Lower limb muscle strengthening exercises in patients with early-stage amyotrophic lateral sclerosis: a case series study.

[Purpose] We investigated whether patients with early-stage amyotrophic lateral sclerosis can improve their voluntary strength with a physical therapy program. [Participants and Methods] This retrospective case series study at a single university hospital included 13 patients with amyotrophic lateral sclerosis (amyotrophic lateral sclerosis functional rating scale-revised ≥35, modified functional ambulation categories score ≥4). Physical therapy was performed for 3 weeks. We investigated knee extension muscle strength and modified functional ambulation categories scores at the start and end of the therapy and calculated the improvement rate of knee extension muscle strength. We performed a regression analysis of the relationship between knee extension muscle strength at the start of the study and the improvement rate. [Results] The knee extension muscle strength improved significantly; however, the effect size was small (0.13). The modified functional ambulation categories scores did not improve significantly. The knee extension muscle strength at the start of the therapy was negatively correlated with the improvement rate (logarithmic transformed linear regression: adjusted R=0.27). [Conclusion] A short-duration exercise program improved lower limb muscle strength in patients with early-stage amyotrophic lateral sclerosis. Additionally, we found that patients with weaker lower limb muscle strength at the start of the therapy demonstrated greater improvement at the end of the therapy.