Effects of changing the tension of elastic bands of lower-limb orthosis with a trunk belt on lower-limb muscle activity during walking: Evidence from a pilot study

This study investigated the impact of varying the tension of the elastic band in a lower-limb orthosis with a trunk belt (hereinafter, lower-limb orthosis) on muscle activity in the lower limbs during walking in healthy adults. Within-subject repeated-measures pilot study. University motion analysis laboratory. The task involved walking 10 m on flat ground for 18 healthy adult males. Two conditions were assessed: walking without lower-limb orthosis and with the orthosis applied to the right lower limb. For the latter, the elastic-band tension in stationary standing position was set to 3 levels: 1.5, 2.0, and 2.5 kgw. A 3-dimensional motion analysis device and surface electromyograph were used. The parameters analyzed were the joint angle and muscle activity of the right lower limb under the 3 elastic-band tensions while walking without and with a lower limb orthosis. The ankle dorsiflexion angle during the swing phase was significantly increased at a tension of 2.5 compared to 1.5 kgw. In addition, the knee flexion angles during both the stance and swing phases were significantly reduced when walking with the orthosis compared to walking without it. Regarding muscle activity, the tibialis anterior showed a significant decrease in muscle activity during the swing phase when walking with a lower-limb orthosis compared to walking without a orthosis. The vastus lateralis showed a significant decrease in muscle activity during the stance and early stance phases when walking with a lower-limb orthosis compared to walking without a orthosis. Furthermore, muscle activity during the swing phase was significantly reduced when walking with the lower-limb orthosis at tensions of 2.0 and 2.5 kgw compared to walking without the orthosis. Lower-limb orthoses may help prevent excessive knee flexion during the stance phase and avoid initial contact of the affected leg with an extended knee when walking in patients with stroke-induced hemiplegia. These findings can guide optimization of orthoses for clinical populations.