title: Effect of transcranial magnetic stimulation on voluntary activation in patients with quadriceps weakness.
abstract: Joint disease causes weakness and wasting of adjacent muscles, in part because of inability to fully activate these muscles voluntarily. Previous findings suggest that transcranial magnetic stimulation (TMS) paired with muscle contractions enhances maximal voluntary contraction force (MVC) in healthy subjects by improving voluntary activation (VA). The aim of the present study was to evaluate whether such an effect is also present in subjects suffering from diminished muscle force due to decreased VA. Three single TMS over resting motor threshold were applied in 10 patients with a mean age of 62 years after total-knee arthroplasty either during MVC or during muscle relaxation (control experiment) in a blinded randomized crossover study. MVC and VA were determined using a twitch-interpolation technique at 1, 15, 30, and 60 min after stimulation. There was a significant effect of TMS on MVC if applied in synchrony with muscle contraction, and this persisted for at least 60 min beyond stimulation. In patients suffering from joint disease, TMS might make physiotherapy more effective.
authors.affiliation: Neuromuscular Research Group, Department of Orthopedics, Otto-von-Guericke University, Leipziger Strasse 44, D-39120 Magdeburg, Germany. dietmar.urbach@medizin.uni-magdeburg.de
authors.forename: Dietmar
authors.initials: D
authors.lastname: Urbach
authors.forename: Alexander
authors.initials: A
authors.lastname: Berth
authors.forename: Friedemann
authors.initials: F
authors.lastname: Awiszus
mesh_terms: D000368:Aged; D001168:Arthritis / Q000150:complications / Q000503:physiopathology; D018592:Cross-Over Studies; D004599:Electric Stimulation Therapy / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007717:Knee / Q000294:innervation / Q000503:physiopathology*; D007719:Knee Joint / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D009433:Neural Inhibition / Q000502:physiology; D050781:Transcranial Magnetic Stimulation / Q000627:therapeutic use*; D016896:Treatment Outcome; D014836:Volition / Q000502:physiology