Yoga and Psychological and Physiological Health

Primary outcomes

1. Perceived Stress Scale

   Time frame: 5 weeks

   A 10-item scale measuring the degree to which situations in one's life are appraised as stressful.The items are rated on a 5-point scale from 0 (never) to 4 (very often). Total scores range from 0 to 40, with higher scores indicating a higher stress level.

2. The Hospital Anxiety and Depression Scale

   Time frame: 5 weeks

   A fourteen item scale which assesses levels of anxiety and depression. Seven of the 14 items relate to anxiety and seven relate to depression. Each item is scored from 0-3. Items can be scored together by subscale (score range: 0-21), or for total scale score (score range: 0-42).

3. The COPE Inventory

   Time frame: 5 weeks

   Assesses 14 conceptually distinct coping strategies. It includes 13 scales with four items each and one single item question to assess different strategies for coping with stress. All items are reported on a 4-point scale.

4. The Insomnia Severity Index

   Time frame: 5 weeks

   A brief screening measure of insomnia and an outcome measure for use in intervention research. The index contains seven items rated on a five-point Likert scale from 0 to 4. Higher scores indicate symptoms of insomnia.

5. Diet

   Time frame: 5 weeks

   A 2-item measure that is used as an exploratory questionnaire. The questions are as follows: Have you changed your eating habits since you started your participation in the study? Categorical answer choices include 1) No, not at all, 2) Yes, to some extent, 3) Yes, to a great extent. A second question is open-ended: If you have changed your eating habits, please describe how. This very brief questionnaire will be given only once at the end of the study to explore whether dietary changes have occurred following the 5-week study period.

6. General Health Questionnaire

   Time frame: 5 weeks

   Consists of 12 items, each one assessing the severity of a mental problem over the past few weeks using a 4-point Likert-type scale (from 0 to 3). These scores generate a total score ranging from 0 to 36 where higher scores indicate worse health.

7. The Harmony in Life Scale

   Time frame: 5 weeks

   Assesses a global sense of harmony in one's life and consists of 5 statements for which participants are asked to indicate degree of agreement on a 7-point Likert scale (1 = strongly disagree, 7 = strongly agree). The harmony score is established by summarizing the 5 statements for each participant, allowing for a maximum score of 35 (range: 5 - 35). Higher scores represent greater harmony in life.

8. The Kentucky Inventory of Mindfulness Skills -Short Version

   Time frame: 5 weeks

   A 20-item multi-dimensional scale of interrelated skills related to what one does while practicing mindfulness, and how one does it.

9. The Brief Experiential Avoidance Questionnaire

   Time frame: 5 weeks

   A questionnaire which consists of 15 items used to assess behavioral avoidance , distress aversion, procrastination, distraction/suppression, repression/denial, and distress endurance. Participants are asked to indicate degree of agreement on a 6-point Likert scale (1 = strongly disagree, 6 = strongly agree). The score is established by summing all items (score range: 15 - 90).

10. The Self-Compassion Scale

    Time frame: 5 weeks

    A 26-item measure with six subscales, tapping the construct of self-compassion. The subscales are self-kindness, self-judgment, common humanity, isolation, mindfulness, and over-identification. Scores of subscales are added together for a total score representative of the level of self-compassion.

11. Fasting blood sampling

    Time frame: 5 weeks

    A total of 3 tubes will be collected for each participant, amounting to a total of 65ml of blood per person. Blood analysis will include stress hormones, inflammatory biomarkers, metabolic profiling, cardiometabolic biomarkers, cholesterol, triglycerides, creatinine, catecholamines (noradrenalin and adrenalin), renin, cortisol, and glucose concentration.

12. Fasting and 120-minute glucose tolerance test (mmol/L)

    Time frame: 5 weeks

    The glucose tolerance test determines how the body responds to glucose (sugar). After a fasting blood sample is taken (see above procedure), participants will be asked to drink a liquid containing glucose. A second blood sample will be taken 120 minutes later.

13. Office and 24-hour blood pressure measurement (mmHg)

    Time frame: 5 weeks

    Blood pressure measurements will be taken periodically by the device for a period of 24-hours.

14. Pulse-wave velocity

    Time frame: 5 weeks

    Measured using a sphygmocor device.

15. Heart rate variability

    Time frame: 5 weeks

    Measured with electrocardiogram during deep breathing. Heart rate variability is is the variation in the time interval between heartbeats.

16. Gut microbiota

    Time frame: 5 weeks

    Fecal samples.