"A 2011 overview of systematic reviews of controlled clinical trials, Lee et al. concluded that "the effectiveness of qigong is based mostly on poor quality research" and "therefore, it would be unwise to draw firm conclusions at this stage." Although a 2010 comprehensive literature review found 77 peer-reviewed RCTs, Lee et al.s overview of systematic reviews as to particular health conditions found problems like sample size, lack of proper control groups, with lack of blinding associated with high risk of bias.A 2015 systematic review of the effect of qigong exercises on cardiovascular diseases and hypertension found no conclusive evidence for effect. Also in 2015, a systemic review into the effects on hypertension suggested that it may be effective, but that the evidence was not conclusive because of the poor quality of the trials it included, and advised more rigorous research in the future. Another 2015 systematic review of qigong on biomarkers of cardiovascular disease concluded that some trials showed favorable effects, but concludes, "Most of the trials included in this review are likely to be at high risk of bias, so we have very low confidence in the validity of the results. Mental health
Many claims have been made that qigong can benefit or ameliorate mental health conditions, including improved mood, decreased stress reaction, and decreased anxiety and depression. Most medical studies have only examined psychological factors as secondary goals, although various studies have shown decreases in cortisol levels, a chemical hormone produced by the body in response to stress.
In 1985, the state-run National Qigong Science and Research Organization was established to regulate the nations qigong denominations. In 1999, in response to widespread revival of old traditions of spirituality, morality, and mysticism, and perceived challenges to State control, the Chinese government took measures to enforce control of public qigong practice, including shutting down qigong clinics and hospitals, and banning groups such as Zhong Gong and Falun Gong. : 161–174 
Since the 1999 crackdown, qigong research and practice have only been officially supported in the context of health and traditional Chinese medicine. The Chinese Health Qigong Association, established in 2000, strictly regulates public qigong practice, with limitation of public gatherings, requirement of state approved training and certification of instructors, and restriction of practice to state-approved forms.Through the forces of migration of the Chinese diaspora, tourism in China, and globalization, the practice of qigong spread from the Chinese community to the world. Today, millions of people around the world practice qigong and believe in the benefits of qigong to varying degrees. Similar to its historical origin, those interested in qigong come from diverse backgrounds and practice it for different reasons, including for recreation, exercise, relaxation, preventive medicine, self-healing, alternative medicine, self-cultivation, meditation, spirituality, and martial arts training. Overview
Practices
Qigong comprises a diverse set of practices that coordinate body (調身), breath (調息), and mind (調心) based on Chinese philosophy. Practices include moving and still meditation, massage, chanting, sound meditation, and non-contact treatments, performed in a broad array of body postures.