title: Age-related sex differences in erector spinae muscle endurance using surface electromyographic power spectral analysis in healthy humans.
abstract: BACKGROUND
  Previous studies reported that the erector spinae muscle is more resistant to fatigue in healthy adult women than in men. However, no study has reported changes in back muscle fatigue with aging in healthy men and women.
  
  
  OBJECTIVE
  The aim of this study was to evaluate age-related changes in muscle fatigue of erector spinae muscle in men and women.
  
  
  METHODS
  This cross-sectional study was conducted in a laboratory.
  
  
  METHODS
  Fifty-three healthy subjects (11 elderly men, 11 elderly women, 17 young men, and 14 young women) without low back pain history.
  
  
  METHODS
  The median frequency (MF) and mean power frequency (MPF) during trunk holding test were derived from the raw electromyographic (EMG) signal using Fast Fourier Transform spectrum analysis program. The rates of changes in MF and MPF were calculated.
  
  
  METHODS
  Subjects performed the unsupported trunk holding test until exhaustion. The results of power spectral analysis of the EMG activity of the left erector spinae muscle were compared in both age groups and sexes.
  
  
  RESULTS
  The endurance time in young men was significantly shorter than in young women. The slopes of MF and MPF in young men were significantly higher than in young women. There were no significant differences in MF and MPF slopes of elderly men and elderly women. Furthermore, the MF and MPF slopes were significantly lower in elderly men than young men but similar in the two women groups.
  
  
  CONCLUSIONS
  Age-related changes in the slopes of MF and MPF of erector spinae muscle occur in healthy men but not in healthy women.
authors.affiliation: Department of Rehabilitation Medicine, Wakayama Medical University, 811-1 Kimiidera Wakayama-shi, Wakayama 641-8509, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsuboi
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohko
authors.forename: Hideaki
authors.initials: H
authors.lastname: Tanina
authors.forename: Ken
authors.initials: K
authors.lastname: Kouda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Umezu
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Tajima
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D001415:Back / Q000502:physiology*; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D012727:Sex Characteristics; D055815:Young Adult
keywords: Aging; Electromyography; Erector spinae muscle; Muscle fatigue; Sex difference