Niels F J Waterval1, Merel-Anne Brehm2, Hilde E Ploeger2, Frans Nollet2, Jaap Harlaar3. 1. Amsterdam UMC, University of Amsterdam, Department of Rehabilitation, Amsterdam Movement Sciences, Meibergdreef 9, Amsterdam, The Netherlands. Electronic address: n.f.waterval@amc.uva.nl. 2. Amsterdam UMC, University of Amsterdam, Department of Rehabilitation, Amsterdam Movement Sciences, Meibergdreef 9, Amsterdam, The Netherlands. 3. Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Rehabilitation Medicine, Amsterdam Movement Sciences, de Boelelaan 1117, Amsterdam, The Netherlands; Department of Biomechanical Engineering, Delft University of Technology, The Netherlands.
Abstract
BACKGROUND: Patients with calf muscle weakness due to neuromuscular disorders have a reduced ankle push-off work, which leads to increased energy dissipation at contralateral heel-strike. Consequently, compensatory positive work needs to be generated, which is mechanically less efficient. It is unknown whether neuromuscular disorder patients compensate with their ipsilateral hip and/or contralateral leg; and if such compensatory joint work is related to walking energy cost. RESEARCH QUESTION: Do patients with calf muscle weakness compensate for the increase in negative joint work by increasing positive ipsilateral hip work and/or positive contralateral leg work? And is the total mechanical work related with walking energy cost? METHODS: Seventeen patients with unilateral flaccid calf muscle weakness and 10 healthy individuals performed the following two tests: i) a barefoot 3D gait analysis at comfortable speed and matched control speed (i.e. 0.4 non-dimensional) to assess lower limb joint work and ii) a 6-minute walk test at comfortable speed to assess walking energy cost. RESULTS: Patients had a lower comfortable walking speed compared to healthy individuals (1.05 vs 1.36 m/s, p < 0.001) and did not increase positive lower limb joint work at comfortable speed. At matched speed (1.25 m/s), patients showed increased positive work at their ipsilateral hip (0.38 ± 0.08 vs 0.27 ± 0.07, p = 0.001) and/or contralateral leg (0.99 ± 0.14 vs 0.69 ± 0.14, p < 0.001). Patients with weakest plantar flexors used both strategies. No relation between total positive work and walking energy cost was found (r = 0.43, p = 0.122). SIGNIFICANCE: Patients with unilateral calf muscle weakness compensated for reduced ankle push-off work by lowering their comfortable walking speed or, at matched speed, by generating additional positive joint work at the ipsilateral hip and/or contralateral leg. The additional positive joint work at matched speed did not explain the elevated walking energy cost at comfortable speed, which needs further exploration.
BACKGROUND:Patients with calfmuscle weakness due to neuromuscular disorders have a reduced ankle push-off work, which leads to increased energy dissipation at contralateral heel-strike. Consequently, compensatory positive work needs to be generated, which is mechanically less efficient. It is unknown whether neuromuscular disorderpatients compensate with their ipsilateral hip and/or contralateral leg; and if such compensatory joint work is related to walking energy cost. RESEARCH QUESTION: Do patients with calfmuscle weakness compensate for the increase in negative joint work by increasing positive ipsilateral hip work and/or positive contralateral leg work? And is the total mechanical work related with walking energy cost? METHODS: Seventeen patients with unilateral flaccid calf muscle weakness and 10 healthy individuals performed the following two tests: i) a barefoot 3D gait analysis at comfortable speed and matched control speed (i.e. 0.4 non-dimensional) to assess lower limb joint work and ii) a 6-minute walk test at comfortable speed to assess walking energy cost. RESULTS:Patients had a lower comfortable walking speed compared to healthy individuals (1.05 vs 1.36 m/s, p < 0.001) and did not increase positive lower limb joint work at comfortable speed. At matched speed (1.25 m/s), patients showed increased positive work at their ipsilateral hip (0.38 ± 0.08 vs 0.27 ± 0.07, p = 0.001) and/or contralateral leg (0.99 ± 0.14 vs 0.69 ± 0.14, p < 0.001). Patients with weakest plantar flexors used both strategies. No relation between total positive work and walking energy cost was found (r = 0.43, p = 0.122). SIGNIFICANCE: Patients with unilateral calfmuscle weakness compensated for reduced ankle push-off work by lowering their comfortable walking speed or, at matched speed, by generating additional positive joint work at the ipsilateral hip and/or contralateral leg. The additional positive joint work at matched speed did not explain the elevated walking energy cost at comfortable speed, which needs further exploration.
Authors: Jorik Nonnekes; Cheriel Hofstad; Annemieke de Greef-Rotteveel; Heleen van der Wielen; Janke H van Gelder; Christian Plaats; Viola Altmann; Fabian Krause; Noël Keijsers; Alexander Geurts; Jan Willem K Louwerens Journal: J Rehabil Med Date: 2021-05-21 Impact factor: 2.912