Plain English Summary
Background and study aims
People who do not do much physical activity or who accumulate excess body fat have an increased risk of diseases such as diabetes and cardiovascular disease. We do not really know why physical inactivity and/or eating more than you need increases risk of disease and we really need to find out more. We believe that chronic low-level inflammation and disturbed metabolism are critically important but it is very difficult to experimentally examine these pathways over a person's lifetime. Based on some recent research, we believe that we can simulate many of these changes through just a short-term intervention where we reduce a person's physical activity and give them more than they would usually eat. First of all, we need to see if the changes that we predict do actually take place and whether exercise can prevent these changes from taking place - and this is the purpose of the present study.
Who can participate?
We are looking for males, aged 18-40 years who are active (exercise more than 30 minutes per day, at least four times per week), who are non-smokers, not taking any drugs and whose weight has been stable for the last 6 months.
What does the study involve?
Participants will be asked to complete a range of preliminary tests (e.g., body mass, maximum oxygen uptake, body composition, habitual physical activity) after which they will complete a 1-week intervention.
Participants will be randomly allocated to one of two groups for the intervention. Both groups will be asked to reduce physical activity to <4000 pedometer steps per day for 7 days. During this period, one group will increase their energy intake by 50%. The other group will perform daily exercise at 70% maximum oxygen uptake for 45 min. This group will also increase energy intake by 50% above normal for 7 days but will also consume additional energy to offset exercise energy expenditure (and thus achieve the same energy surplus as the control group). Before and after the intervention, participants will come to the laboratory in the morning after an overnight fast. A cannula will be inserted for repeat blood sampling and an adipose tissue biopsy will be taken from abdomen. Participants will then consume a glucose-based solution and we will take blood samples over the following 2 hours.
What are the possible risks of participating?
1. Participants will be asked to complete a health questionnaire as well as a Physical Activity Readiness Questionnaire (PAR-Q) prior to participation in this study. The PAR-Q has been designed to identify the small number of adults for whom physical activity may be inappropriate or those who should have medical advice concerning the type of physical activity most suitable for them. In line with good practice, the laboratory is equipped with an automated defibrillator for use in the very unlikely event that resuscitation is required.
2. Participants will have to eat more food than normal. This might cause some inconvenience and discomfort.
3. Participants will have to temporarily interrupt normal exercise patterns and reduce other general physical activity in order to meet the 4000 step target. This might cause some inconvenience. Also, having to limit normal step count may affect some of the other activities that are normally performed (4000 steps would allow a typical office worker to go about their normal working life but not to undertake much additional walking or exercise).
4. A small fat sample will be taken at the beginning and end of the trial from around the waist. All fat samples will be taken by someone who has been specially trained to do so in order to minimise discomfort. There will be some bruising for a few days after taking this sample. There is a small chance of localised infection but good practice minimises this risk.
5. We will measure body fat using a very sophisticated and precise technique (dual energy x-ray absorptiometry or DEXA). DEXA is a non-invasive technique that uses a very low exposure to radiation. The radiation dose is often compared to the small exposure experienced during a short flight (e.g. London to Paris) and is similar to the amount of background radiation that would be received in a normal day living around Bath (and a tiny fraction [1/30th] of the amount of radiation experienced during a typical chest x-ray). This technique is routinely used in hospitals and with elite athletes but at the same time this does represent some exposure to a small amount of radiation. The risks associated with this amount of radiation are described as 'trivial' (less than 1 in ten million per whole body scan).
Where is the study run from?
The research will take place at the University of Bath.
When is study starting and how long is it expected to run for?
Participants can choose when to take part (i.e., the intervention can take place at a time that is convenient to them).
The study is expected to take place between September 2008 and September 2011.
Who is funding the study?
The University of Bath
Who is the main contact?
Dr Dylan Thompson
d.thompson@bath.ac.uk
Trial website
Contact information
Type
Scientific
Primary contact
Dr Dylan Thompson
ORCID ID
http://orcid.org/0000-0002-6312-1518
Contact details
Department for Health
University of Bath
Bath
BA2 7AY
United Kingdom
+44 1225 38 3177
d.thompson@bath.ac.uk
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
N/A
Study information
Scientific title
Can exercise overcome the effects of short term (one week) overfeeding and restricted physical activity on inflammatory markers and metabolic function?
Acronym
Study hypothesis
To determine if exercise can overcome the effects of a week of overfeeding and restricted physical activity on inflammatory markers and metabolic function in young, healthy, lean and active males?
Ethics approval
NHS Bath Research Ethics Committee approved on 19th March 2008, amendment approved on 3rd September 2008 (ref 07/H0101/234)
Study design
Randomised parallel group study
Primary study design
Interventional
Secondary study design
Randomised controlled trial
Trial setting
Other
Trial type
Screening
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
Condition
Obesity
Intervention
Control:
1. Reduce physical activity to < 4000 pedometer steps per day for 7 days
2. Increase energy intake by 50% above normal for 7 days
Intervention:
1. Reduce physical activity to < 4000 pedometer steps per day for 7 days
2. Exercise daily at 70% maximum oxygen uptake for 45 min
3. Increase energy intake by 50% above normal for 7 days plus consume additional energy to offset exercise energy expenditure (and thus achieve the same energy surplus as the control group).
Intervention type
Other
Phase
Not Applicable
Drug names
Primary outcome measure
Changes in insulin sensitivity and glycaemic control. Measured at baseline and at the end of the intervention (i.e., after 7 days).
Secondary outcome measures
1. Other blood measures related to metabolic function and inflammation (e.g., cholesterol, Non-Esterified Fatty Acids [NEFA], Triacylglycerol, alanine aminotransferase [ALT], interleukin (IL)-6, leptin, adiponectin)
2. Changes in adipose tissue gene expression related to metabolic function and inflammation
Measured at baseline and at the end of the intervention (i.e., after 7 days).
Overall trial start date
03/09/2008
Overall trial end date
30/09/2011
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
1. Male, aged 18 to 40
2. Physically active (more than 30 minutes per day 5 days per week)
3. Weight Stable (over the past 6 months)
Participant type
Patient
Age group
Adult
Gender
Male
Target number of participants
28
Participant exclusion criteria
1. Females
2. Smoker
3. Age outside range
4. Positive responses to Physical Activity Readiness Questionnaire
5. Taking medication
6. Doctor diagnosed condition that might interact with study measures (e.g. cardiovascular disease)
Recruitment start date
03/09/2008
Recruitment end date
30/09/2011
Locations
Countries of recruitment
United Kingdom
Trial participating centre
Department for Health
Bath
BA2 7AY
United Kingdom
Sponsor information
Organisation
University of Bath (UK)
Sponsor details
c/o Dr Dylan Thompson
Department for Health
University of Bath
Bath
BA2 7AY
United Kingdom
Sponsor type
University/education
Website
Funders
Funder type
University/education
Funder name
University of Bath (UK)
Alternative name(s)
Funding Body Type
private sector organisation
Funding Body Subtype
academic
Location
United Kingdom
Results and Publications
Publication and dissemination plan
Planned publication in a peer reviewed journal
Intention to publish date
31/12/2013
Participant level data
Available on request
Basic results (scientific)
Publication list
2013 results in http://www.ncbi.nlm.nih.gov/pubmed/24167223