Using the Load-Velocity Profile for Predicting the 1RM of the Hexagonal Barbell Deadlift Exercise

Abstract

The aim of this study was to determine if bar velocity can be used to estimate the one-repetition maximum (1RM) on the hexagonal bar deadlift. Twenty-two NCAA Division I male ice hockey players (age= 21.0 ± 1.5 yrs, height= 182.9 ± 7.3 cm, body mass= 86.2 ± 7.3 kg) completed a progressive loading test using the hexagonal bar deadlift at maximum intended velocity to determine their 1RM. Mean concentric velocity (MV) was measured for each load via a linear position transducer. The a-priori alpha level of significance was set at p = 0.05. MV showed a very strong relationship to %1RM (R2 = 0.85). A non-significant difference and a trivial effect size (ES) were observed between actual and predicted 1RM (p = 0.90, ES = -0.08). Near-perfect correlations were also discovered between actual and predicted 1RM (R = 0.93) with low typical error and coefficient of variation (5.11 kg, 2.53%, respectively). The current study presented results that add the HBD to the list of exercises with established load-velocity relationships. The predictive ability for 1RM HBD indicates that this is a viable means of prediction of 1RM.

Full text

Research Notes
Using the Load-Velocity Profile for Predicting the
1RM of the Hexagonal Barbell Deadlift Exercise
Marcel Lopes dos Santos,
1
J. Bryan Mann,
2
Ricardo Berton,
3
Brent A. Alvar,
4
Robert G. Lockie,
5
and
J. Jay Dawes
1
1
School of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, Oklahoma;
2
Kinesiology and Sports
Science Department, University of Miami, Coral Gables, Florida;
3
School of Physical Education and Sport, University of Sa
˜o Paulo, Sa
˜o
Paulo, Brazil;
4
Department of Kinesiology, Point Loma Nazarene University, San Diego, California; and
5
Department of Kinesiology,
Center for Sports Performance, California State University, Fullerton, Fullerton, California
Abstract
Lopes dos Santos, M, Mann, JB, Berton, R, Alvar, B, Lockie, RG, and Dawes, JJ. Using the load-velocity profile for predicting the
1RM of the hexagonal barbell deadlift exercise. J Strength Cond Res 37(1): 220–223, 2023—The aim of this study was to determine
whether bar velocity can be used to estimate the 1 repetition maximum (1RM) on the hexagonal bar deadlift (HBD). Twenty-two
National Collegiate Athletic Association Division I male ice hockey players (age 521.0 61.5 years, height 5182.9 67.3 cm, and
body mass 586.2 67.3 kg) completed a progressive loading test using the HBD at maximum intended velocity to determine their
1RM. The mean concentric velocity was measured for each load through a linear position transducer. The a priori alpha level of
significance was set at p50.05. The mean concentric velocity showed a very strong relationship to %1RM (R
2
50.85). A
nonsignificant difference and a trivial effect size (ES) were observed between the actual and predicted 1RM (p50.90, ES 520.08).
Near-perfect correlations were also discovered between the actual and predicted 1RM (R50.93) with low typical error and
coefficient of variation (5.11 kg and 2.53%, respectively). This study presented results that add the HBD to the list of exercises with
established load-velocity relationships. The predictive ability for 1RM HBD indicates that this is a viable means of prediction of 1RM.
Key Words: bar velocity, 1 repetition maximum, exercise testing, strength training
Introduction
Traditionally, at thebeginning of a training program, a percentage
of an individual’s 1 repetition maximum (1RM) isused to establish
the training loads to be used for a specific exercise. However, the
use of previously established 1RM values to prescribe exercise in-
tensity may result in individuals using suboptimal training loads as
the training program progresses (8). Furthermore, using previously
established values over time may lead to an accumulation of fatigue
that may contribute toovertraining syndrome and negatively affect
individual results (16). Consequently, prescription of training load
based on barbell velocity has recently gained attention (23). This
method provides immediate feedback, which allows for greater
sensitivity, when assigning daily training intensity.
The hexagonal bar deadlift (HBD) is a variation of the deadlift
that has been shown to put less stress on the lumbar region
(4,5,13,15,22). This is partially because of the fact that when
performing the HBD, there is approximately 75% less horizontal
displacement compared with the straight bar deadlift (SBD) (22).
These differences result in the lifter moving the load over a shorter
distance, which also increases the amount of weight that can be
lifted for a single repetition (15). The HBD not only reduces
biomechanical stress to the lumbar spine but also elicits greater
peak force, velocity, and power outputs when compared with the
SBD at similar loads (4,15,22). For these reasons, the HBD may
be a more advantageous option than the SBD when training
certain populations.
Recently, investigators have focused on assessing the load-
velocity profile during the SBD (2,14,17,19) and reported very
strong relationships (R
2
$0.91, p,0.05) between these vari-
ables. Moreover, the load-velocity profile during the SBD has
shown to be very stable, despite the relative strength level (2,17).
However, the biomechanical stimulus may be altered by the uti-
lization of different variations of the deadlift (22). When com-
pared with the SBD, the HBD elicits significantly greater peak
velocity, peak force, and peak power (22). For these reasons, the
load-velocity profile of the HBD must be determined because the
profile from the SBD may not be directly applicable to this exer-
cise variation. Thus, the purpose of this study was to explore the
load-velocity relationship of the HBD and to determine whether
bar velocity can be used to estimate 1RM HBD. Considering the
very high and consistent load-velocity relationship along a wide
range of loads in the SBD, we hypothesize that a stable load-
velocity profile specific for the HBD can also be established.
Methods
Experimental Approach to the Problem
A cross-sectional design was used to investigate the load-velocity
relationship across a wide range of intensities during the HBD.
Subjects reported to the weight room on a single occasion, in which
the 1RM was assessed. Before the visit, they were instructed to re-
frain from strenuous activity for a minimum of 24 hours that pre-
ceded the testing session. All subjects performed the HBD with a
normal grip on a low-handle hexagonal barbell. They were not
allowedtousechalk,liftingbelts, or lifting straps. After a stan-
dardized general warm-up, subjects performed submaximal
Address correspondence to J.J. Dawes, jay.dawes@okstate.edu.
Journal of Strength and Conditioning Research 37(1)/220–223
ª2022 National Strength and Conditioning Association
220
Copyright © 2022 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.

incremental sets based on relative percentages of their previous
season 1RM values. Incremental sets were set at 65, 75, 80, 90, and
95% of subjects estimated 1RM. After that, subjects attempted to lift
the load that corresponded to their previous 1RM, and increments of
2–5 kg were made until they were unable to complete a single lift.
Subjects were instructed to perform all repetitions at maximum
intended velocity. The fastest repetition at each submaximal set was
considered for the calculations. These data were collected as part of
the team’s normal yearly training program. All testing took place at
the same room and at the same time of the day, under the supervision
of certified strength and conditioning specialists. The study con-
formed to the Declaration of Helsinki and was approved by Okla-
homa State University’s Institutional Review Board for studies
involving human subjects (IRB approval: ED-19-117-STW).
Subjects
Performance testing data for 22 National Collegiate Athletic
Association Division I male ice hockey players (age 521.0 61.5
years, height 5182.9 67.3 cm, and body mass 586.2 67.3 kg)
were analyzed. All subjects had more than 2 years of experience
with resistance training before the study. Institutional review
board approval (IRB #) was obtained before analysis. This re-
search also conformed to the guidelines set forth by the tenets of
the Declaration of Helsinki, and all subjects provided written
informed consent before participation.
Procedures
Subjects completed 1 testing session during the preseason, and all
assessments occurred in the team weight room. Before performing
the 1RM protocol, subjects’age, body mass, and weight were
recorded. Height was recorded using a portable stadiometer
(Seca, Hamburg, Germany), and body mass was recorded using a
digital scale (Tanita Corporation, Tokyo, Japan). The 1RM
protocol was administered in a single session under the supervi-
sion of certified strength and conditioning specialists.
1 Repetition Maximum Protocol for Hexagonal Bar Deadlift.
The proper procedures for the HBD have been previously detailed
(15,22). In summary, with the hexagonal bar resting on the
ground, subjects assumed a position with the knees flexed and the
arms straight, although maintaining a straight back and neutral
spine. They then grasped the low handles of the hexagonal bar
and stood up, although maintaining a straight back until reaching
an erect position with the shoulders retracted.
The initial load for the incremental protocol was based on
1RM values recorded in the previous season. The incremental test
protocol for the 1RM HBD was adapted from similar procedures
reported in the literature (6–8,12,20). Each subject refrained from
strenuous activity for 24 hours before the testing. After a stan-
dardized dynamic warm-up protocol, initial load was set at 65%
and increased to 75, 80, 90, and 95% of estimated 1RM. Three
repetitions were performed for intensities #80% 1RM, 2 for
90% 1RM, and 1 for 95% 1RM. After that, increments of 2–5kg
were made until the subjects were unable to complete a single lift
throughout the entire range of motion with proper form
(i.e., technical failure). The heaviest load lifted by each subject
with proper form was defined as his 1RM. All subjects reached
their 1RM before reaching the NSCA-recommended number of
attempts for 1RM tests (i.e., 5 trials). A rest interval of 3 minutes
after each set was provided.
Bar Velocity Assessment. The mean concentric velocity (MV) in
meters per second (m·s
21
) was collected through a linear position
transducer (GymAware PowerTool, Kinetic Performance Tech-
nology, Mitchell, Australia). The linear position transducer was
placed on the floor directly underneath the bar with the cable
attached on the front of the bar (15). Velocity of the bar was
recorded at 50 Hz. The linear position transducer recorded data
for every repetition for each subject throughout the 1RM test.
From the individualized linear regression equations, the MV at
1RM of each subject was applied to predict the 1RM value. Only
subjects with complete data for each repetition at the corre-
sponding load were considered for analysis.
Statistical Analyses
Statistical analyses were performed using IBM SPSS software version
23 (IBM, New York, NY) and a customized spreadsheet. A Shapiro-
Wilk test was used to verify normal distribution of the sample. Re-
lationships between the load and MV were assessed by fitting second-
order polynomials to the data. It has been reported that there is no
difference in linear functions and second-order polynomial fits (1).
However, some studies have shown that nonlinear functions can
provide better fits than linear functions (9,17,21). Individualized fit-
ting second-order polynomials equation with each load and MV was
also used to predict the %1RM estimate. The individualized MV at
100% 1RM was used to predict the 1RM value. Then, concurrent
validity of the predicted 1RM with reference to the actual 1RM was
examined through Hedge’sgeffect size (ES), Pearson’s correlation
coefficient (R), coefficient of determination (R
2
), typical error (TE),
coefficient of variation (CV) (10), and the associated 95% confidence
intervals (18). For ES, the following thresholds were used: trivial
(0–0.19), small (0.20–0.59), moderate (0.60–1.19), and large
(1.20–1.99) (11). The strength of the Rcoefficient was interpreted as
trivial (,0.1), small (0.1–0.3), moderate (0.3–0.5), strong (0.5–0.7),
very strong (0.7–0.9), or near perfect (.0.9) (11). The Bland-Altman
plot (limits of agreement at 95% and bias) was used to evaluate the
agreement of the 1RM value between the actual 1RM and predicted
1RM (3). Finally, a paired samples t-test was performed between the
actual 1RM and predicted 1RM. The significance level was set at p
#0.05.
Results
The Shapiro-Wilk test revealed that all data were normally distrib-
uted (p.0.05). Figure 1 depicts the results of the second-order
Figure 1. Relationship between the hexagonal bar deadlift
relative load (%1RM) and mean concentric velocity. 1RM 51
repetition maximum.
Predicting 1RM on the Hexagonal Bar Deadlift (2023) 37:1 |www.nsca.com
221
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polynomial regression plotting MV against load (%1RM). A very
strong relationship between MV and load was found, and a pre-
dictive equation was yielded: HBD Relative Load 5(27.17) MV
2
2
(122.9) MV 1133.3 (R
2
50.85, SEE 58.3%). Regarding the 1RM
prediction, the load-velocity relationship underestimated the 1RM
values (absolute difference: 20.18 67.24 kg). However, a non-
significant difference and a trivial ES between the actual and pre-
dicted 1RM was observed (Table 1). Moreover, the actual and
predicted 1RM were near-perfectly correlated (p,0.001) (Table 1).
Finally, concurrent validity analysis, TE, and CV are presented in
Table 1 and the Bland-Altman plot with the limits of agreement at
95% and bias in Figure 2.
Discussion
The current data demonstrated a very strong relationship be-
tween the load and velocity during the HBD. These results make it
possible for coaches and trainers to estimate HBD intensity based
on the MV of the bar. In addition, the results showed excellent
predictive ability for 1RM HBD with a CV of 2.53% and TE of
5.11 kg. These results may be useful for coaches, trainers, and
individuals seeking to estimate appropriate training loads to op-
timize performance when using the HBD.
Supporting our hypothesis, a very strong load-velocity re-
lationship was found (R
2
50.85) in the HBD. This finding cor-
roborates with other studies that showed very strong load-velocity
relationships in the SBD (2,17). In their studies, Mor´
an-Navarro
et al. (17), Benavides-Ubric et al. (2), and Jukic et al. (12) reported
significant R
2
values of 0.96, 0.91, and 0.95, respectively. These
results show the accuracy of general load-velocity regressions.
Interestingly, although the population of this study com-
prised ice hockey athletes, the velocities in this study were very
similar to individuals with moderate resistance training expe-
rience who performed the SBD (2,17). This may be explained
by the stability of the load-velocity profile regardless of relative
strength levels of subjects. In their study with the SBD, Moran-
Navarro et al. (17) divided their subjects in 2 groups based on
individual strength levels. After analyzing the velocity pa-
rameters attained against each % 1RM, Moran-Navarro et al.
(17) found no significant differences between the groups. The
consistency of the velocity measures despite individual levels of
strengthhasalsobeenreportedinotherexercises.Forexam-
ple, Gonzalez-Badillo and Sanchez Medina illustrated how
solid the load-velocity relationship was during a 6-week
training block. Despite an observed increase in 1RM of
9.3%, the difference in the mean test velocity was approxi-
mately 0.01 m·s
21
decline for the posttest from the pretest in a
paused smith machine bench press exercise (9). These results
illustrate the stability of the load-velocity relationship re-
gardless of relative strength levels.
Although this was the first study to explore the load-velocity
relationship of the HBD, some limitations need to be acknowl-
edged. The results from this study should be interpreted with
caution and should not be extrapolated to other deadlift varia-
tions. Because small variations, such as the use of lifting straps,
can alter the entire load-velocity relationship (12), the in-
vestigation of the load-velocity relationship in the HBD with
different handles is warranted. This study did not include a sub-
sequent session in which the test-retest reliability could be
assessed. Future research should consider the addition of a second
Figure 2. Bland-Altman plot depicts differences between the actual 1RM and
predicted 1RM from the load-velocity relationship. u: 95% superior and inferior limits
of agreement; d: bias. 1RM 51 repetition maximum.
Table 1
Concurrent validity analyses of the load-velocity relationship to predict 1 repetition maximum (1RM) of the hexagonal bar deadlift.*
Actual 1RM (kg)
Mean 6SD
Predicted 1RM (kg)
Mean 6SD p ES (95% CI) R(95% CI) TE (95% CI) CV (95% CI)
201.4 619.5 201.5 620.1 0.90 20.08 (20.16 to 0.14) 0.93 (0.84 to 0.97) 5.11 (3.94 to 7.57) 2.53 (1.94 to 3.62)
*ES 5Hedge’s geffect size; R5Pearson’s correlation coefficient; TE 5typical error (kg); CV 5coefficient of variation (%); CI 5confidence intervals.
222
Predicting 1RM on the Hexagonal Bar Deadlift (2023) 37:1
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testing session in which the reliability of the prediction equation
can be assessed.
Practical Applications
This study presented results that add the HBD to the list of
exercises with established load-velocity relationships. This is
particularly useful for coaches and trainers when using
deadlifts in their training programs and opts for the HBD
variation. With HBD velocity measurements at hand, coaches
may have real-time performance feedback allowing them to
determine exercise intensity and monitor neuromuscular fa-
tigue. These data can also assist coaches when implementing
velocity-based training as part of the training program. Fi-
nally, the results showed an excellent predictive ability for
1RM HBD. The prediction equation error was only 0.01%
(i.e., 0.1 kg), which means that barbell velocity is a time-
efficient and reliable way to assess exercise intensity during the
HBD. By performing the HBD with submaximal loads at
maximum intended velocity, athletes can have their %1RM
estimated, which may exclude the need for submaximal or
maximal tests for training load attainment.
Acknowledgments
The authors thank the athletes for their time and commitment
throughout this study and are grateful to Justin Roethlingshoefer
for his assistance with the data collection. This research was
undertaken without additional research funding support. The
content of the manuscript does not constitute endorsement of a
product by the authors or the NSCA. The authors have no
conflicts of interest to disclose.
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