Concurrent validity of barbell force measured from video-based barbell kinematics during the snatch in male elite weightlifters.

Ingo Sandau,Urs Granacher,Helmi Chaabene,Emiliano Cè

doi:10.1371/journal.pone.0254705

Ingo Sandau, Urs Granacher + Show 2 more

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https://doi.org/10.1371/journal.pone.0254705

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Abstract

This study examined the concurrent validity of an inverse dynamic (force computed from barbell acceleration [reference method]) and a work-energy (force computed from work at the barbell [alternative method]) approach to measure the mean vertical barbell force during the snatch using kinematic data from video analysis. For this purpose, the acceleration phase of the snatch was analyzed in thirty male medal winners of the 2018 weightlifting World Championships (age: 25.2±3.1 years; body mass: 88.9±28.6 kg). Vertical barbell kinematics were measured using a custom-made 2D real-time video analysis software. Agreement between the two computational approaches was assessed using Bland-Altman analysis, Deming regression, and Pearson product-moment correlation. Further, principal component analysis in conjunction with multiple linear regression was used to assess whether individual differences related to the two approaches are due to the waveforms of the acceleration time-series data. Results indicated no mean difference (p > 0.05; d = −0.04) and an extremely large correlation (r = 0.99) between the two approaches. Despite the high agreement, the total error of individual differences was 8.2% (163.0 N). The individual differences can be explained by a multiple linear regression model (R2adj = 0.86) on principal component scores from the principal component analysis of vertical barbell acceleration time-series waveforms. Findings from this study indicate that the individual errors of force measures can be associated with the inverse dynamic approach. This approach uses vertical barbell acceleration data from video analysis that is prone to error. Therefore, it is recommended to use the work-energy approach to compute mean vertical barbell force as this approach did not rely on vertical barbell acceleration.

Highlights

Measuring force during resistance training exercises is important to assess and monitor training-induced responses of the neuromuscular system using for instance the force-velocity relationship [1, 2]
Smith and Sands [9] analyzed the associations between vertical barbell acceleration during the performance of the high-pull exercise using video analysis and accelerometer data
As the acceleration-based error associated with force using an inverse dynamic approach (F id) is more prevalent during large and rapid changes of acceleration [10], we were interested in elucidating whether individual differences related to the two approaches are due to the waveforms of the acceleration time-series data

Summary

Introduction

Measuring force during resistance training exercises is important to assess and monitor training-induced responses of the neuromuscular system using for instance the force-velocity relationship [1, 2]. Barbell force measurement during the snatch squat jump, bench press throw, and bench press, the force that can be transferred from the lifter to the barbell is of major interest [3,4,5,6]. As it is difficult under real life conditions to directly measure force at the barbell (e.g., force transducer), barbell force has been determined indirectly using an inverse dynamic approach [4,5,6]. A different methodological approach should be adopted to assess the barbell force using video analysis

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