None listed
Conditions
Brief summary
Advances in technology, while providing a wide and varied range of benefits, have had the effect of engineering an environment where humans are continually encouraged to sit. This shift toward a more sedentary lifestyle has been linked to a myriad of poor health outcomes, including increased risk of cardiovascular disease, diabetes, and all-cause mortality. Compelling evidence indicates that the global burden of chronic disease and premature deaths attributable to physical inactivity is comparable to smoking. Over the past decade, our lab has revealed that sedentary behaviour (sitting) is associated with elevated markers of cardio-metabolic risk, and premature all-cause and cardiovascular disease mortality. Expanding on the evidence provided from observational studies, we have shown a beneficial effect of breaking up prolonged sitting time with light intensity physical activity on postprandial glucose and insulin metabolism, blood pressure and fibrinogen; and that some of these effects are being mediated by changes at the gene and protein expression level. Despite the progress that has been made, there still remains the question “how much sitting is too much”? This is likely to involve a complicated interplay between several different metabolic processes, and requires the ability to use continuous measures to determine the point at which negative effects occur. Teasing out the mechanisms and time-course of the negative impact of prolonged uninterrupted sitting is a vital next step which could help to inform future intervention strategies and activity guidelines. In this pilot trial, we aim to assess the impact of 5 hours of prolonged, uninterrupted sitting on various physiological and metabolic parameters in overweight adults with type 2 diabetes (n=5). These parameters include: (i) muscle activity and posture, leading to musculoskeletal discomfort (ii) the baroreflex and orthostatic intolerance (iii) sympathetic nervous system activity via microneurography One of the main aims of this pilot trial is to test the feasibility of measuring all of these parameters at once, using our standard sitting intervention and musculoskeletal protocols. In particular, we aim to establish whether we can get useful EMG and posture measures with the other equipment and furniture being used; and also determine if we can get clear and meaningful microneurography measurements in the sitting position. We hypothesise that reduced variation in muscle activity resulting from prolonged sitting and poor posture will lead to musculoskeletal discomfort. Moreover, prolonged sitting will lead to baroreflex dysfunction and orthostatic intolerance. Sympathetic nervous system activity will be tested only for feasibility in this pilot study.
Interventions
Participation will involve 2 visits over 1-2 weeks.
1) Consent and screening: including full disclosure of the project aims and requirements; collecting information on medical history; measurements of height, weight, hip and waist, and blood pressure.
2) Experimental Procedure: To minimise potential variability, participants will be asked to refrain from alcohol, caffeine and moderate-to-vigorous activity in the 48 hours prior to the experimental day. They will also be provided with a pre-dinne
Participation will involve 2 visits over 1-2 weeks. 1) Consent and screening: including full disclosure of the project aims and requirements; collecting information on medical history; measurements of height, weight, hip and waist, and blood pressure. 2) Experimental Procedure: To minimise potential variability, participants will be asked to refrain from alcohol, caffeine and moderate-to-vigorous activity in the 48 hours prior to the experimental day. They will also be provided with a pre-dinner meal to be consumed between 7-9pm the night before, after which they will be instructed to fast until the beginning of the trial the next morning. Adherence to these requests will be determined via food and activity diaries. On the morning of the trial, following equipment set-up, the participant will be instructed to sit quietly for an initial 1 hour "steady state" period, during which time measurements will be recorded. The participant will then be provided with a breakfast meal, commencing the experimental condition thereafter. The breakfast meal will consist of 55% carbohydrate, 30% fat and 15% protein, and will provide 33% of daily energy needs, based on the Schofield equation. Participants will be asked to sit quietly in a comfortable chair for five hours. They can watch television, DVD’s or read whilst seated. They will be able to have a toilet break whenever they need, but will otherwise be asked to sit as still as possible to avoid interfering with measurement outcomes. Continuous measures of blood pressure and heart rate (ECG) will be taken. EMG and posture will be recorded every 3 minutes; and discomfort scores every 10 minutes throughout the sitting period. Microneurography of the peroneal nerve will be measured from baseline to 2 hours post meal.
Sponsors
Professor David Dunstan
Study design
Allocation
Non-randomised trial
Intervention model
Single group
Primary purpose
Prevention
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
55 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
Participants will be overweight/obese, based on having a BMI between 25 kg/m2 and 40 kg/m2, previous diagnosis of type 2 diabetes greater than 3 months, and be english speaking.
Exclusion criteria
Conditions for exclusion are: diagnosis of type 2 diabetes for less than 3 months; unable to sit for prolonged periods due to musculoskeletal pain; pregnancy; employment in a non-sedentary occupation; currently watching less than 3 hours of television per day; regularly engaged in moderate-intensity exercise for greater than or equal to 150 min/week for greater than 3 months; use of glucose/lipid lowering/antidepressant medications; pre-menopausal or menopausal women; and major illness/physical problems. These exclusion criteria are necessary to ensure our participants fall within the demographic in which the risk of cardiovascular and diabetic complications due to sedentary behaviour are elevated. This is the target group for future interventions in whom breaks from daily prolonged sitting are likely to be of most benefit.
Outcome results
None listed