The reproducibility of three different indicators of fatigue from
plantar-flexion isokinetic testing at two knee flexion angles is not sufficient
to be termed 'acceptable'
Affiliations: [a] Swedish Winter Sports Research Centre, Department of
Health Sciences, Mid Sweden University, Östersund, Sweden
Note: [] Corresponding author: Kim Hébert-Losier, Swedish Winter
Sports Research Centre, Department of Health Sciences, Mid Sweden University,
Kunskapens väg 8, Hus D, 83125 Östersund, Sweden. Tel.: +41 46 6316
5632; Fax: +41 46 6316 5740; E-mail: kim.hebert-losier@miun.se
Abstract: OBJECTIVE: To characterize the reproducibility of three indicators
of fatigue (FIs) specific to concentric plantar-flexion isokinetic testing at
knee flexion (KF) angles of 0° (straight) and 45° (bent). METHODS: On two separate days one week apart, thirty-four males
performed 50 consecutive maximal concentric isokinetic plantar-flexion
contractions at 60°/s with 0° and 45° of KF. Differences in the
pre- and post-maximal voluntary isometric contraction torques
(FI_{static}), powers during the initial five and last five
isokinetic contractions (FI_{dynamic}) and powers during the
50 isokinetic contractions (FI_{slope}) were used as FIs.
Changes in means, intra-class correlation coefficients (ICCs) and coefficients
of variations (CVs) were computed to quantify the reproducibility of the FIs.
Comparisons were made between the two KF angles and three FIs using two-way
repeated measures ANOVA. RESULTS: For both KF angles and three FIs, ICCs ranged from 0.52 to
0.71 and CVs from 10.0 to 29.3%. The CVs from the two isokinetic-based FIs were
lower than those from the isometric FI and a trend towards larger ICCs at
0° was observed. CONCLUSIONS: The reproducibility of the three FIs was not sufficient
to be termed 'acceptable'. The FI_{slope} and
FI_{dynamic} were more reproducible than
FI_{static} and are recommended – with the knee
straight rather than bent – until more reliable indicators become
available.
