Video-Based System for Automatic Measurement of Barbell Velocity in Back Squat.

Basilio Pueo,Adrian Colomer,Jose J Lopez,Jose M Mossi,Jose M Jimenez-Olmedo

doi:10.3390/s21030925

Basilio Pueo, Adrian Colomer + Show 3 more

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https://doi.org/10.3390/s21030925

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Abstract

Velocity-based training is a contemporary method used by sports coaches to prescribe the optimal loading based on the velocity of movement of a load lifted. The most employed and accurate instruments to monitor velocity are linear position transducers. Alternatively, smartphone apps compute mean velocity after each execution by manual on-screen digitizing, introducing human error. In this paper, a video-based instrument delivering unattended, real-time measures of barbell velocity with a smartphone high-speed camera has been developed. A custom image-processing algorithm allows for the detection of reference points of a multipower machine to autocalibrate and automatically track barbell markers to give real-time kinematic-derived parameters. Validity and reliability were studied by comparing the simultaneous measurement of 160 repetitions of back squat lifts executed by 20 athletes with the proposed instrument and a validated linear position transducer, used as a criterion. The video system produced practically identical range, velocity, force, and power outcomes to the criterion with low and proportional systematic bias and random errors. Our results suggest that the developed video system is a valid, reliable, and trustworthy instrument for measuring velocity and derived variables accurately with practical implications for use by coaches and practitioners.

Highlights

Data collection is of paramount importance for sports scientists, coaches, athletes, and practitioners to objectively assess performance improvements
The instantaneous position tracked by the video system and the linear position transducers (LPTs) system, together with derived instantaneous velocity for the four 1RM percentages, are shown in Figure 6 for one repetition
For low percentages (75% RM), meaning low additional weights, velocity reaches its maximum value across all 1RM percentages (1.42 m/s) for both systems

Summary

Introduction

Data collection is of paramount importance for sports scientists, coaches, athletes, and practitioners to objectively assess performance improvements. One of the most important physical performance metrics is the force exerted by an athlete during physical exercise, as adequate muscular strength is a basic capacity required to perform general sports skills and avoid injuries [3]. The inverse relationship between force and velocity, such as the physical capacity to perform movements in the shortest time possible, has led to an optimized training method known as velocitybased training (VBT) [4,5,6]. Contrary to classical strength training in which the weights are pre-selected, based on the percentage value of maximum capacity, in VBT, the weights are dictated by the velocity that the athlete is attempting to train. The velocity of movement must be monitored in real time to adjust the weight appropriately [7]

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