[Black Square] CIRCULATION EDITORS' PICKS: MOST READ ARTICLES IN EXERCISE PHYSIOLOGY

Circulation. 2013;127:e627-e632.

The following articles are being highlighted as part of Circulation's Topic Review series. This series will summarize the most important manuscripts, as selected by the Editors, published in Circulation and the Circulation subspecialty journals. The studies included in this article represent the most read manuscripts published on the topic of exercise physiology within the last year.

Editor's Comment: In a series of "Most Read Articles" (abstracts) published in Circulation that includes articles from Circulation and subspecialty journals, the topic of exercise physiology was highlighted last month. These are abstracts of articles whose central research content is exercise physiology. There are 18 abstracts that cover the expanse of basic science ("Phosphoinositide 3-Kinase p110a Is a Master Regulator of Exercise-Induced Cardioprotection" and "PI3K Gene Therapy Rescues Cardiac Dysfunction"), to the safety of high-intensity exercise in a population of patients with coronary artery disease ("Cardiovascular Risk of High- Versus Moderate-Intensity Aerobic Exercise in Coronary Heart Disease Patients"), to a study comparing outcomes from a supervised walking program to stenting in patients with peripheral artery disease ("Supervised Exercise Versus Primary Stenting for Claudication Resulting From Aortoiliac Peripheral Artery Disease: Six-Month Outcomes From the Claudication: Exercise Versus Endoluminal Revascularization (CLEVER) Study").

This set of abstracts contains something of interest for every cardiac rehabilitation professional; thus I recommend it highly. Some of the conclusions from these articles include: (1) supervised exercise (once again) is superior to primary stenting for functional outcomes in peripheral artery disease; (2) cardiopulmonary exercise testing is generally safe in patients with high-risk cardiovascular diagnosis (e.g., aortic stenosis, hypertrophic cardiomyopathy, pulmonary hypertension); (3) the risk of event during (and after) both high-intensity and moderate-intensity exercise is low, thus high-intensity exercise should be considered among patients with cardiovascular disease; (4) in patients with chronic systolic heart failure, a modest increase in peak oxygen update from supervised exercise is associated with favorable outcomes including improved morbidity and mortality and lower risk of hospitalization. -JR

[Black Square] SHORT-FORM SUN-STYLE T'AI CHI AS AN EXERCISE TRAINING MODALITY IN PEOPLE WITH COPD

Leung RWM, McKeough ZJ, Peters MJ, Alison JA

Eur Respir J. 2013;41:1051-1057.

The aims of the study were to determine the effect of short-form Sun-style t'ai chi (SSTC) (part A) and investigate exercise intensity of SSTC (part B) in people with chronic obstructive pulmonary disease (COPD). Part A: after confirmation of eligibility, participants were randomly allocated to either the t'ai chi group or control group (usual medical care). Participants in the t'ai chi group trained twice weekly for 12 weeks. Part B: participants who had completed training in the t'ai chi group performed a peak exercise test (incremental shuttle walk test) and SSTC while oxygen consumption (VO₂) was measured. Exercise intensity of SSTC was determined by the per cent of VO₂ reserve. Of 42 participants (mean +/- SD forced expiratory volume in 1 s 59 +/- 16% predicted), 38 completed part A and 15 completed part B. Compared to control, SSTC significantly increased endurance shuttle walk time (mean difference 384 s, 95% CI 186-510); reduced medial-lateral body sway in semi-tandem stand (mean difference -12.4 mm, 95% CI -21- -3); and increased total score on the chronic respiratory disease questionnaire (mean difference 11 points, 95% CI 4-18). The exercise intensity of SSTC was 53 +/- 18% of VO₂ reserve. SSTC was an effective training modality in people with COPD achieving a moderate exercise intensity which meets the training recommendations.

Editor's Comment: Although yoga has received more scientific attention in recent years, it is rather more common to see public displays of t'ai chi, especially if one walks by parks in metropolitan areas. Both these forms of exercise have centuries of tradition and refinement behind them but are largely lacking in a systematic body of study pertaining to their objectively quantified benefits.

This small study (n = 19 patients each in 2 arms), which took 3 years to accrue its subjects, reports on some limited observations on the effects of 2 sessions a week for 12 weeks of t'ai chi in patients with moderate chronic obstructive pulmonary disease (COPD). It does find that there was better exercise capacity, balance, physical performance, quadriceps strength, health-related quality of life, anxiety, and self-efficacy in those who participated in t'ai chi compared to the control arm (that received no exercise training). In part B, it then attempts to quantify the exercise intensity that t'ai chi provides by making the following additional measurements in 15 patients (who had completed the earlier part of the study): oxygen consumption (VO₂), carbon dioxide production (VCO₂), tidal volume, breathing frequency, and minute ventilation both at rest and during ISWT and short-form Sun-style t'ai chi (SSTC). This shows that SSTC reached exercise intensity of a level where patients were utilizing 53 +/- 18% of VO₂ reserve, thereby placing it within the range of minimal effective training intensity for improvement in cardiovascular fitness.

This study is interesting especially because the rehabilitative benefits of t'ai chi have been little studied in COPD. Apart from the expected exercise-associated benefits that occurred, an interesting additional one was the improvement reported in balance. Whether this is actually sufficient to prevent falls is unclear, but no component of conventional pulmonary rehabilitation addresses this frequent problem. T'ai chi, consisting as it does of moderate exercise training and breathing exercises, may be a way of delivering pulmonary rehabilitation without using any additional equipment and in a relatively unobtrusive way. Further studies may allow it to become less alternative medicine and more mainstream. -SK

[Black Square] EFFECTS OF TAI CHI IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE: PRELIMINARY EVIDENCE

Yan J-H, Guo Y-Z, Yao H-M, Pan L

PLoS ONE. 2013;8(4):e61806. doi:10.1371/journal.pone.0061806

Background: Currently, several studies assessed the role of T'ai Chi (TC) in management of chronic obstructive pulmonary disease, but these studies have wide variation of sample and convey inconclusive results. We therefore undertook a meta- analysis to assess the effects of TC.

Methods: A computerized search through electronic databases was performed to obtain sample studies. The primary outcomes were 6-min walking distance (6MWD) and dyspnea. Secondary outcomes included health-related quality of life and pre-bronchodilator spirometry. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated and heterogeneity was assessed with the I2 test. A random-effects meta-analysis model was applied.

Results: Eight randomized controlled trials involving 544 patients met the inclusion criteria. The pooled WMDs were 34.22 m (95% CI 21.25-47.20, P < 0.00001) for 6 MWD, -0.86 units (95% CI -1.44-0.28, P = 0.004) for dyspnea, 70 ml (95% CI 0.02-0.13, P = 0.01) for FEV1, 120 ml (95% CI 0.00-0.23, P = 0.04) for FVC. TC significantly improved the Chronic Respiratory Disease Questionnaire total score, and the St George's Respiratory Questionnaire score except impact score.

Conclusions: Findings suggest that TC may provide an effective alternative means to achieve results similar to those reported following participation in pulmonary rehabilitation programs. Further studies are needed to substantiate the preliminary findings and investigate the long-term effects of TC.

Editor's Comment: T'ai chi, in its 3 main forms (Yang, Chen, and Sun), provides mild to moderate aerobic exercise through a combination of posture alignment, weight shifting, and circular movements; these include elements of muscle endurance and strengthening, balance, relaxation, and breathing control. It is now extending its presence in Western societies and is increasingly visible even beyond practitioners of Chinese origin or descent. Unlike conventional aerobic exercise-endurance and strengthening-the physiological impact of t'ai chi is largely unstudied from a scientific perspective, including its equivalence to more conventional types of exercise. Its role as a form of rehabilitative intervention in chronic obstructive pulmonary disease is largely unknown.

This is exemplified by this meta-analysis by Yan et al where only 8 acceptable studies (4 in English and 4 in Chinese) were found; of these studies, 2 shared the same patient population and were pooled. The overall data suggest that t'ai chi produces an improvement in both exercise capacity, as measured by 6-minute walk distance, and disease-related quality of life, but since comparison with conventional pulmonary rehabilitation was not performed, equivalence is difficult to assume. No adverse effects were reported and adherence was reportedly excellent. The former may merely reflect the small numbers studied and the latter may be a consequence of the populations studied. Without more complete data, all one can say at present is that t'ai chi may be an option in certain pulmonary rehabilitation situations, but neither its comparability nor the actual interventions required are defined enough as yet to predict the results (or even predictable benefit). -SK