Effect of a single session of yoga and meditation on stress reactivity: A systematic review.

This systematic review synthesises the evidence for the effectiveness of a single session of yoga or its components including meditation and breathing techniques in reducing acute stress reactivity in healthy adults. Following the PRISMA guidelines, we searched Medline, EMBASE, Cochrane, CINAHL, and PsycINFO on 30th July 2023 for randomised controlled or crossover trials of yoga components and reporting physiological and/or psychological outcome measure(s) related to stress reactivity. Risk of bias (ROB) was assessed using the Cochrane ROB 2 tool. Data were synthesised narratively. Twenty-one out of 28 eligible studies (n = 2574) relating to 31 interventions (meditation [n = 22], breathing [n = 4] and yoga [n = 5]) reported outcomes in favour of the intervention. Stress reactivity was reported to be reduced by 71% of studies measuring physiological outcomes and 65% of studies measuring psychological outcomes. These studies show that a single session of yoga components is effective in reducing acute stress reactivity in adults and could be recommended for stress management. Future studies with larger populations and a more equal representation of genders and age groups are warranted.

Not All Yoga Styles Are the Same: An International Survey on Characteristics of Yoga Classes.

Objectives: Yoga is a multicomponent activity that has been associated with many health benefits. Different yoga styles contain different combinations and durations of components (e.g., postures, breathing, meditation, relaxation, and chanting). A better description and quantification of yoga components within different styles are important in understanding how different yoga styles contribute to health outcomes. This survey aims to understand the general characteristics and components taught in different yoga styles. Design: An online international survey was sent to yoga teachers (18+ years with >1 year teaching experience) using snowball recruitment. Survey questions included demographic and professional characteristics of participants, specialized yoga style, and details of components typically taught in the class. The analysis included descriptive statistics and a comparison between teachers of traditional versus exercise-based versus therapy styles using χ2 and Kruskal-Wallis tests. Results: Nine hundred and sixty-eight yoga teachers (76.8% female, mean age 43.8 ± 11.1 years) from 64 countries participated in the survey. When grouped according to primary yoga style taught, 70.6% of participants taught traditional (e.g., hatha or ashtanga), 18.4% exercise-based (e.g., vinyasa or power), and 11.0% therapy (e.g., restorative or gentle) styles. Nearly all teachers included physical postures, but breath techniques, chanting, and cleansing were included by significantly more traditional teachers (95.2%, 68.3%, 25.8%, respectively) compared with exercise-based (88.6%, 42.5%, 7.2%) and therapy teachers (93.0%, 43.0%, 10.0%). Variations were reported in the time allocated to each of these class components. Physical postures took up 50.0% of total class time for traditional styles, 60.9% for exercise-based, and 53.9% for therapy styles (p < 0.001). Conversely, breath techniques, meditation, relaxation, and chanting took significantly more of the class time for traditional and therapy compared with exercise-based styles. However, teachers from all styles regarded yoga poses, breathing, meditation, and relaxation as equally important in the yoga class. Conclusions: Exercise-based yoga styles unsurprisingly dedicate more time to physical postures and less time to nonphysical components than traditional and therapy yoga styles. However, all yoga teachers report valuing and including multiple components of yoga practice regardless of the primary style of teaching, which is reflective of the holistic nature of yoga practice. Further research into the benefits of the specific component combinations in different yoga styles is needed to better understand the full potential of yoga practice for health.

Thermoregulation During Pregnancy: a Controlled Trial Investigating the Risk of Maternal Hyperthermia During Exercise in the Heat.

OBJECTIVES: Despite the well-established benefits of exercise, pregnant women are discouraged from physical activity in hot/humid conditions to avoid hyperthermia (core temperature (Tcore) ≥ 39.0 °C). Recent epidemiological evidence also demonstrates greater risk of negative birth outcomes following heat exposure during pregnancy, possibly due to thermoregulatory impairments. We aimed to determine (1) the risk of pregnant women exceeding a Tcore of 39.0 °C during moderate-intensity exercise in the heat; and (2) if any thermoregulatory impairments are evident in pregnant (P) versus non-pregnant (NP) women. METHODS: Thirty participants (15 pregnant in their second trimester or third trimester) completed two separate exercise-heat exposures in a climate chamber (32 °C, 45%RH). On separate occasions, each participant cycled on a semi-recumbent cycle ergometer for 45 min at a workload representative of a moderate-intensity (1) non-weight-bearing (NON-WB), or (2) weight-bearing (WB) activity. Thermoregulatory responses were monitored throughout. RESULTS: The highest rectal temperature observed in a pregnant individual was 37.93 °C. Mean end-exercise rectal temperature did not differ between groups (P:37.53 ± 0.22 °C, NP:37.52 ± 0.34 °C, P = 0.954) in the WB trial, but was lower in the P group (P:37.48 ± 0.25 °C, vs NP:37.73 ± 0.38 °C, P = 0.041) in the NON-WB trial. Whole-body sweat loss was unaltered by pregnancy during WB (P:266 ± 62 g, NP:264 ± 77 g; P = 0.953) and NON-WB P:265 ± 51 g, NP:300 ± 75 g; P = 0.145) exercise. Pregnant participants reported higher ratings of thermal sensation (felt hotter) than their non-pregnant counterparts in the WB trial (P = 0.002) but not in the NON-WB trial, (P = 0.079). CONCLUSION: Pregnant women can perform 45 min of moderate-intensity exercise at 32 °C, 45%RH with very low apparent risk of excessive maternal hyperthermia. No thermoregulatory impairments with pregnancy were observed.

Physical activity interventions for adults who are visually impaired: a systematic review and meta-analysis.

OBJECTIVES: Compared with sighted individuals, people with visual impairment have a higher prevalence of chronic conditions and lower levels of physical activity. This review aims to systematically review physical activity interventions for those with a visual impairment and to assess their effectiveness. DESIGN: A systematic review of articles reporting physical activity interventions in visually impaired individuals was conducted. Medline, EMBASE, The Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, SPORTDiscus and the Physiotherapy Evidence Database were searched in August 2018. Meta-analyses were conducted on randomised controlled trials with the same outcome measure. SETTING: Most interventions were conducted in a group setting, with some including an at-home, self-directed component. PARTICIPANTS: Following identification of a recent systematic review of physical activity interventions in children, our review focused on adults aged 18 years and older with a visual impairment. PRIMARY AND SECONDARY OUTCOME MEASURES: Outcomes included measures of balance, mobility, mental well-being (eg, quality of life), number of falls, muscle strength, flexibility and gait. RESULTS: Eighteen papers from 17 studies met inclusion criteria. Physical activity components include falls prevention and/or balance-based activities, walking, tai chi, Alexander Technique, Yoga, dance, aerobics and core stability training. Significant results in favour of the intervention were reported most commonly in measures of functional capacity (9/17 studies) and in falls/balance-related outcomes (7/13 studies). The studies identified were generally small and diverse in study design, and risk of bias was high across several categories for most studies. Meta-analyses indicated non-significant effects of the included interventions on the Timed Up and Go, Chair Sit Test and Berg Balance Scale. CONCLUSIONS: Physical activity interventions in individuals with visual impairment incorporating activities such as tai chi, Yoga and dance can have positive results, particularly in physical measures such as mobility and balance. However, when performing a meta-analysis of randomised controlled trials, the evidence for effectiveness is less clear. More studies with larger sample sizes, stronger designs and longer follow-up periods are needed. PROSPERO REGISTRATION NUMBER: CRD42018103638.

A single session of hatha yoga improves stress reactivity and recovery after an acute psychological stress task-A counterbalanced, randomized-crossover trial in healthy individuals.

OBJECTIVES: Yoga is promoted as an anti-stress activity, however, little is known about the mechanisms through which it acts. The present study investigated the acute effects of a hatha yoga session, displayed on a video, on the response to and recovery from an acute psychological stressor. METHODS: Twenty-four healthy young adults took part in a counterbalanced, randomized-crossover trial, with a yoga and a control condition (watching TV). Participants attended the laboratory in the afternoon on two days and each session comprised a baseline, control or yoga task, stress task and recovery. Blood pressure (BP), heart rate (HR) and salivary cortisol responses were measured. State cognitive- and somatic-anxiety along with self-confidence were assessed before and after the stressor. RESULTS: Although no difference in the BP or HR responses to stress were found between conditions, systolic BP (p=0.047) and diastolic BP (p=0.018) recovery from stress were significantly accelerated and salivary cortisol reactivity was significantly lower (p=0.01) in the yoga condition. A yoga session also increased self-confidence (p=0.006) in preparation for the task and after completion. Moreover, self-confidence reported after the stress task was considered debilitative towards performance in the control condition, but remained facilitative in the yoga condition. CONCLUSION: Our results show that a single video-instructed session of hatha yoga was able to improve stress reactivity and recovery from an acute stress task in healthy individuals. These positive preliminary findings encourage further investigation in at-risk populations in which the magnitude of effects may be greater, and support the use of yoga for stress reactivity and recovery.

Trait mindfulness is associated with blood pressure and interleukin-6: exploring interactions among subscales of the Five Facet Mindfulness Questionnaire to better understand relationships between mindfulness and health.

Mindfulness based interventions have been associated with improvements in physical health; however, the mechanisms underlying these changes are unclear. The current study explored relationships between trait mindfulness, blood pressure (BP) and interleukin-6 (IL-6). Relationships between physical health variables and (1) a composite score of mindfulness, (2) individual facets of mindfulness and (3) interactions between theoretically relevant pairs of mindfulness subscales were investigated. One hundred and thirty healthy, young adults [M (SD) age = 21.7(2.7) years] reported trait levels of mindfulness (Five Facet Mindfulness Questionnaire, subscales include: observing, describing, acting with awareness (AWA), nonjudging and nonreactivity), had their resting BP measured and underwent a blood draw to assesses circulating IL-6 levels. Age, gender, body mass index, race/ethnicity, depression and perceived stress were obtained and used as covariates. A composite score of trait mindfulness was associated with lower BP and a trend suggested that it was also associated with lower IL-6. Investigation of individual facets of mindfulness revealed interactions between the subscales AWA and nonjudging, such that higher endorsement of AWA was associated with lower BP only when nonjudging was also high. A second interaction was observed between the subscales observing and nonreactivity, such that higher endorsement of observing was associated with lower IL-6 only when levels of nonreactivity were also high. Trait mindfulness was associated with both BP and IL-6. Examining interactions between facets of mindfulness variables may be important in understanding how mindfulness based interventions influence physiology.

Sex differences in the interleukin-6 response to acute psychological stress.

Interleukin-6 (IL-6), an immune regulator that helps coordinate the inflammatory response, may mediate inflammatory disease exacerbation associated with stress. Twenty men and twenty women completed a single session, comprising baseline (20 min), mental arithmetic task (8 min), and recovery (60 min). Blood samples, taken at baseline, immediately after the task, and at +30 and +60 min recovery were analysed for plasma IL-6. Overall, IL-6 increased linearly from baseline to +60 min recovery, and a sex difference was found in the IL-6 response, with men peaking earlier than women. These findings confirm a small delayed IL-6 increase after acute laboratory stress, and reveal sex differences in the profile of the IL-6 response.