Plain English Summary
Background and study aims
As obesity is becoming more common worldwide, more people are undergoing weight-loss surgery such as primary laparoscopic gastric bypass, where the digestive system is re-routed past most of the stomach so that less food is digested and it takes much less food to feel full. Weight-loss surgery often has good results on obesity and related diseases. Little is known, however, about what happens to muscle strength and the abdominal wall after weight-loss surgery. Previous studies have shown that thigh muscle strength is reduced after weight-loss surgery. The aim of this study is to collect information to see whether weight loss causes muscular strength problems that could have an effect on the decision to undergo surgery.
Who can participate?
Patients undergoing primary laparoscopic gastric bypass
What does the study involve?
Blood samples are taken to measure connective tissue and wound healing markers before surgery and 2 weeks, 1 month, 3 months and 6 months after surgery. Tissue samples of the abdominal wall are collected during surgery, and are also tested for connective tissue and wound healing markers. Muscle strength in the abdominal wall and thigh are measured once before and 6 months after surgery. Physical ability and abdominal wall function are also measured using questionnaires before and 6 months after surgery.
What are the possible benefits and risks of participating?
The muscle measurements are generally well tolerated and can heighten awareness of physical ability after surgery. The extra blood samples required in this study can be taken together with regular blood samples before and after surgery. The small (5 mm) tissue samples are not expected to be noticed in any way by the participants as these are taken during surgery.
Where is the study run from?
1. Lycksele Hospital (Sweden)
2. Uppsala University Hospital (Sweden)
When is the study starting and how long is it expected to run for?
October 2015 to September 2019
Who is funding the study?
Umeå University (Sweden)
Who is the main contact?
Dr Jeff Wennerlund
Dr Jeff Wennerlund
Department of Surgery and Orthopedics
+46 (0)950 39124
Prof Ulf Gunnarsson
Department of Surgery and Perioperative Sciences
+46 (0)90 7852909
Does muscle strength and abdominal wall function improve with weight loss after gastric bypass? A clinical observational study
1. Does bariatric surgery improve abdominal wall function after weight loss?
2. Does weight loss after bariatric surgery cause problems with the abdominal wall?
Regional Ethics Review Board, Umeå, 10/1/2016, ref: 2015/367-31
Clinical observational study
Primary study design
Secondary study design
Patient information sheet
Not available in web format, please use contact details to request a participant information sheet (in Swedish only)
Obesity, weight loss, muscle strength
Blood samples are collected to analyze matrix metalloproteinases before surgery, as well as 2 weeks, 1 month, 3 months and 6 months after. Abdominal wall muscle and fascia biopsies are collected during surgery for analysis of matrix metalloproteinases. Abdominal wall and thigh strength are measured with the use of BioDex System 3 before and 6 months after gastric bypass. Physical ability and abdominal wall function are also measured using Ventral Hernia Pain Questionnaire (VHPQ), International Physical Ability Questionnaire (IPAQ) and Visual Analog Scale for abdominal wall function (VAS), all once before and once 6 months after surgery.
Primary outcome measure
1. Matrix metalloproteinases, measured from blood samples taken at baseline (pre-operatively) and 2 weeks, 1 month, 3 months and 6 months postoperatively
2. Abdominal wall and thigh muscle strength, measured with the BioDex System 3 at baseline (pre-operatively) and 6 months post-operatively
3. Physical ability and abdominal wall function, measured using the Ventral Hernia Pain Questionnaire (VHPQ), International Physical Activity Questionnaire (IPAQ), and Visual Analog Scale (VAS) for abdominal wall function at baseline (pre-operatively) and 6 months postoperatively
Secondary outcome measures
No secondary outcome measures
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Patients eligible for primary laparoscopic gastric bypass
2. All patients undergoing primary laparoscopic gastric bypass at Lycksele Hospital are eligible for recruitment
3. Patients undergoing surgery in Uppsala are eligible for collection of blood and tissue samples only
4. All ages
Target number of participants
50 in group with blood and tissue samples along with BioDex measurement and questionnaires. Another 50 with only blood and tissue samples, and questionnaires.
Participant exclusion criteria
If, after inclusion, no or different surgery is planned
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Department of Surgery, Västerbottens läns landsting (County Council)
Hedlundavägen Lycksele Hospital
Trial participating centre
Department of Surgery
Uppsala University Hospital
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
This study is expected to give rise to three publications:
1. The change in matrix metalloproteinases (MMPs) before and after gastric bypass
2. The change in abdominal muscle strength as related to the questionnaires and change in MMPs in both blood and tissue, as well as degree of weight loss
3. The change in thigh muscle strength in relation to the questionnaires and change in MMPs and body weight
The results are to be presented at national and international conferences. Publication is planned in peer-reviewed journals from the later half of 2019 until at least a year later, depending on the trial end date.
IPD sharing plan
The datasets generated during and/or analysed during the current study are/will be available upon request from Dr Jeff Wennerlund (Jeff.Wennerlund@umu.se).
Intention to publish date
Participant level data
Available on request
Basic results (scientific)