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

The Effect of Lowered Physical Activity (Induced by Lower Limb Suspension (ULLS)) on Insulin Sensitivity and Lipid and Glucose Metabolism

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.

Study Overview

• Status: Completed
• Conditions: Insulin Sensitivity
• Intervention / Treatment: Other: unilateral lower limb suspension

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.

• Study Type: Interventional
• Enrollment (Actual): 13
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Netherlands
  • Maastricht, Netherlands, 6200 MD
    • Maastricht University Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Male

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Insulin sensitivity	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.	after 9 days of ULLS

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
intramyocellularlipid content	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.	after 9 days of ULLS
Lipid intermediates	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.	after 9 days of ULLS
Lipid metabolism	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.	after 9 days of ULLS
Glucose metabolism	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.	after 9 days of ULLS

Collaborators and Investigators

• Sponsor: 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)

Publications and helpful links

General Publications

• Bilet L, Phielix E, van de Weijer T, Gemmink A, Bosma M, Moonen-Kornips E, Jorgensen JA, Schaart G, Zhang D, Meijer K, Hopman M, Hesselink MKC, Ouwens DM, Shulman GI, Schrauwen-Hinderling VB, Schrauwen P. One-leg inactivity induces a reduction in mitochondrial oxidative capacity, intramyocellular lipid accumulation and reduced insulin signalling upon lipid infusion: a human study with unilateral limb suspension. Diabetologia. 2020 Jun;63(6):1211-1222. doi: 10.1007/s00125-020-05128-1. Epub 2020 Mar 17.

Study record dates

Study Major Dates

• Study Start: April 1, 2012
• Primary Completion (Actual): August 1, 2013
• Study Completion (Actual): August 1, 2013

Study Registration Dates

• First Submitted: April 10, 2012
• First Submitted That Met QC Criteria: April 10, 2012
• First Posted (Estimate): April 12, 2012

Study Record Updates

• Last Update Posted (Estimate): May 28, 2015
• Last Update Submitted That Met QC Criteria: May 27, 2015
• Last Verified: May 1, 2015

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Immune System Diseases; Hyperinsulinism; Hypersensitivity; Insulin Resistance
• Other Study ID Numbers: NL38795.068.11/METC 11-3-074