Background: Heart rate variability (HRV) as an accurate, noninvasive measure of the Autonomous Nervous System (ANS) can reflect mental health (e.g., stress, depression, or anxiety). Tai Chi and Yoga (Tai Chi/Yoga), as the most widely practiced mind–body exercises, have shown positive outcomes of mental health. To date, no systematic review regarding the long-lasting effects of Tai Chi/Yoga on HRV parameters and perceived stress has been conducted. Objective: To critically evaluate the existing literature on this topic. Methods: Five electronic databases (Web of Science, PubMed, Scopus, SportDiscus and Cochrane Library) were searched from the start of the research project to July 2018. Study selection, data extraction, and study quality assessment were independently carried out by two reviewers. The potentially identified randomized controlled trials (RCT) reported the useful quantitative data that were included only for meta-analysis. Results: meta-analysis of 17 medium-to-high quality RCTs showed significantly beneficial effects on HRV parameters (normalized low-frequency, Hedge’s g = −0.39, 95% CI −0.39 to −0.56, p < 0.001, I2 = 11.62%; normalized high-frequency, Hedge’s g = 0.37, 95% CI 0.22 to −0.52, p < 0.001, I2 = 0%; low-frequency to high-frequency ratio, Hedge’s g = −0.58, 95% CI −0.81 to −0.35, p < 0.001, I2 = 53.78%) and stress level (Hedge’s g = −0.80, 95% CI −1.17 to −0.44, p < 0.001, I2 = 68.54%). Conclusions: Stress reduction may be attributed to sympathetic-vagal balance modulated by mind–body exercises. Tai Chi/Yoga could be an alternative method for stress reduction for people who live under high stress or negative emotions.

Objective. To investigate the effects of practicing Baduanjin Qigong on different health outcomes. Methods. Six electronic databases were used for literature search through entering the following key words: Baduanjin Qigong, quality of life, sleep quality, and health‐related outcomes. Results. Nineteen randomized controlled trials were used for meta‐analysis. The aggregated results from this systematic review have shown significant benefits in favour of Baduanjin Qigong on quality of life (SMD, −0.75; 95% CI −1.26 to −0.24; P = 0.004), sleep quality (SMD, −0.55; 95% CI −0.97 to −0.12; P = 0.01), balance (SMD, −0.94; 95% CI −1.59 to 0.30; P = 0.004), handgrip strength (SMD, −0.69; 95% CI −1.2 to −0.19; P = 0.007), trunk flexibility (SMD, −0.66; 95% CI −1.13 to −0.19; P = 0.006), systolic (SMD, −0.60; 95% CI −0.94 to −0.27; P = 0.0004) and diastolic blood pressure (SMD, −0.46; 95% CI −0.73 to −0.20; P = 0.0005), and resting heart rate (SMD, −0.87; 95% CI −1.47 to −0.27; P = 0.005). The aggregated results of meta‐analyses examining the effect of Baduanjin Qigong on leg power, cardiopulmonary endurance, and pulmonary function remain unclear because of a small number of studies. Conclusions. The aggregated results from this systematic review show that Baduanjin Qigong practice is beneficial for quality of life, sleep quality, balance, handgrip strength, trunk flexibility, systolic and diastolic blood pressure, and resting heart rate. Further studies are necessary to confirm the effects of Baduanjin Qigong on leg power, cardiopulmonary endurance, and pulmonary function (e.g., vital capacity), while considering a long‐term follow‐up. Registration Number. This trial is registered with International Prospective Register of Systematic Reviews (PROSPERO): CRD42016036966.

The combined association of physical activity and sedentary behavior with adverse health factors is not yet clear in the literature. A combined analysis of physical activity level and sedentary behavior may provide evidence of the interrelation between these behavioral variables and the frailty syndrome. Thus, the aim of this study was to examine the relationship between physical activity level, sedentary behavior and frailty in older adults. In this study, we evaluated 457 older adults (age range = 60 to 96 years old) from the Longitudinal Study of the Elderly Health of Alcobaça, Bahia. The frailty condition was defined by the presence of three or more of the following criteria: unintentional weight loss, slow walking speed measured over a 4.57 m test, a reduction of manual grip strength and exhaustion. Based upon these criteria, participants were classified as non-frail or frail. Physical activity level and time spent in sedentary behavior were assessed with the International Questionnaire of Physical Activity. Descriptive statistics were used to characterize the sample. To examine the combined association of physical activity and sedentary behavior with frailty, chi-square and Poisson regression tests were used. Statistical significance was defined as p ≤ 0.05. The prevalence of frailty was 8.8% (n = 40), with higher prevalence observed with increasing age. Low physical activity level combined with excessive time spent in sedentary behavior (physical activity level < 150 min/wk. and sedentary behavior ≥540 min/day) was associated with frailty, resulting in a prevalence ratio of 2.83 (95% CI, 1.23 to 6.52). Frailty is more prevalent among older adults who exhibit insufficient levels of physical activity combined with a great amount of time spent in sedentary behavior, even when adjusted for sociodemographic factors.

This investigation developed models to estimate aspects of physical activity and sedentary behavior from three-axis high-frequency wrist-worn accelerometer data. The models were developed and tested on 20 participants (n = 10 males, n = 10 females, mean age = 24.1, mean body mass index = 23.9), who wore an ActiGraph GT3X+ accelerometer on their dominant wrist and an ActiGraph GT3X on the hip while performing a variety of scripted activities. Energy expenditure was concurrently measured by a portable indirect calorimetry system. Those calibration data were then used to develop and assess both machine-learning and simpler models with fewer unknown parameters (linear regression and decision trees) to estimate metabolic equivalent scores (METs) and to classify activity intensity, sedentary time, and locomotion time. The wrist models, applied to 15-s windows, estimated METs [random forest: root mean squared error (rSME) = 1.21 METs, hip: rMSE = 1.67 METs] and activity intensity (random forest: 75% correct, hip: 60% correct) better than a previously developed model that used counts per minute measured at the hip. In a separate set of comparisons, the simpler decision trees classified activity intensity (random forest: 75% correct, tree: 74% correct), sedentary time (random forest: 96% correct, decision tree: 97% correct), and locomotion time (random forest: 99% correct, decision tree: 96% correct) nearly as well or better than the machine-learning approaches. Preliminary investigation of the models' performance on two free-living people suggests that they may work well outside of controlled conditions.

Purpose: The Godin Leisure-Time Exercise Questionnaire has been a commonly applied measure of physical activity in research among persons with multiple sclerosis over the past decade. This paper provides a comprehensive description of its application and inclusion in research on physical activity in multiple sclerosis. Method: This comprehensive, narrative review included papers that were published between 1985 and 2017, written in English, involved participants with multiple sclerosis as a primary population, measured physical activity, and cited one of the two original Godin papers. Results and Conclusion: There is a broad scope of research that has included the Godin Leisure-Time Exercise Questionnaire in persons with multiple sclerosis. Overall, 8 papers evaluated its psychometric properties, 21 evaluated patterns of physical activity, 24 evaluated correlates or determinants of physical activity, 28 evaluated outcomes or consequences of physical activity, and 15 evaluated physical activity interventions. The Godin Leisure-Time Exercise Questionnaire is a valid self-report measure of physical activity in persons with multiple sclerosis, and further is an appropriate, simple, and effective tool for describing patterns of physical activity, examining correlates and outcomes of physical activity, and provides a sensitive outcome for measuring change in physical activity after an intervention.