RELIABLE MEASUREMENT OF THE TRICEPS SURAE STRETCH REFLEX

  • Ales Dolenec
  • Vajko Strojnik
Keywords: stretch reflex, triceps surae, electromyography, human subjects

Abstract

INTRODUCTION: Reflex occurrence and its modulation play an important role in motor control. A special platform with a leverage system to induce foot movement was constructed to research the triceps surae stretch reflex. The aim of this research was to establish the reliability of reflex measurements with this measurement device. METHODS: Six adult males (age 30.5 ± 5.1 years, height 180.3 ± 4.4 cm, and body mass 71.3 ± 4.6 kg) participated in the study. Each was asked to sit on a rigid chair with their right foot clamped to a pedal. The ankle and knee angles of the right leg were respectively 90 and 120 degrees. Angular displacement of the foot was measured with an electronic goniometer (Penny and Giles, G35, Blackwood Gwent, GB). Electromyograms (EMG) were recorded from the soleus (SO), using surface electrodes placed over the belly of the muscle. The EMG signal was recorded with Biotel 88 (Glonner, München, Germany). A displacement (10 deg) of the pedal was performed at 57 deg/s. Pedal displacement was induced by a weight lowered with a constant velocity on a leverage system to move the pedal. Two measurements were made. Between the first and second measurements, the subjects stood up and took their foot from the pedal. Nine stimuli were recorded each time. Data were acquired at 1000 Hz. A statistical significance of the differences between the first and second measurements was tested with the paired-samples t-test (two-way). RESULTS: [Table...] CONCLUSIONS: There were no statistical differences between the first and the second measurements. It was possible to conclude that the special platform with a leverage system is relevant for the measurement of the short-latency stretch reflex.