title: Comparison of the frequency spectra of surface electromyographic signals from the soleus muscle under normal and altered sensory environments.
abstract: The vestibular, proprioceptive and visual senses of the body are all affected by alterations of the normal sensory environment during weightlessness. This study was designed to observe muscle activation characteristics when a single component of the sensory environment was altered. Partially immersing a subject in a water pool provided a buoyant force upon the lower body, "unloading" the muscles, similar to the effect on the muscles in weightlessness. Surface EMG from the soleus was obtained during the performance of a constant-force isometric contraction. The mean and median characteristic frequencies were calculated from the power spectrum of each trial. Six of ten subjects showed a difference in the characteristic frequencies between the two environments. It appears that for some individuals there are changes in muscle activation characteristics due to influences of the proprioceptive system when exposed to an altered sensory environment.
authors.affiliation: Department of Electrical and Computer Engineering, Kansas State University, Manhattan 66506.
authors.forename: S J
authors.initials: SJ
authors.lastname: Schroeder
authors.forename: C S
authors.initials: CS
authors.lastname: Layne
authors.forename: R A
authors.initials: RA
authors.lastname: Dyer
mesh_terms: D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology*; D009132:Muscles / Q000502:physiology*; D011434:Proprioception