title: Maximum ground reaction force in relation to tibial bone mass in children and adults.
abstract: OBJECTIVE
  The purpose of the study was to assess maximum voluntary forefoot ground reaction force during multiple one-legged hopping (F m1LH) and to determine the correlation between tibial volumetric bone mineral content (vBMC, a valid surrogate of bone strength) and F m1LH.
  
  
  METHODS
  One hundred eighty-five females (8-82 yr old) and 138 males (8-71 yr old) performed multiple one-legged hopping to measure F m1LH acting on the forefoot during landing. Peripheral quantitative computed tomography scans were obtained to assess vBMC at 4%, 14%, 38%, and 66% of tibia length and calf muscle cross-sectional area at the 66% site.
  
  
  RESULTS
  In all 323 participants, F m1LH corresponded to 3-3.5 times body weight, and F m1LH predicted vBMC 14% by 84.0% (P < 0.001). vBMC 14% was better correlated with F m1LH than with the calf muscle cross-sectional area in both males (R2 = 0.841 vs R2 = 0.724) and females (R2 = 0.765 vs R2 = 0.597). F m1LH and vBMC14% both increased during growth and afterward remained constant or decreased with age but never increased above the values reached at the end of puberty. F m1LH decreased by 23.6% between 21-30 and 61-82 yr in females and by 14.0% between 31-40 and 51-71 yr in males. vBMC 14% decreased by 13.7% in females between 21-30 and 61-82 yr but remained unchanged in adult males.
  
  
  CONCLUSIONS
  Multiple one-legged hopping yields the highest (i.e., maximum) ground reaction force relative to other jumping maneuvers. Because bone strength is strongly governed by maximum muscle force, the concurrent assessment of peripheral quantitative computed tomography-derived bone strength and F m1LH might represent a new approach for the operational evaluation of musculoskeletal health.
authors.affiliation: Exercise Physiology, Institute of Human Movement Sciences, ETH Zürich, Zurich, Switzerland.
authors.forename: Elmar
authors.initials: E
authors.lastname: Anliker
authors.forename: Rainer
authors.initials: R
authors.lastname: Rawer
authors.forename: Urs
authors.initials: U
authors.lastname: Boutellier
authors.forename: Marco
authors.initials: M
authors.lastname: Toigo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D011859:Radiography; D013557:Switzerland; D013977:Tibia / Q000000981:diagnostic imaging / Q000502:physiology*; D015898:Tomography Scanners, X-Ray Computed; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult