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Mechanical and magnetic resonance imaging changes following eccentric or concentric exertions.

Authors
Sesto-ME; Chourasia-AO; Block-WF; Radwin-RG
Source
Clin Biomech 2008 Aug; 23(7):961-968
NIOSHTIC No.
20034628
Abstract
BACKGROUND: Prior work has shown that changes in mechanical parameters and magnetic resonance imaging parameters occur following submaximal eccentric activity but it is unclear whether similar changes occur following submaximal concentric activity. This study compared mechanical response parameters and MRI relaxation parameters following submaximal concentric or eccentric exertions. METHODS: This single site, randomized study investigated in vivo changes in human upper limb dynamic mechanical properties following exposure to short term repetitive submaximal eccentric or concentric exertions. Eighteen subjects were assigned to either an eccentric or concentric group and exercised for 30 min at 50% of isometric forearm maximum voluntary contraction. Changes in strength, symptom intensity, magnetic resonance imaging T2 relaxation measurements, which are indicative of edema, and dynamic mechanical parameters (stiffness, effective mass, and damping) were ascertained prior to exercise, 1h after, and 24h later. FINDINGS: Strength decreased following exercise (P<0.01), however only the eccentric exercise group exhibited a reduction in mechanical stiffness (55%, P<0.01) and damping (31%, P<0.05), and an increase (17%, P<0.05) in magnetic resonance imaging T2 relaxation time. INTERPRETATION: The changes in mechanical parameters and magnetic resonance imaging findings following repetitive submaximal eccentric activity could negatively impact the ability of the arm to react to rapid forceful loading during repetitive industrial work activities and may result in increased strain on the upper limb. Similar changes were not observed following concentric exercise.
Keywords
Neuromotor-system-disorders; Neuromuscular-system-disorders; Neuromotor-disorders; Neuromotor-function; Neuromotor-system; Muscle-function; Muscles; Musculoskeletal-system; Laboratory-testing; Humans; Repetitive-work
Contact
Robert G. Radwin, Department of Biomedical Engineering, University of Wisconsin, Madison, WI 53706
CODEN
CLBIEW
Publication Date
20080801
Document Type
Journal Article
Email Address
radwin@bme.wisc.edu
Funding Type
Grant
Fiscal Year
2008
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-007793
Issue of Publication
7
ISSN
0268-0033
Source Name
Clinical Biomechanics
State
WI
Performing Organization
University of Wisconsin, Madison
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