title: Validity of Torque-Data Collection at Multiple Sites: A Framework for Collaboration on Clinical-Outcomes Research in Sports Medicine.
abstract: Collecting torque data using a multimode dynamometer is common in sports-medicine research. The error in torque measurements across multiple sites and dynamometers has not been established.
  
  
  
  To assess the validity of 2 calibration protocols across 3 dynamometers and the error associated with torque measurement for each system.
  
  
  
  Observational study.
  
  
  
  3 university laboratories at separate institutions.
  
  
  
  2 Biodex System 3 dynamometers and 1 Biodex System 4 dynamometer.
  
  
  
  System calibration was completed using the manufacturer-recommended single-weight method and an experimental calibration method using a series of progressive weights. Both calibration methods were compared with a manually calculated theoretical torque across a range of applied weights.
  
  
  
  Relative error, absolute error, and percent error were calculated at each weight. Each outcome variable was compared between systems using 95% confidence intervals across low (0-65 Nm), moderate (66-110 Nm), and high (111-165 Nm) torque categorizations.
  
  
  
  Calibration coefficients were established for each system using both calibration protocols. However, within each system the calibration coefficients generated using the single-weight (System 4 = 2.42 [0.90], System 3a = 1.37 [1.11], System 3b = -0.96 [1.45]) and experimental calibration protocols (System 4 = 3.95 [1.08], System 3a = -0.79 [1.23], System 3b = 2.31 [1.66]) were similar and displayed acceptable mean relative error compared with calculated theoretical torque values. Overall, percent error was greatest for all 3 systems in low-torque conditions (System 4 = 11.66% [6.39], System 3a = 6.82% [11.98], System 3b = 4.35% [9.49]). The System 4 significantly overestimated torque across all 3 weight increments, and the System 3b overestimated torque over the moderate-torque increment.
  
  
  
  Conversion of raw voltage to torque values using the single-calibration-weight method is valid and comparable to a more complex multiweight calibration process; however, it is clear that calibration must be done for each individual system to ensure accurate data collection.
authors: Dept of Kinesiology, Michigan State University, East Lansing, MI.
authors: Christopher
authors: C
authors: Kuenze
authors: Moataz
authors: M
authors: Eltouhky
authors: Abbey
authors: A
authors: Thomas
authors: Mark
authors: M
authors: Sutherlin
authors: Joseph
authors: J
authors: Hart
mesh_terms: D001696:Biomechanical Phenomena; D002138:Calibration; D006801:Humans; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology*; D019415:Torque