Introduction: Analysis of ground reaction forces (GRFs) and symmetries in GRFs have not yet been fully investigated in gait of people with multiple sclerosis (PwMS). However, this method may explain the differences and contradictions that have been discussed in the mechanics of gait in these patients. The objectives of the study were to investigation of GRFs and symmetries in GRFs during gait of PwMS compared with normal human gait.
Methodology: 21 females with MS (divided in two groups of patients with ataxia symptoms, n=11and spastic symptoms n=11, EDSS>4) and a group of healthy women (n=10) between 25-50 years of age participated in the study. A Qualisys motion analysis system with seven cameras and a Kistler force plate were used to measure six variables of GRFs (Fz1, Fz2, Fz3, Fy1, Fy2, Fx) during the gait. A symmetry index (SI) was calculated for six variables of GRFs. ANOVA and post-hoc tukey analysis were used for statistical analysis (P<0.05).
Results: Vertical GRFs (Fz2 or valley force and Fz3 or second force peak) and the shear GRFs (breaking or Fy1 and progressive or Fy2 forces) were significantly lower in both groups of PwMS compared to the normal group (P<0.001). The ataxic group had weaker performance in some of GRF variables compared to the spastic group (P<0.01). There were asymmetries in GRFs during gait of the normal group and PwMS. The asymmetries were high in both groups of PwMS.
Discussion: A leg of the patients, due to disease, is weaker than the other leg.The vertical GRFz3 and the shear GRFy2 (push-off forces) decreased in PwMS, which led to a decrease in walking speed. The reduction in these variables may be due a neuromuscular adaptation to compensate balance deficit.