Intra-rater reliability and validity of various outcome variables of the 30-second chair rise test as assessed by the Leonardo Mechanograph force plate

Thirty-four participants (16 men, 18 women, age: 26.0±4.4 years; BMI: 23.2±4.0 kg/m2) performed 20.6±3.8 repetitions at baseline, with no significant sex differences in time-based (p>0.05) but in force-based parameters (p<0.01). All time-based parameters showed a significant LE (p<0.001) over the first three time points, while most force-based parameters did not (p>0.05). Minor fatigue was detected for power and velocity (p>0.05). ICC values ranged from 0.133-0.964 with better reliability at the late compared to the early time points. The force-based parameters correlated better with the CMJ (r=0.369-0.943) than the time-based parameters (r<0.370). Force and power were higher in the CMJ than in the 30s-CRT.