title: Effects of ankle joint position and submaximal muscle contraction intensity on soleus H-reflex modulation in young and older adults.
abstract: This study investigated the effects of ankle joint position and submaximal contraction intensity on soleus (SOL) H-reflex modulation. Twenty young (25.1 ± 4.8 years) and 20 older adults (74.2 ± 5.1 years) performed plantar flexions during 10%, 30% and 50% maximal voluntary contractions (MVC) and at ankle positions of neutral (0°), plantar flexion (20°) and dorsiflexion (-20°) in a sitting position. The SOL H-reflex gain in older adults was relatively lower than that in young adults during 10%, 30% and 50% MVC. The SOL H-reflex gain was significantly affected by the intensity of plantar flexion in the respective ankle joint position in both age groups. The latency of H-reflex was prolonged in older adults and was ankle joint dependent in young adults. Young adults demonstrated a shorter duration of the H-reflex response than that of older adults. The results indicated that there were age-related changes in the SOL H-reflex during the ankle plantar flexors activities.
authors.affiliation: Dept. of Exercise and Health Sciences, University of Taipei, Taipei, Taiwan.
authors.forename: Yung-Sheng
authors.initials: YS
authors.lastname: Chen
authors.forename: Shi
authors.initials: S
authors.lastname: Zhou
authors.forename: Colleen
authors.initials: C
authors.lastname: Cartwright
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000843:Ankle Joint / Q000502:physiology*; D004576:Electromyography; D005260:Female; D005528:Foot / Q000502:physiology; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D013997:Time Factors; D019415:Torque; D055815:Young Adult