It is believed that a better understanding of how the neuromuscular system responds to external disturbances will help to identify people at risk for falls and to develop treatment approaches or interventions that may be effective in reducing the number of falls. The principal objective of this study was to investigate the contribution of sensory information from plantar cutaneous mechanoreceptors to muscle stretch responses. To accomplish this task, lower extremity muscle EMG signals were recorded in 12 young female subjects with the use of an integrated perturbation device. A toe-up ankle perturbation was generated while varying the quality and quantity of loading force and plantar stimulating pressure.

The results of this study clearly established the importance of the cutaneous mechanoreceptor system in muscle stretch responses, and stressed the importance of future research into sub-somatosensory system integration and compensation. The data showed that, in the time domain, the EMG response occurrence frequency, EMG response latency times, and EMG response amplitudes were all affected by the cutaneous afferent information. In the frequency domain, central frequencies were modulated by somatosensory inputs. This study raised some important questions regarding the classic upright standing research protocol for studying sub-somatosensory systems, such as cutaneous mechanoreceptors. The results from this study may also help in validating the local multi-channel, parallel processing model of the preprogrammed reaction theory.