Testing Equality of Treatments under an Incomplete Block Crossover Design with Ordinal Responses

Effects of Breaking Up Sedentary Behavior With Short Bouts of Yoga and Tai-Chi on Glycemia, Concentration, and Well-Being

BACKGROUND

Investigating the effects of breaking up sedentary behavior with short bouts of Yoga and Tai-Chi on glycemic control, concentration, and well-being in healthy individuals.

METHODS

In this randomized balanced incomplete block study, 15 adults (age = 26 [2.50] y, 8 females) completed 2 of 3 protocols: uninterrupted sitting (Control), sitting interrupted with 3 minutes of Yoga every 30 minutes, or with 3 minutes of Tai-Chi every 30 minutes. Protocols lasted 7.5 hours and included a standardized diet. Glucose was measured every 30 minutes with a glucometer (Abbott FreeStyle Libre). Concentration and well-being were recorded with self-reported ecological momentary assessment. Area under the curve was calculated for glucose data. Statistical analyses were performed as a hierarchical repeated-measures model.

RESULTS

Glucose area under the curve for the Yoga intervention (34.55 [3.12] mmol/L) was significantly lower than the Control (38.14 [3.18] mmol/L; P < .05). There was a trend toward lower glucose in the Tai-Chi group compared with the Control, but no significant differences were found (AUCTai-Chi = 36.64 [3.11] mmol/L; P = .57). Mean concentration in all groups decreased throughout the day, with the largest decrease in the Control. Well-being for the Yoga and Control groups decreased but increased with Tai-Chi. Concentration and well-being responses were not statistically significant between intervention groups.

CONCLUSIONS

Breaking up sedentary behavior using 3-minute bouts of Yoga significantly lowers blood glucose in healthy individuals without compromising concentration or well-being. Tai-Chi did not provide the same significant effect on glucose levels but allowed better maintenance of concentration and well-being. These interventions provide effective ways to combat the deleterious effects of prolonged sedentary time while maintaining concentration and well-being.

Dose-response between frequency of interruption of sedentary time and fasting glucose, the dawn phenomenon and night-time glucose in Type 2 diabetes

AIM

To explore the dose-response between frequency of interruption of sedentary time and basal glucose (fasting glucose, the dawn phenomenon and night-time glucose) in Type 2 diabetes.

METHODS

In a randomized three-treatment, two-period balanced incomplete block trial, 12 people with Type 2 diabetes (age, 60.0 ± 3.2 years; BMI, 30.2 ± 1.4 kg/m² ) completed two of three conditions: sitting for 7 h interrupted every 60 min (Condition 1), 30 min (Condition 2), and 15 min (Condition 3) by 3-min light-intensity walking breaks. The activPAL3 and FreeStyle Libre were used to assess physical activity/sedentary behaviour and continuous glucose profile. Standardized meals were provided, and changes in basal glucose of the nights and early mornings before and after treatment conditions were calculated (mean ± SE).

RESULTS

After treatment conditions, fasting glucose and duration of the dawn phenomenon were lower for Condition 3 (-1.0 ± 0.2 mmol/l, P < 0.02; -3.1 ± 1.3 h, P = 0.004) compared with Condition 1 (-0.1 ± 0.2 mmol/l; 1.9 ± 1.2 h). The magnitude of the dawn phenomenon was reduced in Condition 3 (-0.6 ± 0.4 mmol/l, P = 0.041) compared with Condition 2 (0.6 ± 0.3 mmol/l). Night-time glycaemic variability (coefficient of variation) was reduced in Condition 3 (-9.7 ± 3.9%) relative to Condition 2 (6.1 ± 4.8%, P < 0.03) and Condition 1 (2.5 ± 1.8%, P = 0.02). There was no change in night-time mean glucose.

CONCLUSIONS

Frequent interruptions of prolonged sitting with 3 min of light-intensity walking breaks every 15 min improves fasting glucose, the dawn phenomenon and night-time glycaemic variability, and this might be a simple therapeutic intervention to improve glucose control. Clinicaltrials.gov Identifier: NCT02738996.