title: Effects of repeated ankle plantar-flexions on H-reflex and body sway during standing.
abstract: The study investigated relations between effects of repeated ankle plantar-flexion movements exercise on the soleus Hoffmann (H) reflex and on postural body sway when maintaining upright stance. Ten young volunteers performed five sets of ankle plantar-flexions of both lower limbs. Assessment of the feet centre-of-pressure (COP) displacement and H-reflex tests were carried out in quiet stance before, during and after the exercise. H-max and M-max responses were obtained in 8 subjects and reported as the peak-to-peak amplitudes of the right soleus muscle electromyographic waves. Mean dispersion of COP along the antero-posterior direction increased significantly during the exercise; whilst the overall H-reflex response indicated a reduction without a concomitant modification in the M-max response. H-reflex responses, however, varied between participants during the first sets of exercise, showing two main trends of modulation: either depression or early facilitation followed by reduction of the H-reflex amplitude. The extent of reflex modulation in standing position was correlated to the concentric work performed during the exercise (r=0.85; p<0.01), but not to the antero-posterior COP dispersion. These results suggest that during a repeated ankle plantar-flexions exercise, modulation of the H-reflex measured in upright stance differs across individuals and is not related to changes of postural sway.
authors.affiliation: Department of Applied Physiology, University of Strathclyde, Glasgow, UK. luca.laudani@unict.it
authors.forename: L
authors.initials: L
authors.lastname: Laudani
authors.forename: L
authors.initials: L
authors.lastname: Wood
authors.forename: A
authors.initials: A
authors.lastname: Casabona
authors.forename: R
authors.initials: R
authors.lastname: Giuffrida
authors.forename: G
authors.initials: G
authors.lastname: De Vito
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D005528:Foot / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D004856:Postural Balance / Q000502:physiology*; D016059:Range of Motion, Articular; D055815:Young Adult