GuoLin QiGong@HKU/QMH: Randomised controlled trial of qigong in the treatment of mild essential hypertension.

J Hum Hypertens. 2005 Sep;19(9):697-704. Randomised controlled trial of qigong in the treatment of mild essential hypertension. Cheung BM1, Lo JL, Fong DY, Chan MY, Wong SH, Wong VC, Lam KS, Lau CP, Karlberg JP. Author information Abstract Exercise and relaxation decrease blood pressure. Qigong is a traditional Chinese exercise consisting of breathing and gentle movements. We conducted a randomised controlled trial to study the effect of Guolin qigong on blood pressure. In all, 88 patients with mild essential hypertension were recruited from the community and randomised to Goulin qigong or conventional exercise for 16 weeks. The main outcome measurements were blood pressure, health status (SF-36 scores), Beck Anxiety and Depression Inventory scores. In the qigong group, blood pressure decreased significantly from 146.3+/-7.8/93.0+/-4.1 mmHg at baseline to 135.5+/-10.0/87.1+/-7.7 mmHg at week 16. In the exercise group, blood pressure also decreased significantly from 140.9+/-10.9/93.1+/-3.5 mmHg to 129.7+/-11.1/86.0+/-7.0 mmHg. Heart rate, weight, BMI, waist circumference, total cholesterol, renin and 24 h urinary albumin excretion significantly decreased in both groups after 16 weeks. General health, bodily pain, social functioning and depression also improved in both groups. No significant differences between qigong and conventional exercise were found. In conclusion, Guolin qigong and conventional exercise have similar effects on blood pressure in patients with mild hypertension. While no additional benefits were identified, it is nevertheless an alternative to conventional exercise in the nondrug treatment of hypertension. PMID: 15905884 [PubMed - indexed for MEDLINE] ----------- Original Article Journal of Human Hypertension (2005) 19, 697–704. doi:10.1038/sj.jhh.1001884; published online 19 May 2005 Randomised controlled trial of qigong in the treatment of mild essential hypertension B M Y Cheung1,2, J L F Lo3, D Y T Fong4, M Y Chan5, S H T Wong5, V C W Wong6, K S L Lam1,2, C P Lau1,2 and J P E Karlberg7 1Department of Medicine, University of Hong Kong, Hong Kong, China 2Research Centre of Heart, Brain, Hormone and Healthy Aging, University of Hong Kong, Hong Kong, China 3Department of Paediatrics and Adolescent Medicine, University of Hong Kong, Hong Kong, China 4Department of Nursing Studies, University of Hong Kong, Hong Kong, China 5Department of Physiotherapy, Queen Mary Hospital, University of Hong Kong, Hong Kong, China 6Hong Kong Hospital Authority, Hong Kong, China 7Clinical Trials Centre, University of Hong Kong, Hong Kong, China Correspondence: Dr BMY Cheung, Department of Medicine, University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong, China. E-mail: mycheung@hkucc.hku.hk Received 1 February 2005; Revised 5 April 2005; Accepted 6 April 2005; Published online 19 May 2005. Top of page Abstract Exercise and relaxation decrease blood pressure. Qigong is a traditional Chinese exercise consisting of breathing and gentle movements. We conducted a randomised controlled trial to study the effect of Guolin qigong on blood pressure. In all, 88 patients with mild essential hypertension were recruited from the community and randomised to Goulin qigong or conventional exercise for 16 weeks. The main outcome measurements were blood pressure, health status (SF-36 scores), Beck Anxiety and Depression Inventory scores. In the qigong group, blood pressure decreased significantly from 146.3plusminus7.8/93.0plusminus4.1 mmHg at baseline to 135.5plusminus10.0/87.1plusminus7.7 mmHg at week 16. In the exercise group, blood pressure also decreased significantly from 140.9plusminus10.9/93.1plusminus3.5 mmHg to 129.7plusminus11.1/86.0plusminus7.0 mmHg. Heart rate, weight, BMI, waist circumference, total cholesterol, renin and 24 h urinary albumin excretion significantly decreased in both groups after 16 weeks. General health, bodily pain, social functioning and depression also improved in both groups. No significant differences between qigong and conventional exercise were found. In conclusion, Guolin qigong and conventional exercise have similar effects on blood pressure in patients with mild hypertension. While no additional benefits were identified, it is nevertheless an alternative to conventional exercise in the nondrug treatment of hypertension. Keywords: exercise, qigong, clinical trials Top of page Introduction The cause of essential hypertension remains unknown in most patients. Many hypertensive patients are anxious and anxiety in itself may be a factor in raising the blood pressure in some individuals, most notably the white-coat hypertensives. Relaxation techniques help to lower blood pressure.1 Exercise is also known to decrease blood pressure.2 Regular exercise is recommended in guidelines on the management of hypertension.3, 4 The exact mechanisms that cause the decrease in blood pressure are uncertain. Exercises that also result in relaxation may therefore be useful in decreasing blood pressure. Qigong (pronounced chee-gong) is a series of relaxation, breathing, gentle movement and walking exercises.5, 6 It has been practised in China for centuries. An estimated 60 million people in China practise it daily. It is also popular among overseas Chinese and is gaining popularity in the West. According to traditional Chinese medicine, qi is an energy that flows in the body. Qigong is a means of unblocking and increasing the healthy flow of qi. It is essentially a selftraining process, guided by a manual or a master. Many claims have been made that qigong, may enhance function of the central nervous, cardiovascular, renal, immune and reproductive systems.5, 6, 7 It is also thought to be helpful in patients with malignancies in improving their mood and even prolonging survival.8 Qigong reduces blood pressure in hypertensives as well as reduces 18-hydroxy-11-deoxycorticosterone (18-OH-DOC), an adrenocorticotrophic hormone (ACTH)-dependent adrenal cortical hormone.9 Qigong acutely reduces plasma ACTH while increasing beta-endorphin.10 An echocardiographic study of 120 elderly patients in China showed that after one year of qigong, cardiac output increased and total peripheral resistance decreased, but only in the 'heart-energy-deficient' subgroup.6, 11 The conscious control of breathing is an important element of qigong. Control of breathing has been shown to be useful in reducing blood pressure in hypertensive patients.12, 13 It is not known if qigong lowers blood pressure by this mechanism, but qigong has been shown to improve the ventilatory efficiency for oxygen uptake and carbon dioxide production.14 A follow-up study of 244 hypertensive patients for 18–22 years showed a lower incidence and mortality because of stroke among hypertensives taking antihypertensive medications and practising qigong compared to a nonrandomised control group.15 At the same time, the requirement for medications was also lower. In view of the popularity of qigong and the many claims of benefit, it is necessary to investigate its health effects in man using rigorous scientific methodology. We therefore conducted a randomised controlled trial to examine the effects of one style of qigong, Guolin qigong, on blood pressure in patients with mild essential hypertension. Guolin qigong was introduced more than 50 years ago by Madam Guo, a long-term cancer survivor. Her form of qigong is characterised by a slow walking exercise accompanied by arm movements and twisting of the waist.16 Goulin qigong was chosen for the sake of uniformity and because it was nonreligious, nonpolitical and widely practised in China as well as other parts of the world. Hypertension was chosen as the subject of investigation as blood pressure can be measured objectively as an outcome variable and it is logical to expect a reduction of blood pressure arising from the exercise and relaxation provided by qigong. Accordingly, we tested the hypothesis that qigong reduces blood pressure more than a conventional exercise programme taught by the physiotherapist. Top of page Methods The study was a randomised controlled trial to compare qigong with conventional exercise. The study was designed, monitored and analysed in the Clinical Trials Centre of the University of Hong Kong. An independent data and safety monitoring committee was established for the study. The protocol was approved by the Ethics Committee of Queen Mary Hospital, where the study took place. All subjects gave written consent before participation in the study. Subjects were recruited from the community between April 2000 and June 2001. Advertisements for voluntary subjects were printed in local newspapers and posted on notice boards in the local community. Interested subjects were invited to come for a detailed explanation of the nature of the study and to give informed consent. There were three screening visits on consecutive weeks to establish the diagnosis of hypertension. Eligible subjects then underwent a screening medical examination. Each subject took one placebo tablet daily for 2 weeks. At the end of this single blind run-in period, the subjects were randomised to either Guolin qigong or exercise for 16 weeks if the inclusion and exclusion criteria were satisfied. Randomisation was performed by a statistician who had prepared a randomisation list before the study started. The inclusion criteria were (1) age between 18 and 75 years inclusive; (2) seated systolic blood pressure (SBP) between 140 and 170 mmHg inclusive and/or diastolic blood pressure (DBP) between 90 and 105 mmHg inclusive on at least three separate occasions; and (3) asymptomatic. The exclusion criteria were (1) serious symptomatic cardiac disease including previous myocardial infarction, angina or heart failure; (2) previous transient ischaemic attacks or stroke; (3) secondary hypertension; (4) renal failure (creatinine >200 mumol/l); (5) necessity to continue antihypertensive medications; (6) concomitant illnesses that preclude participation; (7) pregnancy or women who might become pregnant but did not have adequate contraception; and (8) impaired left ventricular function on echocardiography. A medical history was taken and a physician performed a physical examination. The height, weight, waist and hip circumference were measured. Body fat percentage was estimated from the measurement of bioelectrical impedance (Tanita TBF300, Tanita Corporation, Tokyo, Japan). Blood pressure and heart rate were taken at every visit. A trained research nurse measured the blood pressure carefully with the subject in the seated position three times after resting for at least 15 min in a temperature-controlled room. A cuff of appropriate size was fitted to the right arm of the patient. The first inflation was to accustom the subject to the procedure, and the measurement was disregarded. Two subsequent measurements were carried out at 5-min intervals. The mean of these two measurements was used in the data analysis. No antihypertensive medications or medications that affect blood pressure were permitted during the study. If a subject required such medications for clinical reasons, or if the SBP or DBP exceeded 200 or 115 mmHg, respectively, the subject would be withdrawn. Ambulatory 24-hour blood-pressure monitoring (Spacelabs 90217-1B, Spacelabs Medical Ltd, Redmond, WA, USA) was performed just before the randomisation and just before the end of the study. An electrocardiogram was performed at randomisation and at the end of the study. In patients over 60 years old, echocardiography was performed to measure left ventricular mass and left ventricular function using a standard technique.17 Biochemical measurements were made at the randomisation visit and at the end of the study period. These included renal function, full lipid profile, 0900 h cortisol, renin and aldosterone. Subjects were requested to collect urine for 24 h to measure urinary sodium, creatinine, protein and cortisol. Subjects were asked to complete three questionnaires, MOS Short Form 36-item (SF-36), Hong Kong Chinese version, Beck Anxiety Inventory (BAI) Chinese version (Beck Anxiety Inventory. Copyright © 1987, 1990 by Aaron T Beck. Chinese copyright © 1999 by Aaron T Beck) and Beck Depression Inventory (BDI), Second Edition, Chinese version (Beck Depression Inventory: Second Edition. Copyright © 1996 by Aaron T Beck. Chinese copyright © 1999 by Aaron T Beck) at weeks 0, 4, 8 and 16. The MOS Short Form 36-item (SF-36), Hong Kong Chinese version consists of eight scales: physical function (PF), social function (SF), role physical (RP), role emotion (RE), vitality (VT), mental health (MH), general health (GH), and bodily pain (BP).18, 19 The BAI and BDI questionnaires contain 21 questions each. The answer to each question is scored on a scale of 0 to 3. The maximum possible total score is 63 (0–9 normal, 10–18 mild–moderate, 19–29 moderate–severe, 30–63 severe). Permission to use the above instruments was granted prior to the study. Qigong was taught by an instructor with expertise in Guolin qigong. Each subject underwent two 2-h training classes of qigong/exercise per week for 4 weeks. Thereafter, the classes were held monthly until the end of the study. The total amount of time in class was 22 h. The first session consisted of explanations and pressure-relieving exercises. The second to fourth sessions consisted of walking exercises in addition to pressure-relieving exercises. In the fifth session, stretching exercises were introduced. The first seven sessions were training and learning sessions. The eighth session was a revision session. The subjects were asked to practise qigong for 60 min in the morning and 15 min in the evening every day for the duration of the study, comprising walking exercises for 40 min, eight sets of stretching exercises and three sets of pressure-relieving exercises in the morning and three sets of pressure-relieving exercises in the evening. Conventional exercise was taught by a physiotherapist. The schedule and size of the classes, as well as the intensity and amount of exercise matched those in the qigong group. The work load of the stretching, walking and pressure-relieving exercises in qigong was 2.0, 1.7 and 2.1 METs (metabolic equivalent of task, 1 MET is 1 kcal/kg body weight/hour), respectively, whereas that of stretching, walking and stepping in conventional exercise was 1.8, 2.0, 2.1 METs, respectively. This was verified by measuring oxygen consumption in four subjects in the qigong group and 13 subjects in the exercise group (7.0plusminus2.3 ml/min/kg during qigong and 6.1plusminus0.5 ml/min/kg during exercise, P=0.46). Briefly, the first session consisted of relaxation for 5–10 min, walking exercises for 40 min, stretching exercises for 10 min and resting for 5–10 min. In the second session, there was relaxation for 5–10 min, stretching for 10 min, stepping for 15 min, repeat stretching and stepping, then resting for 5–10 min. Thereafter, the session consisted of relaxation for 5–10 min, stretching for 10 min, walking for 40 min, stepping for 10 min and resting for 5–10 min. The stepping exercise was repeated for 15 min in the evening at home. The subjects were asked to perform 60 min of exercise in the morning and 15 min in the evening as above every day. All subjects, whether randomised to qigong or to conventional exercise, were asked to perform the routines daily according to the instructions. The compliance of the subjects was assessed in terms of the number of training classes attended, the number of hours of practise daily, and a performance evaluation (in terms of form, breathing, relaxation and overall mastery) by subjects and the corresponding instructor at 4 and 16 weeks. Performance was scored on a scale of 0 to100. Sample size Our estimate of the standard deviation for the change of DBP after qigong/control exercise was 5 mmHg. To detect a difference of 3 mmHg between the groups using a two-tailed t-test for independent samples required 45 patients per group with a power of 0.8 and a Type I error rate of 0.05.20 Assuming a 10% dropout, 100 patients were needed. Statistical analysis The efficacy analysis included all randomised subjects on an intention-to-treat (ITT) basis. Baseline characteristics in the two randomised groups were compared using chi2 or t-test as appropriate. A linear mixed effects model with a random intercept, qigong/exercise group, baseline value, and week as the covariates together with contrasts were used to examine the effect of qigong on the change of individual measurements after accounting for the baseline value.21 The linear mixed model has the advantage of utilising all available observations from the subjects. As an exploratory analysis, changes between baseline and final visit were analysed separately for each randomised group. Performance evaluations by the instructor and subjects were compared by sign test after accounting for tied observations. Performance scores of subjects in the two groups were compared by Wilcoxon's rank sum test with exact P-value approximated by Monte Carlo simulation of size 99 999. Results are expressed as means and standard deviations unless indicated otherwise. A 5% level of significance was used for all significance tests. The Statistical Analysis System (SAS) version 8.2 was used for the data analysis in this study. Top of page Results A total of 584 individuals were screened, of whom 91 eligible subjects consented to participate in the study and were randomised to Guolin qigong (47) or conventional exercise (44). Subject disposition is shown in Figure 1. Three subjects randomised to conventional exercise withdrew for personal reasons before the start of training sessions. The remaining 88 subjects (47 and 41 in the qigong and exercise groups, respectively) were analysed. Their baseline characteristics are shown in Table 1. Figure 1. Figure 1 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author Subject disposition. Full figure and legend (18K) Table 1 - Baseline characteristics. Table 1 - Baseline characteristics - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author Full table There was no significant difference between the number of training classes attended in the two groups (P=0.12). In the qigong and exercise groups, 24 (51%) and 16 (39%) subjects, respectively, attended all the eight sessions, while 43 (91%) and 34 (83%) subjects, respectively, attended at least six out of eight sessions. At week 4, the scores for performance of qigong were lower than those of conventional exercise, both in self-assessment (42.6plusminus20.2 vs 65.7plusminus19.7%, P<0.001) and in the assessment by the instructor (43.6plusminus20.9 vs 91.9plusminus16.1%, P<0.001), suggesting that qigong was harder to master than conventional exercise. Between week 4 and 16, the performance evaluations did not change significantly. There was only one adverse event: a woman in the qigong group experienced vestibular neuronitis that was not related to the practice of qigong. SBP was higher in the qigong group at baseline (P=0.004), which might be related to the higher mean age in this group (P=0.002). SBP and DBP significantly decreased in both groups by week 16 (P<0.001) (Table 2). The decreases in blood pressure were not significantly different in the two groups; the differences in SBP and DBP reduction between the two groups were 0.59 mmHg (95% CI: -3.73, 4.91; P=0.79) and 1.83 mmHg (95% CI: -0.75, 4.41; P=0.16), respectively. The changes in ambulatory blood pressure were also not significantly different between the two groups. The mean ambulatory DBP in the exercise group decreased by 1.7plusminus0.7 mmHg (P=0.01). Table 2 - Qigong effect on the change of blood pressures and heart rate over time, after accounting for the baseline values. Table 2 - Qigong effect on the change of blood pressures and heart rate over time, after accounting for the baseline values - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author Full table Heart rate was lower in both groups at week 16 compared to baseline (P<0.001) (Table 2). The decrease in heart rate was not significantly different in the two groups. There was no significant change from baseline in the mean ambulatory heart rate in either group. The baseline waist circumference as well as the waist hip ratio was significantly greater in the qigong group (Table 3). Overall, there was a significant decrease in weight (P=0.002), BMI (P=0.002) and waist circumference (P=0.008) at week 16 compared to baseline. There was no significant difference between the two groups in this respect. Table 3 - Changes in physical measurements. Table 3 - Changes in physical measurements - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author Full table Biochemical variables are shown in Table 4. There were significant differences in the baseline HDL cholesterol and 24 h urinary sodium excretion. Total cholesterol, renin and 24 h urinary protein excretion decreased significantly in both groups in the course of the study. Apart from a small increase in plasma sodium in the qigong group, there were no significant changes in the other biochemical variables measured. Table 4 - Changes in laboratory biochemical measurements. Table 4 - Changes in laboratory biochemical measurements - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author Full table Clinical ECG and echocardiographic variables did not change substantially after the practice of qigong or conventional exercise (Table 5). No significant differences were observed between the changes of these measurements in the two treatment groups. Table 5 - Changes in echocardiographic measurements. Table 5 - Changes in echocardiographic measurements - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author Full table There were no significant differences between qigong and exercise in the scores in the SF-36, BAI and BDI questionnaires. Overall, there were favourable changes in the general health (P=0.002), bodily pain (P=0.02) and social functioning (P=0.009) domains of SF-36 (Figure 2); the changes (meanplusminuss.e.) in GH, BP and SF scores were 3.8plusminus2.0, 3.7plusminus3.0 and 4.0plusminus3.4 in the qigong group and 5.4plusminus2.5, 9.7plusminus4.1 and 7.6plusminus2.6 in the exercise group, respectively. Similarly, there was a favourable change in the score (meanplusminuss.e.) for depression in BDI in both the qigong group (-1.9plusminus0.8, P=0.02) as well as the exercise group (-2.2plusminus1.0, P=0.02). Figure 2. Figure 2 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author Changes in the domains of the SF-36 questionnaire between baseline and final visit. The qigong and conventional exercise groups are denoted by solid or broken lines, respectively. Error bars represent standard error of the mean. Full figure and legend (18K) Top of page Discussion Although qigong is practised widely, the amount of literature investigating the claims of its benefit is not substantial. Most studies were not published in English in international journals. In a review of 30 such studies related to qigong and hypertension, Mayer noted various areas of concern, including lack of random assignment, selection biases, placebo response issues, expectancy biases, blinded outcome assessment, adherence to treatment, reliability of blood pressure measurements, regression to the mean, publication biases and lack of consistency of measurement.22 This study was part of a programme of studies to test the efficacy of qigong in the most rigorous possible way in a randomised controlled trial. The subjects were recruited from the community and not from a hospital or secondary or tertiary referral centres. Most were untreated hypertensive patients. As antihypertensive medications were not prescribed during the study period, our results are not confounded by concurrent medications. Enormous care was taken to ensure that the two programmes were matched in terms of contact time and intensity. This study was performed in a single centre, with the same physician and research nurse throughout. There was an independent study monitor to ensure compliance with the protocol and to verify the data, ensuring its completeness and accuracy. The data were entered by an independent person and analysed by a statistician independently. We also studied variables that are less prone to subjectivity, that is, ambulatory blood pressure and echocardiography. The ambulatory DBP decreased in the exercise group but not in the qigong group, although there was no significant difference between the groups. No significant changes in left ventricular mass and ejection fraction were found. This was expected, as the mild changes in blood pressure were unlikely to lead to significant hypertrophy or regression, while the exertion involved was too moderate to cause hypertrophy as seen in athletes. The withdrawal of subjects before completion might have affected the power of the study. The frequency of withdrawal was not unusually high for a study that required lifestyle modification. In the landmark trials of low carbohydrate diets, the discontinuation and loss to follow-up rate was 40%.23, 24 In our study, there was no loss to follow-up and all subjects were accounted for. In any case, the observed difference in blood pressure lowering effect was less than 2 mmHg, which was small and of marginal clinical significance. Patient-centred outcome measures are also very important, as part of the benefit of many nonpharmacological measures may lie in the improvement in perceived quality of life and well-being. We found no difference between qigong and conventional exercises; both improved such variables to more or less the same degree. Our study does not support the hypothesis that qigong exercise offers an extra dimension of benefit in mild hypertension. We have shown that the psychosocial benefits are comparable. Qigong is more complex to master than conventional exercises done in accordance with the instructions of physiotherapists. It may therefore be less universally applicable. On the other hand, there may be cultural and spiritual benefits that our methodology cannot detect; nor have we addressed the possibility that qigong enhances the efficacy of antihypertensive drugs without having a pronounced effect on its own. Nevertheless, we have identified some positive benefits in both regimes besides lowering blood pressure. Both groups achieved a small degree of weight reduction, associated with a decrease in waist circumference, a reduction in urinary protein excretion and improvement in health status. The exercise intensity is low compared to brisk walking (2 vs 5 METs), making it suitable for the majority of the elderly. Indeed, it is lower than current exercise recommendations for the treatment of hypertension.25 In conclusion, our study showed that qigong and conventional exercise have similar effects on blood pressure in hypertensive patients. Qigong is not superior to conventional exercise, but can be used as an alternative to conventional exercise in those who prefer it as a form of nonpharmacological management of hypertension. Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author Top of page Notes Conflict of interest: none. The study was funded by a charitable donation for research from the Li Ka Shing Foundation. The Foundation is not involved in the design, conduct, analysis and reporting of the study. Top of page References Patel C, North WR. Randomised controlled trial of yoga and bio-feedback in management of hypertension. Lancet 1975; 2: 93–95. | Article | PubMed | ChemPort | Kokkinos PF et al. Effects of regular exercise on blood pressure and left ventricular hypertrophy in African-American men with severe hypertension. N Engl J Med 1995; 333: 1462–1467. | Article | PubMed | ChemPort | Chobanian AV et al. National Heart, Lung, and Blood Institute Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; National High Blood Pressure Education Program Coordinating Committee. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. 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Diggle PJ, Liang KY, Zeger SL. Analysis of Longitudinal Data. Oxford University Press: Oxford, 1994. Mayer M. Qigong and hypertension: a critique of research. J Altern Complement Med 1999; 5: 371–382. | PubMed | ChemPort | Samaha FF et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. N Engl J Med 2003; 348: 2074–2081. | Article | PubMed | ISI | ChemPort | Foster GD et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med 2003; 348: 2082–2090. | Article | PubMed | ISI | ChemPort | Wallace JP. Exercise in hypertension. A clinical review. Sports Med 2003; 33: 585–598. | Article | PubMed | Top of page Acknowledgements The generous support from the Li Ka Shing Foundation is gratefully acknowledged. JCM Li was the Clinical Data Manager for the study. Ms SK Chan was the qigong instructor. Echocardiography was performed by Dr Q Wang. Numerous colleagues in the Clinical Trial Centre and Queen Mary Hospital have contributed to the study; their help is invaluable and is greatly appreciated. Permission to use the Chinese (HK) version of SF-36, and the Chinese version of the Beck Anxiety and Depression Inventory is gratefully acknowledged. 'Beck Depression Inventory', 'BDI', 'Beck Anxiety Inventory', and 'BAI' are registered trademarks of The Psychological Corporation, a Harcourt Assessment Company. All rights are reserved.