Reliability of a new instrument for measuring plantarflexor muscle strength.
OBJECTIVE
To test the reliability of a new muscle strength testing instrument (the Strength Measuring Chair [SMC]) designed to quantify isometric strength in the lower extremities, and to determine the agreement between the SMC and an isokinetic dynamometer (Biodex).


METHODS
Isometric strength tests were performed in plantarflexors with 2 different knee positions (60 degrees, 30 degrees). Measurements were taken at 3 different sessions.


METHODS
Strength testing laboratory.


METHODS
Twenty-three able-bodied adults and 15 able-bodied children.


METHODS
Not applicable.


METHODS
Isometric plantarflexor strength.


RESULTS
The reliability of isometric strength measurements of plantarflexors taken in the SMC was excellent for both the adult and children groups (intraclass correlation coefficient range, .84-.87). A Bland-Altman 95% limit of agreement test showed no systematic variation in 3 of the 4 SMC test observations; systematic variation was only observed in the adult group at a knee position of 30 degrees. There was no systematic difference in the adult group between the SMC and the isokinetic dynamometer, but there was a systematic variation in the children's group.


CONCLUSIONS
The SMC reliably measured isometric plantarflexor strength in the tested populations.
Ortqvist
Maria
M
Department of Women & Child Health, Karolinska Institutet, Stockholm, Sweden.
Gutierrez-Farewik
Elena M
EM
Farewik
Markus
M
Jansson
Anna
A
Bartonek
Asa
A
Broström
Eva
E
D000328:Adult; D002648:Child; D002675:Child, Preschool; D004867:Equipment Design; D005080:Exercise Test / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D015203:Reproducibility of Results