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Can Resistance Training Enhance the Rapid Force Development in Unloaded Dynamic Isoinertial Multi-Joint Movements? A Systematic Review

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The objectives of this systematic review were to (a) evaluate whether resistance training can improve the rapid force development in unloaded dynamic isoinertial multi-joint movements and (b) investigate whether these effects differ between untrained/recreationally trained and well-trained individuals. Four electronic databases were screened for studies that measured the effects of resistance training on rapid force development in unloaded dynamic isoinertial multi-joint movements. Twelve studies with a total of 271 participants were included. 11/36 (31%) and 6/17 (35%) of the measures of rapid force development in unloaded dynamic isoinertial multi-joint movements significantly improved following training in the untrained/recreationally trained and well-trained individuals, respectively. Additionally, 7/20 (35%) and 4/16 (25%) of the measures significantly improved during a countermovement and squat jump in the untrained/recreationally trained individuals and 4/6 (67%) and 2/11 (18%) significantly improved during a countermovement and squat jump in the well-trained individuals, respectively. These findings indicate that resistance training has a limited transfer to rapid force development in unloaded dynamic isoinertial multi-joint movements, especially for well-trained individuals and in movements without a countermovement. Furthermore, rapid force development has likely a limited transfer from movements with countermovement to movements without a countermovement and from bilateral movements to unilateral movements. Therefore, it is important to specifically mimic the actual sport movement in order to maximize the transfer of training and testing.
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BRIEF REVIEW
CAN RESISTANCE TRAINING ENHANCE THE RAPID
FORCE DEVELOPMENT IN UNLOADED DYNAMIC
ISOINERTIAL MULTI-JOINT MOVEMENTS?A
SYSTEMATIC REVIEW
BAS VAN HOOREN,
1
FRANS BOSCH,
1
AND KENNETH MEIJER
2
1
Institute of Sports, Fontys University of Applied Sciences, Eindhoven, the Netherlands; and
2
Department of Human Movement
Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+,
Maastricht, the Netherlands
ABSTRACT
Van Hooren, B, Bosch, F, and Meijer, K. Can resistance training
enhance the rapid force development in unloaded dynamic
isoinertial multi-joint movements? A systematic review. J
Strength Cond Res 31(8): 2324–2337, 2017—The objectives
of this systematic review were to (a) evaluate whether resis-
tance training can improve the rapid force development in un-
loaded dynamic isoinertial multi-joint movements and (b)
investigate whether these effects differ between untrained/
recreationally trained and well-trained individuals. Four elec-
tronic databases were screened for studies that measured
the effects of resistance training on rapid force development
in unloaded dynamic isoinertial multi-joint movements. Twelve
studies with a total of 271 participants were included. 10/26
(38%) and 6/14 (43%) of the measures of rapid force devel-
opment in unloaded dynamic isoinertial multi-joint movements
significantly improved following training in the untrained/recrea-
tionally trained and well-trained individuals, respectively. Addi-
tionally, 7/14 (50%) and 3/12 (25%) of the measures
significantly improved during a countermovement and squat
jump in the untrained/recreationally trained individuals and
4/6 (67%) and 2/8 (25%) significantly improved during a coun-
termovement and squat jump in the well-trained individuals,
respectively. These findings indicate that resistance training
has a limited transfer to rapid force development in unloaded
dynamic isoinertial multi-joint movements, especially for well-
trained individuals and in movements without a countermove-
ment. Furthermore, rapid force development has likely a limited
transfer from movements with countermovement to movements
without a countermovement and from bilateral movements to
unilateral movements. Therefore, it is important to specifically
mimic the actual sport movement in order to maximize the
transfer of training and testing.
KEY WORDS rate of force development, muscle slack, co-
contractions, explosive sport performance, high-intensity sport
performance, transfer of training
INTRODUCTION
During most sport situations, there is limited
time to develop force and the capability to
rapidly develop force is therefore of para-
mount importance for successful sport perfor-
mance. Resistance training is one of the training modalities
that is used to improve rapid force development. However,
the effects of resistance training on rapid force develop-
ment are usually assessed in movements with external load
(17,27,29,34,35,42,43,50,56,58,66,68), while there usually
is hardly any or no external load during the actual sports
performance.
Transfer of Loaded Movements to Unloaded Movements
The transfer between a movement performed with external
load in a test or training and the actual sport performance
may be limited when there is no large external load in the
actual sport performance. Indeed, only very small to
moderate correlations have been found between 5 and
10 m sprint performance and several measures of rapid
force development in a loaded countermovement jump
(CMJ) among students (42,43). In another study, several
measures of the rapid force development during a loaded
CMJ could not differentiate between faster and slower pro-
fessional rugby union players (29). Furthermore, only very
small to moderate correlations were found between the
rapid force development during a loaded squat jump (SJ)
or loaded CMJ and 30 m sprint performance in a study
among competitive individuals (66). In contrast, in the only
study that compared the transfer of both loaded and un-
loaded jumps with an isoinertial movement, a stronger
Address correspondence to Bas Van Hooren, basvanhooren@
hotmail.com.
31(8)/2324–2337
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correlation was found between several sprint distances
and the rate of force development in a loaded CMJ com-
pared to the rate of force development in an unloaded SJ
and CMJ (50). These findings are in contrast with the idea
that the addition of external load results in a reduced
transfer to isoinertial movements. However, the latter
study used skeleton athletes and since skeleton involves
pushing against an external load (maximum 43 kg for
men) this may explain the higher correlations for the
loaded jumps in this study. It should be noted though that
there are also other differences between sprinting and
a loaded CMJ. For example, sprinting is an unilateral
activity, while vertical jumping is usually performed bilat-
erally. Differences in the mechanisms of force production
between bilateral and unilateral movements such as
a higher need for stability, alterations in the force-
velocity relationship and interhemispheric inhibition
may also reduce the transfer between these movements
(11,52,62). Additionally, while rapid force development
is frequently measured in a movement with (a large) coun-
termovement (14,29,42,43,46,47,50,66), in many sports
situations there is usually no time to perform a large coun-
termovement. Since the countermovement may take up
muscle slack (which is represented by the delay between
muscular contraction and recoil of the tendinous tissues)
and allow an increased time to build-up activation and
a thus active state (63,64), a movement involving a (large)
countermovement may also limit the transfer to move-
ments with a small or no countermovement.
Although there are some discrepancies and other factors
that may influence the transfer, these findings suggests that
loaded movements generally have a limited transfer to
unloaded movements (i.e., not involving external load such
as barbells, weights, chains, elastic bands, etc.). Training with
an external load may therefore also have a less pronounced
transfer to movements without external load that commonly
assumed.
The aim of this systematic review is therefore to deter-
mine whether training with external load (i.e., resistance
training) can improve the rapid force development in
movements with no, or hardly any external load such as
a CMJ or SJ, performed with body mass only. To answer this
question, we conducted a systematic literature search to
identify studies that investigated changes in rapid force
development in unloaded, dynamic, isoinertial, multi-joint
movements following resistance training.
Delimitations
For this review, resistance training was defined as a training
intervention of at least 4 weeks involving an external load
provided by barbells, weights, chains or elastic bands.
Furthermore, rapid force development was defined as the
force developed during the first 300 ms after onset of force
development because this time frame reflects the time avail-
able for force development in several athletic events (70).
Unloaded Movements. Unloaded movements were defined as
movements that did not involve any other load than body
mass. Some studies used a linear position transducer to
measure rapid force development and this position trans-
ducer applies a pulling force, which could be interpreted as
a loaded movement. However, the resistance provided by
a linear position transducer is small (12) and therefore,
movements performed with a linear position transducer
were also considered unloaded.
Dynamic Movements. Assessments of rapid force develop-
ment were only included when they were performed
in dynamic movements because both multiple and single-
joint isometric assessments of rapid force develop-
ment have a limited transfer to dynamic rapid force
development (4,21,22,25,27,34–36,48,55,66) or dynamic
movements (21,40,66).
Isoinertial Movements. Most movements are characterized by
acceleration and deceleration of a constant mass (i.e.,
isoinertial) and not by moving a changing mass at a constant
velocity (i.e., isokinetic). Hence, the transfer between iso-
kinetic and isoinertial movements is limited (67) and there-
fore, only assessments of rapid force development in
isoinertial movements were included.
Multi-Joint Movements. Finally, most movements are the
result of complex coordinative patterns among multiple-
joints (7,32) and it has been shown that single-joint training
can disrupt these coordination patterns, hereby limiting the
transfer to multi-joint movements (16,39). Therefore, single-
joint isoinertial assessments of rapid force development were
also excluded.
The Effects of Training Experience
It has previously been hypothesised that resistance
training can also result in a decreased capability to rapidly
develop force and this negative effect of resistance training
may be more pronounced in well-trained individuals
compared to untrained and recreationally trained individ-
uals because most of the positive adaptations following
resistance training may already be well developed in well-
trained individuals (63). Negative adaptations such as
a reduced capability to quickly build-up activation and
a reduced capability to co-activate muscles may nega-
tively influence the capability to rapidly develop force.
In contrast, for untrained and recreationally trained indi-
viduals, the positive adaptations following training may
mask the negative influence(s) of resistance training.
Therefore, a second aim is to investigate the degree to
which training experience influences changes in
rapid force development following resistance training. A
subdivision is made for studies that used untrained and
recreationally trained individuals and studies that used
well-trained individuals.
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METHODS
Search Strategy
A systematic review of the literature was conducted in
accordance with the Preferred Reporting Items for System-
atic Reviews and Meta-Analysis Protocol (PRISMA-p) 2015
guidelines (44,51). One researcher (B.V.H.) searched the
electronic databases from Google Scholar, Web of Science,
MEDLINE (via EBSCOhost) and PubMed between January
14, 2016 and January 15, 2016. Relevant studies published
anytime up to January 15, 2016 were included. The following
combination of keywords and Booleans was used: (“rate of
force development” OR “explosive strength” OR “rapid force
production” OR “rapid force development” OR “explosive
force production” OR “explosive force development” OR
“time to peak force” OR “starting strength”) AND (“vertical
jump” OR “countermovement jump” OR “squat jump” OR
“jump squat” OR “squat” OR “overhead throw”) AND
(“resistance training” OR “weightlifting” OR “ballistic train-
ing” OR “external load” OR “strength training” OR “elastic
bands” OR “chains”).
Inclusion Criteria
Eligibility criteria for study inclusion were: (a) written in
English, (b) published in a peer-reviewed journal, (c)
intervention duration of minimum 4 weeks, (d) intervention
that involved an external load such as a barbell, weights,
chains, elastic bands, (e) healthy participants aged between
16 and 65, (f ) measurement of the rapid force development
in unloaded dynamic isoinertial multi-joint movements, (g)
measurement of the rapid force development in the first 300
ms after onset of force development, (h) measurement of the
rapid force development by “time to peak force” or “time to
produce a certain percentage of peak force” or “force at
a certain amount of ms” or “starting strength” or “rate of
force development” or closely related concepts such as
“maximum rate of force development” or “relative rate of
force development.” Forward citation and reference lists of
retrieved full-text articles were examined to identify addi-
tional articles that were not found by the initial search. Only
full-text articles were included so that the methods could be
assessed.
Literature Selection
Studies were screened for eligibility in 2 consecutive phases.
Phase one consisted of screening for (a) duplicates, (b) title,
and (c) abstract. Phase 2 consisted of screening the full article
using the inclusion criteria. Full-text was obtained for all
articles that appeared to meet the inclusion criteria or when
there was uncertainty.
Data Extraction
Data extraction was done by one author (B.V.H.) using
a standardized form. Extracted data from each article
included study identification information, sample size, sex,
age, training experience, frequency and duration of
the training intervention, type of training method, test
movement, measure of rapid force development and infor-
mation required to assess the risk of bias of the study. Data to
calculate the effect size were also extracted for meta-analysis.
Initially, 6 studies that met the inclusion criteria did not
provide enough information to calculate the effect size
(13,15,30,38,39,46) and 4 authors did also not provide this
data after multiple requests. Therefore, a meta-analysis was
not undertaken, but effect sizes were calculated when
possible.
Effect Size Calculation
To allow comparison of the effect magnitude between
studies, effect sizes were calculated for each study (when
possible) by subtracting the pre-test mean from the post-test
mean and dividing this by the standard deviation of the pre-
test (49). When a repeated-measures design was used, the
effect size was calculated from baseline to the latest time
point, excluding a detraining period. Effect sizes rather than
percentage changes where calculated because effect sizes
take into consideration the variance of strength improve-
ments, whereas percentage changes do not. Effect sizes were
interpreted using the scale proposed by Rhea (49) because
the commonly used Cohen scale does not accurately reflect
the relative magnitude of an effect in strength training
research (49). In the Rhea scale, an effect size is considered
,0.50, trivial; 0.50–1.25, small; 1.25–1.9, moderate; and
.2.0, large for untrained individuals, ,0.35, trivial; 0.35–
0.80, small; 0.80–1.50, moderate; and .1.5, large for moder-
ately trained individuals and ,0.25, trivial; 0.25–0.50, small;
0.50–1.0, moderate; and .1.0, large for well-trained individ-
uals (49). This classification means that effect sizes are inter-
preted differently based on the sample’s training experience.
Individuals will be classified as untrained when they have not
been consistently training for 1 year; moderately trained
when they have been training for 1–5 years and well-
trained when they have been training for at least 5 years
(49). Note that this classification does not account for the
skill level of the individual. For example, participation in
(inter)national championships (i.e., elite athlete) does not
necessarily indicate that an individual is well-trained. Elite
or sub-elite athletes can still be relatively untrained when
they have only been training for 1 year. Similarly, individuals
who have been training for at least 5 years are not necessarily
elite athletes when they do not participate in (inter)national
championships. Furthermore, although the individual may
have been training for 6 years, it is well possible that the
exercises in the training program are novel to the individual.
Therefore, this classification does also not consider whether
the individual is experienced with the stimulus employed in
the study (10).
Risk of Bias Assessment
After the literature search and examination, the full-text of
relevant articles was retrieved and a risk of bias assessment
was performed independently by 2 authors (B.V.H. and
K.M.). Disagreements was resolved by discussion before the
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scores were merged into a spreadsheet. Since most risk of
bias assessments such as the Delphi scale, PEDro scale and
Cochrane scale are designed for healthcare interventions,
a modified risk of bias assessment screening scoring system
designed for exercise training studies was adopted (9). We
added one additional point (i.e., point 2) to this scale because
we considered this an important aspect related to the risk of
bias of the study. In addition, we omitted the point related to
the practically useful assessment, since studies that did not
include a useful assessment (e.g., static or isokinetic test)
were not included in this review. Therefore, a 10-item scale
(range 0–20) was used:
1. Clear inclusion criteria;
2. Clear description of the participants training experience;
3. Random allocation of the participants to groups;
4. Clearly defined intervention;
5. Similarity test at baseline for all groups;
6. Use of a control group that did not perform resistance
training;
7. Clearly defined outcome variables;
8. Adequate familiarisation period;
9. Appropriate between-group statistical analysis;
10. Point measures of variability.
The score for each criterion were rated as follows: 0 =
clearly no/not reported; 1 = maybe; and 2 = clearly yes.
Although we acknowledge that some aspects may be more
important than others, each aspect was given equal weight
and the resulting scores were considered ,10, poor; 10–15,
moderate; .15, good, and 20, excellent.
RESULTS
Search Results
The initial literature search yielded 604 records through the
electronic databases (Figure 1). After the removal of 229
duplicates, 375 records were retrained for the review. Title
and abstract screening resulted in the exclusion of 311 and
35 records, respectively. Finally, after screening 29 records
for inclusion/exclusion criteria, 22 records were rejected,
with the reason being isometric/static assessment of rapid
force development (n= 10), no assessment of rapid force
development (n= 8), no English language (n= 1), investi-
gation of acute effects (n= 1), elderly participants (n= 1) and
tests with external load (n= 1). Forward citation and screen-
ing of references yielded 5 more relevant records and there-
fore, 12 records were included in the systematic review.
Study Characteristics
A total of 12 studies has investigated the effects of
resistance training on rapid force development in unloaded
dynamic isoinertial multi-joint movements. Untrained or
recreationally trained individuals were used in 9 studies
(13–16,26,33,36,38,39). A total of 271 participants, of which
Figure 1. Flow chart of the systematic literature search.
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TABLE 1. Risk of bias assessment.*
Study
Clear
inclusion
criteria
Clear description
of the participants
training
experience
Random
allocation of
the participants
to groups
Clearly
defined
intervention
Similarity
test at
baseline for
all groups
Use of
a control
group
Clearly
defined
outcome
variables
Adequate
familiarisation
period
Appropriate
between-
group
statistical
analysis
Point
measures
of
variability Total
Jakobsen
et al.
(33)
00 010220 229
Newton
et al.
(46)
22 210110 2011
Harrison
et al.
(30)
00 220220 2010
Haff et al.
(26)
00 211020 129
Kraemer
et al.
(36)
10 220022 1212
Lamas
et al.
(38)
11 220222 2014
Cormie
et al.
(13)
00 221222 2215
Cormie
et al.
(15)
00 221222 2215
Cormie
et al.
(14)
00 221222 2215
Leirdal
et al.
(39)
00 111022 108
Dalen
et al.
(16)
00 111022 1210
Newton
et al.
(47)
10 000020 025
*0 = clearly no/not reported; 1 = maybe; and 2 = clearly yes.
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TABLE 2. Improvements in rapid force development in unloaded dynamic isoinertial multi-joint movements in untrained and recreationally trained individuals.*
Study
Total
sample
size Age (y)
Years of training
experience;
classification
Frequency;
duration of
resistance
training
Type of
training
Results
Group Test Measure
Effect size
(Rhea) p
Jakobsen
et al.
(33)
94 males 37.8 67.7 Not reported;
untrained
32 per wk;
12 wk
Heavy
resistance
training
HRG (n= 8) Unloaded
CMJ
RFD 1.35;
moderate
#0.05
CG (n= 10) Unloaded
CMJ
RFD 20.25;
trivial
$0.05
Lamas
et al.
(38)
40 males Not
reported
.2 y resistance
training;
recreationally
active
33 per wk;
8wk
Resistance or
power
training
STG (n= 14) Unloaded
CMJ
RFD — $0.05
Unloaded SJ RFD #0.05
PTG (n= 14) Unloaded
CMJ
RFD — $0.05
Unloaded SJ RFD #0.05
CG (n= 12) Unloaded
CMJ
RFD — $0.05
Unloaded SJ RFD #0.05
Cormie
et al.
(14)
32 males 23.4 64.4 Not reported;
weaker
individuals
33 per wk;
10 wk
Heavy back
squats or
ballistic
jump
squats
WPG (n= 8) Unloaded
jump squat
Total RFD 10.06; large #0.05
Eccentric
RFD
8.9; large #0.05
Unloaded SJ Total RFD 0.88; small $0.05
WSG (n= 8) Unloaded
jump squat
Total RFD 1.85;
moderate
$0.05
Eccentric
RFD
2.76; large #0.05
Unloaded SJ Total RFD 1.71;
moderate
#0.05
CG (n= 8) Unloaded
jump squat
Total RFD 20.07;
trivial
$0.05
Eccentric
RFD
20.12;
trivial
$0.05
Unloaded SJ Total RFD 20.16;
trivial
$0.05
Cormie
et al.
(15)
24 males Not
reported
Not reported;
weaker
individuals
33 per wk;
10 wk
Ballistic jump
squats
WPG (n= 8) Unloaded
jump squat
RFD 10.28; large ,0.05
CG (n= 8) Unloaded
jump squat
RFD 20.07;
trivial
$0.05
Cormie
et al.
(13)
24 males 23.9 64.8 Not reported;
relatively weak
individuals
33 per wk;
10 wk
Heavy back
squats
(HSG) or
ballistic
jump
squats
(BSG)
HSG (n= 8) Unloaded
jump squat
RFD 1.54;
moderate
#0.05
BSG (n= 8) Unloaded
jump squat
RFD 10.28; large #0.05
CG (n= 8) Unloaded
jump squat
RFD 20.07;
trivial
$0.05
(continued on next page)
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Kraemer
et al.
(36)
17 males 21.3 61.4 Not reported;
moderately
trained
34 per wk;
8wk
Resistance
and sprint/
plyometric
training
ASG (n= 8) Unloaded
CMJ
Time to 50%
peak force
0.03; trivial $0.05
Unloaded
CMJ
Time to 75%
peak force
0.10; trivial $0.05
MSG (n= 9) Unloaded
CMJ
Time to 50%
peak force
0.03; trivial $0.05
Unloaded
CMJ
Time to 75%
peak force
20.05;
trivial
$0.05
Haff et al.
(26)
36 males
and
females
19.9 60.4 Not reported;
collegiate track
and field
athletes
33 per wk;
6wk
Traditional
resistance
training,
weightlifting
and sprint
training
CrG (n= 15) Unloaded SJ Peak RFD 1.4;
moderate
$0.05
Time of peak
RFD
0.08; trivial $0.05
PG (n= 21) Unloaded SJ Peak RFD 0.2; trivial $0.05
Time of peak
RFD
0.01; trivial $0.05
Leirdal
et al.
(39)
16 men, 6
females
23.2 66.9 Not reported;
generally
trained sport
science
students
(recreationally
active
individuals)
33 per wk;
5wk
Squat with
plantar
flexion or
squat
without
plantar
flexion and
plantar
flexion
separately
Tsingle (n= 11) Unloaded SJ RFD $0.05
Tmulti (n= 11) Unloaded SJ RFD $0.05
Dalen
et al.
(16)
10 males,
3
females
20.3 61.6 Not reported;
sport science
students
(recreationally
active
individuals)
33 per wk;
5wk
Ballistic squat
with plantar
flexion or
ballistic
squat
without
plantar
flexion and
plantar
flexion
separately
MultiJ (n= 7) Unloaded SJ Time to peak
force
0.47; trivial #0.05, but
significant
increase
and thus
slower
SingleJ (n= 6) Unloaded SJ Time to peak
force
2.64; large $0.05
*HRG = heavy resistance training group; CG = control group; STG = strength training group; PTG = power training group; WPG = weaker power training group; WSG: weaker
strength training group; HSG = heavy squat group; BSG = ballistic jump squat group; ASG = athletic shoe group; MSG = meridian elyte shoe group; CrG = creatine supplementation
group; PG = placebo group; Tsingle = single joint training group; Tmulti = multi joint training group; MultiJ = multi joint group; SingleJ = single joint group; RFD = rate of force
development; CMJ = countermovement jump; SJ = squat jump.
A decrease in the time to peak force is indicative of an improved rapid force development.
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TABLE 3. Improvements in rapid force development in unloaded dynamic isoinertial multi-joint movements in well-trained individuals.*
Study
Total
sample
size Age (y)
Years of training
experience;
classification
Frequency;
duration of
resistance
training Type of training
Results
Group Test Measure Effect size p
Cormie
et al.
(14)
32 males 23.4 64.4 Not reported;
stronger
individuals
33 per wk;
10 wk
Ballistic jump squats SPG (n= 8) Unloaded
jump squat
Total RFD 3.05; large #0.05
Eccentric
RFD
2.76; large #0.05
Unloaded SJ Total RFD 0.98;
moderate
$0.05
Cormie
et al.
(15)
24 males Not
reported
Not reported;
stronger
individuals
33 per wk;
10 wk
Ballistic jump squats SPG (n= 8) Unloaded
jump squat
RFD 3.63; large #0.05
Harrison
et al.
(30)
15 males 20.5 62.8 Not reported;
professional and
semi-
professional
rugby players
32 per wk;
6wk
Resisted sprint
training
RS (n= 8) Unloaded SJ
on sledge
apparatus
mRFD — $0.05
Starting
strength
#0.05
Time to peak
RFD
$0.05
CG (n= 7) Unloaded SJ
on sledge
apparatus
mRFD — $0.05
Starting
strength
$0.05
Time to peak
RFD
$0.05
Newton
et al.
(46)
16 males 19 62.2 y of resistance
training and 5 y
of volleyball
training; NCAA
division I
volleyball players
34 per wk;
8wk
Traditional and
ballistic training or
traditional training
only
TBG (n= 8) Unloaded
CMJ
mRFD — $0.05
Unloaded SJ mRFD #0.05
TG (n= 8) Unloaded
CMJ
mRFD — $0.05
Unloaded SJ mRFD $0.05
Newton
et al.
(47)
14 females 20 61.2 Not reported;
NCAA Division 1
volleyball players
32 per wk;
11 wk
Volleyball practice
and 7 wk traditional
resistance training
followed by 4 wk
ballistic resistance
training.
NCAA
volleyball
players
Unloaded SJ Time to peak
force
20.43;
small
$0.05
Unloaded SJ mRFD 0.23; trivial $0.05
Unloaded
CMJ
mRFD 1.04; large #0.05
*SPG = stronger power training group; RS = resistance training; CG = control group; TBG = traditional and ballistic training group; TG = traditional resistance training group;
RFD = rate of force development; mRFD = maximum rate of force development; CMJ = countermovement jump; SJ = squat jump.
A decrease in the time to peak force is indicative of an improved rapid force development.
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61 can be classified as well-trained, were included in either
the experimental group that performed resistance training
or the control group. The mean age of the participants
ranged from 19 to 37 years. Solely males were included in
8 studies (13–15,30,33,36,38,46), 3 study included both
males and females (16,26,39) and one study included fe-
males only (47). The participants were described as
untrained (33), relatively weak (13), recreationally active
(38), sport science students (which are likely recreationally
active) (16,39), moderately trained (36), collegiate track-
and-field athletes (26), professional and semi-professional
rugby players (30), NCAA division I volleyball players
(46,47) and weaker or stronger individuals, based on their
1RM back squat (14,15). Training modalities included tra-
ditional resistance exercises such as the back squat
(13,14,16,33,38,39), ballistic jump squat training (13–15),
resisted sprint training (30) or a combination of some of
these modalities (e.g., resistance and sprint training or resis-
tance training and volleyball practice) (26,36,46,47).
Study durations ranged from 5 to 12 weeks. Rapid
force development was measured during a body mass only
CMJ/jump squat (13–15,33,38,46,47) and/or SJ
(14,16,26,30,38,39,46,47). Rapid force development was as-
sessed using the rate of force development (13–
15,26,33,38,39), maximum rate of force development
(30,46,47), total rate of force development (14), time to
peak/maximum rate of force development (26,30), time
to peak force (16,26,47), starting strength (30) and time to
produce 50, 75 and 100% of maximal force (36). The time
to produce 100% of maximal force (36) and the time to
peak force during the SJ (26) and CMJ (47) were excluded
as measures of rapid force development since they ex-
ceeded the 300 ms time duration set as inclusion criteria.
Risk of Bias Assessment
The mean risk of bias score of the included studies was 11
(range 5–15; Table 1). Therefore, most evidence comes from
studies with a moderate risk of bias. Most studies did not
clearly describe the inclusion criteria, the training experience
of the participants and did not test for similarity at baseline.
Study Findings
Overall, 16 of the 40 (40%) measures of rapid force
development were significantly improved following train-
ing (11/20 and 5/20 or 55 and 25% for the CMJ and SJ,
respectively), indicating that most measures of rapid force
development did not significantly improve following
resistance training. In the next paragraphs, the results of
the studies are subdivided into findings for untrained
and recreationally trained individuals and well-trained
individuals.
Untrained and Recreationally Trained Individuals. Since only
one study used untrained participants, the results of both
untrained and recreationally trained individuals are summa-
rized in Table 2. In the 9 studies among untrained and
recreationally trained individuals, only 10 of the 26 (38%)
measures of rapid force development were significantly
improved following training (7/14 and 3/12 or 50% and
25% for the CMJ and SJ, respectively), indicating that most
measures of rapid force development did not significantly
improve following resistance training.
Well-Trained Individuals. The findings for well-trained indi-
viduals are summarized in Table 3. In the 5 studies that
included well-trained individuals only 6 of the 14 (43%)
measures of rapid force development were significantly
improved following training (4/6 and 2/8 or 67% and 25%
for the CMJ and SJ, respectively), indicating that most meas-
ures of rapid force development did not significantly
improve following resistance training, especially in the SJ.
DISCUSSION
The aim of this systematic review was to investigate
whether resistance training can enhance the rapid force
development in unloaded dynamic isoinertial multi-joint
movements. Overall, resistance training resulted in signif-
icant improvements in only 16 of the 40 (40%) measures of
the rapid force development in unloaded dynamic isoiner-
tial multi-joint movements. These findings suggest that
resistance training has a limited transfer to rapid force
development in movements that are characterised as
unloaded, dynamic, isoinertial and multi-joint (i.e., most
sports and daily living movements).
A second aim was to investigate the degree to which
training experience influences changes in rapid force devel-
opment following resistance training. For this purpose,
a subdivision was made between untrained or recreationally
trained individuals and well-trained individuals. Among
untrained and recreationally trained individuals, resistance
training resulted in significant improvements in only 10 of
the 26 (38%) measures of the rapid force development in
unloaded dynamic isoinertial multi-joint movements. In
addition, only 7/14 (50%) and 3/12 (25%) of the measures
of rapid force development significantly improved in the
CMJ and SJ, respectively. Among well-trained individuals,
resistance training resulted in significant improvements in
only 6 of the 14 (43%) measures of the rapid force
development in unloaded dynamic isoinertial multi-joint
movements. Additionally, 4/6 (67%) and 2/8 (25%) of the
measures of rapid force development significantly improved
in the CMJ and SJ, respectively. These findings suggest that
resistance training has a better transfer to rapid force
development in movements with countermovement for
well-trained individuals than for untrained and recreationally
trained individuals. However, these findings should be
interpreted with caution since there were only a few studies
that included well-trained individuals and studies that used
well-trained individuals have usually not assessed well-
trained elite (world-class) athletes. Additionally, the magni-
tude of improvement is generally smaller for well-trained
Resistance Training For Rapid Force Development?
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individuals (Tables 2 and 3), suggesting that resistance training
does indeed lead to less pronounced improvements of rapid
force development in unloaded dynamic isoinertial multi-joint
movements for well-trained individuals, especially in movements
without a countermovement. For example, in a direct com-
parison between stronger (better trained) and weaker indi-
viduals, the magnitude of improvement in rapid force
development following training was smaller for the stronger
individuals (14,15). In the subsequent paragraphs, we will
attempt to explain these findings and provide implications
for practice and research.
Mechanisms of Rapid Force Development
Several mechanisms such as the maximum voluntary con-
traction strength, muscle-tendon unit stiffness and neural
drive influence the capability to rapidly develop force and
the contribution of these mechanisms changes throughout
the time course of force production (2,20). For example, it
has been found that the first 100 ms of rapid force develop-
ment in isometric and isokinetic movements is primarily
influenced by the neural drive to the muscles (20,23,60),
intrinsic muscle properties such as fiber type and fascicle
length (2,3,6,20) and stiffness of the series elastic element
(6). During longer contractions (i.e., .100 ms), rapid force
development is increasingly influenced by maximum volun-
tary contraction strength (2,3,20,28,60), although neural
drive (2,20) and the stiffness of the series elastic element also
remain important (8,57). Since several studies have found
that these mechanisms can be altered by training, it is likely
that improvements in these mechanisms are responsible for
the significant improvements in rapid force development
observed in some studies. For example, the electromyo-
graphic activity or rate of increase in electromyographic
activity has been found to improve following a wide variety
of training modalities such as dynamic ballistic training
(24,61) dynamic heavy resistance training (1), isometric con-
tractions with an emphasize on rapid force production
(18,59,60) plyometric training (68) and sensimotor training
(23,24). However, all of these studies used untrained or rec-
reationally active individuals. It has previously been hypoth-
esized that resistance training has less pronounced beneficial
adaptations for well-trained individuals because most of the
adaptations such as an increased neural drive or cross-
sectional area may already be well developed (63). Negative
effects of training with an external load may in such situa-
tions be more pronounced.
Time to Build-up Activation and Influence of Muscle Slack. An
external load may allow more time to build-up activation
because the duration of the movement is likely longer than
an unloaded movement. Due to the increased movement
time, the athlete is not forced to quickly build-up activation
and this capability may therefore not be effectively be
trained. Additionally, an external load may take up muscle
slack by taking slack out of the fascicles and tendinous
tissues, by aligning the muscle-tendon unit and stretching
the tendinous tissues, hereby allowing a more rapid force
development compared to when no external load is used
(19,63,64). This may lead to more muscle slack in move-
ments without external load because the athlete’s capability
to perform co-contractions and hence take up muscle slack
may be reduced as a consequence of the supporting effect of
external load (63). Therefore, the potential effects of external
load on the capability to quickly build-up activation and on
muscle slack may partially explain the less pronounced im-
provements in rapid force development for the well-trained
individuals. In addition, this effect may also explain why the
transfer is even more limited in the SJ compared to a CMJ.
Specifically, the countermovement during a CMJ allows
more time to build-up activation (64), hereby potentially
having a similar effect as an external load. However, during
the SJ, there is no countermovement that provides the ath-
lete with more time to build-up activation. Furthermore,
during a SJ, the athlete may need to create co-contractions
to take up muscle slack, whereas the countermovement dur-
ing a CMJ can reduce the degree of muscle slack (64).
Therefore, when rapid force development is assessed during
a SJ, the negative effects of an external load may be more
pronounced.
Influence of Coordination. Training can also result in
a decreased capability to rapidly develop force. For example,
Dalen et al. (16) found a large increase in the time to peak
force during an unloaded SJ following 3 weeks of separate
ballistic squat training without plantar flexion and plantar
flexion training in sport science students. In contrast, the
group that performed a ballistic squat with plantar flexion
showed a trivial increase in the time to peak force. These
findings suggest that it is important to specifically mimic the
intermuscular coordination patterns of the sports movement
to maximise the transfer and to prevent decreases in
performance.
The Transfer of Countermovement Training. In addition to the
possible influence of muscle slack and intermuscular coor-
dination, another possible explanation for the small amount
of significant improvements in rapid force development
following resistance training is that the resistance program
used to improve rapid force development may have a limited
transfer to the test used to measure rapid force development.
Moreover, the test used to measure rapid force development
may also have limited transfer to actual sport performance.
Indeed, several studies have used a movement that involves
a countermovement when measuring the rapid force devel-
opment (14,29,42,43,46,47,50,66), while there is usually no
time to perform a large countermovement in the actual
sport. For example, an elite 100 m sprinter or an elite swim-
mer will not first perform a large countermovement after the
start signal has been given. The countermovement may
take up muscle slack and allow time to build-up activation
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(63–65) and hence reduce the transfer between the test and
actual sport performance. Therefore, assessment of the rapid
force development in a movement involving a countermove-
ment (e.g., vertical countermovement jump or horizontal
broad jump) may provide limited information for the rapid
sport performance in movements where there is no time to
perform a CM.
During the first steps of a sprint, force is primarily
generated by a concentric contraction of the contractile
element (37) and the countermovements produced by the
pendulum motion of the leg may not be large enough to
reduce a considerable amount of muscle slack and the dura-
tion may not be long enough to allow a full build-up of
activation. Therefore, measurement of the rapid force devel-
opment during a SJ may give a better representation of short
acceleration than a CMJ or drop jump. Indeed, a study
among national level skeleton athletes found (only) a moder-
ate correlation between the rate of force development in the
SJ and the 5 m sprint performance and even a smaller cor-
relation between the rate of force development in a CMJ and
the 5 m sprint performance (50).
In summary, although only one study has directly com-
pared the transfer of the rapid force development in
amovementinvolvingacountermovementvs.nocounter-
movement, the results suggest that the performance of
a countermovement also limits the transfer to movements in
which there is no time to perform a large countermovement.
The Transfer of Bilateral Movements to Unilateral Movements.
The studies included in this systematic review measured
the rapid force development in bilateral movements in
which the force production is mainly vertical (e.g., CMJ
and SJ), while the force production is both vertical and
horizontal in most unilateral movements such as sprinting
(29,30,36,41–43,50,54). Differences in the mechanisms
of force production between bilateral and unilateral
movements may also reduce the transfer between these
movements (11,52,62).
Indeed, a study among competitive team sports players
found a moderate correlation between the rate of force
development in a split squat and 5 m sprint performance and
only a small correlation between the rate of force develop-
ment in a back squat and the 5 m sprint performance among
competitive male athletes (54). Furthermore, a study among
(inter)national athletes found that the rapid force develop-
ment during a SJ and drop jump could not predict the sprint
performance over 2.5, 5 m and longer distances (41). Finally,
a study among recreationally trained individuals did not find
significant improvements in several measures of the rapid
force development during an unloaded CMJ, while 40 and
60 yards sprint performance did show a significant improve-
ment (36). The findings of these studies suggest that bilateral
tests have a limited transfer to unilateral movements, espe-
cially for well-trained individuals. However, there are also
some studies that did found simultaneous improvements in
the rate of force development during an unloaded jump
squat and the 5 m sprint performance (13,15). In addition,
another study found simultaneous improvements in the ini-
tial rate of force development during an unloaded SJ and the
30 m sprint performance (30). However, the last 3 studies
used moderately trained individuals and therefore, there is
again a trend for untrained and recreationally trained individ-
uals to show positive transfers, while these transfers are (very)
limited in well-trained individuals. Based on these findings, the
transfer from bilateral movements to unilateral movements
appears to be limited, especially for well-trained individuals.
Future research should therefore investigate whether bilateral
performed resistance training leads to an improved rapid force
development in unloaded dynamic isoinertial unilateral multi-
joint movements among well-trained individuals.
Limitations
There was a high risk of bias for the training experience
(Table 1) and therefore these results should be interpreted
with caution. Usually, only a general subdivision is made
between untrained and trained individuals. However, large
differences may also exist between an elite athlete and a sub-
elite athlete, even though they both have been training for
a long time. For example, an intervention may have a positive
effect on the maximum sprinting speed of professional foot-
ball player, but a detrimental effect on the maximum sprint-
ing speed of an elite 100 m runner. If the goal is to generalize
the results of the intervention to other populations it is
therefore important to correctly classify individuals to their
training status. Since the effect size were usually smaller, and
because there were slightly more significant improvements
in rapid force development for the SJ in untrained and rec-
reationally trained individuals compared to the well-trained
individuals, it may be expected that the resistance training
has less beneficial effects on rapid force development in un-
loaded dynamic isoinertial multi-joint movements in well-
trained elite athletes.
Another limitation is that the results of the included
studies were interpreted based on statistically significance,
instead of effect sizes and confidence intervals (5,31) as
would be possible with a meta-analysis. However, the major-
ity of the studies did not include the information necessary
to calculate the effect size and confidence intervals and most
authors did also not provide this information after multiple
requests. When possible, effect sizes were calculated and
reported in Table 2 to give an indication of the magnitude
of the effect. It should be noted though that the effect size
used in this review it not corrected for changes in the control
group whereas other effect sizes are (45). However, studies
among (sub)elite athletes usually do not include a control
group and therefore it is not possible to calculate an effect
size with correction for changes in the control group for
these studies. Calculation of an effect size with correction
for changes in the control group for untrained and recrea-
tionally trained individuals only would allow comparison
Resistance Training For Rapid Force Development?
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with (sub)elite athletes (45). Therefore, the adopted calcula-
tion of effect size was considered the most appropriate.
Finally, in this systematic review, a training intervention
involving external load was classified as resistance training.
However, there is a wide range of different resistance
training modalities such as ballistic training, hypertrophy
training and maximum strength training. Although these
modalities may have different effects on the rapid force
development, the variety in training programs among studies
was too diverse to allow strong conclusions regarding the
effects of different training modalities on rapid force
development. The results of several studies do however
suggest that ballistic resistance training is more effective than
traditional resistance training (13,14,47). Interestingly, a study
among untrained individuals found that only the group train-
ing with external load significantly improved the rate of force
development during an unloaded CMJ, while the group that
performed technical training did not show a significant
improvement (33). This finding suggests that training with
external load is necessary to improve the rapid force devel-
opment in untrained individuals. However, it is well possible
that the rate of force development would also have been
improved with good technical training, while technical train-
ing of moderate or bad quality may not result in an improved
rapid force development. The exact details concerning the
training program are however usually not reported, which
makes it hard to determine the quality of a training program.
Future research should therefore provide more details con-
cerning the exact training program. The Consensus on Exer-
cise Reporting Template (CERT) provides more information
on the details that should be reported (53).
PRACTICAL APPLICATIONS
The finding that resistance training has a limited transfer to
rapid force development in unloaded dynamic isoinertial
multi-joint movements has several important implications.
First, this finding indicates that current training approaches
to improve high-intensity sports performance or prevent
injuries by improving rapid force development may not be as
effective as commonly assumed. To increase the effective-
ness of these approaches, it is important to train more
specific to maximize the transfer from training to the sports
movement, especially in well-trained individuals. Addition-
ally, it is often assumed that untrained or recreationally
trained individuals do not need specific training since any
training will result in improvements in performance. How-
ever, the findings of this review indicate that specific training
is also important to improve rapid force development in
these individuals.
There are several aspects that influence the transfer
between a movement performed during a test or training
and the sports movement. For example, rapid force devel-
opment has likely a limited transfer from movements with
countermovement to movements without a countermove-
ment and from bilateral movements to unilateral move-
ments. Coaches and researchers should therefore consider
these factors when designing training programs. Addition-
ally, the addition of external load may also decrease the
transfer to unloaded movements. Therefore, special atten-
tion should be paid to the effects of external load, since its
influence is usually overlooked. Based on these findings, we
concur with previous suggestions (69) that it is important to
specifically mimic the actual sport movement in order to
maximize the transfer between movements, especially for
well-trained individuals. However, it should be noted that
this does not mean that all training should exactly mimic
the competition demands since this may eventually lead to
overtraining, an increased risk of injuries and boredom.
CONCLUSION
Resistance training has a limited transfer to rapid force
development in unloaded dynamic isoinertial multi-joint
movements (i.e., most sports and daily living movements)
and this effect is most pronounced in movements that do not
involve a countermovement. Furthermore, the findings also
suggest that this transfer is less pronounced in well-trained
individuals. It is therefore important to specifically mimic the
actual sport movement to maximize the transfer of training
and testing.
ACKNOWLEDGMENTS
The authors have no conflicts of interest to disclose.
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... Considering the most risk of bias assessment scales such as Delphi scale, PEDro scale and Cochrane scale are designed for medical research, studies about training interventions usually get very low score under these methodological scales [34]. We preferred the scale (Table 1) modified by Brughelli et al [34] and Hooren et al. [35]. This scale is deemed more suitable for sport science research, and includes 10 items, with each item rated as: 0 = clearly no/not reported, 1 = maybe, and 2 = clearly yes. ...
... In accordance with the modified scale [34,35], the scores of 14 included articles ranged from 12 to 18, the mean score was 15. ...
... Risk of bias assessment scale[34,35] ...
Article
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Background: Exercises can be categorized into either unilateral or bilateral movements. Despite the topic popularity, the answer to the question as to which (unilateral or bilateral) is superior for a certain athletic performance enhancement remains unclear. Purpose: To compare the effect of unilateral and bilateral resistance training interventions on measures of athletic performance. Methods: Keywords related with unilateral, bilateral and performance were used to search in the Web of Science, Pubmed databases, and Google Scholar and ResearchGate™ websites. Results: 6365 articles were initially identified, 14 met the inclusion criteria and were included in the final analysis, with overall article quality being deemed moderate. The quantitative analysis comprised 392 subjects (aged: 16 to 26 years). Sub-group analysis showed that unilateral exercise resistance training resulted in a large effect in improving unilateral jump performance compared to bilateral training (ES = 0.89 [0.52, 1.26]). In contrast, bilateral exercise resistance training showed a small effect in improving bilateral strength compared to unilateral (ES = -0.43 [-0.71, -0.14]). Non-significant differences were found in improving unilateral strength (ES = 0.26 [-0.03, 0.55]), bilateral jump performance (ES = -0.04 [-0.31, 0.23]), change of direction (COD) (ES = 0.31 [-0.01, 0.63]) and speed (ES = -0.12 [-0.46, 0.21]) performance. Conclusion: Unilateral resistance training exercises should be chosen for improving unilateral jumping performance, and bilateral resistance training exercises should be chosen for improving bilateral strength performance.
... Es decir, una mejora de la coordinación intermuscular, pero porque no también, intramuscular (el sistema nervioso aprende a cómo controlar el movimiento). Por el contrario, aquellos que están entrenados, puede que necesiten más tiempo y la magnitud sea menor en porcentaje (Badillo, 2002;Brearley y Bishop, 2019;Isurrin, 2013;Seitz et al., 2014;Van Hooren et al., 2017). Aun así, Hopkins (2005 en Brearley y Bishop, 2019), recomienda en atletas de élite, que trabajar en post de 0.3-1.5% de optimización de rendimiento, vale la pena. ...
... Cuantiosos siguen entrenando bajo este paradigma, y consiguen mejoras. Con sujetos bien entrenados (más de cinco años), la transferencia de fuerza con cargas altas, realizada generalmente con menor especificidad, al desarrollo de la fuerza rápida ha sido variable (Van Hooren et al., 2017). Pero, el hecho que 38-43% hayan tenido transferencia, es suficiente como para considerarlo pertinente a ese tipo de entrenamiento. ...
Thesis
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La presente tesis busca demostrar la veracidad de la teoría del vector de fuerza, ¿importa la fuerza neta o con qué dirección la manifestamos? Estudio realizado con 15 deportistas activos, a los cuales se testeó con diferentes saltos (verticales y horizontales) y sprint. Se utilizan los coeficientes de correlación de Pearson y Spearman, observándose mayores fuerzas de correlaciones para los saltos horizontales.
... The participants only executed single-joint exercises. Previous evidence shows that multi-joint exercises (squat, leg press, etc.) improve intra-and inter-muscular coordination to a greater extent than single-joint exercises [36]. Therefore, it is presumable that multi-joint exercises could have a greater impact on balance. ...
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Background: Multiple sclerosis (MS) is a neurological disease that affects balance. Among the non-pharmacological strategies to improve this variable, physical exercise is one of the most widely used. However, the benefits of some types of training, such as resistance training, on static balance in this population are still unclear. This study aims to analyze the effects of a resistance training (RT) intervention on balance in people with MS. Methods: Thirty people with MS were randomized to either an experimental (n = 18) or a control (n = 12) group. The RT group performed 10 weeks of lower limb resistance training with a concentric phase at maximum velocity. Static balance was measured before and after intervention. Results: No significant group × time interaction effects were found (ANOVA test) in any of the variables at the end of the intervention. No intragroup differences were found before or after the intervention in the balance variables. Conclusions: Resistance training with a concentric phase at maximum velocity showed no impact on balance in our sample. Future studies should examine programs of longer duration or combined with other types of training, such as balance training, with the aim of obtaining improvements in this variable in people with MS.
... Given lots of risk of bias assessment scales (Cochrane scale, Delphi scale, Pedro scale) are specialized for medical research, trials in sport science usually were evaluated as poor quality in accordance with these methodological scales [23]. We chose the scale (S2 Table) modified by Brughelli et al. [23] and Hooren et al. [24]. This scale is deemed more suitable for sport science research, and includes 10 items, with each item rated as: 0 = clearly no/not reported, 1 = maybe, and 2 = clearly yes. ...
Article
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Background There has been a surge of interest on velocity-based training (VBT) in recent years. However, it remains unclear whether VBT is more effective in improving strength, jump, linear sprint and change of direction speed (CODs) than the traditional 1RM percentage-based training (PBT). Objectives To compare the training effects in VBT vs. PBT upon strength, jump, linear sprint and CODs performance. Data sources Web of science, PubMed and China National Knowledge Infrastructure (CNKI). Study eligibility criteria The qualified studies for inclusion in the meta-analysis must have included a resistance training intervention that compared the effects of VBT and PBT on at least one measure of strength, jump, linear sprint and CODs with participants aged ≥16 yrs. and be written in English or Chinese. Methods The modified Pedro Scale was used to assess the risk of bias. Random-effects model was used to calculate the effects via the mean change and pre-SD (standard deviation). Mean difference (MD) or Standardized mean difference (SMD) was presented correspondently with 95% confidence interval (CI). Results Six studies met the inclusion criteria including a total of 124 participants aged 16 to 30 yrs. The differences of training effects between VBT and PBT were not significant in back squat 1RM (MD = 3.03kg; 95%CI: -3.55, 9.61; I ² = 0%) and load velocity 60%1RM (MD = 0.02m/s; 95%CI: -0.01,0.06; I ² = 0%), jump (SMD = 0.27; 95%CI: -0.15,0.7; I ² = 0%), linear sprint (MD = 0.01s; 95%CI: -0.06, 0.07; I ² = 0%), and CODs (SMD = 0.49; 95%CI: -0.14, 1.07; I ² = 0%). Conclusion Both VBT and PBT can enhance strength, jump, linear sprint and CODs performance effectively without significant group difference.
... The eccentric overload provided by the isoinertial device may be applied directly to specific technical elements, such as COD and shooting movements, allowing the athlete to transfer the external variable overload effects to the real team sport performance. Moreover, isoinertial training provides unknown and unpredictable loads that stimulate different and continuous neuromuscular adaptations during each repetition (Van Hooren et al., 2017). A strong correlation has been found between isoinertial training and athletic performance with unknown loads (Hernández-Davó et al., 2017). ...
Article
The aim of the study was to evaluate the effects of 6-weeks accentuated eccentric training, using a rotary inertial device, on range of motion, assessed with Inter Malleolar Distance test, anthropometry, lower limb explosive and reactive strength, assessed with Squat Jump, Countermovement Jump and 7-Repeated Hop tests, in young elite fencers. Moreover, the effects on hamstring eccentric strength and two technical fencing movements, lunge and advance-advance lunge, were evaluated with motion analysis. The second aim was to evaluate the duration of the accentuated eccentric training residual effects, 6 weeks after the end of the training. Fifty-four male fencers were randomly assigned either to the Inertial Group (IG; n = 26; aged 17.3 ± 1.9 years) such as experimental group, or to the Plyometric Group (PG; n = 28; aged 17.6 ± 2.7 years) such as control group. IG carried out four exercises using the rotary inertial device attached to their waist by a rope. PG carried out several plyometric exercises at the same time in which the IG performed the accentuated eccentric training. MANOVA showed significant improvements in the vertical jumps height post training, with no differences between IG and PG. Significant improvements for technical movements, lunge distance (p = 0.006) and advance-advance lunge distance (p = 0.00005), were found within-group and between-groups (p = 0.00001), with higher improvements in IG than in PG. The univariate analysis showed a significant improvement in lower limb range of motion with higher increase in IG than in PG. The main findings were the significant improvement in lunge and advance-advance lunge distance, maintaining with the same execution time. These results suggested that it is important to apply accentuated eccentric load on specific sport movements.
... We defined repeatability as the agreement between repeated measurements of the same image sequence and test-retest reliability as the agreement of repeated measures of the same participant (5). Only isoinertial movements were included because most human movements are characterized by acceleration and decelerations of a constant mass (isoinertial) rather than moving a changing mass at a constant velocity (isokinetic), and isoinertial movements are, therefore, considered more representative of most sports and daily living movements (124). Studies that used isometric contractions, electrical stimulation, or an external force (resulting in passive-only muscle action) to induce joint or limb movements were also excluded. ...
Article
Full-text available
Background: B-mode ultrasound is often used to quantify muscle architecture during movements. Objectives: 1) Systematically review the reliability of fascicle length (FL) and pennation angles (PA) measured using ultrasound during movements involving voluntary contractions, 2) systematically review the methods used in studies reporting reliability, discuss associated challenges, and provide recommendations to improve the reliability and validity of dynamic ultrasound measurements, 3) provide an overview of computational approaches for quantifying fascicle architecture, their validity, agreement with manual quantification of fascicle architecture, and advantages and drawbacks. Methods: Three databases were searched until June 2019. Studies among healthy human individuals aged 17-85 years that investigated the reliability of FL or PA in lower extremity muscles during isoinertial movements and written in English were included. Results: Thirty studies (n=340 participants) were included for reliability analyses. Between-session reliability as measured by coefficient of multiple correlations (CMC) and coefficient of variation (CV) was FL CMC: 0.89-0.96; CV: 8.3%, and PA CMC: 0.87-0.90; CV: 4.5-9.6%. Within-session reliability was FL CMC: 0.82-0.99; CV: 0.0-6.7%, and PA CMC: 0.91; CV: 0.0-15.0%. Manual analysis reliability was FL CMC: 0.89-0.96; CV: 0.0-15.9%; PA CMC: 0.84-0.90; CV: 2.0-9.8%. Computational analysis FL CMC was 0.82-0.99 and PA CV was 14.0-15.0%. Eighteen computational approaches were identified and these generally showed high agreement with manual analysis and high validity compared to phantoms or synthetic images. Conclusions: B-mode ultrasound is a reliable method to quantify fascicle architecture during movement. Additionally, computational approaches can provide a reliable and valid estimation of fascicle architecture.
... The eccentric overload provided by the isoinertial device may be applied directly to specific technical elements, such as COD and shooting movements, allowing the athlete to transfer the external variable overload effects to the real team sport performance. Moreover, isoinertial training provides unknown and unpredictable loads that stimulate different and continuous neuromuscular adaptations during each repetition (Van Hooren et al., 2017). A strong correlation has been found between isoinertial training and athletic performance with unknown loads (Hernández-Davó et al., 2017). ...
Article
Full-text available
The isoinertial training method owes its efficacy to an accommodated resistance and optimal individualized eccentric overload. The aim of this study was to assess the effects of a 6-week isoinertial eccentric-overload training program - using a flywheel inertial device during the execution of specific soccer exercises - on explosive and reactive strength, sprint ability, change of direction (COD) performance and soccer shooting precision. Thirty-four junior soccer players were randomly assigned to a plyometric training group (PT) (n = 16, aged 13.36 ± 0.80), which underwent a six-week traditional soccer training program, and a flywheel eccentric overload group (FEO) (n = 18, aged 13.21 ± 1.21), which received additional training consisting of two inertial eccentric-overload training sessions per week. Pre and post intervention tests were carried out to assess explosive and reactive strength, sprint ability, COD ability, agility using the Y-agility test (YT) and soccer shooting precision. The FEO showed significantly higher values than the PT in squat jump height (SJh) (p = 0.01), drop jump height (DJh) (p = 0.003), 7 repeated hop test heights (p = 0.001), the Illinois test (ILL) (p = 0.001), and the Loughborough Soccer Shooting Test (SHOT) (p = 0.02). Finally, the FEO showed significant between-group differences in DJh (p = 0.007), ILL (p = 0.0002), YT (p = 0.002), a linear sprint test (SPRINT) (p = 0.001), and SHOT (p = 0.003). These results confirmed the positive effect of isoinertial training. The use of an isoinertial device to overload multidirectional movements in specific sport conditions leads to greater performance improvements than conventional soccer training. The absence of knowledge of the eccentric overload applied by the isoinertial device, which is different in any exercise repetition, may stimulate the athlete's neural adaptations, improving their soccer skills and in particular their soccer shooting precision.
... If this is true, then at least some of the null findings in response to heavy strength training might be explained by the training and testing movement patterns not being similar [23,24] rather than being a specific effect of the training velocity per se. Whilst some evidence of this was provided in a recent review of force development during dynamic, unloaded (and complex) movements (see Van Hooren et al. [30], this evidence may not be relevant to contractile RFD measured during isometric tests as dynamic tests allow movement strategy/technique and factors affecting dynamic muscle function (i.e., force-velocity characteristics) to strongly influence the rate of external force production. A critical, systematic analysis has not been performed on research using isometric RFD tests. ...
Article
Full-text available
Background Muscular rate of force development (RFD) is positively influenced by resistance training. However, the effects of movement patterns and velocities of training exercises are unknown. Objectives To determine the effects of velocity, the intent for fast force production, and movement pattern of training exercises on the improvement in isometric RFD from chronic resistance training. Methods A systematic search of electronic databases was conducted to 18 September, 2018. Meta-regression and meta-analytic methods were used to compute standardized mean differences (SMD ± 95% confidence intervals) to examine effects of movement pattern similarity (between training and test exercises; specific vs. non-specific) and movement speed (fast vs. slow vs. slow with intent for fast force production) for RFD calculated within different time intervals. Results The search yielded 1443 articles, of which 54 met the inclusion criteria (59 intervention groups). Resistance training increased RFD measured to both early (e.g., 50 ms; standardized mean difference [95% CI] 0.58 [0.40, 0.75]) and later (e.g., 200 ms; 0.39 [0.25, 0.52]) times from contraction onset, as well as maximum RFD (RFDmax; 0.35 [0.21, 0.48]). However, sufficient data for sub-analyses were only available for RFDmax. Significant increases relative to control groups were observed after training with high-speed (0.54 [0.05, 1.03]), slow-speed with intent for fast force production (0.41 [0.20, 0.63), and movement pattern-specific (0.38 [0.17, 0.59]) exercises only. No clear effect was observed for slow-speed without intent for fast force production (0.21 [0.00, 0.42], p = 0.05) or non-movement-specific (0.27 [− 0.32, 0.85], p = 0.37) exercises. Meta-regression did not reveal a significant difference between sexes (p = 0.09); however, a negative trend was found in women (− 0.57 [− 1.51, 0.37], p = 0.23), while a favorable effect was found in men (0.40 [0.22, 0.58], p < 0.001). Study duration did not statistically influence the meta-analytic results, although the greatest RFD increases tended to occur within the first weeks of the commencement of training. Conclusions Resistance training can evoke significant increases in RFD. For maximum (peak) RFD, the use of faster movement speeds, the intention to produce rapid force irrespective of actual movement speed, and similarity between training and testing movement patterns evoke the greatest improvements. In contrast to expectation, current evidence indicates a between-sex difference in response to training; however, a lack of data in women prevents robust analysis, and this should be a target of future research. Of interest from a training program design perspective was that RFD improvements were greatest within the first weeks of training, with less ongoing improvement (or a reduction in RFD) with longer training, particularly when training velocity was slow or there was a lack of intent for fast force production.
Chapter
Verletzungen des Kniegelenkes können zu langen Ausfallzeiten im Sport führen. Dieses Kapitel gibt eine Übersicht über Diagnostik und Therapie von akuten und chronischen Beschwerden am Kniegelenk bei Sportlern. Ausgehend von der aktuellen Evidenz wird der kriterienbasierte Rehabilitationsverlauf für die unterschiedlichen Kniegelenkverletzungen dargestellt. Darüber hinaus wird der Return to Sport-Prozess mit den jeweiligen intrarehabilitativen Assessments anhand biomechanischer und verletzungsspezifischer Überlegungen veranschaulicht.
Chapter
Osteoarthritis (OA) is a degenerative disease of the articular cartilage with subchondral bone lesions. Osteoarthritis etiologies are mainly related to age, obesity, strain, trauma, joint congenital anomalies, joint deformities, and other factors. Osteoarthritis seriously affects the quality of life; however, there is no effective way to cure osteoarthritis. Aerobic exercise refers to a dynamic rhythmic exercise involving the large muscle groups of the body with aerobic metabolism. More and more evidence shows that exercise has become a useful tool for the treatment of osteoarthritis. This chapter will discuss the role of exercise in the prevention and treatment of osteoarthritis.
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Two movements that are widely used to monitor athletic performance are the countermovement and squat jump. Countermovement jump performance is almost always better than squat jump performance, and the difference in performance is thought to reflect an effective utilization of the stretch-shortening cycle. However, the mechanisms responsible for the performance enhancing effect of the stretch-shortening cycle are frequently undefined. Uncovering and understanding these mechanism(s) is essential to make an inference regarding the difference between the jumps. Therefore, we will review potential mechanisms that explain the better performance in a countermovement jump as compared to a squat jump. It is concluded that the difference in performance may primarily be related to the greater uptake of muscle slack and the buildup of stimulation during the countermovement in a countermovement jump. Elastic energy may also have a small contribution to enhanced countermovement jump performance. Therefore, a larger difference between the jumps is not necessarily a better indicator of high-intensity sports performance. Although a larger difference may reflect the utilization of elastic energy in a small amplitude countermovement jump as a result of a well-developed capability to co-activate muscles and quickly buildup stimulation, a larger difference may also reflect a poor capability to reduce the degree of muscle slack and buildup stimulation in the squat jump. Because the capability to reduce the degree of muscle slack and quickly buildup stimulation in the squat jump may be especially important to high-intensity sports performance, training protocols might concentrate on attaining a smaller difference between the jumps.
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PurposeTo compare the effects of two different resistance training programs, high intensity (INT) and high volume (VOL), on changes in isometric force (FRC), rate of force development (RFD), and barbell velocity during dynamic strength testing. Methods Twenty-nine resistance-trained men were randomly assigned to either the INT (n = 15, 3–5 RM, 3-min rest interval) or VOL (n = 14, 10–12 RM, 1-min rest interval) training group for 8 weeks. All participants completed a 2-week preparatory phase prior to randomization. Measures of barbell velocity, FRC, and RFD were performed before (PRE) and following (POST) the 8-week training program. Barbell velocity was determined during one-repetition maximum (1RM) testing of the squat (SQ) and bench press (BP) exercises. The isometric mid-thigh pull was used to assess FRC and RFD at specific time bands ranging from 0 to 30, 50, 90, 100, 150, 200, and 250 ms. ResultsAnalysis of covariance revealed significant (p < 0.05) group differences in peak FRC, FRC at 30–200 ms, and RFD at 50–90 ms. Significant (p < 0.05) changes in INT but not VOL in peak FRC (INT: 9.2 ± 13.8 %; VOL: −4.3 ± 10.2 %), FRC at 30–200 ms (INT: 12.5–15.8 %; VOL: −1.0 to −4.3 %), and RFD at 50 ms (INT: 78.0 ± 163 %; VOL: −4.1 ± 49.6 %) were observed. A trend (p = 0.052) was observed for RFD at 90 ms (INT: 58.5 ± 115 %; VOL: −3.5 ± 40.1 %). No group differences were observed for the observed changes in barbell velocity. Conclusions Results indicate that INT is more advantageous than VOL for improving FRC and RFD, while changes in barbell velocity during dynamic strength testing are similarly improved by both protocols in resistance-trained men.
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The bilateral deficit phenomenon, characterized by a reduction in the amount of force from a single limb during maximal bilateral actions, has been shown in various movement tasks, contraction types and different populations. However, bilateral deficit appears to be an inconsistent phenomenon, with high variability in magnitude and existence, and seems to be plastic, as bilateral facilitation has also been shown to occur. Furthermore, many mechanisms underlying this phenomenon have been proposed over the years, but still remain largely unknown. The purpose of this review was to clarify and critically discuss some of the important issues relevant to bilateral deficit. The main findings of this review were: (1) bilateral deficit does not seem to be contraction-type dependent; however, it is more consistent in dynamic compared to isometric contractions; (2) postural stabilization requirements and/or ability to use counterbalances during unilateral actions seem to influence the expression of bilateral deficit to a great extent; strong evidence has been provided for higher-order neural inhibition as a possible mechanism, but requires further exploration using a lower limb model; biomechanical mechanisms, such as differences in shortening velocity between contraction modes and displacement of the force-velocity curve, seem to underlie bilateral deficit in ballistic and explosive contractions; (3) task familiarity has a large influence on bilateral deficit and thus adequate testing specificity is warranted in training/cross-sectional experiments; (4) the literature investigating the relationship between bilateral deficit and athletic performance and injury remains scarce; hence, further research in this area is required.
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