title: Effect of the time of day on central and peripheral fatigue during 2-min maximal voluntary contractions in persons with multiple sclerosis: gender differences.
abstract: There is a lack of data on fatigue changes within 24h among patients with multiple sclerosis. The purpose of this study was to evaluate the effect of time of day on central and peripheral fatigue during a continuous 2-min maximal voluntary contraction of the quadriceps muscle in women and men with multiple sclerosis (MS). We studied age-matched MS patients (range, 40-50years). The inclusion criteria for patients were: a Kurtzke Expanded Disability Status score and a Fatigue Severity Scale score. We found a significant gender difference in central activation ratio (CAR) in the evening. At the end of the 2-min maximal voluntary contraction (MVC), the voluntary torque decreased by about 65% in men and women with MS in both the morning and evening. We also observed that, in women, CAR decreased markedly during the first 30s in the evening test. The most interesting finding of our study is that central fatigue increased, whereas peripheral fatigue decreased markedly in the evening only in women. It remains unclear why women's central fatigue is greater in the evening than in the morning.
authors.affiliation: Center for Movement of Fundamental and Clinical Research, Lithuanian Sports University, Sporto str. 6, LT-44221 Kaunas, Lithuania. Electronic address: vytautas.streckis@lsu.lt.
authors.forename: Vytautas
authors.initials: V
authors.lastname: Streckis
authors.affiliation: Center for Movement of Fundamental and Clinical Research, Lithuanian Sports University, Sporto str. 6, LT-44221 Kaunas, Lithuania.
authors.forename: Albertas
authors.initials: A
authors.lastname: Skurvydas
authors.affiliation: Center for Movement of Fundamental and Clinical Research, Lithuanian Sports University, Sporto str. 6, LT-44221 Kaunas, Lithuania.
authors.forename: Gediminas
authors.initials: G
authors.lastname: Mamkus
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000503:physiopathology*; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000502:physiology; D052097:Quadriceps Muscle / Q000502:physiology; D012737:Sex Factors; D019415:Torque
keywords: Central and peripheral fatigue; Electrical stimulation; Gender; Morning vs. evening; Multiple sclerosis