Inter-session Reliability Of A Linear Position Transducer To Measure Velocity Of Bench Press

PURPOSE: To assess inter-session reliability of a linear position transducer (LPT) to measure mean velocity (MV), peak velocity (PV) and displacement (D) of the barbell bench press (BP) at various submaximal loads. METHODS: Nine participants (Men: N = 6; 24 ± 5 years; 1.71 ± 0.47 m; 81.3 ± 12.0 kg) with prior resistance training experience completed three experimental visits separated by at least 48 hours. On Day 1, following an informed consent, participants were asked to complete a 1-RM assessment for the BP after a standard warm-up. On Days 2 and 3, participants completed two sets of three BP repetitions at submaximal loads equal to 30, 50, 60, and 70% 1-RM in a sequential order, following a standard warm-up. The LPT was attached inside the sleeve of the barbell and placed on the ground with the retractable belt perpendicular to the ground. Barbell position was collected at a sampling rate of 100 Hz, exported into a customized spreadsheet, and filtered with a 0.10s rolling average. The repetition onset was defined as a filtered velocity of 0.15 m•s-1. MV, PV, and D were calculated for each repetition and averaged for each set (SA). The repetition with the fastest MV was defined as the best repetition (BR). Inter-session reliability was assessed using intraclass correlation coefficients (ICC) and differences between sets were assessed using paired samples t-tests. RESULTS: Data is presented in Table 1. Good (ICC 0.75-0.90) to excellent (ICC >0.90) SA reliability was observed at 30 and 50% using MV and PV, however poor SA reliability was observed at 60 and 70%. A similar pattern was observed for BR reliability; however, only good reliability was observed at 30 and 50%. Reliability for D was consistently higher when using SA in comparison to BR. CONCLUSIONS: When assessing MV and PV using the LPT, higher inter-session reliability is observed at lighter intensities whereas heavier intensities provide questionable reliability. The LPT may be better suited for exercise at lighter intensities.