The Effect of Lowered Physical Activity on Insulin Sensitivity and Lipid and Glucose Metabolism

This study is currently recruiting participants. (see Contacts and Locations)
Verified May 2013 by Maastricht University Medical Center
Sponsor:
Information provided by (Responsible Party):
Lena Bilet, Maastricht University Medical Center
ClinicalTrials.gov Identifier:
NCT01576250
First received: April 10, 2012
Last updated: May 22, 2013
Last verified: May 2013
  Purpose

The purpose of this study is to investigate the effects of lowered physical activity (resulting in decreased muscle mitochondrial oxidative capacity) alone and together with increased plasma free fatty acid availability (by infusion of a clinically widely used lipid emulsion (Intralipid)) on insulin sensitivity and glucose and lipid metabolism. To this end, we will compare skeletal muscle insulin sensitivity and glucose and lipid metabolism (within one subject) after 9 days of immobilization of one leg (unilateral lower limb suspension(ULLS))(decreased muscle mitochondrial oxidative capacity) versus an active control leg (unchanged muscle mitochondrial oxidative capacity). Further, changes in IMCL and fatty acid intermediates will be investigated in the immobilized vs the control leg, and this will be related to insulin sensitivity. The effectiveness of the ULLS intervention will be tested by measuring muscle mitochondrial oxidative capacity in both the immobilized and the control leg. All measurements will be performed both in the immobilized and control leg after 9 days of ULLS.


Condition Intervention
Immobilization
Other: unilateral lower limb suspension

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Basic Science
Official Title: The Effect of Lowered Physical Activity (Induced by Lower Limb Suspension (ULLS)) on Insulin Sensitivity and Lipid and Glucose Metabolism

Resource links provided by NLM:


Further study details as provided by Maastricht University Medical Center:

Primary Outcome Measures:
  • Insulin sensitivity [ Time Frame: after 9 days of ULLS ] [ Designated as safety issue: No ]
    After 9 days of ULLS a muscle biopsy will be derived before and after a 5 h lipid infusion,from both the immobilized and the control leg. Insulin sensitivity will further be investigated from the skeletal muscle tissue ex vivo.


Secondary Outcome Measures:
  • intramyocellularlipid content [ Time Frame: after 9 days of ULLS ] [ Designated as safety issue: No ]
    After 9 days of ULLS a muscle biopsy will be derived before and after a 5 h lipid infusion,from both the immobilized and the control leg. Muscle tissue will immediately be frozen and stored for later determination of Intramyocellular lipid content.

  • Lipid intermediates [ Time Frame: after 9 days of ULLS ] [ Designated as safety issue: No ]
    After 9 days of ULLS a muscle biopsy will be derived before and after a 5 h lipid infusion,from both the immobilized and the control leg. Lipid intermediates will further be investigated from the skeletal muscle tissue ex vivo.

  • Lipid metabolism [ Time Frame: after 9 days of ULLS ] [ Designated as safety issue: No ]
    After 9 days of ULLS a muscle biopsy will be derived before and after a 5 h lipid infusion,from both the immobilized and the control leg. Lipid metabolism will further be investigated from the skeletal muscle tissue ex vivo.

  • Glucose metabolism [ Time Frame: after 9 days of ULLS ] [ Designated as safety issue: No ]
    After 9 days of ULLS a muscle biopsy will be derived before and after a 5 h lipid infusion,from both the immobilized and the control leg. Glucose metabolism will further be investigated from the skeletal muscle tissue ex vivo.


Estimated Enrollment: 22
Study Start Date: April 2012
Estimated Study Completion Date: April 2014
Estimated Primary Completion Date: April 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: unilateral lower limb suspension
This is an intervention study, where each subject will undergo 12 days of unilateral lower limb suspension. Randomly, the dominant or the non-dominant leg of the subject will be suspended by attachment of a sling to a non-rigid ankle brace and to a harness on the upper body and unloaded from all weight bearing. The knee will be slightly flexed at an angle of 130°. Hip, knee and ankle will be fully mobile. The sling will be used during all locomotory activity, and the subjects will use crutches for walking.
Other: unilateral lower limb suspension
This is an intervention study, where each subject will undergo 12 days of unilateral lower limb suspension. Randomly, the dominant or the non-dominant leg of the subject will be suspended by attachment of a sling to a non-rigid ankle brace and to a harness on the upper body and unloaded from all weight bearing. The knee will be slightly flexed at an angle of 130°. Hip, knee and ankle will be fully mobile. The sling will be used during all locomotory activity, and the subjects will use crutches for walking.

Detailed Description:

In the Netherlands and worldwide, the number of individuals suffering from obesity and type 2 diabetes mellitus is rising steadily. It is well established that obesity predisposes individuals to accumulation of excessive fat in non-adipose tissues such as the liver, the heart and skeletal muscle (called steatosis or ectopic fat accumulation). Furthermore, in sedentary humans ectopic fat accumulation in skeletal muscle is strongly associated with insulin resistance. However, paradoxically, IntraMyoCellular Lipid (IMCL) content is also increased in highly insulin sensitive endurance trained subjects (known as the athlete's paradox). This is suggesting that IMCL per se is not causative in skeletal muscle insulin resistance. The increased IMCL storage following endurance training serves to match training-induced increase in oxidative capacity and reliance on fat as a substrate during exercise, whereas in obesogenic/diabetogenic conditions the high fat availability is not matched by improved oxidative capacity. It is therefore speculated that under the latter conditions, the lipid intermediates of IMCL metabolism such as diacylglycerol (DAG), ceramides and fatty acyl-CoAs will accumulate and impede cellular insulin signalling. The rate of oxidative capacity is regulated by mitochondria, which are cellular organelles responsible for cellular energy production and cellular metabolism. Therefore, the overall hypothesis of this project is that a low muscle mitochondrial oxidative capacity can lead to muscle fat accumulation and/or accumulation of lipid intermediates when fatty acid availability is high, and this may result in insulin resistance in skeletal muscle.

  Eligibility

Ages Eligible for Study:   18 Years to 35 Years
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Men between 18-35 years of age at time of enrolment
  • Non smoking
  • No recent bone fractures of the limbs
  • No cardiovascular medication or other medication
  • No family history of thrombosis
  • No engagement in programmed exercise for more than two hours a week
  • Stable dietary habits
  • No contra-indication for MRI

Exclusion Criteria:

  • Regular smokers
  • Participation in other studies
  • Female sex
  • Recent bone fractures of the limbs
  • Medication use
  • Cardiovascular disease
  • Family history of type 2 diabetes mellitus
  • Family history of thrombosis
  • Contraindications for MRS scans:
  • Electronic implants such as pacemakers or neurostimulator
  • Iron-containing foreign bodies in eyes or brain
  • Some hearing aids and artificial (heart) valves which are contraindicated for MRS
  • Claustrophobia
  • Participants, who do not want to be informed about unexpected medical findings, or do not wish that their physician will be informed, cannot participate in the study
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01576250

Contacts
Contact: Lena Bilet, MSc 0031 43 3884258 l.bilet@maastrichtuniversity.nl
Contact: Patrick Schrauwen, Professor 0031 42 3881502 p.schrauwen@maastrichtuniversity.nl

Locations
Netherlands
Maastricht University Medical Center Recruiting
Maastricht, Netherlands, 6200 MD
Sponsors and Collaborators
Maastricht University Medical Center
Investigators
Study Director: Patrick Schrauwen, Ph.D. Maastricht University Medical Center (MUMC)
Principal Investigator: Lena Bilet, MSc. Maastricht University Medical Center (MUMC)
  More Information

Additional Information:
No publications provided

Responsible Party: Lena Bilet, PhD student, Maastricht University Medical Center
ClinicalTrials.gov Identifier: NCT01576250     History of Changes
Other Study ID Numbers: NL38795.068.11/METC 11-3-074
Study First Received: April 10, 2012
Last Updated: May 22, 2013
Health Authority: Netherlands: Medical Ethics Review Committee (METC)

ClinicalTrials.gov processed this record on September 18, 2014