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Abstract

This study aimed to analyze the agreement between five bar velocity monitoring devices, currently used in resistance training, to determine the most reliable device based on reproducibility (between-device agreement for a given trial) and repeatability (between-trial variation for each device). Seventeen resistance-trained men performed duplicate trials against seven increasing loads (20-30-40-50-60-70-80 kg) while obtaining mean, mean propulsive and peak velocity outcomes in the bench press, full squat and prone bench pull exercises. Measurements were simultaneously registered by two linear velocity transducers (LVT), two linear position transducers (LPT), two optoelectronic camera-based systems (OEC), two smartphone video-based systems (VBS) and one accelerometer (ACC). A comprehensive set of statistics for assessing reliability was used. Magnitude of errors was reported both in absolute (m s⁻¹) and relative terms (%1RM), and included the smallest detectable change (SDC) and maximum errors (MaxError). LVT was the most reliable and sensitive device (SDC 0.02–0.06 m s⁻¹, MaxError 3.4–7.1% 1RM) and the preferred reference to compare with other technologies. OEC and LPT were the second-best alternatives (SDC 0.06–0.11 m s⁻¹), always considering the particular margins of error for each exercise and velocity outcome. ACC and VBS are not recommended given their substantial errors and uncertainty of the measurements (SDC > 0.13 m s⁻¹).
Reproducibility and Repeatability of Five Different Technologies for Bar
Velocity Measurement in Resistance Training
JAVIER COUREL-IBA
´N
˜EZ,
1
ALEJANDRO MARTI
´NEZ-CAVA,
1
RICARDO MORA
´N-NAVARRO,
1
PABLO ESCRIBANO-PEN
˜AS,
1
JAVIER CHAVARREN-CABRERO,
2
JUAN JOSE
´GONZA
´LEZ-BADILLO,
3
and JESU
´SG. PALLARE
´S
1
1
Human Performance and Sports Science Laboratory, Faculty of Sport Sciences, University of Murcia, C/ Argentina s/n,
Santiago de la Ribera, Murcia, Spain;
2
Department of Physical Education, University of Las Palmas de Gran Canaria, Las
Palmas de Gran Canaria, Spain; and
3
Faculty of Sport, Pablo de Olavide University, Seville, Spain
(Received 19 January 2019; accepted 5 April 2019)
Associate Editor Stefan M. Duma oversaw the review of this article.
AbstractThis study aimed to analyze the agreement
between five bar velocity monitoring devices, currently used
in resistance training, to determine the most reliable device
based on reproducibility (between-device agreement for a
given trial) and repeatability (between-trial variation for each
device). Seventeen resistance-trained men performed dupli-
cate trials against seven increasing loads (20-30-40-50-60-70-
80 kg) while obtaining mean, mean propulsive and peak
velocity outcomes in the bench press, full squat and prone
bench pull exercises. Measurements were simultaneously
registered by two linear velocity transducers (LVT), two
linear position transducers (LPT), two optoelectronic cam-
era-based systems (OEC), two smartphone video-based
systems (VBS) and one accelerometer (ACC). A comprehen-
sive set of statistics for assessing reliability was used.
Magnitude of errors was reported both in absolute (m s
21
)
and relative terms (%1RM), and included the smallest
detectable change (SDC) and maximum errors (MaxError).
LVT was the most reliable and sensitive device (SDC 0.02–
0.06 m s
21
, MaxError 3.4–7.1% 1RM) and the preferred
reference to compare with other technologies. OEC and LPT
were the second-best alternatives (SDC 0.06–0.11 m s
21
),
always considering the particular margins of error for each
exercise and velocity outcome. ACC and VBS are not
recommended given their substantial errors and uncertainty
of the measurements (SDC >0.13 m s
21
).
KeywordsStandard error of measurement, Velocity-based
resistance training, Exercise testing, Monitoring, Strength
performance, Validity.
INTRODUCTION
Considerable research attention has been paid to
monitoring movement velocity during resistance
training in recent years.
14,15,26,30
Velocity-based resis-
tance training (VBRT) has been proposed as an
effective method to better characterize the resistance
training stimulus and, specifically, to more precisely
gauge the actual effort or intensity at which athletes
train. VBRT requires the use of particular technologies
to monitor bar velocity during training, and it has
multiple practical applications.
15,25,28,3033
VBRT has
been found to be a robust, non-invasive and highly
sensitive method to estimate key performance indica-
tors, such as the relative loading intensity, maximum
strength (one-repetition maximum, 1RM) and the level
of effort and neuromuscular fatigue incurred during a
training set.
15,22,25,28,31,32
These practical applications
are however dependent on the actual degree of relia-
bility exhibited by the different existing technologies
and particular devices currently used for measuring bar
velocity. It has been shown that small changes in the
velocity developed against some reference workloads
are accompanied by critical improvements in the neu-
romuscular and functional performance of well-trained
athletes. For instance, an increment in mean concentric
velocity of just 0.07 to 0.10 m s
21
is associated with
improvements of ~5% 1RM strength in main resis-
tance exercises such as the bench press (BP), full back
squat (SQ) and prone bench pull (PBP).
15,22,31,32
Thus,
in order to successfully implement a VBRT interven-
tion, it is imperative to use sufficiently accurate and
reliable technologies for measuring bar velocity.
16
Address correspondence to Jesu´ s G. Pallare
´s, Human Perfor-
mance and Sports Science Laboratory, Faculty of Sport Sciences,
University of Murcia, C/ Argentina s/n, Santiago de la Ribera,
Murcia, Spain. Electronic mail: jgpallares@um.es
Annals of Biomedical Engineering (2019)
https://doi.org/10.1007/s10439-019-02265-6
BIOMEDICAL
ENGINEERING
SOCIETY
2019 Biomedical Engineering Society
... Alternatively, Marcos-Pardo et al. 14 used the Chronojump System (Boscosystem, Spain), which is a linear position transducer (LPT) that transfers the data through an interface to a computer and calculates the velocity through the numerical differentiation of time-displacement data. Although the T-Force and Chronojump systems seem valid and reliable for measuring lifting velocity during resistance exercises in strength-trained young adults 5,11,[20][21][22][23] , it remains unknown whether these devices present the same validity, agreement, and reliability levels when used by the older population in resistance machines, like the leg press and chest press. In this regard, the different characteristics of the two velocity measurement devices can lead to different velocity outputs and random errors since LVT enables a direct velocity measurement 23,24 , and LPT indirectly estimates velocity through the differentiation of the displacement data concerning time data 25,26 . ...
... Evaluating the reliability of a device or test allows researchers to understand the variations in the results 27 . The intra-device analysis enables the comparison of velocity outcome measures from the same device under identical intervention conditions made by the same participant 11,20 . Conversely, the inter-device analysis enables the comparison of velocity outcome measures from a given participant when simultaneously using two or more devices 26 . ...
... Previous studies with strength-trained young adults have already shown the absolute reliability of mean velocity in both systems in the bench press (CV values of 4.3% in the T-Force and 4.5% in the Chronojump) 23 , as well as in the bench press and squat (CV values of 1.9% in the bench press and 2.5% in the squat when using the T-Force and 4.3% in the bench press and 3.9% in the squat when using the Chronojump) 20 . Although the CV values of our study were considered with acceptable absolute reliability (< 10%), they were slightly higher than the results of the previous studies. ...
Article
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The current study aimed to analyze the validity and reliability of the T-Force and Chronojump systems to measure the movement velocity in the leg press (LP) and chest press (CP) exercises in older people. Eighteen older adults (6 men and 12 women, 79.9 ± 8.5 years) performed a set of procedures over three weeks: (i) the first week was to familiarize participants with the testing procedures, (ii) the second was to perform a progressive loading test until reaching one-repetition maximum (1RM) in the LP and CP, and (iii) in the third week, participants performed three repetitions against five loads (40, 50, 60, 70, and 80% of 1RM). The mean velocity of each repetition was recorded simultaneously through the T-Force and Chronojump devices. Linear regressions (coefficient of determination [r²] and standard error of the estimate [SEE]) analyzed the inter-device validity, and Bland-Altman plots illustrated the systematic differences between devices. A mixed-effects model estimated the mean velocity differences between devices. The relative reliability was analyzed by the intra-class correlation coefficient (ICC[1,k]), while the absolute reliability was by the standard error of measurement (SEM) and the coefficient of variation (CV). The results showed that the T-Force and Chronojump presented a high association level in measuring mean velocity in the LP and CP (r² range: 0.96–0.99; SEE range: 0.01–0.02 m·s− 1) and low systematic bias (0.02–0.03 m·s− 1). The mean velocity values of T-Force were significantly higher than Chronojump only for 40% 1RM (p = 0.04). Excellent reliability inter-device (ICC range: 0.95–0.98; CV range: 1.7–3.2%) and intra-device (ICC range: 0.90–0.97; CV range: 3.4–6.5%) was observed. This study shows that the T-Force and Chronojump systems are valid and reliable for measuring movement velocity in the CP and LP machines when used by older adults.
... Several studies have analyzed and compared the reliability and validity of different velocity measuring devices. Although a myriad of wearable sensors has been developed and commercialized for providing velocity feedback during RT, controversy still remains regarding the reliability and validity of these devices [14][15][16][17][18][19]. For this reason, the most common devices used for measuring movement velocity are the LPT (derives velocity from the recorded displacement-time data using the inverse dynamic approach) and LVT (directly provides velocity measurements through the recording of electrical signals that are proportional to the cable's extension velocity) [3,20]. ...
... For this reason, the most common devices used for measuring movement velocity are the LPT (derives velocity from the recorded displacement-time data using the inverse dynamic approach) and LVT (directly provides velocity measurements through the recording of electrical signals that are proportional to the cable's extension velocity) [3,20]. In general, these instruments have shown high intra-device agreement and reliability and low magnitude of error [14,17,18,21,22]. However, LPT and LVT are considered expensive (>USD 1500) and may not be practical outside of laboratory settings because they need to be connected to a PC. ...
... However, LPT and LVT are considered expensive (>USD 1500) and may not be practical outside of laboratory settings because they need to be connected to a PC. Fortunately, the implementation of wireless technology, Bluetooth and Wi-Fi, and the reduction in material costs has increased their portability, simplicity, and accessibility, although the available data regarding the reliability and validity of this type of devices are scarce [14,17,18,23]. In this line, Vitruve (Vitruve, Madrid, Spain) is a relatively new LPT with a considerably lower price (USD 490) that allows data transmission (100 Hz) via Bluetooth and can be viewed in real time through a specific app available for Android or iOS. ...
Article
Full-text available
This study aimed to analyze the intra-device agreement of a new linear position transducer (Vitruve, VT) and the inter-device agreement with a previously validated linear velocity transducer (T-Force System, TF) in different range of velocities. A group of 50 healthy, physically active men performed a progressive loading test during a bench press (BP) and full-squat (SQ) exercise with a simultaneous recording of two VT and one TF devices. The mean propulsive velocity (MPV) and peak of velocity (PV) were recorded for subsequent analysis. A set of statistics was used to determine the degree of agreement (Intraclass correlation coefficient [ICC], Lin’s concordance correlation coefficient [CCC], mean square deviation [MSD], and variance of the difference between measurements [VMD]) and the error magnitude (standard error of measurement [SEM], smallest detectable change [SDC], and maximum errors [ME]) between devices. The established velocity ranges were as follows: >1.20 m·s−1; 1.20–0.95 m·s−1; 0.95–0.70 m·s−1; 0.70–0.45 m·s−1; ≤0.45 m·s−1 for BP; and >1.50 m·s−1; 1.50–1.25 m·s−1; 1.25–1.00 m·s−1; 1.00–0.75 m·s−1; and ≤0.75 m·s−1 for SQ. For the MPV, the VT system showed high intra- and inter-device agreement and moderate error magnitude with pooled data in both exercises. However, the level of agreement decreased (ICC: 0.790–0.996; CCC: 0.663–0.992) and the error increased (ME: 2.8–13.4% 1RM; SEM: 0.035–0.01 m·s−1) as the velocity range increased. For the PV, the magnitude of error was very high in both exercises. In conclusion, our results suggest that the VT system should only be used at MPVs below 0.45 m·s−1 for BP and 0.75 m·s−1 for SQ in order to obtain an accurate and reliable measurement, preferably using the MPV variable instead of the PV. Therefore, it appears that the VT system may not be appropriate for objectively monitoring resistance training and assessing strength performance along the entire spectrum of load-velocity curve.
... For example, an increase in mean concentric velocity of 0.07-0.10 m/s is associated with ã 5% increase in 1RM strength in the full back squat (Courel-Ibáñez et al., 2019;González-Badillo & Sánchez-Medina, 2010;Sánchez-Medina et al., 2017). Therefore, the primary aim of this study is to quantify the validity of outcome measures obtained from the Metric VBT mobile application (repetition-detection, barbell RoM, mean barbell velocity) designed to monitor VBT in gym-based settings. ...
... Considering that a change of 0.07-0.10 m/s in mean concentric velocity represents an approximate 5% change in 1RM strength for back squats (Courel-Ibáñez et al., 2019;González-Badillo & Sánchez-Medina, 2010;Sánchez-Medina et al., 2017), this variability suggests that for the same exercise intensity, the device may identify the relative effort inconsistently by ±25%. These errors in measuring exercise intensity compromise the effectiveness of VBT, which relies on the assumption that lift velocity is consistently predictable for given percentages of an individual's 1RM (González-Badillo & Sánchez-Medina, 2010). ...
Article
Full-text available
Background Velocity-based training (VBT) is commonly used for programming and autoregulation of resistance training. Velocity may also be measured during resistance training to estimate one repetition maximum and monitor fatigue. This study quantifies the validity of Metric VBT, a mobile application that uses camera-vision for measuring barbell range of motion (RoM) and mean velocity during resistance exercises. Methods Twenty-four participants completed back squat and bench press repetitions across various loads. Five mobile devices were placed at varying angles (0, ±10, and ±20°) perpendicular to the participant. The validity of Metric VBT was assessed in comparison to Vicon motion analysis using precision and recall, Lin’s concordance correlation coefficient, and Bland-Altman plots. Proportional bias was assessed using linear regression. Results Metric VBT accurately detected over 95% of repetitions. It showed moderate to substantial agreement with the Vicon system for measuring RoM in both exercises. The average Limits of Agreement (LoA) for RoM across all camera positions were −5.45 to 4.94 cm for squats and −5.80 to 3.55 cm for bench presses. Metric VBT exhibited poor to moderate agreement with the Vicon system for measuring mean velocity. The average LoA for mean velocity were 0.03 to 0.25 m/s for squats and −5.80 to 3.55 m/s for bench presses. A proportional bias was observed, with bias increasing as repetition velocity increased. Conclusions Metric VBT’s wide LoA for measuring RoM and mean velocity highlights significant accuracy concerns, exceeding acceptable levels for practical use. However, for users prioritizing repetition counts over precise RoM or mean velocity data, the application can still provide useful information for monitoring workout volume.
... Lifting velocity was measured with a linear velocity transducer (T-Force System Ergotech). 18 Warm-up consisted of 2 sets of 6 BP repetitions with 0.2, and 20 kg, respectively. To analyze the maximal unloaded velocity (V 0 ), the first set consisted of 3 repetitions with a rigid plastic bar (bar weight <0.2 kg, under free-weight conditions). ...
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Purpose: To investigate the effects of 3 training volumes in the bench-press exercise performed with interrepetition rest periods, matched for fatigue, on strength gains and neuromuscular adaptations. Methods: Forty-three resistance-trained men were randomized into 3 groups: low (LOW), moderate (MOD), and high (HIG) volume. The intensities increased from 70% to 85% of 1-repetition maximum (1RM) over the 8-week training period. Each session consisted of only 1 set with short interrepetition rest periods. LOW performed only 3 repetitions per session (8-wk total: 48 repetitions); MOD completed 15, 12, 10, and 8 repetitions per session with 70%, 75%, 80%, and 85% 1RM, respectively (8-wk total: 180); and HIG performed 24, 21, 18, and 15 repetitions per session with 70%, 75%, 80%, and 85% 1RM, respectively (8-wk total: 312). Progressive loading and fatigue tests were conducted in the bench-press exercise before and after the training period. Electromyography (EMG) signals from the triceps brachii were registered during these tests. Results: HIG and MOD showed higher velocity loss than LOW (16% vs 12%). No significant group × time interaction was observed for any variable. All groups improved significantly in all strength-related variables, except for maximal unloaded velocity, where only MOD obtained significant gains. Only LOW and MOD induced significant improvements in EMG. MOD obtained the greatest effect sizes in almost all strength variables. Conclusions: No significant differences were found in the performance gains obtained by each group despite the wide differences in the total volume accumulated by each group.
... We used a range of 0.03 m·s −1 to consider that the absolute load matched the target velocity under study because this value is the smallest detectable change for MPV in BP when using the setting of this study. 26 Each MNR test had a specific warm-up as follows: (1) MNR test with 40% 1RM: 6 and 4 repetitions with 20% and 30% 1RM, respectively; (2) MNR test with 60% 1RM: 6, 4, and 3 repetitions with 30%, 40%, and 50% 1RM, respectively; and (3) MNR test with 80% 1RM: 6, 4, 3, and 2 repetitions with 40%, 50%, 60%, and 70% 1RM, respectively. A 2-minute rest between the warm-up sets was used. ...
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Purpose : This study analyzed the influence of 2 velocity-based training-load prescription strategies (general vs individual load–velocity equations) on the relationship between the magnitude of velocity loss (VL) and the percentage of repetitions completed in the bench-press exercise. Methods : Thirty-five subjects completed 6 sessions consisting of performing the maximum number of repetitions to failure against their 40%, 60%, and 80% of 1-repetition maximum (1RM) in the Smith machine bench-press exercise using generalized and individualized equations to adjust the training load. Results : A close relationship and acceptable error were observed between percentage of repetitions completed and the percentage of VL reached for the 3 loading magnitudes and the 2 load-prescription strategies studied ( R 2 from .83 to .94; standard error of the estimate from 7% to 10%). A simple main effect was observed for load and VL thresholds but not for load-prescription strategies. No significant interaction effects were revealed. The 40% and 60% 1RM showed equivalence on data sets and the most regular variation, whereas the 80% 1-repetition maximum load showed no equivalence and more irregular variation. Conclusion : These results suggest that VL is a useful variable to predict percentage of repetitions completed in the bench-press exercise, regardless of the strategy selected to adjust the relative load. However, caution should be taken when using heavy loads.
... These findings point to a need for VBT devices with high degrees of sensitivity. Recent efforts have employed more robust statistical methods to assess VBT device suitability by reporting standard error of the measurement (SEM) and smallest detectable change (SDC) in addition to interpreting Bland-Altman plots and correlation-based agreement measures (9). The SEM quantifies how scores on an assessment tend to deviate from the true score due to inherent error in the measurement technique and is, therefore, also an estimate of precision and reliability. ...
... The absolute loads (in kg) were individually adjusted to ensure the corresponding MPV matched ( ± 0.03 m · s -1 ) the prescribed %1RM for each session. We used a range of 0.03 m · s -1 since it has been shown that this value is the smallest detectable change in MPV when using the T-Force System in the BP exercise on a Smith machine [26]. Then, the corresponding protocol was carried out. ...
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