title: Isometric endurance of the back extensors in school-aged adolescents with and without low back pain.
abstract: OBJECTIVE
  Studies on back extensor endurance in adolescents are scarce. This study sought to establish reference data and pattern of back extensor endurance in school-aged adolescents with and without low-back pain (LBP) from Nigeria.
  
  
  METHODS
  This study recruited 625 adolescents aged 11 to 19 years from eight randomly selected secondary schools. The modified Biering-Sørensen test of Static Muscular Endurance (BSME) was used to assess isometric endurance of the back extensors. Demographic and anthropometric data were collected. A modified LBP questionnaire was used to assess the presence of LBP. Descriptive and inferential analyses were used to analyze data. Significance was set at 0.05 alpha-level.
  
  
  RESULTS
  The mean isometric holding time (IHT) of all the participants was 132.9 $\pm$ 65.6. Males had significantly higher significant (p=0.026) IHT than females. Adolescents without LBP had a higher significant IHT (p=0.042) than those with reported history of previous LBP and those with present LBP (p=0.000) respectively. Using percentile values, poor endurance was defined as IHT that is < 90.0 s and < 67 s for males and females respectively; medium endurance was defined as IHT that ranged between 90 and 193 s and 67 and 170 s for males and females respectively while good endurance was defined as IHT that is > 193 s and > 170 s for males and females respectively. IHT was significantly related to each of body mass index, hip circumference and waist-to-hip ratio (p < 0.05).
  
  
  CONCLUSIONS
  Isometric back extensors endurance in Nigerian adolescents was comparable to the original Biering-Sørensen mean value. Majority of the participants had medium endurance performance with the back endurance pattern in the ratio 1:2:1. Male had higher isometric back extensors endurance than females. Decreased isometric back extensors endurance was associated with the presence of LBP in adolescents.
authors.affiliation: Department of Medical Rehabilitation, Obafemi Awolowo University, Ile-Ife, Nigeria. obnik2001@yahoo.co.uk
authors.forename: Olubusola E
authors.initials: OE
authors.lastname: Johnson
authors.forename: Chidozie E
authors.initials: CE
authors.lastname: Mbada
authors.forename: Christopher O
authors.initials: CO
authors.lastname: Akosile
authors.forename: Oyinade A
authors.initials: OA
authors.lastname: Agbeja
mesh_terms: D000293:Adolescent; D001415:Back / Q000502:physiology*; D015992:Body Mass Index; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D017116:Low Back Pain / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D009549:Nigeria; D010807:Physical Endurance / Q000502:physiology*; D016684:Prone Position / Q000502:physiology; D012727:Sex Characteristics; D013997:Time Factors; D055815:Young Adult