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Effect of Knee Position on Muscle Loss During Leg Immobilization

1 juli 2026 bijgewerkt door: Marlou Dirks, Wageningen University

A Novel Angle: Manipulating Knee Position to Understand Muscle Deterioration During Leg Immobilization

This study looks at what happens to leg muscles when the knee is kept straight or bent during five days of wearing a brace. We want to find out if keeping the knee bent (so the thigh muscle is stretched) helps prevent muscle loss compared to keeping the knee straight. Thirty healthy adults will take part. They will wear a knee brace for five days and have several tests before and after, including scans, blood samples, and small muscle samples. The results may help doctors find better ways to protect muscles when people cannot move, for example after surgery or illness.

Studie Overzicht

Toestand

Nog niet aan het werven

Conditie

Interventie / Behandeling

Gedetailleerde beschrijving

Short periods of physical inactivity, as occur during illness, surgery, or injury, lead to rapid and substantial losses of muscle mass, strength, and metabolic health, often with incomplete recovery in vulnerable individuals. In older adults, repeated bouts of disuse are thought to contribute significantly to age-related sarcopenia. Despite decades of research, the underlying mechanisms remain incompletely elucidated, and effective therapeutic interventions are lacking.

Mechanistically, any muscle atrophy must occur due to a negative muscle protein net balance (MPNB), which can be caused by a decline in muscle protein synthesis (MPS), an increase in muscle protein breakdown (MPB), or a combination of both. Normally, exercise and dietary protein stimulate MPS and maintain muscle mass. During disuse, however, exercise is often impossible, and inactive muscle shows a blunted response to dietary protein. Consequently, these potent strategies become ineffective or even harmful in inactive individuals, highlighting the need for alternative approaches.

Animal studies indicate that immobilizing a muscle in a lengthened (stretched) position can attenuate disuse-induced muscle atrophy and functional decline compared to a shortened position. Whether this phenomenon also occurs in humans, and whether passive muscle length and tension influence muscle metabolism during disuse, remain unexplored.

The objective of this study is to assess whether immobilizing the quadriceps in a lengthened versus neutral position during disuse attenuates losses of muscle mass, function, and metabolic health.

In this randomized, controlled human intervention study with 2 parallel groups 30 healthy, normal weight males and females (18-40 years old, BMI between 18 and 30 kg·m-2) will undergo 5 days of unilateral leg immobilization using a knee brace that prevents voluntary quadriceps contraction. In the neutral group, the leg is fixed in full extension (0° flexion), while in the lengthened group it is fixed at 60° flexion, stretching the quadriceps.

The effects on muscle protein net balance (MPNB), quadriceps muscle volume , muscle quality, muscle strength, fatigue resistance, and muscle mitochondrial bioenergetics will be assessed.

Studietype

Ingrijpend

Inschrijving (Geschat)

30

Fase

  • Niet toepasbaar

Deelname Criteria

Onderzoekers zoeken naar mensen die aan een bepaalde beschrijving voldoen, de zogenaamde geschiktheidscriteria. Enkele voorbeelden van deze criteria zijn iemands algemene gezondheidstoestand of eerdere behandelingen.

Geschiktheidscriteria

Leeftijden die in aanmerking komen voor studie

  • Volwassen

Accepteert gezonde vrijwilligers

Ja

Beschrijving

Inclusion Criteria:

  • Healthy males and females
  • Aged from 18-40 years at the time of signing informed consent
  • 18.5 < BMI < 30 kg·m-2
  • Must be willing and able to communicate and participate in the whole study

Exclusion Criteria:

  • Smoking
  • Diabetes (Type 1, Type 2, or genetic form of diabetes)
  • Any diagnosed cardiovascular (heart) disease or high blood pressure (≥140 mmHg systolic and/or ≥90 mmHg diastolic)
  • Chronic use of any prescribed or over the counter pharmaceuticals that may modulate muscle protein metabolism (excluding oral contraceptives and contraceptive devices).
  • A personal or family history of thrombosis, epilepsy, seizures or schizophrenia.
  • Prone to keloid forming (i.e. hyperplastic growth of scars).
  • Any known disorders in muscle metabolism
  • Regular use of dietary protein and/or amino acid supplements (>3 times per week)
  • Currently involved in a structured progressive resistance training programme (>3 times per week)
  • Known allergy to lidocaine
  • Known severe kidney problems
  • Allergy to one or multiple amino acids
  • Recent (within the last 6 months) or current musculoskeletal injury (e.g. leg fracture)
  • Having received or ingested a stable isotope tracer containing 15N in the past
  • Contra-indications for MRI such as incompatible metal objects in the body and claustrophobia.
  • Currently taking part in other scientific research
  • Pregnant or breastfeeding
  • Unable to give consent

Studie plan

Dit gedeelte bevat details van het studieplan, inclusief hoe de studie is opgezet en wat de studie meet.

Hoe is de studie opgezet?

Ontwerpdetails

  • Primair doel: Fundamentele wetenschap
  • Toewijzing: Gerandomiseerd
  • Interventioneel model: Parallelle opdracht
  • Masker: Geen (open label)

Wapens en interventies

Deelnemersgroep / Arm
Interventie / Behandeling
Actieve vergelijker: Neutral Knee Position
Participants in this group wear a knee brace in full extension (0°) for five consecutive days.
Unilateral knee immobilization at 0° flexion for 5 days using a brace; post-immobilization metabolic testing with tracer infusions and biopsies
Experimenteel: Flexed Knee Position
Participants in this group wear a knee brace in flexion (60°) for five consecutive days.
Unilateral knee immobilization at 60° flexion for 5 days using a brace; post-immobilization metabolic testing with tracer infusions and biopsies

Wat meet het onderzoek?

Primaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Muscle protein net balance (MPNB)
Tijdsspanne: Baseline to 3 hours after tracer infusion
Muscle protein net balance expressed as %/h and calculated as the difference between muscle protein synthesis (MPS; fractional synthesis rate, FSR) and muscle protein breakdown (MPB; fractional breakdown rate, FBR), measured in skeletal muscle following 5 days of unilateral knee immobilization
Baseline to 3 hours after tracer infusion

Secundaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Thigh muscle volume
Tijdsspanne: Baseline and after 5 days of immobilization
Thigh muscle volume, including muscle length and cross-sectional area, measured via Magnetic Resonance Imaging (MRI)
Baseline and after 5 days of immobilization
Muscle strength
Tijdsspanne: Baseline and after 5 days of immobilization
Maximal voluntary muscle strength measured as peak torque using isokinetic dynamometry
Baseline and after 5 days of immobilization
Muscle fatigue
Tijdsspanne: Baseline and after 5 days of immobilization
Muscle fatigue assessed as decline in force during repeated contractions measured using isokinetic dynamometry
Baseline and after 5 days of immobilization
Intramuscular fat content
Tijdsspanne: Baseline and after 5 days of immobilization
Intramuscular lipid content measured using 1H-magnetic resonance spectroscopy (1H-MRS)
Baseline and after 5 days of immobilization
Muscle metabolite concentrations
Tijdsspanne: Baseline and after 5 days of immobilization
Carnosine and acetylcarnitine concentrations in skeletal muscle measured using 1H-magnetic resonance spectroscopy (1H-MRS)
Baseline and after 5 days of immobilization
Mitochondrial respiration
Tijdsspanne: Baseline and after 5 days of immobilization
Mitochondrial respiration measured as oxygen consumption in permeabilized muscle fibres using high-resolution respirometry
Baseline and after 5 days of immobilization
Mitochondrial reactive oxygen species production
Tijdsspanne: Baseline and after 5 days of immobilization
Mitochondrial reactive oxygen species (ROS) production measured using fluorescence-based detection in permeabilized muscle fibres
Baseline and after 5 days of immobilization
Mitochondrial calcium retention capacity
Tijdsspanne: Baseline and after 5 days of immobilization
Calcium retention capacity measured in permeabilized muscle fibres using fluorescence-based assays
Baseline and after 5 days of immobilization
Muscle gene expression related to atrophy
Tijdsspanne: Baseline and after 5 days of immobilization
Expression of genes involved in muscle atrophy measured in skeletal muscle biopsy samples using molecular analysis techniques (e.g. qPCR or RNA sequencing)
Baseline and after 5 days of immobilization
Muscle protein markers of atrophy
Tijdsspanne: Baseline and after 5 days of immobilization
Protein expression of markers related to muscle protein synthesis and breakdown measured in skeletal muscle biopsy samples
Baseline and after 5 days of immobilization

Andere uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Height
Tijdsspanne: Baseline (pre-intervention)
Height measured in meters
Baseline (pre-intervention)
Plasma amino acid concentration
Tijdsspanne: Baseline to 3 hours after tracer infusion
Plasma concentration of amino acids measured in venous blood samples
Baseline to 3 hours after tracer infusion
Serum insulin concentration
Tijdsspanne: Baseline and up to 3 hours after tracer infusion
Serum insulin concentration measured in venous blood samples
Baseline and up to 3 hours after tracer infusion
Body weight
Tijdsspanne: Baseline (pre-intervention)
Body weight measured in kilograms
Baseline (pre-intervention)
Body mass index (BMI)
Tijdsspanne: Baseline (pre-intervention)
Body mass index calculated as kg/m²
Baseline (pre-intervention)
Body composition
Tijdsspanne: Baseline (pre-intervention)
Fat mass and lean mass measured using DXA
Baseline (pre-intervention)

Medewerkers en onderzoekers

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Sponsor

Medewerkers

Publicaties en nuttige links

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Algemene publicaties

Studie record data

Deze datums volgen de voortgang van het onderzoeksdossier en de samenvatting van de ingediende resultaten bij ClinicalTrials.gov. Studieverslagen en gerapporteerde resultaten worden beoordeeld door de National Library of Medicine (NLM) om er zeker van te zijn dat ze voldoen aan specifieke kwaliteitscontrolenormen voordat ze op de openbare website worden geplaatst.

Bestudeer belangrijke data

Studie start (Geschat)

1 augustus 2026

Primaire voltooiing (Geschat)

1 maart 2028

Studie voltooiing (Geschat)

1 juni 2028

Studieregistratiedata

Eerst ingediend

17 april 2026

Eerst ingediend dat voldeed aan de QC-criteria

1 juli 2026

Eerst geplaatst (Werkelijk)

8 juli 2026

Updates van studierecords

Laatste update geplaatst (Werkelijk)

8 juli 2026

Laatste update ingediend die voldeed aan QC-criteria

1 juli 2026

Laatst geverifieerd

1 juli 2026

Meer informatie

Termen gerelateerd aan deze studie

Andere studie-ID-nummers

  • NL010759

Informatie over medicijnen en apparaten, studiedocumenten

Bestudeert een door de Amerikaanse FDA gereguleerd geneesmiddel

Nee

Bestudeert een door de Amerikaanse FDA gereguleerd apparaatproduct

Nee

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