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Quadriceps muscle function and fatigue in women with Addison's disease
Author(s) -
Jakobi Jennifer M.,
Killinger Donald W.,
Wolfe Bernard M.,
Mahon Jeffrey L.,
Rice Charles L.
Publication year - 2001
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.1108
Subject(s) - medicine , muscle fatigue , stimulation , cardiology , anesthesia , electromyography , physical medicine and rehabilitation
In nine patients with Addison's disease (mean ± SE: 51 ± 2 years) receiving conventional steroid treatment, and nine age‐matched healthy controls (56 ± 2 years), we investigated maximum voluntary quadriceps force (MVC) and contractile properties evoked with stimulation and central activation both at rest and during a submaximal intermittent fatigue task. The MVC was similar (−3%), but twitch tension (−27%) and central activation were significantly less (−7%), and tetanic half‐relaxation time was ∼40% slower in the patients. Twitch amplitudes were potentiated by 6% in the patients, but unchanged in the control group. The patients self‐terminated a submaximal intermittent fatigue protocol (0.6 duty cycle) at ∼5 ± 1 min, whereas the controls stopped when they lost 50% of MVC force (∼10 ± 1 min). Force loss was similar between groups over the first 5 min of the fatigue task. In the patient group, maximal and submaximal relative integrated electromyogram (IEMG) increased significantly in the first minute of fatigue and remained elevated, whereas the controls exhibited a gradual increase in submaximal IEMG with little change in maximal IEMG. These results indicate that conventionally treated Addison's patients have similar MVC strength, but altered contractile properties and decreased endurance compared with controls. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1040–1049, 2001