Do regular activity breaks from prolonged sitting improve the cardiometabolic profile of women with polycystic ovary syndrome? The PCOS BREAKS Study

A randomised, acute crossover trial involving two conditions will be conducted in 22 overweight/obese women with diagnosed PCOS in a controlled clinical environment. The two conditions will include; 1) 3-hours of uninterrupted sitting (SIT); and 2) 3-hours of sitting with 3-min simple resistance activity breaks every 30 minutes (BREAKS). Participants must be of reproductive age (18-45 years), have a BMI between 25-35 kg/m2, medically diagnosed with PCOS (clinician confirmed) and have no existing injuries or dietary allergies. Three days prior to beginning the two conditions, participants will visit the Baker and be fitted with: a continuous glucose monitoring system ([CGM], a small device that records glucose levels every 5 minutes); an ActivPal (fitted on the right thigh) and an ActiGraph watch (fitted on the right wrist). Participants will be asked to wear all three monitors 24 hours/day (including sleeping and showering) until the morning after completing the condition days. While wearing the monitors, participants will be asked to complete a brief activity log and sleep questionnaire (approximate 2-3 minutes to complete) the morning of every day the monitors are worn. In the 48 hours prior to both condition days, participants will be asked to refrain from consuming alcohol and caffeine, and from participating in any moderate to vigorous physical activity (exercise). The day before the condition day, participants will be asked to record all food and beverages that they consume in a food log diary. They will then be asked to consume this same diet the day before the last condition day. The night prior to each condition day, participants will consume a standardised dinner (provided by the researchers). Participants will also be asked to go to bed at their normal bedtime. The morning of both condition days, participants will arrive in a fasting state and a cannula will be inserted into a vein in their left arm. During the 1-hr steady state, participants will have a fasted blood sample taken, blood pressure measure taken, a ‘Flow-Mediated Dilatation (FMD) test’ (a non-invasive test that measures the blood flow in the leg) taken and asked to complete a fatigue questionnaire. Throughout the 3-hr trial, blood samples will be taken every 30 minutes, blood pressure every hour and three additional FMD test (between 0.5-1 hour, 1.5-2.0h and post 3.0h). Two additional tests examining fatigue levels will also be completed at 1.5 hours and immediately post trial (prior to the last FMD test). On commencement of the trial, participants will be asked to record all food and drinks consumed for the rest of the day, and asked to repeat this same diet for condition day 2. They will also be asked to continue to wear the three monitors until the following morning and post them back using the replied paid envelope. Participants will return to complete the last condition day following a 7-day wash out period and after adhering to the same 48-hour restrictive period as described above (in total, 9 days). After completing the last condition day, participants will be asked to repeat the same diet as condition day 1 and to wear the monitors all three monitors until the following morning (and post back using the replied paid envelope). Where possible the two condition days will be performed in the follicular phase of the participant’s menstrual cycle.