Abstract
The aim of this study was to investigate the reliability of fatigue indicators calculated
from peak torque and total work during isokinetic speeds of 60, 90, 120 and 180° · s−1 during a hip fatigue protocol. 10 males suffering from a history of unilateral functional
ankle instability and 10 male healthy controls performed 5 maximal concentric contractions
on an isokinetic dynamometer. Following a 4 min rest period subjects were instructed
to perform repeated maximal concentric contractions to fatigue, which was defined
as 3 consecutive repetitions below 50% of the maximum peak torque value. Each testing
speed was randomised with 24 h between speeds. The subjects were asked to return to
the laboratory 7 days later to repeat the 4 speeds, with 24 h between speeds. Muscle
fatigue was determined for each testing speed by the fatigue index, the percent decrease
in performance and the slope of the regression equation. The most reliable fatigue
determination method was the slope of the regression equation, when testing at a speed
of 120° · s−1. It is recommended that future investigators examine and plot their data before choosing
the slope of the regression equation as their fatigue indicator, as a linear model
is required.
Key words
intraclass correlation coefficient - standard error of measurement - functional
ankle instability - fatigue index - percent decrease in performance - slope of the
regression equation
