Central and Peripheral Fatigue Indices following Resistance Exercise with and without Blood Flow Restriction Among People with Multiple Sclerosis

Introduction: Muscle fatigue is a prevalent and challenging symptom in people with multiple sclerosis (PwMS), typically involving pronounced central (e.g., reduced corticospinal excitability) and relatively lower peripheral contributions (e.g., metabolic stress) compared to healthy controls. Blood flow restriction (BFR) applied during resistance exercise is an innovative approach to facilitate exercise benefits among PwMS. Therefore, the purpose of this investigation was to examine how distinct resistance exercise approaches including high-load (HL), low-load (LL), and LL with blood flow restriction (LLBFR) affect central and peripheral fatigue when applied in a clinically-relevant, real-world context. Methods: Twelve females (42±12 yrs) and three males (41±10 yrs) with MS performed unilateral leg extensions with a HL (3×12 at 70% of one repetition maximum [1RM]), LL (1×30, 3×15 at 30% 1RM), and LLBFR (LL with 60% limb occlusion pressure). Prior to and immediately after each exercise bout, maximal voluntary isometric contraction (MVIC) torque and indices of central (surface electromyographic [sEMG] amplitude, superimposed twitch torque [STT], V WAVE /M WAVE ) and peripheral (potentiated twitch torque [PTT]) fatigue were assessed. Results: There were similar acute decreases in MVIC torque (− 21.0% relative to baseline; p<0.001, g=1.486), but exercise-specific decreases in PTT between LLBFR (−37.1%; p<0.001, g=1.135) and HL (−14.2%; p=0.093, g=0.440). STT increased (+24.5%, p=0.018, g=0.650), while there were decreases in sEMG amplitude (−9.7%; p=0.004, g=0.852) and V WAVE /M WAVE (−7.9%; p<0.001, g=1.037) that were not different among conditions. Conclusions: LLBFR may represent a more effective resistance exercise strategy for PwMS due to its ability to induce greater peripheral fatigue, a proxy for metabolic stress.