title: Test-Retest Reliability of Isokinetic Knee Strength Measurements in Children Aged 8 to 10 Years.
abstract: BACKGROUND
  Isokinetic dynamometry is a useful tool to objectively assess muscle strength of children and adults in athletic and rehabilitative settings. This study examined test-retest reliability of isokinetic knee strength measurements in children aged 8 to 10 years and defined limits for the minimum difference (MD) in strength that indicates a clinically important change.
  
  
  OBJECTIVE
  Isokinetic knee strength measurements (using the Biodex System 4) in children will provide reliable results.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  In 22 healthy children, 5 maximal concentric (CON) knee extensor (KE) and knee flexor (KF) contractions at 2 angular velocities (60 deg/s and 180 deg/s) and 5 maximal eccentric (ECC) KE/KF contractions at 60 deg/s were assessed 7 days apart. The intraclass correlation coefficient (ICC2.1) was used to examine relative reliability, and the MD was calculated on the basis of standard error of measurement.
  
  
  RESULTS
  ICCs for CON KE/KF peak torque measurements were fair to excellent (range, 0.49-0.81). The MD% values for CON KE and KF ranged from 31% to 37% at 60 deg/s and from 34% to 39% at 180 deg/s. ICCs in the ECC mode were good (range, 0.60-0.70), but associated MD% values were high (>50%). There was no systematic error for CON KE/KF and ECC KE strength measurements at 60 deg/s, but systematic error was found for all other measurements.
  
  
  CONCLUSIONS
  The dynamometer provides a reliable analysis of isokinetic CON knee strength measurements at 60 deg/s in children aged 8 to 10 years. Measurements at 180 deg/s and in the ECC mode were not reliable, indicating a need for more familiarization prior to testing.
  
  
  CONCLUSIONS
  The MD values may help clinicians to determine whether a change in knee strength is due to error or intervention.
authors.affiliation: Department of Health Sciences, Rehabilitation Medicine Research Group, Lund University, Lund, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Fagher
authors.affiliation: Department of Health Sciences, Division of Physiotherapy, Lund University, Lund, Sweden.
authors.forename: Annelie
authors.initials: A
authors.lastname: Fritzson
authors.affiliation: Department of Health Sciences, Division of Physiotherapy, Lund University, Lund, Sweden.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Drake
mesh_terms: D000367:Age Factors; D002648:Child; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D015203:Reproducibility of Results
keywords: child; dynamometry; knee joint; reproducibility of results; strength testing