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Relationship Between Velocity Loss and Repetitions in Reserve in the Bench Press and Back Squat Exercises

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  • Centro de Investigación en Rendimiento Físico y Deportivo, Universidad Pablo de Olavide

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This study aimed to compare the pattern of repetition velocity decline during a single set to failure performed against four relative loads in the bench press (BP) and full squat (SQ) exercises. Following an initial test to determine 1RM strength and load-velocity relationships, twenty men performed one set of repetitions to failure (MNR test) against loads of 50-60-70-80% 1RM in BP and SQ, on eight random order sessions performed every 6-7 days. Velocity against the load that elicited a ~1.00 m•s-1 (V1 m•s-1 load) was measured before and immediately following each MNR test and it was considered a measure of acute muscle fatigue. The number of repetitions completed against each relative load showed high interindividual variability in both BP (CV: 15-22%) and SQ (CV: 26-34%). Strong relationships were found between the relative loss of velocity in the set and the percentage of performed repetitions in both exercises (R2 = 0.97 and 0.93 for BP and SQ, respectively). Equations to predict repetitions left in reserve from velocity loss are provided. For a given magnitude of velocity loss within the set (15-65%), the percentages of performed repetitions were lower for the BP compared to the SQ for all loads analyzed. Acute fatigue following each set to failure was found dependent on the magnitude of velocity loss (r = 0.97 and 0.99 for BP and SQ, respectively) but independent of the number of repetitions completed by each participant (p > 0.05) for both exercises. The percentage of velocity loss against the V1 m•s-1 load decreased as relative load increased, being greater for BP than SQ. These findings indicate that monitoring repetition velocity can be used to provide a very good estimate of the number (or percentage) of repetitions actually performed and those left in reserve in each exercise set, and thus to more objectively quantify the level of effort incurred during resistance training.
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RELATIONSHIP BETWEEN VELOCITY LOSS AND
REPETITIONS IN RESERVE IN THE BENCH PRESS AND
BACK SQUAT EXERCISES
DAVID RODRI
´GUEZ-ROSELL,
1
JUAN MANUEL YA
´N
˜EZ-GARCI
´A,
1
LUIS SA
´NCHEZ-MEDINA,
2
RICARDO MORA-CUSTODIO,
1
AND JUAN JOSE
´GONZA
´LEZ-BADILLO
1
1
Physical Performance and Sports Research Center, Pablo de Olavide University, Seville, Spain; anAU1 d
2
Studies, Research and
Sports Medicine Center, Government of Navarre, Pamplona, SpainAU2
ABSTRACT
Rodrı
´guez-Rosell, D, Ya
´n
˜ez-Garcı
´a, JM, Sa
´nchez-Medina, L,
Mora-Custodio, R, and Gonza
´lez-Badillo, JJ. Relationship
between velocity loss and repetitions in reserve in the bench
press and back squat exercises. J Strength Cond Res XX(X):
000–000, 2018—This study aimed to compare the pattern of
repetition velocity decline during a single set to failure per-
formed against 4 relative loads in the bench press (BP) and
full squa
AU3 t (SQ) exercises. After an initial test to determine 1
repetition maximum (1RM) strength and load-velocity relation-
ships, 20 men performed one set of repetitions to failure (MN
AU4 R
test) against loads of 50, 60, 70, and 80% 1RM in BP and SQ,
on 8 random order sessions performed every 6–7 days. Veloc-
ity against the load that elicited a ;1.00 m$s
21
(V1 m$s
21
load) was measured before and immediately after each MNR
test, and it was considered a measure of acute muscle fatigue.
The number of repetitions completed against each relative load
showed high interindividual variability in both BP (coefficient of
variation [CV]: 15–22%) and SQ (CV: 26–34%). Strong rela-
tionships were found between the relative loss of velocity in the
set and the percentage of performed repetitions in both exer-
cises (R
2
= 0.97 and 0.93 for BP and SQ, respectively). Equa-
tions to predict repetitions left in reserve from velocity loss are
provided. For a given magnitude of velocity loss within the set
(15–65%), the percentages of performed repetitions were
lower for the BP compared with the SQ for all loads analyzed.
Acute fatigue after each set to failure was found dependent on
the magnitude of velocity loss (r= 0.97 and 0.99 for BP and
SQ, respectively) but independent of the number of repetitions
completed by each participant (p.0.0
AU5 5) for both exercises.
The percentage of velocity loss against the V1 m$s
21
load
decreased as relative load increased, being greater for BP than
SQ. These findings indicate that monitoring repetition velocity
can be used to provide a very good estimate of the number (or
percentage) of repetitions actually performed and those left in
reserve in each exercise set, and thus to more objectively quan-
tify the level of effort incurred during resistance training.
KEY WORDS exercise prescription, velocity-based resistance
training, level of effort, muscle failure, degree of fatigue AU6
INTRODUCTION
Configuration of the AU7exercise stimulu AU8s during resis-
tance training (RT) depends on the manipulation
of several acute variables such as exercise type
and order, loading magnitude, number of repeti-
tions and sets, rests duration, and movement velocity (1,8).
Among these variables, training volume has been considered
a critical factor in achieving a specific training outcome (8),
as it has been shown to affect neural (6), hypertrophic (22),
metabolic (14), and hormonal responses (10) and subsequent
functional and neuromuscular adaptations to RT.
Training volume is generally determined from the total
number of sets and repetitions performed during a training
session (1,8). Thus, in most studies, it is prescribed using
a specific number of repetitions to be completed in each
exercise set by all participants. However, the maximum (to
failure) number of repetitions that can be completed against
a given relative load (percentage of 1 repetition maximum, %
1RM) has been found to present a large variability between
individuals (5,20). Thus, several studies (5,15,20,21) have re-
ported coefficients of variation (CVs) ranging from ;20 to
;50% for the maximum number of repetitions completed
against different relative loads (50–90% 1RM), with
the minimum number of completed repetitions representing
;50% of the maximum repetitions number in both upper-
(5,20) and lower-limb (15,20,21) exercises. Therefore, if dur-
ing a training session, all participants perform the same num-
ber of repetitions per set against a given relative load, it is
possible that they are exerting a different level of effort or
Address correspondence to David Rodrı
´guez-Rosell,
davidrodriguezrosell@gmail.com.
00(00)/1–11
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degree of fatigue, as the number of repetitions that remains
undone or repetitions left in reserve (5,9,16) in each set
might considerably differ between individuals. In this regard,
instead of performing a fixed, predetermined, number of rep-
etitions, it has been suggested to stop or terminate each
training set as soon as a predetermined magnitude or per-
centage of velocity loss is reached (5,9,13,16).
Research has shown that monitoring repetition velocity is
an objective, practical, and noninvasive indicator of muscle
fatigue during RT (3,5,12,16). In addition, the magnitude of
velocity loss incurred during RT has also been shown as an
objective indicator of metabolic and hormonal stress induced
by different exercise protocols (3,9,13,16). A very recent
study (9) showed that the absolute velocities associated to
stopping a set before failure, leaving a certain number of
repetitions in reserve (2, 4, 6, or 8 repetitions), were very
similar for loads of 65, 75, and 85% 1RM and showed a high
reliability (CV: 4.4–8.0%) in 4 RT exercises. Another study
has recently reported (5) a strong relationship (R
2
= 0.96–
0.97; SEE = 4.69–5.75%) between the relative loss of velocity
in a set and the percentage of performed repetitions with
respect to the maximum number that can be completed in
the bench press (BP) exercise against 8 different loads (50–
85% 1RM, in 5% increments). In this study (5), it was also
observed that the percentage of performed repetitions for
a given magnitude of velocity loss was very similar for all
loads used, especially for those ranging between 50 and 70%
1RM, although the maximum number of repetitions com-
pleted against each relative load was significantly different
(;25 212 repetitions). Moreover, the percentage of per-
formed repetitions for a given magnitude of velocity loss in
the set showed a high absolute reliability (CV: 2.1–6.6%) (5).
This novel finding is of great practical application because by
monitoring repetition velocity during training, it is possible
to estimate how many repetitions are left in reserve
(i.e., repetitions that remain undone) in a BP set (5). How-
ever, considering that several differences exist in terms of
muscle mass, fiber type distribution, duration of muscle con-
traction, and biomechanics between upper- and lower-limb
muscles (23), it is likely that a different pattern of repetition
velocity decline may exist between the BP and the full back
squat (SQ). Furthermore, although the relationship between
the percentage of velocity loss in the set (e.g., 30% loss in
repetition velocity) and the percentage of performed repeti-
tions (e.g., 50% of the maximum possible number) against
a given relative load was found independent of the maximum
number of possible repetitions (5), it is unclear whether the
number of repetitions completed until reaching a certain
percentage of velocity loss in the set influences the degree
of induced fatigue.
In an attempt to find answers to the questions raised
above, the main aim of this study was to analyze the
relationship between repetitions performed and velocity
decline during a single set to failure performed against 4
different submaximal loads (50, 60, 70, and 80% 1RM) in the
BP and SQ exercises. Secondarily, we also aimed to quantify
the percentage of velocity loss attained against an individual
reference load after each set to failure as an indicator of the
acute degree of fatigue.
METHODS
Experimental Approach to the Problem
A descriptive AU9, cross-sectional research design was used to
analyze the magnitude of velocity loss incurred during and
after a single set to failure performed against 4 different loads
in the BP and SQ exercises. Participants performed 9 sessions,
separated by a period of 6–7 days. During the first session,
a progressive loading test for the determination of 1RM
strength and individual load-velocity relationships in the BP
and SQ was conducted. During the remaining 8 sessions, 4
tests of maximum number of repetitions to failure (MNR test)
in each exercise (BP and SQ) were performed against loads of
50, 60, 70, and 80% 1RM. Sessions were performed in random
order for each participant. Relative loads were determined
from the load-velocity relationship for the BP and SQ
(4,17,18). The percentage change in mean propulsive velocity
(MPV) pre-post exercise (i.e., before and after each MNR
test) against an individual reference load was used as an indi-
cator of acute fatigue after each MNR test. Thus, this study
design allowed for the determination of: (a) differences in the
percentage of completed repetitions for different magnitudes
(percentages) of velocity loss in the set against each load; (b)
the percentage of performed repetitions when a given veloc-
ity loss is reached in the BP compared with the SQ; and (c)
differences in the degree of fatigue between subgroups of
participants who completed a higher vs. a lower number of
repetitions per set during the MNR tests. In the preceding 2
weeks of this study, 4 preliminary familiarization sessions
were undertaken with the purpose of emphasizing proper
execution technique in the BP and SQ. The participants were
required to refrain from any type of RT during the 2 days
preceding each testing session.
Subjects
A grou AU10p of 20 young healthy men (mean 6SD: age 25.0 6
3.5 years; height 1.77 60.06 m; and body AU11mass 76.0 67.2
kg) AU12volunteered to participate in this study. Participants were
physically active sport science students with at least 8
months of RT experience (1–3 sessions$wk
21
) and were
accustomed to performing the BP and SQ exercises with
correct technique. No physical limitations, health problems,
or musculoskeletal injuries that could affect testing were re-
ported. None of the participants were taking drugs, medica-
tions, or substances expected to affect physical performance.
The investigation was conducted in accordance with the
Declaration of Helsinki and was approved by the Research
Ethics Committee of Pablo de Olavide University. After
being informed of the purpose and experimental procedures,
the participants signed a written informed consent form
before participation.
Velocity Loss for Monitoring Resistance Exercises
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Testing Procedures
Anthropometric assessments and medical examinations
were conducted during the first session. Testing sessions
were performed at the same time of day (61 hour) for each
participant and under similar environmental conditions
(;20–228C and ;55–65% humidity). Strong verbal
encouragement was provided during all tests to motivate
subjects to give a maximal effort.
Isoinertial Progressive Loading Tests in the Bench Press and Full
Squat Exercises. These tests were mainly performed: (a) to
estimate the weight (kg) that each subject had to use, so that
the lifting velocity of the first repetition matched the
specified target MPV of each of the 4 relative loads to be
used; and (b) to make a description of the subjects’ charac-
teristics. The BP testing protocol was performed following
the exact protocol described elsewhere (4,5,19). Participants
laid supine on a flat bench, with their feet resting flat on the
floor and hands placed on the bar slightly wider (2–3 cm)
than shoulder width. The position on the bench was care-
fully adjusted, so that the vertical projection of the bar cor-
responded with each participant’s intermammary line.
Participants were not allowed to bounce the bar off their
chests or raise the shoulders or trunk off the bench. Two
telescopic bar holders with a precision scale were placed at
the left and right sides of the Smith machine to: (a) precisely
replicate the individual eccentric range of movement
between trials and (b) impose a pause or delay between
the eccentric and concentric phases of the BP exercise.
The bar holders were positioned, so that the bar stopped
;1 cm above each participant’s chest. After lowering the
bar at a controlled mean eccentric velocity (;0.30–0.50
m$s
21
), participants stopped for ;1.0 seconds at the bar
holders (momentarily releasing the weight but keeping con-
tact with the bar), and thereafter, they performed a purely
concentric push at maximal intended velocity. This momen-
tary pause between phases was imposed to minimize the
contribution of the rebound effect and allow for more reli-
able, consistent measures (11). Similarly, a detailed descrip-
tion of the SQ testing protocol has been recently provided
elsewhere (9,26,2 AU138). Participants started from an upright
position, descending in a continuous motion until the pos-
terior thighs and calves made contact with each other, then
immediately reversed motion and ascended back to the
starting position. Unlike the eccentric phase, which was per-
formed at a normal, controlled velocity, subjects were
required to always execute the concentric phase of either
the BP or SQ at maximal intended velocity. The individual
position for the BP (position on the bench as well as grip
widths) and SQ exercise (feet position and placement of the
hands on the bar) was measured for each participant, so that
they could be reproduced in all testing sessions. The warm-
up consisted of 5 minutes of running at a self-selected easy
pace, 5 minutes of upper- or lower-body joint mobilization
exercises, followed by 2 sets of 8 and 6 repetitions (3-minute
rest) with loads of 20 and 30 kg, respectively. The initial load
was set at 20 kg and 30 kg for all participants in the BP and
SQ exercise, respectively, and was gradually increased in 10-
Figure 1. Velocity-based methods of quantifying neuromuscular fatigue in this study. The example corresponds to a test of maximal number of repetitions to
failure against a load of ;60% 1RM in the BP exercise for a representative participant. Mean propulsive velocity loss against the V1 m$s
21
load (246.8%) and
MPV loss over the set (282.7%) are calculated. See text for details. 1RM = 1 repetition maximum; BP = bench press; MPV = mean propulsive velocity.
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TABLE 1. Descriptive variables for the exercise sets to failure performed against the 4 loading magnitudes under study in the bench press and squat exercises.*
50% 1RM 60% 1RM 70% 1RM 80% 1RM
BP
(;0.93 m$s
21
)
SQ
(;1.13 m$s
21
)
BP
(;0.79 m$s
21
)
SQ
(;0.98 m$s
21
)
BP
(;0.62 m$s
21
)
SQ
(;0.82 m$s
21
)
BP
(;0.48 m$s
21
)
SQ
(;0.68 m$s
21
)
MPV
BEST
(m$s
21
) 0.93 60.01§k¶# 1.13 60.02§k 0.79 60.01k¶# 0.99 60.01k 0.62 60.01¶# 0.82 60.01¶ 0.47 60.01# 0.69 60.02
(0.91–0.94) (1.10–1.16) (0.77–0.81) (0.96–1.01) (0.60–0.64) (0.79–0.85) (0.45–0.49) (0.66–0.71)
MPV
LAST
(m$s
21
) 0.14 60.03# 0.28 60.04 0.13 60.02# 0.26 60.07 0.13 60.03# 0.29 60.04 0.12 60.02# 0.27 60.04
(0.09–0.22) (0.19–0.35) (0.09–0.19) (0.16–0.42) (0.06–0.18) (0.24–0.37) (0.08–0.16) (0.21–0.34)
Velocity loss (%)z84.8 63.8k¶# 75.5 63.9k 83.7 63.0k¶# 73.6 66.6k 79.3 64.8¶# 64.6 64.7¶ 73.9 65.3# 60.2 66.7
(76.1–90.5) (68.9–83.1) (76.3–88.1) (56.6–87.9) (70.5–90.3) (55.8–70.7) (65.9–82.9) (48.9–70.2)
Rep 25.2 65.5§k¶# 23.4 67.7§k 19.3 62.8k¶# 16.2 65.0k 12.3 62.3¶# 9.6 63.3¶ 7.7 61.5# 6.0 61.5
(19–40) (15–44) (15–24) (10–31) (9–18) (5–18) (5–10) (4–10)
Load (kg) 38.0 65.2§k¶# 60.5 611.3§k 44.6 66.8k¶# 72.0 611.8k 54.4 67.8¶# 84.8 612.6¶ 63.1 67.8# 92.6 614.4
(27.5–45) (47.5–90) (30–55) (57.5–99) (34–65) (67.5–111) (44–74) (73.0–122.5)
*1RM = 1 repetition maximum; BP = bench press; SQ = full squat; MPV
BEST
= mean propulsive velocity of the fastest (usually first) repetition in the set; MPV
LAST
= mean
propulsive velocity of the last completed repetition in the set; Rep = number of completed repetitions in the set.
Data are mean 6SD (range).
zStatistically significant “exercise 3load magnitude” interaction: p,0.01.
§Statistically significant differences with respect to: 60% 1RM.
kStatistically significant differences with respect to: 70% 1RM.
Statistically significant differences with respect to: 80% 1RM.
#SQ exercise.
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TABLE 2. Percentage of completed repetitions out of the maximum possible number when a given magnitude of mean propulsive velocity (MPV) loss is reached
in each set to failure in the bench press and squat exercises.*
Velocity loss (%)
Percentage of repetitions completed
50% 1RM 60% 1RM 70% 1RM 80% 1RM
BP
(;0.93 m$s
21
)
SQ
(;1.13 m$s
21
)
BP
(;0.79 m$s
21
)
SQ
(;0.98 m$s
21
)
BP
(;0.62 m$s
21
)
SQ
(;0.82 m$s
21
)
BP
(;0.48 m$s
21
)
SQ
(;0.68 m$s
21
)
10 23.0 62.8 25.6 66.2 21.3 63.5 26.9 65.7¶ 23.4 63.3 32.6 66.6z§¶ 29.7 63.4z§k36.6 65.6z§k
15 31.4 63.4 34.7 67.0 29.0 63.5 35.6 66.8¶ 31.0 63.5 41.2 67.8z§¶ 37.1 64.0z§k44.4 66.7z§k
20 39.4 64.1 43.3 67.7 37.4 63.7 43.8 67.6¶ 38.4 63.8 49.3 68.7z§¶ 44.2 64.6z§k51.9 67.8z§¶
25 46.8 64.7 51.2 68.2¶ 44.4 63.8 51.4 68.2¶ 45.4 64.2 56.9 69.3z§¶ 51.0 65.2z§k59.0 68.7z§¶
30 53.7 65.1 58.6 68.5¶ 51.1 64.0 58.6 68.5¶ 52.2 64.5 63.9 69.5z§¶ 57.4 65.6z§k65.7 69.4z§¶
35 60.2 65.5 65.4 68.5¶ 57.5 64.1 65.3 68.5¶ 58.6 64.7 70.4 69.4z§¶ 63.5 65.9§k72.0 69.9z§¶
40 66.1 65.7 71.7 68.2¶ 63.5 64.1 71.4 68.2¶ 64.7 64.7 76.4 68.9¶ 69.3 66.1§ 77.9 610.3z§¶
45 71.5 65.7 77.3 67.7¶ 69.2 64.1 77.1 67.7¶ 70.5 64.7 81.8 68.0¶ 74.7 66.1§ 83.4 610.7z§¶
50 76.5 65.6 82.4 66.9¶ 74.6 64.0 82.3 66.9¶ 75.9 64.6 86.7 66.9¶ 79.8 65.9 88.5 611.0z§¶
55 80.9 65.3 86.9 65.8¶ 78.6 63.8 86.9 66.1¶ 81.1 64.5 91.1 65.6¶ 84.5 65.6 93.3 611.3z§¶
60 84.8 64.9 90.8 64.6¶ 83.2 63.6 91.1 65.3¶ 85.9 64.3 94.9 64.4¶ 88.9 65.2 97.6 611.8z§¶
65 88.3 64.4 94.1 63.3¶ 87.6 63.4 94.8 65.1¶ 90.5 64.1 98.2 64.2¶ 93.0 64.8 101.6 612.5z§¶
*1RM = 1 repetition maximum; BP = bench press; SQ = full squat.
Data are mean 6SD.
zStatistically significant differences with respect to: 50% 1RM.
§Statistically significant differences with respect to: 60% 1RM.
kStatistically significant differences with respect to: 70% 1RM.
BP exercise.
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kg increments until the attained MPV was lower than 0.4
m$s
21
for the BP or 0.7 m$s
21
for the SQ exercise. There-
after, the load was individually adjusted with smaller incre-
ments (5 down to 1 kg), so that 1RM could be precisely
determined. During the test, 3 repetitions were executed
for light (,50% 1RM), 2 for medium (50–80% 1RM), and
only one for the heaviest (.80% 1RM) loads. Interset rests
were 3 minutes for the light and medium loads and 5 minutes
for the heaviest loads.
Tests of Maximum Number of Repetitions to Failure. Participants
performed 8 MNR tests (4 in each exercise) against loads of
50, 60, 70, and 80% of 1RM, respectively. As indicated above,
relative loads were determined from the load-velocity
relationship for the BP and SQ (4,18). Equations used to
estimate the MPV corresponding to each load were the fol-
lows: MPV = (0.00003 3%1RM) 2(0.0204 3%1RM) +
1.889, and MPV = (20.00006977 3%1RM) 2(0.005861 3
%1RM) + 1.608, for BP and SQ, respectively (4,18). Thus,
a target MPV to be attained in the first (usually the fastest)
repetition of the set in each session was used as an estima-
tion of %1RM, as follows: (a) ;0.93 m$s
21
(50% 1RM),
;0.79 m$s
21
(60% 1RM), ;0.62 m$s
21
(70% 1RM), and
;0.47 m$s
21
(80% 1RM) for BP (4); and (b) ;1.13 m$s
21
(50% 1RM), ;0.98 m$s
21
(60% 1RM), ;0.82 m$s
21
(70%
1RM), and ;0.68 m$s
21
(80% 1RM) for SQ (18). Thus,
before starting each set to failure, the absolute load (kg) for
each participant was individually adjusted to match the
velocity associated (60.02 and 60.03 m$s
21
for the BP
and SQ exercises, respectively) with the %1RM intended
for each session. Participants were required to move the
bar as fast as possible during the concentric phase of each
repetition, from the first repetition until reaching muscle
failure. Specifically, for the BP exercise, the participants were
required to perform each repetition descending the bar in
a controlled manner and maintain a static position during
;1.0 seconds at the end of the eccentric phase (stopped on
the bar holders) before lifting the bar as fast as possible on
Figure 2. Relationships between the magnitude of velocity loss experienced over the set and the number of repetitions performed (out of the maximum, to
failure, possible number) for the 4 loads under study (50, 60, 70, and 80% 1RM) in the BP and SQ exercises. 1RM = 1 repetition maximum; BP = bench press;
MPV = mean propulsive velocity; SQ = full squat.
Velocity Loss for Monitoring Resistance Exercises
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hearing a verbal command, exactly as performed in the pro-
gressive loading test for this exercise.
Determination of the Load That Elicited a 1-m$s
21
Mean Pro-
pulsive Velocity. In each session, participants warmed up by
performing 3 sets of 6 down to 3 repetitions (3-minute rests)
with increasing loads up to the individual load that elicited
a;1.00-m$s
21
(1.00 60.02 m$s
21
for BP and 1.00 60.02
m$s
21
for SQ) MPV (V1 m$s
21
load). This value was chosen
because it is a sufficiently high velocity, which is attained
against medium loads (;45 and ;60% 1RM for BP and
SQ, respectively), and it allows a good expression of the
effect of loading on velocity, besides being a relatively easy
to move and well-tolerated load (16). The V1 m$s
21
load
(kg) was thus taken as a pre-exercise reference measure
against which to compare the velocity loss experienced after
each of the MNR tests. The pre-post exercise decline of
velocity against this V1 m$s
21
load was considered as a mea-
sure of acute muscle fatigue (3,12,16). Participants executed 3
maximal effort consecutive repetitions against the V1 m$s
21
load right before starting each MNR test and again imme-
diately after completing the last repetition of the MNR test
(load was changed in 5–10 seconds with the help of spot-
ters). Strong verbal encouragement and velocity feedback in
every repetition were provided throughout all testing ses-
sions to motivate participants to give a maximal effort.
Velocity Measures. Several velocity outcome measures were
used as performance variables in this study: (a) MPV of each
repetition; (b) MPV of the fastest (usually first) repetition in
the set (MPV
BEST
); (c) MPV of the last completed repetition
in the set (MPV
LAST
); (d) loss of MPV over each exercise
set, defined as: 100 (MPV
LAST
2MPV
BEST
)/MPV
BEST
; and
(e) the percentage change in MPV pre-post exercise attained
against the V1 m$s
21
load. The average MPV of the 3 rep-
etitions before exercise was compared with the average
MPV of the 3 repetitions performed immediately after the
exercise set (i.e., 100 [average MPV
post
2average MPV
pre
]/
average MPV
pre
)(16).F1 Figure 1 shows an example of these 2
ways of calculating the magnitude of velocity loss (over the
set and pre-post exercise against the V1 m$s
21
load) for
a representative participant and MNR test in the BP
exercise.
Measurement Equipment and Data Acquisition. Height and
body mass were determined using a medical stadiometer and
scale (Seca 710; Seca Ltd., Hamburg, Germany) with the
participants wearing only underclothes. All sessions were
performed using a Smith machine with no counterweight
mechanism (Multipower Fitness Line, Peroga, Spain). A
linear velocity transducer with its associated software (T-
Force Dynamic Measurement System, Version 3.60, Ergo-
tech, Murcia, Spain) was used to measure and register the
bar velocity of each repetition, which was sampled at 1,000
Hz. The reliability of this system has been reported
elsewhere (16). The velocity measures used in this study
correspond to the mean velocity of the propulsive phase
(MPV) of each repetition (19). The propulsive phase was
defined as that portion of the concentric phase during which
the measured acceleration (a) is greater than acceleration
due to gravity (i.e., a$29.81 m$s
22
)(19).
Statistical Analyses
Standard statistical methods were used for the calculation of
the mean, SD, CV, and Pearson’s correlation coefficients (r).
Relationships between the percentage loss of MPV over the
set and the percentage of performed repetitions against the
Figure 3. Mean loss of MPV against the V1 m$s
21
load corresponding
to each loading magnitude (A) and relationships between mean loss of
MPV over the set and mean loss of MPV against the V1 m$s
21
load (B).
Significant differences between the BP and SQ exercises: *p,0.05;
***p,0.001. Significant differences with respect to ;80% 1RM: #p,
0.05, ###p,0.001. Significant differences with respect to ;70%
1RM: †††p,0.001. 1RM = 1 repetition maximum; BP = bench press;
MPV = mean propulsive velocity; SQ = full squat.
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different load magnitudes were studied by fitting second-
order polynomials to data. Similarly, relationships between
the relative load and the percentage loss of MPV against the
V1 m$s
21
load were studied by fitting second-order polyno-
mials to data. A 2 (exercise: BP vs. SQ) 34 (load magnitude:
50 vs. 60% vs. 70 vs. 80% 1RM) repeated-measures analysis
of variance was conducted to analyze the intraexercise and
between-exercise differences for all variables (MPV
BEST
,
MPV
LAST
, percentage velocity loss, number of repetitions,
and percentage of repetitions performed). Bonferroni post
hoc procedures were performed to locate the pairwise differ-
ences between the mean values. A t-test for independent
samples was used to compare the changes in the percentage
loss of MPV pre-post exercise against the V1 m$s
21
load
between those participants who performed a low vs. a high
number of repetitions in each set to failure. Significance was
accepted at p#0.05. All analyses were performed using
SPSS software version 17.0 (SPSS, Chicago, IL, USA).
RESULTS
The values for 1RM strength
were 79.6 611.05 and 115.6 6
16.9 kg for the BP and SQ ex-
ercises, respectively. The MPV
values corresponding to 1RM
were 0.14 60.06 m$s
21
for
BP and 0.31 60.04 m$s
21
for
SQ.
Characteristics of MNR Tests
T1Table 1 summarizes the char-
acteristics of each set to failure
performed against the 4 loads
under study in the BP and SQ.
A significant “exercise 3load
magnitude” interaction (p,
0.01) was observed for velocity loss in the set, whereas there
was no such interaction in the other variables analyzed. No
significant differences were found between the expected or
targeted MVP values and the fastest MPV value (MPV
BEST
)
of each set for any of the loads used in any exercise. Average
MPV values of the last completed repetition of each set
(MPV
LAST
) were very similar for all the loads used (Table 1),
and no significant differences were found between the aver-
age MPV
LAST
of each MNR test and the average MPV value
of 1RM for any exercise. As loading magnitude increased,
both the number of performed repetitions and the magni-
tude of MPV loss progressively decreased for the BP and SQ
(Table 1). The number of repetitions and the loss of MPV
over the set were significantly greater in the BP compared
with the SQ for the 4 loads examined. The number of rep-
etitions performed against each load showed a high interin-
dividual variability in both exercises, with greater variability
in the SQ (CV: 25.9–33.9%) compared with the BP (CV:
14.5–21.8%).
TABLE 3. Number of repetitions completed by each group (LRG vs. HRG) against
the 4 loading magnitudes under study.*
Load
BP SQ
LRG (n= 10) HRG (n= 10) LRG (n= 10) HRG (n= 10)
50% 1RM 21.2 61.2 29.2 65.1z17.7 62.0 29.0 67.1z
60% 1RM 16.9 61.2 21.7 61.5z12.5 61.6 19.9 64.5z
70% 1RM 10.7 61.3 13.9 62.0z7.2 61.1 12.0 62.9z
80% 1RM 6.6 61.0 8.8 61.0z4.8 60.6 7.1 61.3z
*BP = bench press; SQ = full squat; LRG = low number of repetitions group; HRG = high
number of repetitions group; 1RM = 1 repetition maximum.
Data are mean 6SD.
zStatistically significant differences between-groups: p,0.001.
Figure 4. Comparison of the loss of MPV pre-post exercise against the V1 m$s
21
load experienced by 2 groups of participants: those who completed a high
(HRG) vs. a low number of repetitions (LRG) in each set to failure against the 4 loads under study (50, 60, 70, and 80% 1RM) in the BP (A) and the SQ (B)
exercises. See text for details. BP = bench press; SQ = full squat.
Velocity Loss for Monitoring Resistance Exercises
8
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Relationship Between the Percentage of Performed
Repetitions and the Percentage of Mean Propulsive
Velocity Loss
In the BP, the percentages of performed repetitions when
a given percentage of MPV loss (10–65%) was reached were
very similar for loads ranging from 50 to 70% 1RM, whereas
these percentages of performed repetitions were slightly
greater for 80% 1RM (
T2 Table 2). In the SQ, these percentages
were very similar for 50 and 60% 1RM but were progres-
sively greater for 70 and 80% 1RM, respectively (Table 2).
Prediction equations to estimate the percentage of per-
formed repetitions when a given magnitude of velocity loss
is reached in an exercise set, for the 4 loads under study, are
provided in
F2 Figure 2 for the SQ and BP. There was a signif-
icant “exercise 3load magnitude” interaction in the percent-
age of performed repetitions when the magnitude of velocity
loss in the set ranged from 10 to 30%, whereas no significant
“exercise 3load magnitude” interactions were observed
when the magnitude of velocity loss was higher than 30%.
Comparisons between both exercises showed that for the
same magnitude of MPV loss over the set, the percentage
of performed repetitions was always greater for the SQ than
for the BP for all loads used (Table 2 and Figure 2).
Mean Propulsive Velocity Loss Against the V1 m$s
21
Load
The loss of MPV pre-post exercise against the V1 m$s
21
load was statistically significant (p,0.05–0.001) for all
MNR tests. This loss of MPV against the V1 m$s
21
load
gradually decreased as the load magnitude increased in both
exercises (
F3 Figure 3A). A significant “exercise 3load magni-
tude” interaction (p,0.01) was found for this variable, with
the loss of MPV against the V1 m$s
21
load being signifi-
cantly greater in the BP compared with the SQ for all 4
loads. When data from both exercises were pooled, a signif-
icant positive correlation (r= 0.930; p,0.001) was found
between the loss of MPV over the set and the loss of MPV
against the V1 m$s
21
load (Figure 3B).
Mean Propulsive Velocity Loss Against the V1 m$s
21
Load:
Comparison Between Groups That Perform a Low vs. a High
Number of Repetitions per Set
To study whether the percentage loss of MPV pre-post
exercise against the V1 m$s
21
load was dependent on indi-
vidual differences in the maximum (to failure) number of
repetitions that could be performed per set, participants were
ranked according to the number of repetitions completed.
Thus, the total sample of 20 participants was further divided
into 2 subgroups of 10 participants each, for each load mag-
nitude used: a low number of repetitions group (LRG) and
a high number of repetitions group (HRG). The number of
repetitions completed by each group is reported in
T3 Table 3.
No significant differences in the average loss of MPV pre-
post exercise against the V1 m$s
21
load were found between
groups for any of the load magnitudes used in the BP or SQ
(
F4 Figure 4).
DISCUSSION
The main aim of this study was to compare the pattern of
repetition velocity decline during a set to failure performed
against different loads (50, 60, 70, and 80% 1RM) in the BP
and SQ exercises to assess whether the magnitude of velocity
loss incurred during an exercise set could be used as an
indicator or predictor of the number of repetitions left in
reserve. The results of the current study extend and confirm
those found in a recent study (5) by showing that the magni-
tude of MPV loss and the percentage of performed repetitions
against each load are strongly related in both the BP (R
2
=
0.97 for all 4 loads) and the SQ (R
2
= 0.93 for all 4 loads)
exercises (Figure 2), regardless of the number of repetitions
to failure completed by each participant (Table 1). This find-
ing enables us to estimate with a high precision the percentage
of repetitions that has already been completed in an exercise
set (and therefore how many repetitions are left in reserve) as
soon as a given magnitude of velocity loss is incurred in any of
these 2 exercises (Table 2 and Figure 2). Using the velocity loss
within the set as a tool for prescribing and monitoring RT
volume, rather than prescribing a fixed number of repetitions
to perform against a given load, seems an important step for-
ward toward a more rational and comprehensive character-
ization of the resistance exercise stimulus compared with
a traditional volume configuration (repetitions per set).
Therefore, using this novel approach, instead of establishing
a given, fixed, number of repetitions to be performed for each
participant, each training set should be terminated as soon as
a given percentage of velocity loss is reached.
This study also seems to indicate that the relationship
between the percentage of velocity loss in the set and the
percentages of performed repetitions depends on the relative
load being lifted and the type of exercise used. Thus, in the
BP exercise, the percentages of performed repetitions
corresponding to the different velocity losses reached (from
10 to 65%) were very similar for loads of 50–70% 1RM,
whereas these percentages were slightly (;5%) greater for
80% 1RM (Table 2). These results are very similar to those
recently reported for loads between 50 and 85% 1RM in the
BP (5). Unlike the BP, the percentage of performed repeti-
tions in the SQ in each set to failure when the magnitude of
MPV loss ranged from 10 to 65% was very similar for 50 and
60% 1RM, whereas it was progressively higher for 70% 1RM
and 80% 1RM (;4.2 and ;5%, respectively) (Table 2).
These results are partially in contrast with those showed
by Izquierdo et al. (7) who reported that the pattern of
repetition velocity decline and the relative number of repe-
titions performed was similar for loads of 60–75% 1RM in
both the SQ and BP exercises. Several methodological differ-
ences that could explain these contrasting results include the
following: (a) monitoring first’s repetition velocity to deter-
mine the relative load; (b) use of different exercises (parallel
squat vs. full squat); (c) particular way of performing the BP
exercise (including or not a pause between the eccentric and
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Copyright ª2018 National Strength and Conditioning Association
concentric phases); and (d) lifting velocity in each repetition
(controlled by means of a metronome vs. maximal intended
velocity).
Interestingly, the comparison between both training exer-
cises used in this study (BP vs. SQ) showed that a given
percentage of velocity loss over the set resulted in a greater
percentage of repetitions being completed (and, therefore, less
repetitions left in reserve) in the SQ compared with the BP for
all loads analyzed (Table 2 and Figure 2). As already indicated,
this finding could be explained by the smaller range of veloc-
ity loss over the set achievable for the SQ compared with the
BP, which is a direct consequence of the mean velocity of the
1RM of each exercise (16) (considerably slower velocities can
be reached in the BP compared with the SQ). A deeper anal-
ysis of the results revealed that, for each loading magnitude,
these differences between exercises in the percentage of per-
formed repetitions were greater as the magnitude of velocity
loss over the set increased. In addition, the difference in the
percentage of repetitions completed between the BP and SQ
exercise was higher as the load increased (Table 2 and Fig-
ure 2). These results seem to indicate that the prescription of
RT volume by means of the magnitude (percentage) of veloc-
ity loss in the set should be specific for each exercise and
relative load used. Thus, to complete the same percentage
of repetitions in both exercises, a greater magnitude of MPV
loss over the set should be allowed in the BP compared with
the SQ, as follows: ;5, ;6, ;8, and ;7% higher velocity loss
for 50, 60, 70, and 80% 1RM, respectively.
Because muscle fatigue has been traditionally defined as
a loss of force-generating capability with an eventual
inability to sustain exercise at the required or expected level
(2), the percentage velocity loss attained against the V1
m$s
21
load can be considered a good expression of the
degree of fatigue experienced during exercise (16). In this
study, the loss of MPV pre-post exercise against the V1
m$s
21
load gradually decreased as the loading magnitude
increased in both exercises (Figure 3A). In fact, both opera-
tional methods of quantifying muscle fatigue in this study
(MPV loss against the V1 m$s
21
load and MPV loss over
the set) were strongly related in both the BP (r= 0.930; p,
0.001) and SQ (r= 0.989; p,0.001) exercises (Figure 3B).
Thus, it seems that the greater the magnitude of MPV loss
experienced over an exercise set, the greater is the degree of
fatigue being incurred. This is in agreement with previous
results from Sa
´nchez-Medina and Gonza
´lez-Badillo (16)
who compared the percentage of MPV loss against the V1
m$s
21
load when performing sets to failure against loads of
12RM, 10RM, 8RM, 6RM, and 4RM. In this study (16),
a very high correlation was also found between percentage
loss of M PV over 3 sets and the percentage loss of M PV pre-
post exercise against the V1 m$s
21
load for both SQ (r=
0.91) and BP (r= 0.97) exercises.
Finally, another important finding of this study was that
the average loss of MPV pre-post exercise against the V1
m$s
21
load was very similar between those participants who
performed a high or a low number of repetitions (LRG vs.
HRG) during each set to muscle failure for all loads used in
both the BP and SQ (Figure 4). To the best of our knowl-
edge, this is the first study showing that the degree of fatigue
induced during an exercise set (measured by the percentage
loss of MPV against the V1 m$s
21
load) is not related to the
maximal number of repetitions completed. In agreement
with a previous study (5), the present results emphasize
the validity of using the percentage of MPV loss over the
set as a variable for monitoring training volume during RT
rather than prescribing a fixed number of repetitions to per-
form against a given load because the percentage of MPV
loss over the set seems to be a remarkably accurate and
objective indicator of the number of repetitions left in
reserve, regardless of the number of repetitions that each
participant is able to complete against a given relative load.
CONCLUSIONS
These results provide relevant practical information for
coaches and strength and conditioning professionals for
monitoring and prescribing training volume during RT in 2
fundamental training exercises such as the BP and SQ. The
main findings of this study were that: (a) a higher number of
repetitions was performed, and a higher magnitude of MPV
loss over the set was experienced for each of the exercise sets
to failure performed in the BP compared with the SQ against
all loads under study (50, 60, 70, and 80% 1RM); (b) there was
a strong relationship between the relative loss of MPV over
the set and the percentage of performed repetitions (out of the
maximum possible number) against all loads used in both
exercises; (c) for a given magnitude of MPV loss (from 15 to
65%) reached in the set, the percentages of performed
repetitions were lower for the BP compared with the SQ for
all 4 loads analyzed; (d) the acute fatigue after a single set to
failure depends on the magnitude of MPV loss experienced
over the set; (e) the loss of MPV pre-post exercise decreased as
the loading magnitude increased, being greater for the BP
than the SQ for all loads used; and (f) the percentage of MPV
loss attained against the V1 m$s
21
load after a single set to
muscle failure is independent of the number of repetitions
completed by each participant in both the BP and SQ
exercises.
PRACTICAL APPLICATIONS
The current study provides novel insight into the monitoring
and prescription of the resistance exercise stimulus. Because
of the strong relationship observed between the percentage of
velocity loss over the set and the percentage of repetitions
completed, and considering that the degree of fatigue is
similar for all participants regardless of the number of
repetitions performed to achieve a certain velocity loss in
the set, coaches and strength and conditioning professionals
should consider using the magnitude of velocity loss attained
in each exercise set as a tool for monitoring training volume
during RT. In this regard, the training volume during each
Velocity Loss for Monitoring Resistance Exercises
10
Journal of Strength and Conditioning Research
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Copyright ª2018 National Strength and Conditioning Association
exercise set should be configured using a certain magnitude of
velocity loss to be allowed (expressed as a relative loss in
repetition velocity from the fastest to the slowest repetition of
each set) rather than prescribing a fixed number of repetitions
to perform by all athletes with a given load. This novel
approach for monitoring training volume during RTallows us:
(a) to determine the actual degree or level of effort (relation-
ship between the repetitions actually performed and those left
in reserve) being incurred by an athlete during each exercise
set and (b) to equalize the level of effort for each subject during
RT, although, for that purpose, each subject might need to
perform a different number of repetitions per set against
a given relative load. The limit of velocity loss to be reached in
each set (e.g., 15, 30, or 40%) should be set in advance
depending on the training goal being pursued, the particular
exercise to be performed, the loading magnitude chosen, as
well as the training experience and performance level of the
athlete. Our results have also shown that there exist some
small differences in terms of the percentage of repetitions that
can be completed for a given magnitude of velocity loss over
the set which depend on the particular exercise (BP vs. SQ)
and load used. These differences should be taken into account
when prescribing training volume by means of the magnitude
of repetition velocity loss experienced during a training set in
different exercises.
ACKNOWLEDGMENTS
The authors greatly appreciate the commitment and dedi-
cation of all participants of this study who performed
a maximum effort in each of the testing sessions. The
authors have no professional relationships with companies
or manufacturers that might benefit from the results of this
study. There was no financial support for this project. The
results of this study do not constitute endorsement of any
product by the authors or by the National Strength and
Conditioning Association.
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... VBT is based on the finding that a linear relationship exists between lifting velocity and load intensity, which allows the prediction of the 1RM as valid indicator of maximal force capacity without the athlete taking the risk of an injury with high loading [6,10]. It was recently shown in 20 strength-trained males that the relative loss in lifting velocity during a set-to-exhaustion of full back squats is strongly related to the repetitions left in reserve, thus serving as a good estimate of muscular fatigue [11]. Furthermore, peak lifting velocity was found to correlate with relative peak power during the 1RM back squat in 21 male college athletes; yet, no correlations were found between peak lifting velocity and training age or femur length in the same study group [9]. ...
... Looking at the trajectory of the velocity during the concentric phase of the back squat, the so-called sticking region ( Figure 1) has been identified as the weakest and most constraining element of squat performance, as it has a profound impact on the load that the athlete is able to lift [11]. The sticking region is the region during the concentric phase in which a loss in lifting velocity and a decrease in vertical acceleration occurs and has been shown to be associated with changes in the activation timing of the knee and hip extensors with increasing neuromuscular fatigue [12][13][14][15][16]. ...
... Prior to data acquisition, the participants completed an individual warm-up session of 5-10 min and a set of squats without weights to familiarize themselves with the training equipment and test protocol. The squat performance testing protocol was based on the most current knowledge in VBT with clear instructions given by a trained coach on the order of tests and how to execute the free weight back squat with maximum voluntary lifting velocity [10,11]. VBT recommendations were adopted as an objective approach to assess squat performance by means of velocity measures during exercise execution. ...
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Identifying key criteria of squat performance is essential to avoiding injuries and optimizing strength training outcomes. To work towards this goal, this study aimed to assess the correlation between lower limb anatomy and back squat performance during a set-to-exhaustion in resistance-trained males and females. Optical motion captures of squat performance and data from magnetic resonance imaging (MRI) of the lower limbs were acquired in eight healthy participants (average: 28.4 years, four men, four women). It was hypothesized that there is a correlation between subject-specific musculoskeletal and squat-specific parameters. The results of our study indicate a high correlation between the summed volume of the hamstrings and quadriceps and squat depth normalized to thigh length (r = −0.86), and a high correlation between leg size and one-repetition maximum load (r = 0.81), respectively. Thereby, a marked difference was found in muscle volume and one-repetition maximum load between males and females, with a trend of females squatting deeper. The present study offers new insights for trainers and athletes for targeted musculoskeletal conditioning using the squat exercise. It can be inferred that greater muscle volume is essential to achieving enhanced power potential, and, consequently, a higher 1RM value, especially for female athletes that tend to squat deeper than their male counterparts.
... The second category of studies reported velocity data that allowed for RIR estimations [22][23][24][53][54][55][56][57][58][59][60][61][62][63][64][65]. Utilizing the most representative citations available [66][67][68][69], equations were utilized or created to predict the maximum possible number of repetitions at a given load based on the repetitions performed and the intra-set VL. These equations were matched by exercise, loading range, training status, sex, and concentric intended velocity as closely as possible. ...
... For example, Pareja-Blanco and colleagues [22] reported a mean velocity loss of 41.9 ± 1.9% in the VL40 group. Using the reported average number of repetitions per set (6.5 ± 0.9) and load used (75% of 1RM), the maximum possible number of repetitions was predicted using the regression equations for the Smith-machine squat published by Rodriguez-Rosell et al. [66]. ...
... When subtracting the average number of repetitions performed per set reported by Pareja-Blanco et al. [22], the estimated RIR was 1.81. However, because the average load reported 6 was 75% of 1RM, we averaged the estimated RIR created from the equations for 70% and 80% of 1RM from Rodriguez-Rosell [66], resulting in the final estimated RIR for the VL40 group of 1.67. The prediction equations that were used for each velocity loss study can be found in supplementary file 1. ...
... repetitions performed with respect to the maximum number that can be completed) [5]. Indeed, recent studies have reported strong relationships between the VL experienced in a set and the percentage of performed repetitions with respect to the maximum number that can be completed in bench press and back-squat exercises with different loads [6,9]. In one study [6], it was observed that the percentage of performed repetitions for a given magnitude of VL was very similar for all loads used, especially for those ranging between 50 and 70% 1RM, although the maximum number of repetitions completed against each relative load was significantly different. ...
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Purpose This study aimed to quantify the potential variability in the volume of work completed after reaching different velocity loss (VL) thresholds and determine the effects of sex, training status and history, as well as psychological traits on the reliability and magnitude of the amount of work completed after reaching different VL thresholds using different loads in the back-squat exercise. Methods Forty-six resistance-trained people (15 females and 31 males; 18 to 40 years of age) with a wide range of strength levels, training experience, and different training practices were recruited and performed a one-repetition maximum (1RM) test, and two repetitions to failure (RTF) tests 72 h apart. RTF tests were performed with 70, 80, and 90% of 1RM with 10 min of rest between sets. The Bland–Altman analysis for multiple observations per participant and equivalence tests were used to quantify the variability in the volume of work completed after reaching different VL thresholds, whereas linear and generalised mixed-effects models were used to examine the effects of different moderators on the stability and magnitude of the amount of work completed after reaching different VL thresholds. Results The findings of the present study question the utility of using VL thresholds to prescribe resistance training (RT) volume as the agreement in the amount of work completed across two consecutive testing sessions was not acceptable. Regardless of the load used, females completed more repetitions than males across VL thresholds, while males performed repetitions at higher velocities. In addition, individuals with higher levels of emotional stability also tended to perform more repetitions across VL thresholds. Finally, sex, choice of load, strength levels and training practices, as well as emotional stability affected the linearity of the repetition–velocity relationship and when sets terminated. Conclusion Using the same VL thresholds for all individuals, while assuming generalisability of the stimuli applied, would likely lead to variable acute physiological responses to RT and divergent neuromuscular adaptations over long term. Therefore, VL monitoring practices could be improved by considering sex, training status, history, and psychological traits of individuals due to their effects on the variability in responses to different VL thresholds.
... To overcome these critical aspects, an alternative methodology known as velocity-based training (VBT) has been developed (Rodríguez-Rosell et al., 2020;Pelland et al., 2022;Zhang et al., 2022). VBT consists in monitoring the speed at which the load is lifted using a linear position transducer (LPT) and then estimating the 1RM (González- Badillo and Sánchez-Medina, 2010) This is possible thanks to the relationship between load and velocity, where the higher the load, the lower the execution velocity (González- Badillo and Sánchez-Medina, 2010). ...
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Introduction: This study aimed to determine if adjusting the loads via velocity-based training (VBT) in each session is more efficient in monitoring the relative intensity than programming loads assessing 1RM pre-training. Methods: To achieve this, six national level sprinters were randomly divided into two groups, i.e., adjusting loads (AL, n = 3) and not adjusting loads (NAL, n = 3), during twelve sessions of a squat training (ST) program. During this training intervention, the AL group adjusted the intensity for each session in the squat exercise depending on the speed the load was lifted after warmup. The NAL group, instead, progressed in the squat exercise referring to the 1RM estimated at pre-test. In addition, Parallel Squat (PSQ), Countermovement Jump (CMJ), Squat Jump (SJ), 30 m sprint standing start (30S) and 30 m sprint flying start (30F) tests were carried out before and after conducting the ST program. Results: Interestingly, AL performed the ST near their estimated velocities at 70%—75% 1RM, however with a wider gap at 80%—85% 1RM. The NAL group, instead, did not presented such a detectable behaviour across the whole ST. Moreover, both groups demonstrated improved performances in PSQ, CMJ, and SJ, whereas there were little changes in 30S and 30F after ST. Additionally, AL obtained a greater effect size than NAL in PSQ (0.60 vs. 0.35) but lower effect size in CMJ, SJ, 30S, and 30F (0.41 vs. 0.63, 0.30 vs. 0.40, 0.04 vs. 0.28 and 0.22 vs. 0.24). However, percentage change was greater in AL in all tests. Discussion: Based on these findings, we can conclude that further investigation into the AL strategy in VBT is warranted for sprinter athletes’ daily strength practices. The AL technique shows promise as a valuable tool for accurately adjusting and monitoring medium-high training loads to ensure they align with the intended intensity.
... The first point to consider, which is essential to clarify before progressing in the discussion, is that the Corner and StrikeTec punch trackers did not always provide specific units of measurement for their variables, nor did they always specify whether the variables were derived from the mean or peak. As with most sport-related movements, there are instances where, e.g., peak velocity may be more important than mean velocity (or vice versa) (17,29,32,35). However, only Hykso specified whether its data represented peak or mean values (Hykso specifically states that it measures peak velocity). ...
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Omcirk, D, Vetrovsky, T, Padecky, J, Malecek, J, and Tufano, JJ. Validity of commercially available punch trackers. J Strength Cond Res XX(X): 000-000, 2023-This study determined how well data from commercially available punch trackers (Corner, Hykso, and StrikeTec) related to gold-standard velocity and force measures during full-contact punches. In a quasi-randomized order, 20 male subjects performed 6 individual rear straight punches, rear hooks, and rear uppercuts against a wall-mounted force plate. Punch tracker variables were compared with the peak force of the force plate and to the peak (QPV) and mean velocity (QMV) assessed through Qualisys 3-dimensional tracking. For each punch tracker variable, Pearson's correlation coefficient, mean absolute percentage error (MAPE), and mean percentage error (MPE) were calculated. There were no strong correlations between punch tracker data and gold-standard force and velocity data. However, Hykso "velocity" was moderately correlated with QMV (r = 0.68, MAPE 0.64, MPE 0.63) and QPV (r = 0.61, MAPE 0.21, MPE -0.06). Corner Power G was moderately correlated with QMV (r = 0.59, MAPE 0.65, MPE 0.58) and QPV (r = 0.58, MAPE 0.27, MPE -0.09), but Corner "velocity" was not. StrikeTec "velocity" was moderately correlated with QMV (r = 0.56, MAPE 1.49, MPE 1.49) and QPV (r = 0.55, MAPE 0.46, MPE 0.43). Therefore, none of the devices fared particularly well for all of their data output, and if not willing to accept any room for error, none of these devices should be used. Nevertheless, these devices and their proprietary algorithms may be updated in the future, which would warrant further investigation.
Chapter
Personalized learning is one of the main characteristics of an Intelligent Tutoring System (ITS). In the case of strength development, individualization consists in defining exercise characteristics starting from a program template and adjusting the function of several data such as trainee characteristics, calibration test results, fatigue level estimation, or estimation of the number of repetitions in reserve. A recent ITS built for supporting the development of strength skills is Selfit, currently in the second release. Most data collected within Selfit is subjective and relies on trainees’ self-evaluation abilities. To complete them with objective ones, a study evaluating the relevance of Velocity-Based Training (VBT) demonstrates that an ITS's GUI module can collect the speed of realization of a movement performed by a trainee through computer vision technologies. A batch of 25 athletes, from which 14 experienced rugby players and 11 elite swimmers, performed 2 sets at 80% of their 1-repetition maximum back-squat in their usual practice environment. A smartphone was used to record sagittal plane video and track the shape of the weight plate from which the barbell center was derived. The added value of the approach is that the system can support the definition of an objective measure of the difference between prescribed and realized exercise. Lessons from the study support the definition of requirements to enhance the Selfit v2.0 learning individualization functionalities.
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Geschwindigkeitsbasiertes Krafttraining verbessert die Sprung-, Spring- und Kraftleistung. Die Autoren haben verschiedene Studien miteinander verglichen, um herauszufinden, ob die Trainingseffekte hierbei besser sind als bei traditionellem Krafttraining.
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This study assessed the reliability of mean concentric bar velocity from 3- to 0-repetitions in reserve (RIR) across four sets in different exercises (bench press and prone row) and with different loads (60 and 80% 1-repetition maximum; 1RM). Whether velocity values from set one could be used to predict RIR in subsequent sets was also examined. Twenty recreationally active males performed baseline 1RM testing before two randomised sessions of four sets to failure with 60 or 80% 1RM. A linear position transducer measured mean concentric velocity of repetitions, and the velocity associated with each RIR value up to 0-RIR. For both exercises, velocity decreased between each repetition from 3- to 0-RIR (p ≤ 0.010). Mean concentric velocity of RIR values was not reliable across sets in the bench press (mean intraclass correlation coefficient [ICC] = 0.40, mean coefficient of variation [CV] = 21.3%), despite no significant between-set differences (p = 0.530). Better reliability was noted in the prone row (mean ICC = 0.80, mean CV = 6.1%), but velocity declined by 0.019-0.027 m·s-1 (p = 0.032) between sets. Mean concentric velocity was 0.050-0.058 m·s-1 faster in both exercises with 60% than 80% 1RM with (p < 0.001). At the individual level, the velocity of specific RIR values from set one accurately predicted RIR from 5- to 0-RIR for 30.9% of repetitions in subsequent sets. These findings suggest that velocity of specific RIR values vary across exercises, loads and sets. As velocity-based RIR estimates were not accurate for 69.1% of repetitions, alternative methods to should be considered for autoregulating of resistance exercise in recreationally active individuals.
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This study aimed to explore the acute effect of four velocity-based resistance training (VBT) protocols on 2000-meter rowing ergometer (RE2000) time-trial, as well as the behavior of the maximal neuromuscular capacities when RE2000 is performed alone or preceded by VBT protocols in the same session. Fifteen male competitive rowers (15-22 years) undertook five randomized protocols in separate occasions: i) RE2000 alone (control condition); ii) VBT against 60% of one-repetition maximum (1RM) with a velocity loss in the set of 10% followed by RE2000 (VBT60-10+RE2000); iii) VBT against 60% 1RM with a velocity loss in the set of 30% followed by RE2000 (VBT60-30+RE2000); iv) VBT against 80% 1RM with a velocity loss in the set of 10% followed by RE2000 (VBT80-10+RE2000); v) VBT against 80% 1RM with a velocity loss in the set of 30% followed by RE2000 (VBT80-30+RE2000). The load-velocity relationship (load-axis intercept [L0], velocity-axis intercept [v0], and area under the load-velocity relationship line [Aline]) was used to evaluate before and after each protocol the maximal neuromuscular capacities during the prone bench pull exercise. The time-trial was significantly longer for VBT60-30+RE2000 and VBT80-30+RE2000 than for RE2000, VBT60-10+RE2000 and VBT80-10+RE2000 (all P<0.001; ES=0.10-0.15). L0 and Aline were significantly reduced after all protocols (P<0.001; ES=0.10-0.13), with Aline reduction more accentuated for VBT60-10+RE2000, VBT60-30+RE2000, VBT80-30+RE2000, and RE2000 (all P=0.001; ES=0.11-0.18) than for VBT80-10+RE2000 (P=0.065; ES=0.05). Therefore, VBT protocols with greater velocity loss in the set (30% vs. 10%) negatively affected subsequent rowing ergometer performance, in line with impairment in Aline pulling performance.
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The use of bar velocity to estimate relative load in the back squat exercise was examined. Eighty strength-trained men performed a progressive loading test to determine their one-repetition maximum (1RM) and load-velocity relationship. Mean (MV), mean propulsive (MPV) and peak (PV) velocity measures of the concentric phase were analyzed. Both MV and MPV showed a very close relationship to %1RM (R2 = 0.96), whereas a weaker association (R2 = 0.79) and larger SEE (0.14 vs. 0.06 m•s-1) was found for PV. Prediction equations to estimate load from velocity were obtained. When dividing the sample into three groups of different relative strength (1RM/body mass), no differences were found between groups for the MPV attained against each %1RM. MV attained with the 1RM was 0.32 ± 0.03 m•s-1. The propulsive phase accounted for 82% of concentric duration at 40% 1RM, and progressively increased until reaching 100% at 1RM. Provided that repetitions are performed at maximal intended velocity, a good estimation of load (%1RM) can be obtained from mean velocity as soon as the first repetition is completed. This finding provides an alternative to the often demanding, time-consuming and interfering 1RM or nRM tests and allows to implement a velocity-based resistance training approach.
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Prescribing training intensity and volume is a key problem when designing resistance training programmes. One approach is to base training prescription on the number of repetitions performed at a given percentage of repetition maximum due to the correlation found between these two measures. However, previous research has raised questions as to the accuracy of this method, as the repetitions completed at different percentages of 1RM can differ based upon the characteristics of the athlete. The objective of this study was therefore to evaluate the effect of an athlete's training background on the relationship between the load lifted (as a percentage of one repetition maximum) and the number of repetitions achieved. Eight weightlifters and eight endurance runners each completed a one repetition maximum test on the leg press and completed repetitions to fatigue at 90, 80 and 70% of their one repetition maximum. The endurance runners completed significantly more repetitions than the weightlifters at 70% (39.9 ± 17.6 versus 17.9 ± 2.8; p < 0.05) and 80% (19.8 ± 6.4 versus 11.8 ± 2.7; p < 0.05) of their one repetition maximum but not at 90% (10.8 ± 3.9 versus 7.0 ± 2.1; p > 0.05) of one repetition maximum. These differences could be explained by the contrasting training adaptations demanded by each sport. This study suggests that traditional guidelines may underestimate the potential number of repetitions that can be completed at a given percentage of 1RM, particularly for endurance trained athletes.
Article
This study analyzed whether the loss of repetition velocity during a resistance exercise set was a reliable indicator of the number of repetitions left in reserve. Following the assessment of one-repetition (1RM) strength and full load-velocity relationship, thirty men were divided into three groups according to their 1RM strength/body mass: novice, well-trained and highly-trained. On two separate occasions and in random order, subjects performed tests of maximal number of repetitions to failure against loads of 65%, 75% and 85% 1RM in four exercises: bench press, full squat, prone bench pull and shoulder press. For each exercise, and regardless of the load being used, the absolute velocities associated to stopping a set before failure, leaving a certain number of repetitions (2, 4, 6 or 8) in reserve, were very similar and showed a high reliability (CV 4.4-8.0%). No significant differences in these stopping velocities were observed for any resistance training exercise analyzed between the novice, well-trained and highly-trained groups. These results indicate that by monitoring repetition velocity one can estimate with high accuracy the proximity of muscle failure and, therefore, to more objectively quantify the level of effort and fatigue being incurred during resistance training. This method emerges as a substantial improvement over the use of perceived exertion to gauge the number of repetitions left in reserve.
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This study aimed to analyze: 1) the pattern of repetition velocity decline during a single set to failure against different submaximal loads (50-85% 1RM) in the bench press exercise; and 2) the reliability of the percentage of performed repetitions, with respect to the maximum possible number that can be completed, when different magnitudes of velocity loss have been reached within each set. Twenty-two men performed 8 tests of maximum number of repetitions (MNR) against loads of 50-55-60-65-70-75-80-85% 1RM, in random order, every 6-7 days. Another 28 men performed 2 separate MNR tests against 60% 1RM. A very close relationship was found between the relative loss of velocity in a set and the percentage of performed repetitions. This relationship was very similar for all loads, but particularly for 50-70% 1RM, even though the number of repetitions completed at each load was significantly different. Moreover, the percentage of performed repetitions for a given velocity loss showed a high absolute reliability. Equations to predict the percentage of performed repetitions from relative velocity loss are provided. By monitoring repetition velocity and using these equations, one can estimate, with considerable precision, how many repetitions are left in reserve in a bench press exercise set.
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Resistance exercise intensity is commonly prescribed as a percent of 1 repetition maximum (1RM). However, the relationship between percent 1RM and the number of repetitions allowed remains poorly studied, especially using free weight exercises. The purpose of this study was to determine the maximal number of repetitions that trained (T) and untrained (UT) men can perform during free weight exercises at various percentages of 1RM. Eight T and 8 UT men were tested for 1RM strength. Then, subjects performed 1 set to failure at 60, 80, and 90% of 1RM in the back squat, bench press, and arm curl in a randomized, balanced design. There was a significant (p < 0.05) intensity x exercise interaction. More repetitions were performed during the back squat than the bench press or arm curl at 60% 1RM for T and UT. At 80 and 90% 1RM, there were significant differences between the back squat and other exercises; however, differences were much less pronounced. No differences in number of repetitions performed at a given exercise intensity were noted between T and UT (except during bench press at 90% 1RM). In conclusion, the number of repetitions performed at a given percent of 1RM is influenced by the amount of muscle mass used during the exercise, as more repetitions can be performed during the back squat than either the bench press or arm curl. Training status of the individual has a minimal impact on the number of repetitions performed at relative exercise intensity.
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We compared the effects of two resistance training (RT) programs only differing in the repetition velocity loss allowed in each set: 20% (VL20) vs 40% (VL40) on muscle structural and functional adaptations. Twenty-two young males were randomly assigned to a VL20 (n = 12) or VL40 (n = 10) group. Subjects followed an 8-week velocity-based RT program using the squat exercise while monitoring repetition velocity. Pre- and post-training assessments included: magnetic resonance imaging, vastus lateralis biopsies for muscle cross-sectional area (CSA) and fiber type analyses, one-repetition maximum strength and full load-velocity squat profile, countermovement jump (CMJ), and 20-m sprint running. VL20 resulted in similar squat strength gains than VL40 and greater improvements in CMJ (9.5% vs 3.5%, P < 0.05), despite VL20 performing 40% fewer repetitions. Although both groups increased mean fiber CSA and whole quadriceps muscle volume, VL40 training elicited a greater hypertrophy of vastus lateralis and intermedius than VL20. Training resulted in a reduction of myosin heavy chain IIX percentage in VL40, whereas it was preserved in VL20. In conclusion, the progressive accumulation of muscle fatigue as indicated by a more pronounced repetition velocity loss appears as an important variable in the configuration of the resistance exercise stimulus as it influences functional and structural neuromuscular adaptations.
Article
This study compared the time course of recovery following two resistance exercise protocols differing in the number of repetitions per set with regard to the maximum possible (to failure) number. Ten men performed three sets of 6 versus 12 repetitions with their 70% 1RM (3 × 6 [12] versus 3 × 12 [12]) in the bench press (BP) and squat (SQ) exercises. Mechanical [CMJ height, velocity against the 1 m s(-1) load (V1 -load)], biochemical [testosterone, cortisol, growth hormone, prolactin, insulin-like growth factor-1, creatine kinase (CK)] and heart rate variability (HRV) and complexity (HRC) were assessed pre-, postexercise (Post) and at 6, 24 and 48 h-Post. Compared with 3 × 6 [12], the 3 × 12 [12] protocol resulted in significantly: higher repetition velocity loss within each set (BP: 65% versus 26%; SQ: 44% versus 20%); reduced V1 -load until 24 h-Post (BP) and 6 h-Post (SQ); decreased CMJ height up to 48 h-Post; greater increases in cortisol (Post), prolactin (Post, 48 h-Post) and CK (48 h-Post); and reductions in HRV and HRC at Post. This study shows that the mechanical, neuroendocrine and autonomic cardiovascular response is markedly different when manipulating the number of repetitions per set. Halving the number of repetitions in relation to the maximum number that can be completed serves to minimize fatigue and speed up recovery following resistance training.
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This study analyzed the time course of recovery following 2 resistance exercise protocols differing in level of effort: maximum (to failure) vs. half-maximum number of repetitions per set. 9 males performed 3 sets of 4 vs. 8 repetitions with their 80% 1RM load, 3×4(8) vs. 3×8(8), in the bench press and squat. Several time-points from 24 h pre- to 48 h post-exercise were established to assess the mechanical (countermovement jump height, CMJ; velocity against the 1 m·s(-1) load, V1-load), biochemical (testosterone, cortisol, GH, prolactin, IGF-1, CK) and heart rate variability (HRV) and complexity (HRC) response to exercise. 3×8(8) resulted in greater neuromuscular fatigue (higher reductions in repetition velocity and velocity against V1-load) than 3×4(8). CMJ remained reduced up to 48 h post-exercise following 3×8(8), whereas it was recovered after 6 h for 3×4(8). Significantly greater prolactin and IGF-1 levels were found for 3×8(8) vs. 3×4(8). Significant reductions in HRV and HRC were observed for 3×8(8) vs. 3×4(8) in the immediate recovery. Performing a half-maximum number of repetitions per set resulted in: 1) a stimulus of faster mean repetition velocities; 2) lower impairment of neuromuscular performance and faster recovery; 3) reduced hormonal response and muscle damage; and 4) lower reduction in HRV and HRC following exercise. © Georg Thieme Verlag KG Stuttgart · New York.
Article
Abstract This study analysed the effect of imposing a pause between the eccentric and concentric phases on the biological within-subject variation of velocity- and power-load isoinertial assessments. Seventeen resistance-trained athletes undertook a progressive loading test in the bench press (BP) and squat (SQ) exercises. Two trials at each load up to the one-repetition maximum (1RM) were performed using 2 techniques executed in random order: with (stop) and without (standard) a 2-s pause between the eccentric and concentric phases of each repetition. The stop technique resulted in a significantly lower coefficient of variation for the whole load-velocity relationship compared to the standard one, in both BP (2.9% vs. 4.1%; P = 0.02) and SQ (2.9% vs. 3.9%; P = 0.01). Test-retest intraclass correlation coefficients (ICCs) were r = 0.61-0.98 for the standard and r = 0.76-0.98 for the stop technique. Bland-Altman analysis showed that the error associated with the standard technique was 37.9% (BP) and 57.5% higher (SQ) than that associated with the stop technique. The biological within-subject variation is significantly reduced when a pause is imposed between the eccentric and concentric phases. Other relevant variables associated to the load-velocity and load-power relationships such as the contribution of the propulsive phase and the load that maximises power output remained basically unchanged.