Victoria University, Australia
Michaela is a researcher in the field of stress, inflammation, wellbeing and mental health. She has drawn attention to the impact of stress on mental health and cognitive outcomes, and the mediating influence of non-pharmacological stress mediating interventions, such as diet, exercise and mindfulness on these outcomes. She has researched the impact of stress both in the context of chronic illness, and young people in Australia experiencing chronic, normative stress related to their academic demands.
Introduction and Aims: Practices that include yoga asanas for the management of stress are increasingly popular; however, the neurobiological effects of these practices on stress reactivity are not well understood. Many studies investigating the effects of such practices fail to include an active control group. Given the frequency with which people are selecting such interventions as a form of self-management, it is important to determine their effectiveness. Thus, this review investigates the effects of practices that include yoga asanas, compared to an active control, on physiological markers of stress.
Methods: A meta-analysis of randomised controlled trials published in English compared practices that included yoga asanas to an active control on stress-related physiological measures. MEDLINE, AMED, CINAHL, PsycINFO, SocINDEX, PubMed and Scopus were searched. Randomised controlled trials were included if they assessed at least one of the following outcomes: heart rate, blood pressure, heart rate variability, mean arterial pressure, C-reactive protein, interleukins or cortisol. Meta-analysis was undertaken using Comprehensive Meta-Analysis Software Version 3. Subgroup analysis was conducted for different yoga and control group types, different populations, length of intervention, and method of data analysis.
Results: Forty two studies were included in the meta-analysis. Interventions that included yoga asanas were associated with reduced evening cortisol, waking cortisol, ambulatory systolic blood pressure, resting heart rate, high frequency heart rate variability, fasting blood glucose, cholesterol and low density lipoprotein, compared to active control. However, the reported interventions were heterogeneous.
Conclusions: Practices that include yoga asanas appear to be associated with improved regulation of the sympathetic nervous system and hypothalamic-pituitary-adrenal system in various populations.