Effects of using TENS as Electro-tactile Feedback for Postural Balance under Muscle Fatigue Condition

Impaired postural control following muscle fatigue (MF) can result in falling, which can lead to fracture or other trauma. Transcutaneous electrical nerve stimulation (TENS) can reduce the muscle weakness that occurs due to MF and electro-tactile feedback can help guide the user to achieve postural or movement goals by providing sensory augmentation. The aim of the presented work is to evaluate experimentally the concept that these two effects can be applied simultaneously through the use of TENS as electro-tactile feedback. In this proof-of-concept study, two healthy participants stood in the one-leg stance while in MF condition for 30 seconds under 'No TENS', 'TENS Continuous' and 'TENS Feedback' conditions. Their medio-lateral trunk tilt was recorded during all trials. Electro-tactile feedback was achieved by modulating TENS intensity according to body sway in the medio-lateral direction. The results show that, as compared to the No TENS condition, there was no substantial improvement in postural stability under the TENS Continuous condition. However, the TENS Feedback condition resulted in the highest level of postural stability. Due to the small sample group in this pilot study, it is not possible to conclusively prove the benefits of using TENS as a feedback modality. However, results of both the male and female participants suggest that TENS may hold promise for use as a new electro-tactile biofeedback modality for postural improvement with the added benefit of alleviating the effects of muscle fatigue. In the future, studies with larger sample groups will be undertaken to demonstrate clearly the benefits of using TENS as electro-tactile biofeedback.