title: Children have a reduced maximal voluntary activation level of the adductor pollicis muscle compared to adults.
abstract: OBJECTIVE
  The role of nervous factors in the muscle strength difference between children and adults is debated, and the level of physical activity may confound this comparison. The purpose of this study was thus to compare, between children and adults, the maximal voluntary activation level (MVA) of the adductor pollicis (AP) muscle, which is weakly influenced by the level of physical activity.
  
  
  METHODS
  Thirteen boys (11.6 ± 0.1 years) and eight men (25.6 ± 1.5 years) were involved in this study. Neuromuscular function assessment included the evaluation of maximal voluntary contraction (MVC) force and of the MVA from peripheral magnetic stimulations of the ulnar nerve. The cross-sectional area of the AP muscle was determined with ultrasonography and used to calculate the specific force. A theoretical value of specific force, extrapolated for a full MVA, was finally computed (specific force@100 % MVA).
  
  
  RESULTS
  MVC force (66.8 ± 6.2 vs. 111.0 ± 4.5 N, respectively; P < 0.001) and MVA (85.0 ± 2.7 vs. 94.8 ± 1.4 %, respectively; P < 0.05) were significantly lower in children compared to adults. The specific force was lower in children compared to adults (46.8 ± 3.6 vs. 56.9 ± 2.5 N/cm(2), respectively; P < 0.05), but the specific force@100 % MVA did not differ between groups.
  
  
  CONCLUSIONS
  The results suggest that on an untrained muscle such as the AP muscle, the reduced ability of children to voluntarily activate their muscle could partly account for the difference of muscle strength between children and adults.
authors.affiliation: Université Clermont Auvergne, Université Blaise Pascal, Laboratoire des Adaptations Métaboliques à l'Exercice en Conditions Physiologiques et Pathologiques (AME2P, EA 3533), BP 10448, 63000, Clermont-Ferrand, France, vincent.martin@univ-bpclermont.fr.
authors.forename: V
authors.initials: V
authors.lastname: Martin
authors.forename: V
authors.initials: V
authors.lastname: Kluka
authors.forename: S
authors.initials: S
authors.lastname: Garcia Vicencio
authors.forename: F
authors.initials: F
authors.lastname: Maso
authors.forename: S
authors.initials: S
authors.lastname: Ratel
mesh_terms: D000328:Adult; D002648:Child; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D013933:Thumb / Q000502:physiology; D014459:Ulnar Nerve / Q000502:physiology*; D055815:Young Adult