Inter-set Reliability Of A Linear Position Transducer To Measure Velocity And Displacement During Bench Press

PURPOSE: To determine inter-set reliability of a linear position transducer (LPT) measuring velocity and displacement (D) during bench press using two distinct techniques to identify repetitions. METHODS: Nine healthy men and women (Men: N = 6; 24 ± 5 years; 1.71 ± 0.47 m;81.3 ± 12.0 kg) with at least six months of resistance training experience attended the laboratory on two separate occasions: first to complete an informed consent and a one-repetition maximum(1RM) of the bench press before returning at least 48 hours later for the exercise trial. Each trial consisted of a standard warm-up and two sets of three bench press repetitions at 30%, 50%, 60%and 70% of their previously established 1RM. The LPT was attached to the barbell at the medial aspect of the sleeve and perpendicular to the ground. Barbell position was collected at 100 Hz and filtered with a 0.10s rolling average while repetition onset was defined as a filtered velocity of0.15 m•s-1. Mean velocity (MV), peak velocity (PV) and D were calculated from changes in position for the average of three repetitions (AR), and the repetition with the highest MV (BR).Inter-set reliability was assessed using Intra class Correlations (ICC) and paired samples t-tests to assess differences between sets. RESULTS: Data are presented in Table 1. A strong AR reliability (ICC > 0.900) was observed for MV and PV, while BR reliability was lower for both MV and PV, especially at higher intensities. Significant differences were observed between sets at 60% 1RM for the BR MV and PV. Reliability for D was consistently higher when calculated with AR rather than BR; though reliability was consistently lower for D than MV and PV. CONCLUSION: Data suggest that MV and PV inter-set reliability is stronger when calculated based on AR rather than BR. Data also indicate strong reliability for AR MV and PV between two sets of bench press during the same session. This may allow practitioners to collect data in fewer sets, reducing the time required for data collection.