Anticipation of elbow joint perturbation shortens the onset time of the reflex EMG response in biceps brachii and triceps brachii

Abstract

This study aimed to investigate the influence of the anticipation of a perturbation torque applied to extend the elbow joint on the onset time of reflex electromyogram (EMG) responses. A perturbation torque generated by an electromagnetic torque motor system was applied to the forearm of five subjects during trials. The trials were divided into an anticipated (AN) condition-perturbation torque applied after the auditory signal-and an unanticipated (UAN) condition-suddenly applied perturbation. To detect the reflex EMG response in the biceps brachii (Bb) and triceps brachii (Tb) muscles, a new method involving the discrete wavelet transform and outlier tests was used. We found that the onset time of the reflex response in both the muscles in the AN condition was significantly shorter than that in the UAN condition. The angle of transition from flexion to extension, which was induced by the reflex response of Bb, was also significantly smaller in the AN condition than in the UAN condition. The results indicate that the anticipation of an applied perturbation torque decreases the onset time of the reflex response in the Bb and Tb.

Human elbow motor learning skills of varying loads: Proof of internal model generation using joint stiffness estimation

“…Based on the previous study that human elbow stretch reflex response is in excess of 40ms (Koike et al, 2007), we set the length of the reflex loop delay to 40ms (Sampling rate of the system is 1kHZ). For each time , the optimal timevarying parameters were estimated by minimizing the mean square error, ( ) between smoothed IRF, ̂( ) based estimated torque with measured torque ( ) (Fig.…”

Posture and hand load alter muscular response to sudden elbow perturbations

“…Given this dependence on anticipatory muscle action, an understanding of the system's initial state, including postural demands and loading is important. Furthermore, anticipating a perturbation (Koike and Yamada, 2007), as well as the direction and magnitude of an applied perturbation (Franklin et al, 2003) influences the contribution of the reflex response. The reflex contribution to joint stability in the upper extremity requires further attention given that the neuromuscular delay associated with a reflex can cause instability (Jacks et al, 1988).…”

Effects of Predictability of Load Magnitude on the Response of the Flexor Digitorum Superficialis to a Sudden Fingers Extension

“…Shortening in response latency within the timing interval of the short-latency reflex was observed when a quick joint perturbation was anticipated by motor imagery [13] , acoustic [11] or visual [12] cues. To our knowledge this is the first study in which the latency of muscle response, including the short-latency component, was associated with the load predictability.…”

“…Only few authors have associated the changes in muscle response with information provided before the occurrence of the perturbation. Some investigators have reported shortening of the reflex latency when the mechanical perturbation was anticipated by acoustic [11] or visual [12] signals or by motor imagery [13] .…”