Effect of the application of somatosensory and excitomotor electrical stimulation during quiet upright standing balance

Somatosensory (which activates sensory neurons only) and excitomotor (which activates both motoneurons and sensory neurons) electrical stimulations applied on the musculature of the lower-limb are likely to facilitate and disturb balance control respectively. The aim of this study was to compare the possible balance control modifications induced by somatosensory (SS) and excitomotor (EX) electrical stimulations applied on the quadriceps femoris in quiet standing condition. Kinetics and kinematics parameters were recorded with a force platform (displacements of center of foot pressure) and a 3D analysis system (hip, knee and ankle angles) respectively during a postural task. Twenty healthy young male participants carried out a monopedal postural task (i.e., unilateral stance) in three conditions: SS stimulation (1ms; 10Hz; 7 +/- 2 mA i.e., twice the intensity corresponding to the sensory threshold), EX stimulation (400 mu s; 50 Hz; 20 +/- 5 mA i.e., twice the intensity corresponding to the motor threshold), and a control (CONT) condition without stimulation. The results showed no significant differences between the three conditions except for the knee' angle which was higher in the EX condition (167.3 +/- 11.6 vs 164.3 +/- 5.8 and 163.9 +/- 8) ( p < 0.005) than in the two other conditions (SS stimulation and CONT). This means that the EX stimulation induced a postural position change (i.e., a slight knee extension) during the monopedal postural task without altering balance control. Overall, on the basis of the stimulation parameters used in the present work, neither the SS stimulation, nor the EX stimulation facilitated or disturbed postural balance. (C) 2020 IPEM. Published by Elsevier Ltd. All rights reserved.

Automated summary

Differences in knee angle were observed between excitomotor stimulation and the other conditions, suggesting a slight knee extension without affecting balance control during a monopedal postural task. Overall, neither somatosensory nor excitomotor stimulation had a significant impact on postural balance in this study.