Acute and longitudinal effects of weighted vest training on sprint-running performance: a systematic review

Abstract

This systematic review aimed to quantify the acute and longitudinal effects that occur with weighted vests during sprint-running. PubMed, SPORTDiscus, and Web of Science were searched using the Boolean phrases (vest OR trunk) AND (sprint*) AND (resist* OR weight OR load*). From 170 articles retrieved, 11 studies (6 acute, 5 longitudinal) met the inclusion criteria. Vest loads (5–40% body mass) were found to significantly increase acute over-ground times (10–50 m 4.1–16.9%, effect sizes [ES] = 0.93–3.11) through significantly decreased velocity (−2.2% to −17.3%, ES = −0.41 to −3.19), horizontal force (−5.9% to −22.1%, ES = −0.85 to −3.30), maximal power (−4.3% to −35.6%, ES = −0.32 to −3.44), and flight times (−8.3% to −14.6%, ES = −0.88 to −1.03), while increasing contact times (14.7–19.6%, ES = 1.80–3.17). Treadmill sprints were less effected until loads >11% body mass were used. Improvements in velocity (1.2–1.3%, ES = 0.24–0.37) and times (10–50 m 1.2–9.4%, ES = 0.25–3.30) were found in longitudinal studies (5.6–18.9% body mass, 3–7 weeks). Future studies should focus on determining the optimum load and volume to clearly establish the training benefits of this form of resisted sprinting.

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Sports Biomechanics
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Acute and longitudinal effects of weighted
vest training on sprint-running performance: a
systematic review
Paul Macadam, John B. Cronin & Erin H. Feser
To cite this article: Paul Macadam, John B. Cronin & Erin H. Feser (2019): Acute and longitudinal
effects of weighted vest training on sprint-running performance: a systematic review, Sports
Biomechanics, DOI: 10.1080/14763141.2019.1607542
To link to this article: https://doi.org/10.1080/14763141.2019.1607542
Published online: 09 May 2019.
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Acute and longitudinal effects of weighted vest training on
sprint-running performance: a systematic review
Paul Macadam
a
, John B. Cronin
a
and Erin H. Feser
a,b
a
Sports Performance Research Institute New Zealand (SPRINZ) at AUT Millennium, Auckland University of
Technology, Auckland, New Zealand;
b
Exercise Science and Health Promotion, Arizona State University,
Phoenix, USA
ABSTRACT
This systematic review aimed to quantify the acute and longitudi-
nal effects that occur with weighted vests during sprint-running.
PubMed, SPORTDiscus, and Web of Science were searched using
the Boolean phrases (vest OR trunk) AND (sprint*) AND (resist* OR
weight OR load*). From 170 articles retrieved, 11 studies (6 acute, 5
longitudinal) met the inclusion criteria. Vest loads (5–40% body
mass) were found to significantly increase acute over-ground
times (10–50 m 4.1–16.9%, effect sizes [ES] = 0.93–3.11) through
significantly decreased velocity (−2.2% to −17.3%, ES = −0.41 to
−3.19), horizontal force (−5.9% to −22.1%, ES = −0.85 to −3.30),
maximal power (−4.3% to −35.6%, ES = −0.32 to −3.44), and flight
times (−8.3% to −14.6%, ES = −0.88 to −1.03), while increasing
contact times (14.7–19.6%, ES = 1.80–3.17). Treadmill sprints were
less effected until loads >11% body mass were used.
Improvements in velocity (1.2–1.3%, ES = 0.24–0.37) and times
(10–50 m 1.2–9.4%, ES = 0.25–3.30) were found in longitudinal
studies (5.6–18.9% body mass, 3–7 weeks). Future studies should
focus on determining the optimum load and volume to clearly
establish the training benefits of this form of resisted sprinting.
ARTICLE HISTORY
Received 17 December 2018
Accepted 9 April 2019
KEYWORDS
Wearable resistance; resisted
sprints; kinematics; kinetics;
specificity
Introduction
Possessing sprint-running ability is considered a vital prerequisite for athletic success in
a wide array of sports activities (Murphy, Lockie, & Coutts, 2003). To improve sprint-
running performance an athlete generally focuses on two aspects of training: the first
aims to improve the magnitude and rate of effective force and power output; and,
the second aims to improve the technical efficiency of the sprinting action (Cissik,
2004). Various forms of acyclic and cyclic resisted strength training are commonly used
to increase force and power output (Behrens & Simonson, 2011; Rumpf, Lockie,
Cronin, & Jalilvand, 2016; Tufano & Amonette, 2018), while sprint drills in addition
to sprint-running itself, are often used for technique emphasis (Cissik, 2004). An
alternative method that blends both training approaches (resistance + technique) is
the use of additional load being added to the athlete during participation in sprint drills
via a weighted vest (Cronin & Hansen, 2006). Weighted vests are a form of wearable
CONTACT Paul Macadam paul.macadam@aut.ac.nz
SPORTS BIOMECHANICS
https://doi.org/10.1080/14763141.2019.1607542
© 2019 Informa UK Limited, trading as Taylor & Francis Group

resistance that enables an overload to be evenly distributed near an individual’s centre
of mass, potentially increasing the ability to produce ground reaction forces and power
production during sprint-running (Macadam, Cronin, & Simperingham, 2017).
This form of resisted sprint training aligns with the principles of specificity of
training and the principles of individualisation and progressive overload (Faccioni,
1994; Macadam et al., 2017). Resisted sprint training is designed to increase neural
activation and strength of the lower limbs, thus increasing sprint velocity, without
unduly affecting the sprinting technique (Cissik, 2004; Faccioni, 1994). As the addi-
tional external mass is added around the torso, there may be less direct disruption to
joint and step kinematics from the limbs. Furthermore, unlike other forms of resisted
sprinting, weighted vests enable athletes to perform other motor actions such as jumps,
bounds and change of direction. Previously researchers have shown that horizontal
forces were higher during the acceleration phase, and vertical forces gradually increased
with increases in velocity during the maximum-velocity phase (Rabita et al., 2015).
Therefore, weighted vest training may be appropriate to specifically target reactive
strength development for maximum velocity sprinting, while the horizontal component
of leg drive can be overloaded through sleds, parachutes or ropes (Cronin & Hansen,
2006; Rey, Padrón-Cabo, & Fernández-Penedo, 2017; Young, Benton, & Pryor, 2001).
Given that force is the product of mass and acceleration, weighted vest sprint training
may result in high forces due to the high accelerations even though when the mass is
relatively light. These high accelerative forces performed in a movement specific con-
text, provide an ideal form of coordination training that may optimise training adapta-
tion and crossover to sporting performance (Hrysomallis, 2012). Given the purported
benefits of weighted vest training, the purpose of this review was to quantify the acute
and longitudinal effects that occur with weighted vests during sprint-running. Of
particular interest was to: 1) identify the mechanistic determinants of changes that
occur in sprinting with weighted vests; 2) determine whether vest loading enabled
improvement in sprint speed and, 3) detail critical loading parameters for these
changes. Such an approach will provide practitioners with a better understanding of
the effects of vest loading and how to best program for speed changes using such
resisted overload. We hypothesised that acute sprint times would be increased (i.e.,
slower) with weighted vest sprint-running, and that longitudinal sprint training with
a weighted vest would improve sprint performance times.
Methods
The review was conducted in accordance with PRISMA (Preferred Reporting Items for
Systematic Reviews and Meta-analyses) statement guidelines (Moher, Liberati, Tetzlaff,
& Altman, 2009). A systematic search of the research literature was undertaken for
acute (cross-sectional) and longitudinal studies assessing the effects of weighted vests on
sprint-running performance from international peer-reviewed journals. Studies were
found by searching PubMed, SPORTDiscus, and Web of Science electronic databases
from inception to November 2018. The following Boolean phrases were used for the
searches (vest OR trunk) AND (sprint*) AND (resist* OR weight OR load*). Additional
studies were also found by reviewing the reference lists from retrieved studies.
2P. MACADAM ET AL.

Inclusion and exclusion criteria
Studies with injury-free participants of any age, sex or activity level were included. No
restrictions were imposed on publication date or publication status. Studies were
limited to the English language. Studies incorporating a direct assessment of acute
performance changes during sprint-running that occurred when the weighted vest was
being worn were included. Post-activation potentiation (PAP) studies, where changes
are only assessed after the load was removed, were excluded. Studies that used other
forms of resistance, such as sled towing, or attached the resistance via alternative
methods to a vest, as in limb loads or belts, were also excluded.
Study selection
One reviewer (PM) searched the databases and selected studies. Two other reviewers
were available to assist with study eligibility. No disagreements about the appropriate-
ness of an article were encountered. A search of electronic databases and a scan of
article reference lists revealed 170 relevant studies (Figure 1). After applying the
inclusion and exclusion criteria 11 studies (six acute studies and five longitudinal
studies) were retained for further analysis.
Records identified through electronic database searching
(n =164)
PubMed 45
SPORTDiscus 55
Web of Science 64
Additional records identified through hand searches of reference lists
and online journal
(n = 6)
Records screened for relevance on title
(n = 102)
Records screened for relevance on abstract
(n = 60)
Full-text articles screened for eligibility
(n = 16)
Studies included in qualitative synthesis
(n = 11
[
6 acute, 5 longitudinal])
Duplicate removal
(n = 70 records excluded)
Full-text articles excluded (n = 5):
5 load not attached via vest
Title selection
(n = 42 records excluded)
Abstract selection
(n = 44 records excluded)
Figure 1. Flow chart of article selection through the different phases of the systematic review.
SPORTS BIOMECHANICS 3

Methodological quality score
Methodological quality was assessed using the quality index of Downs and Black (1998)
modified version (Moens et al., 2018). A value of 0 or 1 was assigned to the different
subcategories of the following items: reporting, external validity, and internal validity.
A total score < 10/17 was considered to be low quality, while scores ≥10/17 were
presumed to be high quality (Moens et al., 2018).
Study analyses
Studies that reported Cohen’seffect size (ES) were described as trivial (<0.2), small
(<0.21–0.5), moderate (0.51–0.79) and large (>0.8) (Cohen, 1988). Where ES was not
provided, it was determined by calculating the mean difference between groups, and then
dividing the result by the pooled standard deviation (Cohen, 1988). ES was unable to be
calculated for sprint times, step length and step frequency from Cronin, Hansen,
Kawamori, and McNair (2008) as either the mean or standard deviation were not provided
in these variables.
Results
Methodological quality score
Quality assessment scores of the 11 articles included ranged from 10 to 14, with an
average score of 11.6 out of 17, indicating a high methodological quality for the studies
reviewed (Table 1).
Study characteristics
There was a total of 113 participants (109 male, four female) from six acute studies and
41 males from five longitudinal studies (Table 1). Participants that were included in the
analyses were characterised as either healthy sedentary, recreationally active or compe-
titive athletes from various sporting backgrounds, as described by the authors of the
reviewed articles. To allow comparison between studies, absolute load data were con-
verted to ratio data represented as a percentage of body mass (%BM). When scaled to
BM, the vest loading ranged from 5% to 40% BM. The effects of weighted vests on
sprint-running performance are summarised through six acute (Table 2) and five
longitudinal studies (Table 3).
Acute effects of weighted vests on sprint-running
Six studies reported the acute effects of weighted vests on sprint-running performance,
kinematics and kinetics (Table 2). The vest loads used ranged from 5% to 40% BM with
over ground sprints being performed over 30 m to 50 m, and treadmill sprints being
completed over a 6-s period. Four studies assessed the effects of vest loading during
over ground sprint-running (Carlos-Vivas et al., 2018a; Carlos-Vivas, Marín-Cascales,
Freitas, Perez-Gomez, & Alcaraz, 2018b; Cronin et al., 2008; Konstantinos et al., 2014).
From the lightest loading of 5% BM, no significant changes in kinematics or kinetics
4P. MACADAM ET AL.

were found, while sprint times were not reported with this loading magnitude (Carlos-
Vivas et al., 2018a). Vest loading of 8% BM resulted in significantly increased split times
(i.e., sprints were slower, 4.1–5.1%, ES = 0.93–1.54) at all distances between 10 and
50 m (Konstantinos et al., 2014). Two studies used 10% BM (Carlos-Vivas et al., 2018a,
2018b) and reported decreases in Vmax (−4.3% to −4.7%, ES = −1.03 to −1.05) and
Pmax (−2.0% to −10.8%, ES = −0.06 to −0.99), though only significant decreases were
Table 1. Study characteristics of all studies reviewed (n = 11).
Study
Participants (gender, age,
height, mass)
Weighted vest load
(% body mass) Sprint distance
Study
duration
Quality
score
Cronin et al.
(2008)
16 males, 4 females
(19.9 ± 2.2 years, 176 ±
8 cm, 76.5 ± 10.7 kg)
Competitive athletes from
mixed sports
15, 20 30 m Acute 10
Clark et al. (2010) 6 males
(19.7 ± 0.1 years, 182 ±
8 cm, 79.1 ± 5.3 kg)
NCAA Division 3 lacrosse
players
18.5 55 m
(measurement between
18.3 m to 54.9 m)
7 weeks 13
Rantalainen et al.
(2012)
8 males
(32.2 ± 6.4 years, 178 ±
5 cm, 81.8 ± 8 kg)
Sedentary participants
5.6 10 m 3 weeks 14
Cross et al. (2014) 13 males
(22.9 ± 3.3 years; 179 ±
6 cm, 82.5 ± 8.4 kg)
Sport active university level
athletes
10.9, 21.8 6 s on a non-motorised
force treadmill
Acute 10
Konstantinos et al.
(2014)
24 males,
(18–23 years, 178 ± 5 cm,
74.2 ± 8.9 kg)
Sport science students
8, 15, 20 50 m Acute 11
Simperingham
and Cronin
(2014)
8 males
(29.2 ± 3.8 years, 177.1 ±
7.5 cm, 81.8 ± 9.7 kg)
Athletic sprint-based
athletes
5 6 s on a non-motorised
force treadmill
Acute 10
Barr et al. (2015) 8 males,
(22.4 ± 2.7 years 182 ±
6 cm, 95.3 ± 7.1 kg)
National rugby players
12 40 m 8 days 11
Scudamore et al.
(2016)
9 males
(21 ± 2 years, 181 ± 1 cm,
91.1 ± 4.4 kg)
Fitness active participants
Week 1–11.2 ± 0.6
Week 2–13.2 ± 0.7
Week 3–16.1 ± 0.4
36.6 m 3 weeks 14
Rey et al. (2017) 10 males
(23.6 ± 2.7 years, 178.5 ±
4.9 cm, 72.9 ± 5.2 kg)
Amateur soccer players
18.9 ± 2.1 30 m 6 weeks 13
Carlos-Vivas et al.
(2018a)
25 males
(18–25 years, 179.5 ±
5.0 cm, 72.2 ± 6.7 kg)
Semi-professional soccer
players
5, 10, 15 30 m Acute 11
Carlos-Vivas et al.
(2018b)
23 males
(20.8 ± 1.5 years, 180.0 ±
6.0 cm, 75.3 ± 7.3 kg)
Semi-professional soccer
players
10, 20, 30, 40 30 m Acute 11
SPORTS BIOMECHANICS 5

Table 2. Acute effects of weighted vests on sprint-running performance, kinematics and kinetics in order of % loading (n = 6).
Study
Load %
body mass Sprint distance Sprint times Kinematics Kinetics
Simperingham and
Cronin (2014)
5 6 s non-motorised force
treadmill
5m−0.6% (ES −0.06)
10 m −0.8% (ES −0.09)
20 m 0.0% (ES 0.00)
25 m 0.4% (ES 0.02)
Peak velocity −1.2% MVP (ES 0.15)
CT 3.8%* AP (ES 0.58), 4.7 %* MVP (ES 0.58)
FT −15%* AP (ES −0.44), −7.9% MVP (ES −0.30)
SL 0.0% AP (ES 0.00), 2.5% MVP (ES 0.23)
SF −0.7% AP (ES 0.12), −3.8% MVP (ES 0.61)
Relative peak VGRF −5.4%* AP (ES
−0.58), −6.4%* MVP (ES −0.53)
Relative mean VGRF −3.8%* AP (ES
−0.55) −4.0%* MVP (ES −0.50)
HGRF −1.0% AP (ES 0.10), −2.7% MVP
(ES 0.22)
PPO −1.4% AP (ES −0.07), −4.3% MVP
(ES −0.25)
Carlos-Vivas et al.
(2018a)
5 30 m Vmax −2.2% (ES −0.41) Pmax −4.3% (ES −0.32)
Konstantinos et al.
(2014)
850m
(from a flying start)
10 m 4.1%* (ES 0.93)
20 m 4.7%* (ES 1.54)
30 m 4.6%* (ES 1.37)
40 m 5.1%* (ES 1.51)
50 m 4.6%* (ES 1.40)
Carlos-Vivas et al.
(2018a)
10 30 m Vmax −4.3% (ES −0.81) Pmax −2.0% (ES −0.06)
Carlos-Vivas et al.
(2018b)
10 30 m 30 m 4.3% ** (ES 0.99) Vmax −4.7% ** (ES 1.05)
Vo −5.2% ** (ES −1.03)
Fo −5.9% ** (ES −0.85)
Pmax −10.8% ** (−0.99)
RFmax −4.6%** (ES −0.93)
DRF −0.1% (ES −0.04)
Cross et al. (2014) 10.9 6 s non-motorised force
treadmill
Peak velocity −3.6% * (ES −0.38)
CT 4.1% AP (ES 0.38), 5.6%* MVP (ES 0.98)
FT −20% AP (ES −0.64) −17.4% MVP* (ES −0.89)
SL −4.4%* MVP (ES −0.33)
SF 0.8% MVP (ES −0.10)
Peak VGRF −4.1% AP (ES −0.34), 3.1%
MVP (ES 0.21)
Mean VGRF 3.4% AP (ES 0.34), 3.4% MVP
(ES 0.29)
HGRF −6.1% AP (ES −0.31), 0.8% MVP
(ES 0.02)
PPO 0.0% AP (ES 0.00), −3.7% MVP (ES
−0.10)
Cronin et al. (2008) 15 30 m 10 m 7.5%*
30 m 10.0%*
CT 14.3–15.3%* (ES 1.80–2.10)
FT −8.3% to −9.8%* (ES −0.63 to −0.78)
SF −2.7–6.1%*
SL (significantly decreased % unknown)
Konstantinos et al.
(2014)
15 50 m
(from a flying start)
10 m 6.9%* (ES 1.6)
20 m 7.4%* (ES 2.4)
30 m 6.9%* (ES 2.0)
40 m 7.5%* (ES 2.2)
50 m 7.3%* (ES 1.9)
(Continued)
6P. MACADAM ET AL.

Table 2. (Continued).
Study
Load %
body mass Sprint distance Sprint times Kinematics Kinetics
Carlos-Vivas et al.
(2018a)
15 30 m Vmax −7.3% (ES 1.26) Pmax −4.6% (ES—0.17)
Cronin et al. (2008) 20 30 m 10m 9.3%*
30 m 11.7%*
CT 14.7–19.6%* (ES 2.00–3.17)
FT −12.0% to −14.6%* (ES −0.88 to −1.03)
SF −2.7–6.1%*
SL (significantly decreased % unknown)
Konstantinos et al.
(2014)
20 50 m
(from a flying start)
10 m 9.9%, (ES 2.4)
20 m 9.3%, (ES 3.5)
30 m 9.2%, (ES 2.8)
40 m 9.9%, (ES 2.8)
50 m 8.2%, (ES 2.5)
Carlos-Vivas et al.
(2018b)
20 30 m 30 m 8.0%** (ES 1.89) Vmax −8.4%** (ES −1.94)
Vo −9.2%** (ES −1.97)
Fo −11.2%** (ES −1.73)
Pmax −19.4%** (ES −1.93)
RFmax −8.3%** (ES −1.85)
DRF 0.7% (ES 0.18)
Cross et al. (2014) 21.8 6 s on a non-motorised
force treadmill
Peak velocity −5.7 %* (ES −0.61)
CT 1.4% AP (ES 0.18), 9.2%* MVP (ES 1.67)
FT −26.7% AP* (ES −1.45), −18.9% MVP* (ES −1.06)
SL −4.4%* MVP (ES −0.34)
SF −1.5% MVP (ES −0.20)
Peak VGRF 3.7% AP (ES 0.19), 8.2%* MVP
(ES 0.70)
Mean VGRF 10.6%* AP (ES 1.32), 11.1%*
MVP (ES 1.16)
HGRF −6.3% AP (ES-0.30), −6.3% MVP
(ES −0.16)
PPO 7.9% AP (ES 0.27), −14.3%* MVP (ES
−0.47)
Carlos-Vivas et al.
(2018b)
30 30 m 30 m 11.8%** (ES 2.52) Vmax −11.7%** (ES −2.51)
Vo −12.6%** (ES −2.52)
Fo −16.7%** (ES −2.53)
Pmax −27.3%** (ES −2.64)
RFmax −12.5%** (ES −2.61)
DRF 2.5%* (ES 0.75)
Carlos-Vivas et al.
(2018b)
40 30 m 30 m 16.9%** (ES 3.11) Vmax −16.1%** (ES −3.19)
Vo −17.3%** (ES −3.19)
Fo −22.1%** (ES −3.30)
Pmax −35.6%** (ES −3.44)
RFmax −17.1%** (ES −3.39)
DRF 3.1%* (ES 0.81)
* significant differences p < 0.05, ** significant differences p < 0.001,
AP = acceleration phase, CT = contact time, DRF = decrease in ratio of forces, as a percentage, ES = effect size, FT = flight time, Fo = theoretical maximum horizontal force in N/
kg, MVP = maximum velocity phase, PPO = peak power output in W, Pmax = maximum horizontal power output in W/kg, RFmax = maximum ratio of forces, as a percentage,
SF = step frequency, SL = step length, VGRF = vertical ground reaction force, Vmax = maximum velocity in m/s, Vo = theoretical maximum velocity in m/s
SPORTS BIOMECHANICS 7

Table 3. Longitudinal effects of weighted vests on sprint-running performance and kinematics in order of % loading (n = 5).
Study
Load %
body
mass Sprint distance Training period Sprint times Kinematics
Rantalainen
et al.
(2012)
5.6 10 m
(from a flying
start)
3 weeks, 6 training sessions
Vest worn all day excluding sport activates on 3 days
a week
Velocity 1.3% (7.33 to 7.42 m/s, ES 0.37)
Scudamore
et al.
(2016)
11.6–16.1 36.6 m 3 weeks, 9 training sessions
Vests worn all day for at least 8 hours a day and at
least 4 days a week (vest worn an average 34
hours a week)
36.6 m −1.5%* (4.69 to 4.58 s, ES −1.8)
Barr et al.
(2015)
12 40 m 8 days, 10 training sessions
Vest worn all day when standing and walking.
Removed for rugby training and gym exercises,
though worn when resting between exercises.
10 m 0.0% (1.76 to 1.76 s, ES 0.0)
30–40 m 0.0% (1.12 to 1.12 s, ES 0.0)
40 m 0.0% (5.33 to 5.33 s, ES 0.17)
CT 0.0% AP (ES 0.18), 8.9 %* MVP (ES 0.09)
SL 0.8% AP (ES 0.07), 2.5% MVP (ES 0.28)
FT 0.0% AP (ES 0.25), 8.4%, MVP ES 0.4)
Clark et al.
(2010)
18.5 55 m
(measurement
18.3 to
54.9 m)
7 weeks, 13 training sessions
Vest worn during 2 × 60 min sessions a week of
periodised sprint training
18.3 to 54.9 m −1.2% (4.41 to 4.36 s, ES
−0.25)
Velocity 1.2% (ES 0.24)
StL −2.2%, (ES 0.37)
StF 3.4%, (ES 0.78)
CT −1.5%, (ES 0.25)
FT −5.4%, (ES 1.0)
Rey et al.
(2017)
18.9 30 m 6 weeks, 12 training sessions
Vest worn during 2 sessions a week of periodised
sprint training
10 m −9.4%**, (1.78 to 1.61 s, ES −1.77)
30 m −6.1%**, (4.34 to 4.08 s, ES −3.30)
* significant differences p < 0.05, ** significant differences p < 0.001,
AP = acceleration phase, CT = contact time, ES = effect size, FT = flight time, MVP = maximum velocity phase, SF = step frequency, SL = step length, StF = stride frequency, StL =
stride length
8P. MACADAM ET AL.

found by Carlos-Vivas et al. (2018b). Furthermore, Carlos-Vivas et al. (2018b) reported
a significant increase in 30 m time (4.3%, ES = 0.99) and significant decreases in Vo
(−5.2%, ES −1.03), Fo (−5.9%, ES −0.85) and RFmax (−4.6%, ES −0.93) with this
loading. Three studies used 15% BM (Carlos-Vivas et al., 2018a; Cronin et al., 2008;
Konstantinos et al., 2014) with significant increases in split times (10–50 m 7.5–10%, ES
= 1.6–2.0) and contact time (14.3–15.3%, ES = 1.80–2.10), while significant decreases
were found in flight time (−8.3% to −9.8%, ES = −0.63 to −0.78), step frequency (−2.7%
to −6.1%) and step length (% unknown). From the three studies that used 20% BM
(Carlos-Vivas et al., 2018b; Cronin et al., 2008; Konstantinos et al., 2014) significant
increases in split times (10–50 m 9.3–11.7%, ES = 2.4–3.5) and contact time
(14.7–19.6%, ES = 2.0–3.1) were found, while significant decreases occurred in Vo
(−9.2%, ES = −1.97), Vmax (−8.4%, ES = −1.94), flight time (−12.0% to −14.6%, ES =
−0.88 to −1.03), step frequency (−2.7% to −6.1%) and step length (% unknown).
Moreover, significant decreases in Vo (−9.2%, ES = −1.97), Fo (−11.2%, ES = −1.73),
Pmax (−19.4%, ES = −1.85) and RFmax (−8.3%, ES = −1.85) were found with this
loading (Carlos-Vivas et al., 2018b). Carlos-Vivas et al. (2018b) used the two heaviest
loads of 30% and 40% BM and found that 30 m sprint time was significantly increased
(11.8–16.9%, ES = 2.52–3.11), while significant decreases were found in Vo (−12.6% to
−17.3%, ES = −2.52 to −3.19) and Vmax (−11.7%to −16.1%, ES = −2.51 to—3.19).
Moreover, Fo (−16.7% to −22.1%, ES = −2.53 to −3.30), Pmax (−27.3% to −35.6%, ES =
−2.64 to −3.44), RFmax (−12.5% to −17.1%, ES = −2.61 to −3.39), and DRF (2.5–3.1%,
ES = 0.75–0.81) were all significantly changed.
Two research groups performed vest loaded sprints on a non-motorised treadmill for
6 s with loads ranging from 5% to 21.8% BM (Cross, Brughelli, & Cronin, 2014;
Simperingham & Cronin, 2014). Sprints with 5% BM resulted in contact time being
significantly increased (3.8–4.7%, ES = 0.58) during the acceleration and maximum
velocity phases, while flight time was only significantly decreased (−15%, ES = −0.44)
during the acceleration phase. Moreover, vest loading of 5% BM significantly decreased
peak vertical ground reaction force (−5.4%, ES −0.58, acceleration phase, −6.4%, ES =
−0.53, maximum velocity) and mean vertical ground reaction force (−3.8%, ES = −0.55,
acceleration, −4.0%, ES = −0.50, maximum velocity) (Simperingham & Cronin, 2014).
Peak velocity (−3.6% ES = −0.38) was significantly decreased with vest loads of 10.9%
BM, while during the maximum velocity phase step length (−4.4%, ES = −0.33), flight
time (−17.4%, ES = −0.89), and contact time (4.1–9.2%, ES = 0.98–1.67) were signifi-
cantly changed (Cross et al., 2014). No significant changes in kinetics were found with
this load. The heavier 21.8% BM vest load resulted in significant decreases in peak
velocity (−5.7%, ES = −0.57), step length (−4.4%, ES = −0.34, maximum velocity phase)
and flight time (−18.9% to −26.7%, ES = −1.06 to −1.67), with increases in contact time
(9.2% ES = 1.67, maximum velocity phase) (Cross et al., 2014). Moreover, significantly
increased peak vertical ground reaction force (8.2%, ES = 0.70, maximum velocity
phase), mean vertical ground reaction force (10.6%, ES 1.32%, and 11.1%, ES = 1.16,
acceleration and maximum velocity phases, respectively), and decreased peak power
output (−14.3%, ES = −0.47, maximum velocity phase) were found with this loading
(Cross et al., 2014).
SPORTS BIOMECHANICS 9

Longitudinal effects of weighted vests on sprint-running
The longitudinal effects of weighted vests training on sprint-running performance and
kinematics are reported from five studies (Table 3). No kinetics were reported from any
of the studies. The vest loads used ranged from 5.6% to 18.9% BM with overground
sprints being performed over 10 m to 55 m. Two studies utilised vest loading only
during training sessions (Clark, Stearne, Walts, & Miller, 2010; Rey et al., 2017), while
the remaining three studies had participants wear the vests for the majority of the day
for at least three days per week (Barr, Gabbett, Newton, & Sheppard, 2015; Rantalainen,
Ruotsalainen, & Virmavirta, 2012; Scudamore et al., 2016). Three weeks of vest loading
with 5.6% BM improved velocity during a 10 m sprint by 1.3% (p > 0.05, ES = 0.37)
(Rantalainen et al., 2012) while incremental vest loading (11.6–16.1% BM) over the
same time period resulted in a significant improvement (1.5%, ES = 1.8) in 36.6 m time
(Scudamore et al., 2016). In contrast, during a shorter eight-day training period, 12%
BM loading had no significant effect on 10 m or 40 m sprint time, though contact time
was significantly decreased (8.9%, ES = 0.09) during the maximum velocity phase (Barr
et al., 2015). No significant changes were found in sprint time or kinematics over
a 55 m distance following a seven-week training period with 18.5% BM (Clark et al.,
2010). However, significant improvements in 10 m (9.4%, ES = 1.77) and 30 m (6.1%,
ES = 3.30) sprint performance were found with 18.9% BM vest loading following
a 6-week training period (Rey et al., 2017).
Discussion and implications
Acute effects of weighted vests on sprint-running performance
The acute effects of weighted vest sprint-running were reported from six studies.
Weighted vest loading (5–40% BM) was found to significantly increase sprint times
in over ground sprint-running at all distance (10 m to 50 m), with measures of velocity
significantly decreased in a linear fashion with incremental vest loads. Carlos-Vivas
et al. (2018b) found incremental loads of 10% BM resulted in maximum velocity being
decreased by 4–5% with each increment. It appears that weighted vest loading had
a greater effect on sprint performance during the maximum velocity phase than the
acceleration phase. Cronin et al. (2008) reported that 15% and 20% BM vest loading
produced greater changes at 30 m (9.6–11.7%) compared to 10 m (7.5–10%), while at
the same distance Konstantinos et al. (2014) using vest loads of 8%, 15%, and 20% BM
found similar results when comparing 30 m (4.6%, 6.9%, 9.6%) to 10 m (4.1%, 6.9%,
9.2%) distances. Konstantinos et al. (2014) also reported 40 m and 50 m sprint times
and found that greater increases in time were found at 40 m (5.1%, 7.9%, 9.9%)
compared to 50 m (4.6%, 7.3%, 8.2%) with all loads, respectively. Reasons, why the
40 m time was more effected than the 50 m time, are unknown, though Konstantinos
et al. (2014) reported that participants reached their maximum velocity between 20 and
40 m, thus it could be speculated that vest loading has a greater effect on attaining
maximum velocity than maintaining maximum velocity. Furthermore, as sprints were
performed from a flying start, participants may have already been decelerating
(fatiguing).
10 P. MACADAM ET AL.

Cronin et al. (2008) assessed changes in step kinematics during overground sprinting
and reported significantly longer contact times, and significantly shorter flight times,
step frequencies and step lengths. Contact times (14.3–19.6%) and flight times (−8.3%
to −14.6%) were found to be more affected than step frequency (~-2.6 to −6.1%).
Regarding kinetics, incremental loads of 10% BM (10% to 40% BM) were found to
significantly decrease maximum horizontal force by 6–7% and maximum horizontal
power output by 11–14% with each increment increase (Carlos-Vivas et al., 2018b).
While incremental loads of 5% BM (5% to 15% BM) resulted in similar levels of
decreases (−4.3% to −4.7%) in maximum horizontal power output, in a similar study
(Carlos-Vivas et al., 2018a). Carlos-Vivas et al. (2018b) was the only study to report the
maximum ratio of forces and decrease in ratio of forces, with all loads (10–40% BM)
significantly decreasing maximum ratio of forces (−4.6% to −17.1%), while decreases in
ratio of forces were only significantly changed (2.5–3.1%) with loads of ≥30% BM.
Therefore, potential reasons for the acute decreases in sprint performance appear to
result from the weighted vest overloading a participant during the stance phase to such
an extent that lower levels of horizontal force and power are produced.
From the two studies (Cross et al., 2014; Simperingham & Cronin, 2014) that used
weighted vests (5–21.9% BM) during treadmill sprints, similar outcomes to over ground
sprint kinematics were reported, that is contact and flight times were more affected by
vest loading than step frequency and length, and the maximum velocity phase was more
affected than the acceleration phase. Contact times were significantly increased
(3.8–9.2%) and flight times were significantly decreased (−15% to −26.7%) with all
vest loads with greater changes found in the maximum velocity phase compared to the
acceleration phase. In contrast, only step length was significantly decreased (−4.4%)
with loads of ≥10.9% with step frequency unchanged, while velocity was also only
significantly decreased with vest loads of ≥10.9% BM (−3.6% to −5.7%). Vertical ground
reaction force was significantly decreased with 5% BM loading (−5.4% acceleration,
−6.4%, maximum velocity), unaffected with 10.9% BM, and significantly increased
(10.6% acceleration, 11.1% maximum velocity) with 21.8% BM. Similar to kinematic
changes, greater changes in vertical ground reaction force were found during the
maximum velocity phase as compared to the acceleration phase. It would seem that
loads >10% BM are required to significantly decrease vertical ground reaction forces.
Longitudinal effects of weighted vests on sprint-running performance
The effects of weighted vest loading on sprint-running performance were investigated in
five studies. All research groups reported improvements in velocity and sprint times,
though not all findings were statistically significant. Due to the differences in training
periods (8 days, 3 weeks, 6 weeks and 7 weeks), sprint distances (10, 30, 36.6, 40 and 55 m)
and vest loads (5.6%, 11.6–16.1%, 12%, 18.5% and 18.9% BM) inter-study comparisons are
problematic and should be interpreted with caution. In addition, the total training sessions
with a weighted vest varied between studies, and three of the studies used a hypergravity
intervention i.e., meaning participants wore the weighted vest for most of the day.
Previously hypergravity interventions have been found to elicit significant improve-
ments in jump performance, lower limb power output, and a rightward shift in the force-
velocity profile following a 3-week period with loads ranging 7–13% BM (Bosco, 1985;
SPORTS BIOMECHANICS 11

Bosco, Rusko, & Hirvonen, 1986;Boscoetal.,1984). However, comparable changes are
not apparent in sprint-running studies most likely due to the methodological differences
between studies. Rantalainen et al. (2012) and Scudamore et al. (2016) both utilised the
same 3-week hypergravity training period used by Bosco (Bosco, 1985;Boscoetal.,1986,
1984). A significant improvement in 36.6 m sprint time (1.5%) was found with incre-
mental weekly vest loading (11.6–16.1% BM) in fitness trained participants (Scudamore
et al., 2016). While an increase in velocity (1.3%) was reported over 10 m following vest
loading of 5.6% BM in sedentary participants, the authors reporting the findings were not
significant (Rantalainen et al., 2012). Differences in findings between studies may relate to
the greater load used by Scudamore et al. (2016) coupled with a greater number of training
sessions completed (9 vs. 6). The differences in participants training backgrounds may also
have resulted in the fitness trained participants being able to cope with the additional vest
loading, whereas the sedentary participants may have struggled with exercising with an
additional overload. Moreover, it has been proposed that weighted vests may have
agreatereffect on maximum velocity sprinting compared to acceleration phase sprinting,
thus the differences in sprint distance (10 m vs. 36.6 m) should be considered as
confounding conclusions. The third study to employ hypergravity loading was completed
on rugby athletes and measured performance changes at 10 m and 40 m, however, this
study used a much shorter training period (eight days) compared to the other studies
reviewed. Though no changes in sprint performance at either distance were found
following the 8-day intervention, Barr et al. (2015) did report that two of the eight
participants improved sprint performance highlighting that responses to vest loaded
training are participant specific. As this study had the shortest training period, a longer
duration may have been required to elicit significant improvements, though the significant
decrease in contact time (maximum velocity phase) in this short period illustrated that
positive adaptations were apparent, thus with a greater duration (e.g., ≥3weeks)significant
improvements in sprint performance may have eventuated.
The remaining two studies both used similar vests magnitudes (18.5% and 18.9%
BM) and completed a similar number of training sessions (12 and 13) though differed
in sprint distance (30 m vs. 55 m) (Clark et al., 2010; Rey et al., 2017). Clark et al. (2010)
reported a non-significant improvement in sprint time (1.2%) measured over 18.5 m to
55 m, while significant improvements in 10 m (9.4%) and 30 m (6.1%) sprint perfor-
mance were reported by Rey et al. (2017). Of note, both studies found that sprint
performance from the control groups were similar to the weighted vest group’s changes
with no significant differences between the groups. Therefore, sprint training, indepen-
dent of load, had a positive effect on sprint performance, thus questioning the need for
resisted vest loading. However, Rey et al. (2017) did note that the nature of improve-
ments in sprint performance were different between the groups with the control group
achieving greatest improvement at 10 m, whereas the vest loaded group had the greatest
improvement at 30 m. This finding supports the proposal that vest loading may be
more beneficial for maximum velocity phase sprinting due to the increased vertical load
at foot contact.
In summary, weighted vest loading has a greater impact on contact and flight times
than step length and frequency variables, which influences the acceleration of the body’s
centre of mass downwards, relating to reduced or similar vertical ground reaction force
until the use of relatively heavy vest loads (>20% BM). Horizontal force and power
12 P. MACADAM ET AL.

production were reduced with vest loading as little as 5% BM. Though both acceleration
and maximum velocity phases were affected, the additional vertical loading from the vest
seems to have a greater affect during maximum velocity sprinting on both kinematics and
kinetics resulting in greater decreases in sprint times at maximum velocity phases. It is
possible that the maximum velocity phase of sprint running is more sensitive to the
vertical loading with vest loads due to the importance of vertical force production in
producing maximum velocity sprint running (Weyand, Sternlight, Bellizzi, & Wright,
2000). Moreover, Cronin and Hansen (2006) suggested that a weighted vest increased
the vertical load during ground contact, increasing vertical braking forces, and may
effectively overload the stretch-shortening cycle, thus has better application during max-
imum velocity speed. Longitudinal training with weighted vests has focused on two
general methodologies: hypergravity intervention during activities of daily living and
hypergravity training while sprint running. One is highly specific to the intended outcome
(resistance training at high velocity, i.e., wearing vest while sprinting) and the other is
opposing training specificity (wearing a load all day likely slows down activities of daily
living and is resistance training at slow velocities). Studies that used weighted vests during
sprint running sessions found that sprint performance from the control groups were
similar to the weighted vest group’schanges—no significant differences between the
groups. Large variations in study methodologies (use of WR, training period, WR amount,
populations used) make it inappropriate to formulate discrete conclusions on the long-
itudinal effects of weighted vests on sprint running performance.
Limitations and future research
Due to the heterogeneity of the included studies (magnitude of the load, intervention
duration, and participants) caution is warranted when interpreting the findings of this
review and their implications for practice. The magnitude of loads (5% to 40% BM)
differed considerably in studies as did participant training backgrounds meaning that it
is difficult to clearly establish the optimum loading for sprint-running. Three of the five
longitudinal studies involved the weighted vest being worn for most of the day, thus
making the comparison to other studies or generalisation to typical practice proble-
matic. Moreover, the vest was not worn for two studies during sport training events.
Future research is required to more fully understand the acute and longitudinal
effects of weighted vests on sprint-running performance. It is recommended that
research replicates similar vest magnitudes and sprint distances to verify the findings
of this review. The sporting backgrounds and technical proficiency of the participants
can influence both the kinematic and kinetic changes during weighted vest interven-
tions. This was particularly evident during the longitudinal studies when highly trained
participants were compared to recreationally or sedentary participants. Moreover,
athletes with different levels of experience and skills may require modified loading
magnitudes (i.e., more or less %BM) to enable positive sprint adaptation. Whether vest
loading of > 40% BM would be beneficial in sprint-running has also yet to be
investigated though the practicality of loading and attaching that amount of resistance
to the torso would be challenging and may be more suitable to sledge loading where
greater loads can easily be applied.
SPORTS BIOMECHANICS 13

Conclusion
Though several limitations and gaps exist in the research, some general comments can
be made about the use of weighted vests. Sprinting with a weighted vest results in
a significant acute reduction in velocity and increase in sprint times during over ground
sprint-running with loads of 5–40% BM, while velocity was only significantly decreased
with vest loads of ≥10.9% BM in treadmill sprints. During weighted vest sprinting,
contact and flight times were more affected by loading as opposed to step frequency and
step length. The reduction in flight time, which reduced the influence of the accelera-
tion of the body’s centre of mass downwards, resulted in the vertical ground reaction
force being reduced or remaining relatively the same until a relatively heavy vest load (>
20% BM) was used. Incremental loads of 10% BM were found to significantly decrease
maximum horizontal force by 6–7% and maximum horizontal power output by
11–14%. Though some performance improvements with weighted vest sprinting were
found in longitudinal studies of three weeks or more, the full benefits of this training
method on mechanistic determinants and performance are yet to be clearly established.
Future research is required to define the optimum load and volume to clearly establish
if there are any training benefits to this form of resisted sprinting.
Disclosure statement
No potential conflict of interest was reported by the authors.
ORCID
Paul Macadam http://orcid.org/0000-0002-2077-5386
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