TIME

Treatment tested

• HIIT

Compared with

• MCT

Other measures (4)

Inclusion Criteria: * adult age (≥ 18 years) * definite MS diagnosis according the 2017 revised McDonald criteria * PPMS/SPMS phenotype according to the 2013 revised Lublin criteria * Expanded Disability Status Scale (EDSS) score ≤ 6.0 * Informed Consent as documented by signature of participants and PI Exclusion Criteria: * severe lower extremity spasticity or severe concomitant disease states (i.e., orthopaedic, cardiovascular, metabolic, psychiatric (e.g., substance abuse), other neurological, other serious medical conditions) impairing the ability to participate * inability to follow study procedures (e.g., due to language barriers) * suspected non-compliance * previous enrolment into the current study * enrolment of the investigator, his/her family members, employees, and other dependent persons

Endurance training is a cornerstone of rehabilitation in Multiple Sclerosis (MS) due to its beneficial effects on multiple MS-related symptoms, such as health-related quality of life, aerobic capacity (VO2peak), functional mobility, gait, depressive symptoms, and fatigue. Persons with progressive phenotypes of MS, namely primary progressive MS (PPMS) and secondary progressive (SPMS), represent a minor proportion of the total MS population, thus having been underrepresented in previous studies. The generalizability of existing evidence may be compromised by differences in symptom expression between MS phenotypes, with a dominance of motor symptoms (i.e., paraspasticity and/or paraparesis) in PPMS and SPMS. Adding up to this, clinical experiences of neurologists and sports scientists reveal that the effects of endurance exercise are characterized by a distinct time course, firstly inducing a minor and transient deterioration of motor symptoms that is followed by motor symptom alleviation beyond baseline level. This phenomenon was mainly related to the performance of High-Intensity Interval training (HIIT), but not to moderate-intensity continuous training (MCT). Therefore, this pilot study aims to systematically investigate the time course of acute motor effects on spasticity, functional mobility, gait, and dexterity in persons with PPMS and SPMS following two different endurance training protocols, that are HIIT and MCT.