BACKGROUND: @entity19383 ( @entity19383 ) @entity1 have structural @entity16 resulting in increased compensatory cortical activity during (submaximal) performance. However, functional effects of changed cortical output are difficult to measure. The interpolated-twitch technique allows for measurement of voluntary activation (VA) necessary for force production. This study aimed to determine VA, force, and muscle @entity1295 during brief and sustained contractions in @entity19383 @entity1 . Because @entity1295 effects are not confined to the motor system, we additionally examined fatiguing effects on cognitive performance. METHODS: Twenty-five @entity19383 and 25 sex-, age-, and education-matched @entity1 performed brief (5 seconds) and sustained (2 minutes) maximal index finger abductions. To evaluate VA, double-pulse twitches were evoked before, during, and after contractions. Additionally, data were compared with data obtained in @entity3780 ( @entity3780 ) @entity1 . Subjects also performed choice-reaction time tasks before and after the sustained contraction. RESULTS: During brief contractions, VA (85% vs 94%, P = .004) and force (25 N vs 32 N, P = .011) were lower for @entity19383 @entity1 than controls. During sustained contractions, VA (P = .001) was also lower, resulting in greater force decline (73% vs 63%, P < .001) and reduced peripheral @entity1295 (19% vs 50%, P < .001). Comparisons with @entity3780 resulted in lower VA, greater force decline, and greater estimated central @entity1295 in @entity19383 . @entity19383 @entity1 were slower (P < .001) and made more errors (P < .001) than controls, but neither group reduced their performance after the sustained contraction. CONCLUSION: @entity19383 @entity1 had lower VA than @entity3780 @entity1 and controls. The importance of voluntary activation for muscle force and fatigability warrants targeted rehabilitation strategies.

Reduced Voluntary Activation During Brief and Sustained Contractions of a Hand Muscle in Secondary-Progressive Multiple Sclerosis XXXX .

@entity1 :: ('9606', 'Species') :: ['participants', 'patients'] @entity3780 :: ('MESH:D020529', 'Disease') :: ['relapsing-remitting multiple sclerosis', 'RRMS'] @entity16 :: ('MESH:D009422', 'Disease') :: ['cortical damage'] @entity1295 :: ('MESH:D005221', 'Disease') :: ['fatigue'] @entity19383 :: ('MESH:D020528', 'Disease') :: ['Secondary-progressive multiple sclerosis', 'SPMS']
@entity1 :: (9606,Species) :: ['Patients']
