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

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.

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Validity and Reliability of an Inertial Sensor for Wheelchair Court Sports Performance

Journal of Applied Biomechanics ◽

10.1123/jab.2013-0148 ◽

2014 ◽

Vol 30 (2) ◽

pp. 326-331 ◽

Cited By ~ 10

Author(s):

Barry S. Mason ◽

James M. Rhodes ◽

Victoria L. Goosey-Tolfrey

Keyword(s):

High Speed ◽

Inertial Sensor ◽

Systematic Bias ◽

Sports Performance ◽

Random Errors ◽

Validity And Reliability ◽

Monitoring Tool ◽

Wheelchair Athletes ◽

Reliable Assessment ◽

Coefficients Of Variation

The purpose of the current study was to determine the validity and reliability of an inertial sensor for assessing speed specific to athletes competing in the wheelchair court sports (basketball, rugby, and tennis). A wireless inertial sensor was attached to the axle of a sports wheelchair. Over two separate sessions, the sensor was tested across a range of treadmill speeds reflective of the court sports (1.0 to 6.0 m/s). At each test speed, ten 10-second trials were recorded and were compared with the treadmill (criterion). A further session explored the dynamic validity and reliability of the sensor during a sprinting task on a wheelchair ergometer compared with high-speed video (criterion). During session one, the sensor marginally overestimated speed, whereas during session two these speeds were underestimated slightly. However, systematic bias and absolute random errors never exceeded 0.058 m/s and 0.086 m/s, respectively, across both sessions. The sensor was also shown to be a reliable device with coefficients of variation (% CV) never exceeding 0.9 at any speed. During maximal sprinting, the sensor also provided a valid representation of the peak speeds reached (1.6% CV). Slight random errors in timing led to larger random errors in the detection of deceleration values. The results of this investigation have demonstrated that an inertial sensor developed for sports wheelchair applications provided a valid and reliable assessment of the speeds typically experienced by wheelchair athletes. As such, this device will be a valuable monitoring tool for assessing aspects of linear wheelchair performance.

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Reliability and Validity of the Polar V800 Sports Watch for Estimating Vertical Jump Height

Journal of Sports Science and Medicine ◽

10.52082/jssm.2021.149 ◽

2021 ◽

pp. 149-157

Author(s):

Manuel V. Garnacho-Castaño ◽

Marcos Faundez-Zanuy ◽

Noemí Serra-Payá ◽

José L. Maté-Muñoz ◽

Josep López-Xarbau ◽

...

Keyword(s):

High Speed ◽

Vertical Jump ◽

Reliability And Validity ◽

Force Platform ◽

Systematic Bias ◽

High Speed Camera ◽

Jump Height ◽

Random Errors ◽

Physically Active ◽

Vertical Jump Height

This study aimed to assess the reliability and validity of the Polar V800 to measure vertical jump height. Twenty-two physically active healthy men (age: 22.89 ± 4.23 years; body mass: 70.74 ± 8.04 kg; height: 1.74 ± 0.76 m) were recruited for the study. The reliability was evaluated by comparing measurements acquired by the Polar V800 in two identical testing sessions one week apart. Validity was assessed by comparing measurements simultaneously obtained using a force platform (gold standard), high-speed camera and the Polar V800 during squat jump (SJ) and countermovement jump (CMJ) tests. In the test-retest reliability, high intraclass correlation coefficients (ICCs) were observed (mean: 0.90, SJ and CMJ) in the Polar V800. There was no significant systematic bias ± random errors (p > 0.05) between test-retest. Low coefficients of variation (<5%) were detected in both jumps in the Polar V800. In the validity assessment, similar jump height was detected among devices (p > 0.05). There was almost perfect agreement between the Polar V800 compared to a force platform for the SJ and CMJ tests (Mean ICCs = 0.95; no systematic bias ± random errors in SJ mean: -0.38 ± 2.10 cm, p > 0.05). Mean ICC between the Polar V800 versus high-speed camera was 0.91 for the SJ and CMJ tests, however, a significant systematic bias ± random error (0.97 ± 2.60 cm; p = 0.01) was detected in CMJ test. The Polar V800 offers valid, compared to force platform, and reliable information about vertical jump height performance in physically active healthy young men.

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Audio-Based System for Automatic Measurement of Jump Height in Sports Science

Sensors ◽

10.3390/s19112543 ◽

2019 ◽

Vol 19 (11) ◽

pp. 2543

Author(s):

Basilio Pueo ◽

Jose J. Lopez ◽

Jose M. Jimenez-Olmedo

Keyword(s):

High Speed ◽

Muscle Power ◽

Audio Signal ◽

Automatic Measurement ◽

Flight Time ◽

Systematic Bias ◽

Jump Height ◽

Random Errors ◽

Signal Processing Algorithm ◽

Sports Science

Jump height tests are employed to measure the lower-limb muscle power of athletic and non-athletic populations. The most popular instruments for this purpose are jump mats and, more recently, smartphone apps, which compute jump height through manual annotation of video recordings to extract flight time. This study developed a non-invasive instrument that automatically extracts take-off and landing events from audio recordings of jump executions. An audio signal processing algorithm, specifically developed for this purpose, accurately detects and discriminates the landing and take-off events in real time and computes jump height accordingly. Its temporal resolution theoretically outperforms that of flight-time-based mats (typically 1000 Hz) and high-speed video rates from smartphones (typically 240 fps). A validation study was carried out by comparing 215 jump heights from 43 active athletes, measured simultaneously with the audio-based system and with of a validated, commercial jump mat. The audio-based system produced nearly identical jump heights than the criterion with low and proportional systematic bias and random errors. The developed audio-based system is a trustworthy instrument for accurately measuring jump height that can be readily automated as an app to facilitate its use both in laboratories and in the field.

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The Reliability and Validity of Current Technologies for Measuring Barbell Velocity in the Free-Weight Back Squat and Power Clean

Sports ◽

10.3390/sports8070094 ◽

2020 ◽

Vol 8 (7) ◽

pp. 94

Author(s):

Steve W. Thompson ◽

David Rogerson ◽

Harry F. Dorrell ◽

Alan Ruddock ◽

Andrew Barnes

Keyword(s):

Peak Velocity ◽

Reliability And Validity ◽

Systematic Bias ◽

Mean Velocity ◽

Validity Data ◽

Back Squat ◽

Free Weight ◽

Device Reliability ◽

Measurement Units ◽

Power Clean

This study investigated the inter-day and intra-device reliability, and criterion validity of six devices for measuring barbell velocity in the free-weight back squat and power clean. In total, 10 competitive weightlifters completed an initial one repetition maximum (1RM) assessment followed by three load-velocity profiles (40–100% 1RM) in both exercises on four separate occasions. Mean and peak velocity was measured simultaneously on each device and compared to 3D motion capture for all repetitions. Reliability was assessed via coefficient of variation (CV) and typical error (TE). Least products regression (LPR) (R2) and limits of agreement (LOA) assessed the validity of the devices. The Gymaware was the most reliable for both exercises (CV < 10%; TE < 0.11 m·s−1, except 100% 1RM (mean velocity) and 90‒100% 1RM (peak velocity)), with MyLift and PUSH following a similar trend. Poorer reliability was observed for Beast Sensor and Bar Sensei (CV = 5.1–119.9%; TE = 0.08–0.48 m·s−1). The Gymaware was the most valid device, with small systematic bias and no proportional or fixed bias evident across both exercises (R2 > 0.42–0.99 LOA = −0.03–0.03 m·s−1). Comparable validity data was observed for MyLift in the back squat. Both PUSH devices produced some fixed and proportional bias, with Beast Sensor and Bar Sensei being the least valid devices across both exercises (R2 > 0.00–0.96, LOA = −0.36–0.46 m·s−1). Linear position transducers and smartphone applications could be used to obtain velocity-based data, with inertial measurement units demonstrating poorer reliability and validity.

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The ADR Encoder is a reliable and valid device to measure barbell mean velocity during the Smith machine bench press exercise

Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology ◽

10.1177/17543371211062811 ◽

2021 ◽

pp. 175433712110628

Author(s):

Alejandro Pérez-Castilla ◽

Sergio Miras-Moreno ◽

Agustín J García-Vega ◽

Amador García-Ramos

Keyword(s):

Bench Press ◽

High Reliability ◽

Low Cost ◽

Reliability And Validity ◽

Systematic Bias ◽

Random Errors ◽

Strength And Conditioning ◽

Mean Velocity ◽

Standard Linear ◽

Monitoring Devices

Velocity-based training is a contemporary resistance training method, which uses lifting velocity to prescribe and assess the effects of training. However, the high cost of velocity monitoring devices can limit their use among strength and conditioning professionals. Therefore, this study aimed to examine the reliability and concurrent validity of an affordable linear position transducer (ADR Encoder) for measuring barbell velocity during the Smith machine bench press exercise. Twenty-eight resistance-trained males performed two blocks of six repetitions in a single session. Each block consisted of two repetitions at 40%, 60%, and 80% of their estimated one-repetition maximum. The mean velocity of the lifting phase was simultaneously recorded with the ADR Encoder and a gold-standard linear velocity transducer (T-Force® System). Both devices demonstrated high reliability for measuring mean velocity (ADR Encoder: CVrange = 2.80%–6.40% and ICCrange = 0.78–0.82; T-Force® System: CVrange = 3.27%–6.62% and ICCrange = 0.77–0.81). The ADR Encoder provided mean velocity at 40%1RM with a higher reliability than the T-Force® System (CVratio = 1.17), but the reliability did not differ between devices at higher loads (60%1RM–80%1RM) (CVratio ≤ 1.08). No fixed or proportional bias was observed for the different loads using least-products regression analysis, while the Bland–Altman plots revealed low systematic bias (0.01 m·s−1) and random errors (0.03 m·s−1). However, heteroscedasticity of the errors was observed between both devices ( R2 = 0.103). The high reliability and validity place the ADR Encoder as a low-cost device for accurately measuring mean velocity during the Smith machine bench press exercise.

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A Novel Approach to 1RM Prediction Using the Load-Velocity Profile: A Comparison of Models

Sports ◽

10.3390/sports9070088 ◽

2021 ◽

Vol 9 (7) ◽

pp. 88

Author(s):

Steve W. Thompson ◽

David Rogerson ◽

Alan Ruddock ◽

Leon Greig ◽

Harry F. Dorrell ◽

...

Keyword(s):

Velocity Profile ◽

Linear Models ◽

Pearson Correlation ◽

Correlation Coefficients ◽

Systematic Bias ◽

Combined Method ◽

Linear Modeling ◽

Mean Velocity ◽

Back Squat ◽

Novel Approach

The study aim was to compare different predictive models in one repetition maximum (1RM) estimation from load-velocity profile (LVP) data. Fourteen strength-trained men underwent initial 1RMs in the free-weight back squat, followed by two LVPs, over three sessions. Profiles were constructed via a combined method (jump squat (0 load, 30–60% 1RM) + back squat (70–100% 1RM)) or back squat only (0 load, 30–100% 1RM) in 10% increments. Quadratic and linear regression modeling was applied to the data to estimate 80% 1RM (kg) using 80% 1RM mean velocity identified in LVP one as the reference point, with load (kg), then extrapolated to predict 1RM. The 1RM prediction was based on LVP two data and analyzed via analysis of variance, effect size (g/ηp2), Pearson correlation coefficients (r), paired t-tests, standard error of the estimate (SEE), and limits of agreement (LOA). p < 0.05. All models reported systematic bias < 10 kg, r > 0.97, and SEE < 5 kg, however, all linear models were significantly different from measured 1RM (p = 0.015 <0.001). Significant differences were observed between quadratic and linear models for combined (p < 0.001; ηp2 = 0.90) and back squat (p = 0.004, ηp2 = 0.35) methods. Significant differences were observed between exercises when applying linear modeling (p < 0.001, ηp2 = 0.67–0.80), but not quadratic (p = 0.632–0.929, ηp2 = 0.001–0.18). Quadratic modeling employing the combined method rendered the greatest predictive validity. Practitioners should therefore utilize this method when looking to predict daily 1RMs as a means of load autoregulation.

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Comparison of the two most commonly used gold-standard velocity monitoring devices (GymAware and T-Force) to assess lifting velocity during the free-weight barbell back squat exercise

Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology ◽

10.1177/17543371211029614 ◽

2021 ◽

pp. 175433712110296

Author(s):

Danica Janicijevic ◽

Amador García-Ramos ◽

Juan Luis Lamas-Cepero ◽

Felipe García-Pinillos ◽

Aitor Marcos-Blanco ◽

...

Keyword(s):

Systematic Bias ◽

Maximal Velocity ◽

Force Coefficient ◽

Mean Velocity ◽

Back Squat ◽

Free Weight ◽

Squat Exercise ◽

The Right ◽

Monitoring Devices ◽

Overall Reliability

This study aimed to compare the reliability and agreement of mean velocity (MV) and maximal velocity (Vmax) between the two velocity monitoring devices (GymAware vs T-Force) most commonly used in the scientific literature. Twenty resistance-trained males completed two testing sessions. The free-weight barbell back squat one-repetition maximum (1RM) was determined in the first session (125.0 ± 24.2 kg; mean ± standard deviation). The second session consisted of two blocks of 16 repetitions (six repetitions at 45% 1RM and 65% 1RM, and four repetitions at 85% 1RM). Half of the repetitions were performed with the GymAware on the left side of the barbell and the other half of the repetitions were performed on the right side of the barbell (opposite placement for the T-Force). MV and Vmax were recorded simultaneously with the GymAware and T-Force. The overall reliability, which was calculated pooling together the data of three loads, did not differ between the T-Force (coefficient of variation (CV) = 5.28 ± 1.79%) and GymAware (CV = 5.79 ± 2.26%) (CVratio = 1.10), but the reliability was higher for Vmax (CV = 5.08 ± 1.79%) compared to MV (CV = 5.98 ± 2.73%) (CVratio = 1.18). MV was significantly higher for the T-Force ( p < 0.001, Δ = 4.42%), but no significant differences were detected between the devices for Vmax ( p = 0.455, Δ = 0.22%). These results support the use of both the GymAware and T-Force as gold-standards in studies designed to validate other velocity monitoring devices. However, systematic bias, albeit rather constant, exists for the magnitude of MV between the two devices.

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