Walking-induced motor fatigability in
Multiple Sclerosis: underlying mechanisms and the preliminary effect of
sequential resistance and walking-specific endurance training.
In approximately 60% of patients with Multiple Sclerosis (MS), the ability to walk gets progressively worse and might be due to so-called motor fatigability. Ankle push off plays an important role in walking. It generates eighty percent of the energy required during normal walking and is also strongly related to walking speed. An insufficient ankle push off leads to a higher energy cost of walking and slower walking speed. Therefore, it is hypothesized that walking-induced motor fatigability is mainly determined by a gradual decline of ankle push off during prolonged walking. Improving resistance to motor fatigability of the ankle push off may improve rehabilitation interventions to improve walking. Effects of conventional resistance and endurance training have shown mixed results. Due to the limited exercise tolerance, a combined program in which both resistance training and endurance training reach sufficient intensity is not feasible in persons with MS. A sequential exercise program in which the resistance training, targeted at the calf muscles, serves as a preconditioning phase for walking-specific endurance training, may be an effective alternative in which both modalities can be trained at a sufficient frequency, intensity, and specificity.
Objective: a) To study the relationship between ankle push off and walking-induced motor fatigability and the potential confounders of this relationship in persons with progressive MS and healthy controls. b) To assess the feasibility and preliminary effect of a targeted, sequential resistance plus walking –specific endurance training regime on walking-induced motor fatigability in persons with MS.
Study design: a) cross-sectional study comparing MS with healthy controls, and b) a longitudinal intervention pilot-study in patients with MS.
Study population: 10 ambulant patients with progressive MS and 10 healthy, age- and gender-matched controls.
Pilot intervention: a sequential exercise program for 4 months with three sessions per week. The first eight weeks consist of progressive resistance training (2-3 sets, 8-12 reps, 60-70% 1RM). The second eight weeks consist of progressive walking-specific high intensity endurance training (3-6 four-minute bouts at 70-90%HRmax alternated with four-minutes bouts at comfortable walking speed).
Main study parameters/determinants: walking-induced motor fatigability, with the central determinant: ankle push off power. Additional outcome parameters: spatiotemporal gait characteristics, energy cost of walking, feasibility outcomes of the pilot intervention and measurement procedures. Additional determinants: gastrocnemius muscle strength, gastrocnemius central and peripheral activation, calf muscle fatigability, aerobic capacity, perceived fatigue, exercise self-efficacy
Planning: Study completed; writing phase
- Beckerman et al. Quantifying muscle fatigue during walking in people with Multiple Sclerosis. Multiple Sclerosis 25 (7); Conference proceeding (RIMS Annual Meeting 2019)
- Heine et al. 2018; Preliminary effectiveness of a sequential exercise intervention on gait function in ambulant patients with multiple sclerosis - a pilot study; Clinical Biomechanics; https://doi.org/10.1016/j.clinbiomech.2018.12.012