditation with slow, gentle movements, deep breathing, and relaxation. The intensity of tai chi is equivalent to walking 6 km/hr, and moderately increases heart rate.
Recent studies have uncovered evidence of multiple benefits of tai chi for RA patients, including reduced disability and fatigue and positive effects on range of motion. A randomized controlled pilot study showed that tai chi reduced RA symptoms and disease activity, and improved quality of life.
However, the effect of tai chi exercise on endothelial function and arterial stiffness in RA had not been studied.
This study included 56 female patients with stable RA, over the age of 50. Researchers assigned these patients to one of two groups: 29 to a tai chi exercise group and 27 to a control group matched for age and body mass index.
The tai chi group participated in a 60-minute group exercise session once a week for 3 months. The program focused on small to large degrees of motion, knee flexion, straight and extended head and trunk, combined rotation of head, neck and extremities, and symmetrical diagonal arm and leg movements. Movements could be adjusted to the functional and comfort level of the individual.
The control group received information about lifestyle modification, including smoking cessation and weight loss, and advice about appropriate regular exercise.
The final analysis included all 29 in the intervention group and 14 in the control group (13 controls discontinued). There was a relatively high prevalence of a history of metabolic disorders in both groups — for example, 41.4% of the tai chi and 57.1% of the control groups had dyslipidemia, and 51.7% of the tai chi and 57.1% of the control groups had hypertension.
At 3 months, FMD increased in the tai chi group by 1.90%, from 5.85% to 7.75%, and decreased in the control group by 0.54%, from 6.31% to 5.78% (P=0.002).
In the tai chi group, there was a significant reduction in baPWV (-93.6 cm/sec), but not in the control group (a change of 52.6 cm/sec, P=0.02).
Tai chi was also associated with a significant improvement in total cholesterol, with a decrease of 7.8 mg/dL compared to an increase of 2.9 mg/dL in the control group (P=0.03).
The mechanism by which tai chi improves lipid profiles remains uncertain, although change in body fat ratio and insulin resistance might influence lipids, noted the authors. Positive lipid changes likely play a role in improving endothelial dysfunction and arterial stiffness, they said.
Since lipids could have affected changes in FMD and baPWV, the researchers performed an analysis that adjusted for improvement in total cholesterol. That analysis showed that the indirect effects of tai chi on FMD and baPwV through total cholesterol were not significant, whereas the direct effects of tai chi were (P=0.004 for FMD and P=0.02for baPWV).
“As expected, these data further support the notion that tai chi exercise may lower cardiovascular risk in RA patients via a beneficial effect on the arterial wall, independently of the improvement in lipid profile,” wrote the authors.
The mechanisms by with tai chi improves endothelial function and arterial stiffness are unclear. One suggestion is that the meditative component of the exercises reduces stress, which can mediate a range of effects by attenuating the sympathoadrenal axis.
The study results suggest that tai chi exercise “can be a useful behavioral strategy for CVD prevention, as well as for promotion of aerobic exercise and physical activity in patients with RA,” according to the authors.
The small sample size and the considerable number of controls who were lost to follow-up were among the limitations of the study. In addition, the study couldn’t determine that improvements in vascular function are the direct consequence of tai chi since it didn’t assess physical activity, which also reduces cardiovascular risk factors.
The authors reported no conflicting interests.
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