Placebo-induced changes in behavioural parameters during gait: a pilot study

Behavioural evidence shows placebo modulations of motor performance. Different studies in this field supported that placebo improves sensible physical parameters such as force and speed. However, the effect of placebo on more complicated indices like harmony and symmetry of movement during gait has not been studied up to today. We explored if a placebo modulation of motor performance could affect this sort of indices. Three groups of healthy participants executed a motor task by walking on a treadmill as fast as possible (just below the threshold of running). One experimental group was instructed verbally that treatment with transcutaneous electrical nerve stimulation (TENS, applied on gastrocnemius muscle) would induce motor enhancement. After applying the placebo procedure, the experimental group achieved better motor performance (more coordinated and symmetric) compared to two control groups (not influenced by the placebo treatment).