Validity and reliability of an optoelectronic system to measure movement velocity during bench press and half squat in a Smith machine

Abstract

The purpose of this study was to determine the validity and reliability of a camera-based optoelectronic system to measure movement velocity during bench press and half squat at different load intensities. A total of 22 active males (age: 28.2 ± 3.9 years; one-repetition maximum bench press: 77.9 ± 19.0 kg; one-repetition maximum half squat: 116.6 ± 22.5 kg) participated in this study. After an initial one-repetition maximum testing session, participants performed five repetitions for each load (40%, 60% and 80% one-repetition maximum) and exercise (bench press and half squat) on a Smith machine in the second testing session. A third testing session was used for the test–retest reliability study. Time, displacement and mean propulsive velocity were simultaneously determined by the reference method (T-Force system) and the Velowin system. In bench press, ordinary least products regression analysis revealed low fixed biases for mean propulsive velocity at 40%, time at 60% and displacement at 80% one-repetition maximum (intercept = 0.065 m s−1, −28.02 ms and 0.87 cm, respectively). In half squat, low fixed biases were also detected for mean propulsive velocity at 40% and 80% one-repetition maximum (intercept = −0.040 and 0.023 m s−1, respectively), time at 40% and 60% one-repetition maximum (intercept = −53.05 and −101.85 ms, respectively) and displacement at 60% one-repetition maximum (intercept = −1.95 cm). Proportional bias was only observed for mean propulsive velocity at 80% bench press. In half squat, there was proportional bias for time and mean propulsive velocity at 40% one-repetition maximum, and also for time at 60% one-repetition maximum. The reliability test showed low and comparable fixed and proportional biases between systems across exercises and intensities. Velowin confirmed to be a valid and reliable system to measure movement velocity across a wide range of intensities (40%–80% one-repetition maximum) for two basic strength exercises through a robust statistical approach. Velowin would provide coaches and trainers with a suitable, affordable and easy-to-use equipment capable of measuring movement velocity in various exercises at different load intensities.

Wearable and telemedicine innovations for Olympic events and elite sport

“…To date, most attempts to quantify performance in situ have been restricted to the use of high-speed cameras. Quantitative 2D video analysis is the simplest approach of motion analysis and has a number of practical advantages to sport scientists and coaches 14,15 .…”