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- Title
Changes in brain functional connectivity and muscle strength independent of elbow flexor atrophy following upper limb immobilization in young females.
- Authors
Seo, Freddie; Clouette, Julien; Huang, Yijia; Potvin‐Desrochers, Alexandra; Lajeunesse, Henri; Parent‐L'Ecuyer, Frédérike; Traversa, Claire; Paquette, Caroline; Churchward‐Venne, Tyler A.
- Abstract
Muscle disuse induces a decline in muscle strength that exceeds the rate and magnitude of muscle atrophy, suggesting that factors beyond the muscle contribute to strength loss. The purpose of this study was to characterize changes in the brain and neuromuscular system in addition to muscle size following upper limb immobilization in young females. Using a within‐participant, unilateral design, 12 females (age: 20.6 ± 2.1 years) underwent 14 days of upper arm immobilization using an elbow brace and sling. Bilateral measures of muscle strength (isometric and isokinetic dynamometry), muscle size (magnetic resonance imaging), voluntary muscle activation capacity, corticospinal excitability, cortical thickness and resting‐state functional connectivity were collected before and after immobilization. Immobilization induced a significant decline in isometric elbow flexion (−21.3 ± 19.2%, interaction: P = 0.0440) and extension (−19.9 ± 15.7%, interaction: P = 0.0317) strength in the immobilized arm only. There was no significant effect of immobilization on elbow flexor cross‐sectional area (CSA) (−1.2 ± 2.4%, interaction: P = 0.466), whereas elbow extensor CSA decreased (−2.9 ± 2.9%, interaction: P = 0.0177) in the immobilized arm. Immobilization did not differentially alter voluntary activation capacity, corticospinal excitability, or cortical thickness (P > 0.05); however, there were significant changes in the functional connectivity of brain regions related to movement planning and error detection (P < 0.05). This study reveals that elbow flexor strength loss can occur in the absence of significant elbow flexor muscle atrophy, and that the brain represents a site of functional adaptation in response to upper limb immobilization in young females. What is the central question of this study?To what extent does 14 days of upper limb immobilization affect muscle strength, muscle size and neuromuscular function in young females?What is the main finding and its importance?Fourteen days of upper limb immobilization induces a significant decline in muscle strength as well as changes in resting state functional connectivity between brain regions implicated in motor learning and feedback, with little effect on muscle size, corticospinal excitability and voluntary muscle activation capacity. These findings suggest that the nervous system may play a role in the initial decline in muscle function with upper arm immobilization in young females.
- Subjects
FUNCTIONAL magnetic resonance imaging; SKELETAL muscle; MAGNETIC resonance imaging; FLEXOR muscles; MUSCLE strength
- Publication
Experimental Physiology, 2024, Vol 109, Issue 9, p1557
- ISSN
0958-0670
- Publication type
Article
- DOI
10.1113/EP091782