OBJECTIVE: To determine if task performance and fatigability during rapid repetitive exercise of the lower limb differ in a group of MS subjects compared to a control group, and what central changes accompany the development of fatigue and the period of recovery. METHODS: Transcranial magnetic stimulation (TMS) was used to compare motor evoked potential (MEP) responses between 10 clinically definite MS subjects (7F, 33-64 years of age; EDSS <or= 4; MRC grade >or= 4/5) and 13 control subjects during and after 5 bouts of a 15-second maximum rate foot-tapping task performed at 1 minute intervals. RESULTS: Maximum voluntary contraction (MVC) force of ankle dorsiflexion was lower (15 %) in the MS group compared to controls; however there were no differences in the rate of foot tapping. The rate of foot tapping decreased during each bout of exercise to a comparable degree in both groups, but there was no overall deterioration in performance across the 5 repeat bouts in either group. MS subjects showed a greater decline in strength than controls after exercise (20.7+/-7.7% vs. 6+/-3.6%; p<0.05). MEP amplitude increased significantly for the exercised limb in both groups, but the increase was greater in MS subjects (65.9+/-27% vs. 31+/-19.6%; MS vs. control; p<0.05). MEP amplitude also increased for the non-exercised limb in controls (40.6+/-15.6%, p<0.01) but not in MS subjects. CONCLUSIONS: Mild to moderately affected MS subjects can perform a fatiguing exercise requiring a high level of central motor control but this is associated with a greater strength loss and increase in corticomotor excitability compared to unaffected individuals. SIGNIFICANCE: Central adaptive processes are likely to have a significant role in maintaining task performance in MS.
OBJECTIVE: To determine if task performance and fatigability during rapid repetitive exercise of the lower limb differ in a group of MS subjects compared to a control group, and what central changes accompany the development of fatigue and the period of recovery. METHODS: Transcranial magnetic stimulation (TMS) was used to compare motor evoked potential (MEP) responses between 10 clinically definite MS subjects (7F, 33-64 years of age; EDSS <or= 4; MRC grade >or= 4/5) and 13 control subjects during and after 5 bouts of a 15-second maximum rate foot-tapping task performed at 1 minute intervals. RESULTS: Maximum voluntary contraction (MVC) force of ankle dorsiflexion was lower (15 %) in the MS group compared to controls; however there were no differences in the rate of foot tapping. The rate of foot tapping decreased during each bout of exercise to a comparable degree in both groups, but there was no overall deterioration in performance across the 5 repeat bouts in either group. MS subjects showed a greater decline in strength than controls after exercise (20.7+/-7.7% vs. 6+/-3.6%; p<0.05). MEP amplitude increased significantly for the exercised limb in both groups, but the increase was greater in MS subjects (65.9+/-27% vs. 31+/-19.6%; MS vs. control; p<0.05). MEP amplitude also increased for the non-exercised limb in controls (40.6+/-15.6%, p<0.01) but not in MS subjects. CONCLUSIONS: Mild to moderately affected MS subjects can perform a fatiguing exercise requiring a high level of central motor control but this is associated with a greater strength loss and increase in corticomotor excitability compared to unaffected individuals. SIGNIFICANCE: Central adaptive processes are likely to have a significant role in maintaining task performance in MS.
Authors: Gary W Thickbroom; Paul Sacco; Allan G Kermode; Sarah A Archer; Michelle L Byrnes; Andrew Guilfoyle; Frank L Mastaglia Journal: J Neurol Date: 2006-04-10 Impact factor: 4.849
Authors: Gary W Thickbroom; Michelle L Byrnes; Sarah A Archer; Allan G Kermode; Frank L Mastaglia Journal: J Neurol Date: 2005-03-06 Impact factor: 4.849
Authors: Chris H Polman; Stephen C Reingold; Gilles Edan; Massimo Filippi; Hans-Peter Hartung; Ludwig Kappos; Fred D Lublin; Luanne M Metz; Henry F McFarland; Paul W O'Connor; Magnhild Sandberg-Wollheim; Alan J Thompson; Brian G Weinshenker; Jerry S Wolinsky Journal: Ann Neurol Date: 2005-12 Impact factor: 10.422
Authors: Awad M Almuklass; Leah Davis; Landon D Hamilton; Taian M Vieira; Alberto Botter; Roger M Enoka Journal: J Neurophysiol Date: 2018-01-03 Impact factor: 2.714
Authors: Gilles Allali; Helena M Blumen; Hervé Devanne; Elvira Pirondini; Arnaud Delval; Dimitri Van De Ville Journal: Neurophysiol Clin Date: 2018-10-25 Impact factor: 3.734