title: Reproducibility of jumping mechanography and traditional measures of physical and muscle function in older adults.
abstract: CONCLUSIONS
  Improved approaches to assess functional change over time are needed to optimally reduce fall/fracture risk; jumping mechanography (JM) may be one such methodology. In this study, JM parameters were more reproducible than traditional functional tests. JM may be better able to demonstrate efficacy of interventions to mitigate sarcopenia.
  
  
  BACKGROUND
  Jumping mechanography (JM), a tool using maximal countermovement jumps performed on a force plate, may more reliably assess muscle function than traditional methods. The purpose of this study was to examine JM retest reliability in older adults compared with commonly used muscle and physical function assessments.
  
  
  METHODS
  Community-dwelling individuals age≥70 years performed physical and muscle function assessments including the short physical performance battery (SPPB), grip strength, and JM on multiple occasions over 3 months. JM parameters included body weight-corrected peak power and jump height. Appendicular lean mass was measured by dual energy x-ray (DXA). Mixed effects linear regression models were used to estimate between- and within-person variability summarized as intra-class correlation coefficients (ICC).
  
  
  RESULTS
  Ninety-seven individuals (49 females, 48 males, mean age 80.7 years) participated. All testing was well tolerated; no participant sustained injury. Jump power, height, and grip strength were greater (p<0.0001) in men than women. Grip strength, jump power, and height had excellent ICCs (0.95, 0.93, and 0.88, respectively); chair rise, SPPB score, and gait speed had lower ICCs (0.81, 0.77, and 0.76, respectively).
  
  
  CONCLUSIONS
  In older adults, JM has excellent retest reliability, is stable over time, and can be performed safely. JM retest reliability was comparable to grip strength and possibly better than SPPB and gait speed. JM is a promising tool for muscle function assessment in older adults. Comparison of this approach with traditional assessment tools in longitudinal interventional studies is needed.
authors.affiliation: Osteoporosis Clinical Research Program, University of Wisconsin-Madison, 2870 University Avenue, Suite 100, Madison, WI, 53705, USA, bbuehring@medicine.wisc.edu.
authors.forename: B
authors.initials: B
authors.lastname: Buehring
authors.forename: D
authors.initials: D
authors.lastname: Krueger
authors.forename: E
authors.initials: E
authors.lastname: Fidler
authors.forename: R
authors.initials: R
authors.lastname: Gangnon
authors.forename: B
authors.initials: B
authors.lastname: Heiderscheit
authors.forename: N
authors.initials: N
authors.lastname: Binkley
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology; D005080:Exercise Test / Q000379:methods; D005260:Female; D015577:Geriatric Assessment / Q000379:methods; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D015203:Reproducibility of Results; D055948:Sarcopenia / Q000175:diagnosis / Q000503:physiopathology*