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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
... Traditional interpretations of correlations and linear relationship coe cients (i.e., values > 0.90 as very high) previously failed to con rm devices' reliability 19,20 . Similarly, MV and PV between pairs of the same device in the present study all showed high r and ICC values (i.e., ~ 0.98). ...
... Since velocity monitoring devices, among other purposes, are used to leverage the utility of the load-velocity relationship it is crucial to evaluate their magnitudes of error in both absolute (i.e., m/s) and relative, practical terms (i.e., %1RM), as done in the present study. Furthermore, for the assessment of technological variability stricter criteria than previously used should be adopted, as recently recommended by Courel et al. 19 For instance, if one considers CV values of < 10% and ICC values > 0.90 to represent good reliability of a given device, then one also must accept the remaining 10% error in the measurement. While these criteria could be seen as more than rigorous in social sciences, it is not enough for the assessment of technological devices. ...
... While these criteria could be seen as more than rigorous in social sciences, it is not enough for the assessment of technological devices. In this regard, Courel et al. 19 suggested ICC > 0.99, CV < 3.5%, RSE < 0.03 m/s for velocity monitoring devices to be considered reliable and possess acceptable sensitivity. Following these recommendations, only MV and PV from GymAware and MV from Vmaxpro can be used for RT monitoring and prescription, as previously concluded based on other statistical parameters provided in the present study. ...
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... The reliability of observations with My Jump 2 under different conditions was assessed through a set of statistics testing the level of agreement and the magnitude of errors [23]. With regards to the agreement, correlation analysis includes Pearson's (r), intraclass (ICC), and concordance (CCC) correlation coefficients. ...
... good 0.95-0.99, and very good >0.99 [26], similarly to reliability studies of other sports science studies [23,41]. For this reason, comparisons with published studies are focused on ICC value, rather than the associated qualitative assessment. ...
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... All sessions were performed on a Smith machine (Multipower, Technogym), and repetitions were measured and recorded using a linear velocity transducer (T-Force Dynamic Measurement System; Ergotech Consulting Ltd., Murcia, Spain). A complete analysis of this device's reliability is reported elsewhere [19,20]. The velocity measures reported in this study corresponded to the mean velocity of the propulsive phase (i.e., MPV), defined as the portion of the concentric action during which the measured acceleration is greater than acceleration due to gravity (−9.81 m·s −1 ) [20]. ...
... Consequently, before starting the first set in each testing session, adjustments in the proposed load (kg) were individually made to match the scheduled target MPV (±0.03 m·s −1 ) associated with the %1RM that was set for the specific session. A range of 0.03 m·s −1 was used since it has recently been shown that the smallest detectable change in MPV when using the T-Force System is 0.03 m·s −1 [19]. Once the load (kg) was adjusted, it was maintained for the three sets. ...
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... Both tests were performed on a Smith machine (Multipower Fitness Line, Peroga, Murcia, Spain) coupled with a reliable linear velocity transducer (T-Force System, Ergotech, Murcia, Spain) [22]. Two spotters were positioned on each side of the barbell in both exercises to guarantee safety. ...
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... 28 Muscular strength measurements included a handgrip (HG) test using a calibrated digital dynamometer (Takei 5401-C, Shinagawa-Ku, Tokyo), the 5-time sit-to-stand test, 29 a 3-second isometric knee extension test at 110° of knee flexion angle using a force sensor (Chronojump, BoscoSystem, Barcelona) recording in Newtons (N), 30 and a progressive submaximal loading test using a Smith machine for the bench press (BP) and half squat (HSQ) exercises, using a linear velocity transducer (T-Force, Ergotech Consulting, Murcia, Spain). 31 The progressive loading tests were performed from a starting load of 5 kg, increasing to reach a target mean propulsive velocity corresponding to ~50% of the 1-repetition maximum effort (1RM): 0.89-0.93 m s −1 for the BP 32 and 0.66-0.70 ...
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... Regarding the devices used, the linear position transducer (T-Force System, Ergotech, Spain) reports an ICC of 0.99 (Courel-Ibáñez et al., 2019) to measure the velocity of the bar during muscle strength exercises. Moreover, the linear encoder (MuscleLab Power model MLPRO, Ergotest Technology, Langesund, Norway) presents an association of r = 0.646 with muscle power measured through the Nottingham Power Rig (Lindemann et al., 2015). ...
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... The propulsive phase was defined as the portion of the concentric phase during which barbell acceleration is greater than the acceleration due to gravity (Sanchez-Medina et al. 2010). Repeatability of the device and analysis methods have been reported elsewhere (Courel-Ibáñez et al. 2019). The highest MPV from one of the three trials was taken forward to further analyses. ...
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... Muscular strength measures included a handgrip test using a calibrated digital dynamometer (Takei 5401-C, Shinagawa-Ku, Tokyo), the 5-time sit-to-stand test, a 3 s isometric knee extension test at 110° of knee flexion angle using a force sensor (Chronojump, BoscoSystem, Barcelona) recording in Newtons (N) [36], and a progressive submaximal loading test in Smith machine for the bench press (BP) and half squat (HSQ) exercises using a linear velocity transducer (T-Force, Ergotech Consulting, Murcia, Spain) [37]. The progressive loading tests were performed from a starting load of 5 kg and increasing up to reaching a target mean propulsive velocity corresponding to ~ 50% of the 1-repetition maximum effort (1RM). ...
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... The MPV (bar velocity during the propulsion phase, defined as the portion of the concentric phase in which the bar acceleration is ≥ −9.81 m.s −2 (Sanchez-Medina et al., 2010)) was measured using a linear position transducer (Chronojump Boscosystem®, Barcelona, Spain), with a frequency of 1.000 Hz connected to one end of the Olympic bar. Previous studies found that this technology is highly reliable for measuring bar velocity(Courel-Ibáñez et al., 2019;Pérez-Castilla et al., 2019). ...
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