title: The reliability of hand-held dynamometry for strength assessment during electrically induced muscle contractions.
abstract: OBJECTIVE
  To determine inter- and intra-tester reliability of strength measurements during maximal electrically induced contractions (MEIC) using a hand-held dynamometer (HHD).
  
  
  METHODS
  Thirty-seven healthy young female adults, mean age (SD) 23.4 (2.4) years, were tested by two examiners during two sessions, with order of examiners randomized. Biphasic pulses (phase duration--300 µs; pulse frequency--75 Hz) were employed in order to induce contractions of the quadriceps femoris muscle at a maximally tolerated current level. Strength of maximal voluntary isometric contractions (MVIC) and of MEIC was recorded with a HHD utilizing a stabilization belt.
  
  
  RESULTS
  Good to excellent inter- and intra-tester reliability were determined with intra-class correlation coefficients ranging between 0.8 and 0.9, and no bias in the Bland-Altman plots. The 95% repeatability ranged between 8.7 and 13.0 kg for the MVIC and MEIC, and between 20.7 and 25.6% for the % MVIC.
  
  
  CONCLUSIONS
  Our results confirm previous findings indicating good to excellent reliability of quadriceps femoris muscle MVIC assessment with a HHD. However, a high 95% repeatability range indicates the HHD is not sufficiently reliable as an indicator of the force level attained during electrically induced contractions. Other methods need to be investigated to assist in determining whether MEIC have reached therapeutic levels.
authors.affiliation: Department of Physical Therapy, Faculty of Social Welfare and Health Sciences, University of Haifa , Mount Carmel, Haifa , Israel.
authors.forename: Einat
authors.initials: E
authors.lastname: Kodesh
authors.forename: Yocheved
authors.initials: Y
authors.lastname: Laufer
mesh_terms: D000328:Adult; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D006225:Hand; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D052097:Quadriceps Muscle / Q000502:physiology*; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Hand-held dynamometer; maximal voluntary isometric contractions; neuromuscular electrical stimulation; reliability