Ergometer and dynamometer used to test isometric leg strength.
CED
CONTRACTION
(A) Custom-made ergometer for the isometric maximal voluntary contraction during knee extension. The participant’s left ankle was attached to the ergometer’s lever arm about 3 cm above the lateral malleolus. Adjustable straps and pads on the chest and hip were used to minimize extraneous body movements. (B) Custom-made ankle dynamometer for the isometric maximal voluntary contraction during plantar flexion. The participant’s foot was fixed to the bottom plate with a strap to prevent plantar extension. The position of the knee was fixed with a clamp to prevent the lifting of the heel. Figure adapted with permission from Kümmel et al., [Force (KE, analogue signals of the ergometer load cells) and torque data (PF) were amplified (Kistler 5006 and 5015, Kistler Group, Winterthur, Switzerland), sampled at a frequency of 1000 Hz (CED Power1401, CED Ltd., Milton, UK) and recorded and stored for further analyses with MATLAB (version R2020b, MathWorks Inc., Massachusetts, USA). The analyses consisted of correcting potential offsets and applying a 6th-order zero-lag Butterworth filter (cut-off frequency 15 Hz). For KE, torque was calculated for every participant as the product of force (N) times the perpendicular distance (m) between the lateral epicondyle of the left knee to the lever arm of the ergometer. The peak torque (N⋅m) of every trial for both KE and PF was extracted, and the highest of the three trials was kept for further analysis.