title: Muscle strength and its relationship with skeletal muscle mass indices as determined by segmental bio-impedance analysis.
abstract: OBJECTIVE
  Despite increasing interest in bio-impedance analysis (BIA) for estimation of segmental skeletal muscle mass (SMM), published results have not been entirely convincing. Furthermore, a better understanding of the relationship between muscle strength and SMM will be useful in interpreting outcomes of physical/training interventions particularly in groups with diverse body sizes (e.g. men vs women). This study aimed to measure SMM in the upper body (upper extremity and torso), to determine its correlation with muscle strength and to examine the effects of gender on muscle strength-muscle mass relationship.
  
  
  METHODS
  Segmental (upper extremity and torso) SMM and muscle strength in five distinct shoulder planes (forward flexion, abduction in scapular plane, abduction in coronal plane, internal and external rotation) were measured in 45 healthy participants (22 males, 23 females) with mean age 30.3 years. Statistical analysis included independent t tests, Pearson correlation, and multiple regression analysis.
  
  
  RESULTS
  Men and women differed significantly in body mass (BMI: 25.9 ± 4.3 vs 23 ± 3.6) and SMM (p < 0.01). A strong relationship correlation was found between the five shoulder strength measurements and upper extremity SMM (r = 0.66-0.80, p < 0.01), which was not affected by gender. There was a significant gender difference (p < 0.01) in absolute shoulder strength, but not after normalisation to the SMM.
  
  
  CONCLUSIONS
  BIA-estimated SMM of upper extremity and torso was highly correlated with upper extremity (shoulder) strength independent of gender. SMM may, therefore, be useful for the normalisation of muscle strength allowing size-independent comparisons of muscle strength in individuals with diverse physical characteristics.
authors.affiliation: School of Health Sciences, Liverpool Hope University, Liverpool, L16 9JD, UK, alizado@hope.ac.uk.
authors.forename: Omid
authors.initials: O
authors.lastname: Alizadehkhaiyat
authors.forename: David H
authors.initials: DH
authors.lastname: Hawkes
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Kemp
authors.forename: Anthony
authors.initials: A
authors.lastname: Howard
authors.forename: Simon P
authors.initials: SP
authors.lastname: Frostick
mesh_terms: D000328:Adult; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D009929:Organ Size; D012737:Sex Factors; D060726:Torso / Q000033:anatomy & histology / Q000502:physiology; D034941:Upper Extremity / Q000033:anatomy & histology / Q000502:physiology