title: Evaluation of methods for normalizing muscle strength in elite and young athletes.
abstract: BACKGROUND
  The following equation has been most often used in order to present recorded muscle strength (F) normalised for various measures of body size (such as body mass m) Fnor = F x m(-b). Since previous studies have provided inconsistent results, the purpose of the present one was to assess the value of the exponential parameter b (b-value) that (a) provides both the normalised strength independent of body mass and (b) demonstrates the highest possible correlation between the normalised strength and standard tests of movement performance.
  
  
  METHODS
  Thirteen groups of male and female athletes of both different age and different sport specialisation were tested for maximal isometric force of various leg muscle groups, as well as for vertical and standing long jump.
  
  
  RESULTS
  The data obtained on most of the experimental groups suggested that the b-value close to the theoretically predicted b=0.67, but also different from b=0 and b=1, should be used for calculation of the normalised strength independent of body mass. Although the strength normalised using b=0.67 and b=1 demonstrated higher correlation with jumping performance than the non-normalised strength (i.e., b=0), the data also suggested that b>1 could provide the highest prediction of movement performance.
  
  
  CONCLUSIONS
  Muscle strength should be calculated as force per kg(2/3) rather than as absolute force or force calculated per kg of body mass in order to assess strength independent of body size in routine testing of muscle function. However, different and probably task specific normalisation methods could be required in order to predict performance of various movement tasks by assessed muscle strength.
authors.affiliation: Centre for Musculo-Skeletal Research, National Institute for Working Life, Umea, Sweden. jaric@niwl.se
authors.forename: S
authors.initials: S
authors.lastname: Jaric
authors.forename: D
authors.initials: D
authors.lastname: Ugarkovic
authors.forename: M
authors.initials: M
authors.lastname: Kukolj
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D002648:Child; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012016:Reference Values