ArticlePDF Available

Abstract and Figures

The effects of vest loading on sprint kinetics and kinematics during the acceleration and maximum velocity phases of sprinting are relatively unknown. A repeated measures ANOVA with post hoc contrasts was used to determine whether performing 6 s maximal exertion sprints on a non-motorized force treadmill, under two weighted vest loading conditions (9 and 18 kg) and an un-loaded baseline condition, affected the sprint mechanics of thirteen males from varying sporting backgrounds. Neither vest load promoted significant change in peak vertical ground reaction force (GRF-z) outputs compared to baseline during acceleration, and only 18 kg loading increased GRF-z at maximum velocity (8.8%; ES = 0.70). Mean GRF-z significantly increased with 18 kg loading during acceleration and maximum velocity (11.8 to 12.4%; ES = 1.17 to 1.33). Horizontal force output was unaffected, although horizontal power was decreased with the 18 kg vest during maximum velocity (-14.3%; ES = -0.48). Kinematic analysis revealed decreasing velocity (-3.6 to -5.6%; ES = -0.38 to -0.61), decreasing step length (-4.2%; ES = -0.33 to -0.34), increasing contact time (5.9 to 10.0%; ES = 1.01 to 1.71), and decreasing flight time (-17.4 to -26.7%; ES = -0.89 to -1.50) with increased loading. As a vertical vector-training stimulus, it appears that vest loading decreases flight time, which in turn reduces GRF-z. Furthermore, it appears heavier loads than traditionally recommended are needed to promote increases in GRF-z output during maximum velocity sprinting. Finally, vest loading offers little as a horizontal vector-training stimulus and actually compromises horizontal power output.
Content may be subject to copyright.
Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand; and
School of Exercise, Biomedical and Health Science, Edith Cowan University, Perth, Australia
Cross, MR, Brughelli, ME, and Cronin, JB. Effects of vest
loading on sprint kinetics and kinematics. J Strength Cond Res
28(7): 1867–1874, 2014—The effects of vest loading on sprint
kinetics and kinematics during the acceleration and maximum
velocity phases of sprinting are relatively unknown. A repeated
measures analysis of variance with post hoc contrasts was
used to determine whether performing 6-second maximal exer-
tion sprints on a nonmotorized force treadmill, under 2
weighted vest loading conditions (9 and 18 kg) and an un-
loaded baseline condition, affected the sprint mechanics of
13 males from varying sporting backgrounds. Neither vest load
promoted significant change in peak vertical ground reaction
force (GRF-z) outputs compared with baseline during acceler-
ation, and only 18-kg loading increased GRF-z at the maximum
velocity (8.8%; effect size [ES] = 0.70). The mean GRF-z sig-
nificantly increased with 18-kg loading during acceleration and
maximum velocity (11.8–12.4%; ES = 1.17–1.33). Horizontal
force output was unaffected, although horizontal power was
decreased with the 18-kg vest during maximum velocity
(214.3%; ES = 20.48). Kinematic analysis revealed decreas-
ing velocity (23.6 to 25.6%; ES = 20.38 to 20.61), decreas-
ing step length (24.2%; ES = 20.33 to 20.34), increasing
contact time (5.9–10.0%; ES = 1.01–1.71), and decreasing
flight time (217.4 to 226.7%; ES = 20.89 to 21.50) with
increased loading. As a vertical vector-training stimulus, it seems
that vest loading decreases flight time, which in turn reduces
GRF-z. Furthermore, it seems that heavier loads than that are
traditionally recommended are needed to promote increases in
the GRF-z output during maximum velocity sprinting. Finally, vest
loading offers little as a horizontal vector-training stimulus and
actually compromises horizontal power output.
KEY WORDS vest loading, sprint mechanics, horizontal force,
vertical force, acceleration, maximum velocity
An athlete’s ability to accelerate and attain maxi-
mal velocity is reliant on the relationship between
the force production capability of the body and
the ability of the athlete to harness and effectively
use that force in time periods relative to the activity (7).
Furthermore, it has been proposed that the direction of force
application plays a larger role in increasing the acceleration
than the amount of force applied (24) and that greater accel-
erations and maximal velocities have been achieved through
lower but more forward-oriented forces (18,23,24).
Retaining a high ratio of horizontal to total force production
seems to be key to enhance acceleration and maximum
velocity (24). Understanding which training techniques
may present such mechanical overload would seem impor-
tant to optimize the development of these speed qualities.
Resisted sprint techniques, such as sled or vest weighted
sprinting, offer a specific approach to overloading during
common sport movements. (1,5,11,21,22). Potentially, these
techniques could elicit positive effects on sprint kinematics (i.
e., contact time, flight time, step length, and step frequency)
by increasing the athlete’s ability to generate vertical and
horizontal forces. Although studies examining the acute
and longitudinal effects of sled towing on sprint performance
are increasingly common, there are few studies that examine
the effects of vest loading on similar performance character-
istics (6,8). Notably, it has been suggested that sled towing
and vest loading may overload the neuromuscular system in
a different manner. For example, sled towing, particularly at
higher percentages of body mass (BM) (16), has been pro-
posed to offer a greater horizontal vector-training stimulus
whereas vest sprinting is more vertically oriented (7). Under-
standing the mechanical adaptations associated with vest
loading in greater detail is of interest to these researchers.
It has been suggested that the heavier the external loading,
the greater disruption to normal sprint kinematics—therefore,
in best practice, the optimal loading for sprinting would be
one that minimally affects running mechanics, while supply-
ing an appropriate overload stimulus to promote adaption
(2,22). To date, only 3 recent articles have examined the use
of weighted vests on sprint performance and kinematics
(2,6,8). Of these studies, 2 examined the acute effects of vest
loading (9–20% of BM) on sprint kinematics and reported
Address correspondence to Matt R. Cross,
Journal of Strength and Conditioning Research
Ó2014 National Strength and Conditioning Association
VOLUME 28 | NUMBER 7 | JULY 2014 | 1867
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
a decrease in velocity (23.8%) and an increase in sprint time
(7.5–11.7%) with loading in comparison with unresisted con-
ditions (2,8). In addition, vest sprinting has been shown to
affect step/stride length (20.5 to 25.2%) and frequency
(22.4 to 22.7%) and several other kinematic variables in
comparison with unloaded sprinting (2,8). A study by Bosco
et al. (3), highlighted the ability to increase power through
periodization involving external loading around the torso in
the form of a weighted belt. However, as can be observed from
this brief treatise of the litera-
ture, the kinetics-associated vest
loading is relatively unexplored,
and there is certainly no research
profiling kinetics across a variety
of vest loads.
The acceleration and maxi-
mum velocity phases of sprinting
require different mechanical de-
mands on the sprinter (7,9). The
acceleration phase requires long
contact periods, short flight
times, positive net horizontal
forces, and a greater forward
trunk lean in comparison with
the maximum velocity phase
(1,9). Thus, each phase may
respond differently to the same
vest load and therefore warrant
specific loading protocols
(1,9,28). No previous studies
have examined the effects of
vest sprinting on acceleration
or maximum velocity phase kinetics during sprint running.
Thus, the means of effectively manipulating vest load to cause
changes in the force profile for specific adaptation is currently
unknown. Such information is important to strength and con-
ditioning and sprint coaches for programming purposes. The
aim of this study, therefore, was to analyze the effects of vest
loading on sprint kinetics and kinematics during the acceler-
ation and maximum velocity phases while sprinting on a non-
motorized treadmill (NMT) ergometer.
Experimental Approach to
the Problem
A cross-sectional design was
used to investigate the effects
of vest loading on kinematics
and kinetics during accelera-
tion and maximum velocity
sprinting. All subjects per-
formed maximum effort
6-second sprints on an NMT
with and without vest loading
first 2 steps (i.e., first stride) of
the 6-second sprint and 10
steps once the subjects at-
tained maximum velocity
were averaged for final values.
Data were then compared
using a repeated measures
analysis of variance (ANOVA)
with Bonferroni post hoc
Figure 1. Image of sprint trial on the nonmotorized treadmill under braking load.
Figure 2. Image of treadmill set-up and foot braking of belt.
Vest Sprinting Kinetics and Kinematics
Journal of Strength and Conditioning Research
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
analyses to determine statistical difference between
Thirteen sport-active (rugby codes, n= 6; track sprinters, n=2;
field hockey n= 1; miscellaneous sporting codes, n=4),
weightlifting, healthy male
university-level athletes volun-
teered to take part in this study
(22.9 63.3 years old; BM:
82.5 68.4 kg; stature: 179.1 6
6.6 cm). All athletes provided
written informed consent before
participating, and completed a
health questionnaire to ensure
that they were fit for testing.
The Institutional Ethics Com-
mittee of Auckland University
of Technology provided
approval for this study.
Equipment. A Woodway Force
3.0 (Eugene, OR, USA) NMT
ergometer was used to quantify the sprint kinetics and
kinematics (Figure 1). This ergometer is a modernized equiv-
alent of the original NMT system introduced by Lakomy
(19) and has been implemented (4,25) and validated (12).
Nonmotorized treadmill ergometry pertaining to both the
training and measurement of performance variables have
Figure 3. A representative sprinting velocity-time curve during a 6-second maximum effort sprint.
Figure 4. A representative GRF-z-time curve during a 6-second maximum effort sprint. The arrows indicate the first 2 steps (i.e., first stride) during the
acceleration phase and the 10 steps during maximum constant velocity.
Journal of Strength and Conditioning Research
VOLUME 28 | NUMBER 7 | JULY 2014 | 1869
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
been explored in depth during sprinting (13–15,20,26,27).
The NMT system used in this study featured a user-driven
vulcanized rubber belt, the mechanics of which feature 12
guiding rollers and 114 ball bearings. The subjects were har-
nessed around the waist to a vertical strut at the rear of the
system. A nonelastic tether secured the harness to a load cell
and a locking vertical-sliding gauge allowed the collection of
horizontal force data. This sliding gauge was manually
adjustable (and securable) to each subject’s hip height to
enable horizontal alignment of the tether to the load cell
during running trials. Calibration of the load cell took place
before the testing session by hanging a selection of known
weights from the tether as instructed by the manufacturer.
Vertical force output was collected using 4 load cells posi-
tioned beneath the NMT belt. The vertical load cells were
calibrated before and after testing using known loads placed
on top of the stationary treadmill belt. The velocity of the
treadmill belt was collected by 2 optical speed microsensors
located at the rear of the treadmill belt. Calibration for this
measurement was not needed because the distance recorded
per rotation of the belt did not change, and unit conversion
was hardcoded into the NMT software. Power output was
measured by the NMT as the product of the force exerted on
the horizontal load cell and the velocity of the treadmill belt.
All variables were collected at a sampling rate of 200 Hz,
using a hardwired system interface (XPV7 PCB; Fitness
Technology, Adelaide, Australia). Primary analysis took
place within a custom-built LabVIEW software program
(LabVIEW; National Instruments, Texas, USA).
Resisted Conditions. Weighted vests were used to supply the
vertical loading, and each subject performed the trials as
usual on the NMT system. The vests were loaded with small
sandbags that could be added or removed in increments of
approximately 200 g. The load could be distributed evenly
around the subject’s torso, up to approximately 20 kg per
vest. The 2 loading conditions included absolute loads of
9 and 18 kg. Previous researchers have used vest loads
between 7 and 20% of relative BM (2,3,8), and the loads
chosen for this study align with such loading parameters.
Procedures. Participants were required to report on a single
day for approximately 2.5 hours of preparation, familiariza-
tion, and testing. Close-fitting sports clothing and running
shoes were worn throughout. First, the subjects’ height,
mass, and age were determined and recorded. The subjects
were then required to undergo a
standardized warm-up and
familiarization. Initially, the sub-
jects jogged unloaded on the
treadmill for 90 seconds. During
this time, the subjects were
encouraged to vary their pace
to familiarize themselves with
the feeling of accelerating on
the foreign running surface.
Two build-up sprints of 70 and
80% of the subjects’ expected
maximum velocity were then
performed based on the findings
of semi-professional Australian
Rules footballers sprinting on
an NMT (4). This consisted of
a 3-second submaximal acceler-
ation to the determined velocity,
holding that velocity for 5 sec-
onds, and then decelerating. To
conclude the warm-up protocol,
a 3-second maximum acceler-
ation was performed. This
entailed a tester applying a sta-
tionary brake to the treadmill
track to enable the subject to
lean against the harness so as
to simulate a block start. Based
on their performance in this step
of the protocol, subjects were
allowed the opportunity to
TABLE 1. Test-retest reliability based on coefficient of variation (CV) and
intraclass correlation (ICC) for sprint kinetics and kinematics.*
Baseline 9-kg vest 18-kg vest
CV (%) ICC CV (%) ICC CV (%) ICC
Velocity (m/s)
Peak 1.6 0.98 1.9 0.98 2.2 0.98
GRF-z (N)
Acceleration 3.1 0.98 3.8 0.97 7.0 0.86
Maximum velocity 1.8 0.99 2.9 0.99 3.4 0.98
GRF-z mean (N)
Acceleration 1.6 0.99 1.4 1.00 8.8 0.70
Maximum velocity 1.5 1.00 1.4 1.00 1.9 0.99
Acceleration 5.8 0.89 6.5 0.92 9.0 0.74
Maximum velocity 6.5 0.87 6.6 0.97 5.5 0.93
Acceleration 6.1 0.92 8.2 0.96 16.0 0.59
Maximum velocity 6.6 0.94 7.5 0.97 6.8 0.95
Contact time (ms)
Acceleration 5.6 0.82 4.6 0.88 5.2 0.88
Maximum velocity 2.8 0.89 4.5 0.63 2.9 0.89
Flight time (ms)
Acceleration 9.2 0.90 6.3 0.93 11.2 0.88
Maximum velocity 4.2 0.97 6.1 0.98 9.1 0.96
Step frequency (Hz)
Maximum velocity 2.1 0.94 3.2 0.93 2.1 0.96
Step length (m)
Maximum velocity 2.0 0.99 2.0 0.99 17.9 0.92
*GRF-z = peak vertical force; H
= peak horizontal force; P
= peak power output.
Vest Sprinting Kinetics and Kinematics
Journal of Strength and Conditioning Research
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
complete another trial of the blocked-start. Between each sec-
tion of the warm-up, subjects were allowed to rest for 60
seconds, followed by a 2–4-minute rest period preceding the
first trial.
The data collection consisted of 6-second maximal
velocity sprints under the 3 conditions. As per the warm-
up protocol, the treadmill belt was blocked from behind
(Figure 2). Starting position for all sprints was standardized
with subjects starting with the right foot back, and then,
they were instructed to lean into the harness. Throughout
each 6-second trial, subjects were given continuous verbal
encouragement to promote maximal effort. The loading
protocols consisted of 2 absolute vest loads (9 and 18 kg).
One to three trials, dependent on the success of the initial
and subsequent collections, were performed for each con-
dition. If more than 1 trial was collected, the trial with the
highest maximum velocity was selected for analysis. The
participant order was staggered and randomized, 4–6 sub-
jects performed the testing protocol in a cycled format
to maximize time efficiency and concurrently allow each
subject appropriate rest. Rest between trials was less than
4 minutes for each participant after each trial.
Statistical Analyses
Data was collected during the acceleration and maximum
velocity phases of each 6-second sprint (Figure 3). The
“first stride” was defined as the first 2 steps after the initial
push-off. “Maximum constant velocity” was defined as the
10 steps after the maximum velocity was attained and
maintained. The first 2 steps during the acceleration phase
and 10 steps during the maximum velocity phase were
averaged for final analysis (Figure 4). Velocity measures,
peak horizontal force, peak GRF-z, mean GRF-z, and
power output were obtained from the LabVIEW program
as described previously. Contact time was determined from
0 N to the moment it returned to a null reading (i.e., 0–0 N).
Flight time was measured from the moment of last ground
contact of one foot to the moment of first contact of the
other foot. Stride frequency was determined by the follow-
ing formula: 1/(contact time + flight time). Stride length
was determined through the following formula: peak veloc-
ity/stride frequency.
Seven of the participants completed 2 trials at each
loading condition to determine test-retest reliability of the
sprint kinetics and kinematics
variables. Intraclass correlation
coefficient and coefficient of
variation were calculated for
each variable (Table 1). Means
and SDs were determined for
each variable under each loading
condition and were used as
measures of centrality and
spread of data. Normal distribu-
tion of the data was checked
using the Sharpio-Wilk statistic.
A repeated measures ANOVA
with Bonferroni post hoc con-
trasts was used to determine sig-
nificant kinematic and kinetic
differences between loads (body
weight, 9 and 18 kg) for each
condition (acceleration and
maximum velocity). All varia-
bles, excluding step length, step
frequency, and peak velocity,
were analyzed in both the accel-
eration and maximum velocity
phases. Statistical significance
criterion was set at an alpha
level of p#0.05. Additionally,
effect sizes (ES) were calcu-
lated using the following equa-
tion: ES = (high value2low
value)/((high value SD +low
value SD)/2). Effect sizes were
described as large (ES .1.2),
TABLE 2. Kinetic and kinematic variable outputs over the acceleration and
maximum velocity phases under loading protocols.*
Loading conditions
Baseline 9-kg vest 18-kg vest
Velocity (m/s)
Peak 5.86 60.54 5.65 60.565.53 60.55
GRF-z (N)
Acceleration 1613 6175 1547 6210 1674 6177
Maximum velocity 1923 6259 1983 6304 2093 6229
GRF-z mean (N)
Acceleration 990 697 1027 6120 1107 680
Maximum velocity 1165 6130 1205 6146 1309 6117
Acceleration 482 6109 453 678 452 693
Maximum velocity 270 678 272 681 253 665
Acceleration 1272 6413 1271 6362 1380 6380
Maximum velocity 1600 6544 1540 6560 1372 6416
Contact time (ms)
Acceleration 222 618 213 628 225 615
Maximum velocity 169 67.9 179 612186 612
Flight time (ms)
Acceleration 45 610 36 617 33 66
Maximum velocity 69 614 57 61356 610
Step frequency (Hz)
Maximum velocity 4.15 60.33 4.18 60.27 4.09 60.26
Step length (m)
Maximum velocity 1.42 60.19 1.36 60.171.36 60.16
*GRF-z = peak vertical force; H
= peak horizontal force; P
= peak power output.
Significantly different from baseline.
Journal of Strength and Conditioning Research
VOLUME 28 | NUMBER 7 | JULY 2014 | 1871
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
moderate (0.6 ,ES ,1.2), small (0.2 ,ES ,0.6), and
trivial (ES ,0.2) (10).
Kinematic Variables
Peak velocity decreased significantly between both vest
conditions (23.6 to 25.63%; ES = 20.38 to 20.61) in com-
parison with baseline unloaded sprinting (Table 2). Step fre-
quency remained statistically unchanged by external loading;
however, step length significantly decreased in both vested
conditions (24.2% [both conditions]; ES = 20.33 to 20.34)
in comparison with baseline. Contact time during the acceler-
ation phase was statistically unchanged respective to the base-
line condition. During the maximum velocity phase, significant
increases in contact time (5.9–10.0%; ES = 1.01–1.71) com-
pared with baseline were observed in both vest conditions.
The 18-kg vest condition flight time during the acceleration
phase was significantly decreased (226.7%; ES = 21.50) com-
pared with baseline. During the maximum velocity phase, both
vest conditions resulted in significantly decreased flight time
(217.4 t o 218.8%; ES = 20.89 to 21.08).
Kinetic Variables
Peak GRF-z output during the acceleration phase was
statistically unchanged relative to the baseline condition.
During the maximum velocity phase, only the 18-kg vest
condition produced significantly greater peak GRF-z (8.8%;
ES = 0.70) as compared with the baseline. During both the
acceleration and maximum velocity phases, the 18-kg vest
significantly increased the mean GRF-z compared with the
baseline (11.8–12.4%; ES = 1.17–1.33). Vest loading had no
significant effect on horizontal force output in either the
acceleration or the maximum velocity phases. There were
no significant variations from baseline for power output dur-
ing the acceleration phase; however, during the maximum
velocity phase, the 18-kg vest condition resulted in a signifi-
cantly lower horizontal power output compared with the
unloaded baseline conditions (214.3%; ES = 20.48).
This is the first study, to the best of our knowledge, that has
investigated the effects of vest loading on sprint kinetics along
with sprint kinematics during the acceleration phase and
maximum velocity phase of sprinting. Both vest loads
significantly decreased the maximal velocity output. The
3.5% decrease with approximately a 10.9% load (9 kg) of
mean subject BM is comparable with the findings of Alcaraz
et al. (2) who reported a 3.8% decrease in velocity with a 9%
BM load. Moreover, Cronin et al. (8) reported a 9.3–11.7%
increase in 30-m sprint times with a vest load of 15–20%
BM. Vest loading seems to have similar effects on peak velocity
outputs on NMT ergometry as over-ground sprinting.
The effects of additional external loading on step frequency
and step length may explain the decrements in velocity
observed in this study. In over-ground running, vest or belt
loading has been reported to significantly reduce the overall
stride length, and typically decrease step frequency (2,8).
Furthermore, the added loading will usually increase the
ground contact time (2,8) and decrease the flight time (2)
during the gait cycle. The results from this study concur with
this trend, with the addition of external loading decreasing
step length (24.2%), increasing contact time at the maximum
velocity (5.9–10.1%), and decreasing the flight time during
both acceleration (226.7%) and maximum velocity phases
(217. 4 to 218.8%). The significant decrease in flight time
observed at maximum velocity may suggest that the added
vertical load supplied by the vest essentially limited the sub-
jects’ ability to propel their body into a flight phase.
The relationship between external loading and GRF-z
output is of interest, particularly to those wishing to overload
such forces for a specific training purpose. Interestingly, no
significant increases in peak GRF-z relative to baseline with
vest loading during the acceleration phase were observed in
this study. Moreover, only the 18-kg vest resulted in a large
increase in the mean GRF-z during acceleration (11.8%). It
would seem that vest loading might not be an appropriate
resisted method to overload the acceleration phase vertical
GRF-z, especially in terms of lighter loading protocols
similar to those used in this study. At maximum velocity,
only the 18-kg vest load resulted in a moderate increase in
GRF-z over the baseline condition (8.8%). Similar to the
acceleration phase, a moderate increase in the mean GRF-z
was observed with the 18-kg vest alone (12.4%). It seems that
greater training loads than the traditional recommendation
of 7–15% BM (2,8) may be needed to promote significant
increases in GRF-z production. However, as previous loading
parameters have been assigned on the basis of minimization of
technical alterations, trainers will need to decide whether the
possibility of compromising technique is an acceptable trade-
off for an increased GRF-z training stimulus.
The fact that peak GRF-z did not increase during the
acceleration phase highlights an interesting phenomenon
whereby the addition of mass to the subject does not result
in a corresponding increase in GRF-z. It would be expected
that an increase in peak GRF-z would be similar to the mass
added with each vest load (i.e., 88.3–176.6 N); however, this
was not the case. It seems that additional mass may not
provide as great a GRF-z training stimulus as initially
thought, and other training methods need to be explored
to overload GRF-z production capabilities, especially during
acceleration. This phenomenon is most likely explained by
the additional vertical loading affecting the rise and fall of the
center of mass (COM) during the flight phase, i.e., significant
reduction in flight phase time. If the flight height of the
COM is reduced, then there will be a concomitant reduction
in the GRF-z. It would seem that this reduction in flight time
(rise and fall of COM) counters the effect of the additional
mass. Similar findings have been reported during running at
submaximum velocities while subjects carried compliant poles
(18). Kram (17) found that an additional load of 19% body
Vest Sprinting Kinetics and Kinematics
Journal of Strength and Conditioning Research
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
weight only increased peak GRF-z by 4.7% and reduced flight
times by 35%. Future research quantifying the path of the
COM is needed to validate this contention.
Vest loading did not result in any significant effects on
horizontal force output during either the maximum velocity
or acceleration phases. Cronin et al. (8) reported a decrease
in forward trunk lean with vest sprinting, likely illustrating
a reduction in the subjects’ ability to control the added mass
added to their frame. Because forward lean has been reported
as a mechanical determinant of horizontal force production
(18,23), it is likely that vest loading affected the subjects’ ability
to produce force in a horizontal direction through a limitation
in their ability to effectively control the added mass and resul-
tant forces.
The addition of vest loading did not result in any
significant effects on power output during the acceleration
phase. Only during the maximum velocity phase did the
18-kg vest condition result in a small decrease in power
compared with the baseline condition (214.3%). Bosco et al.
(3) highlighted the possibility for increases in vertical power
from vest weighted training; however, the results of this
study certainly do not support such a contention. This dis-
sonance can be explained by the different power calculations
in both studies; the power output for the NMT is calculated
as the product of horizontal force and velocity. Because hor-
izontal force production was unaffected and velocity reduced
by vest loading, it is unlikely that vest loading would provide
a horizontal power stimulus. It could be speculated that the
same would be true of the value of vest loading as a vertical
power-training stimulus—that is, given the nonsignificant
changes in GRF-z production and the decrement in velocity
with additional load, it is unlikely that vest loading would
overload vertical power to any great extent. Therefore, if
there is a strong relationship between power production
and sprint performance, as some researchers have alluded
to (11), then careful consideration needs to be given to the
selection of training modalities that maximize horizontal and
vertical power output.
There are several limitations in this study that should be
noted. First, the athlete sample represents a collection of team,
individual and casual sport athletes of varying abilities. Second,
because the loads chosen in this study were absolute, the
loading protocols chosen represented a different percentage of
BM for each participant. In a practical sense, this may not be
possible or probable in an application to the field—hence why
absolute loading was chosen in this study—however future
studies should either select a sample with similar character-
istics (i.e., a team of rugby union forwards), or calculate loads
based on a percentage of each subject mass. Third, although
the Woodway treadmill offers a more realistic running experi-
ence to standard motorized treadmills, particularly for maximal
sprinting, it differs to over-ground running. Maximum sprint
performances are typically 25–30% slower on the Woodway
NMT. Maximum velocity has however been shown to be valid
in comparison with over-ground sprinting (12). Fourth, vertical
and horizontal force data on the treadmill were not collected
from the same location. This could be addressed in future
studies with tri-axial force-plates imbedded beneath the
track (25). Finally, mechanisms for the findings were not
investigated because maximum sprint velocity significantly
decreased with each load. A more detailed analysis could be
conducted in the future if sprint velocity were maintained
with increasing vest loading.
A fundamental tenet of strength and conditioning practice is
matching the training stimulus to the individual needs of the
athlete, which in turn should produce the desired adaptation.
Important in such an approach is understanding the
mechanical stimuli certain training methods provide. In
terms of vest loading, it is thought that this type of training
provides a means of improving the vertical eccentric/
concentric force capability of athletes during cyclic activities
such as hopping, bounding, and running. It would seem,
however, that the interaction between load and the use of
this training method in producing the desired adaptation
may be more complicated than initially thought. Increasing
vest loading using the loading parameters of this study had
little effect on GRF-z. It would also seem that the vest loads
offered little as a horizontal and vertical power-training
stimulus. Given these findings, careful consideration needs to
be given to the choice of load and utilization of this type of
training if increasing GRF-z production of the athlete is
a training goal. It may be that heavier vest loads than initially
thought are needed to overload cyclic vertical strength and
power, but the effect of such loading on sprint kinematics/
technique needs investigation.
In summary, vest loading may have a place in the preparation
of the athlete, however, understanding when and for what
reason it should occur in the athlete plan is fundamental to
targeted individualized programming. Furthermore, as maxi-
mal effort sprinting is a complex interplay between a number
of different variables, the reader needs to be cognizant that the
optimal training solution for sprinting performance is not
a single modality, but a combination of several. Identifying
individual needs and matching these with modalities that
address the individual’s mechanical/physiological limitations
would seem fundamental in improving strength and condi-
tioning practice and optimizing sprint performance.
The authors wish to thank the committed group of subjects
for their participation in this study. This project did not
receive external financial assistance, and none of the authors
hold any conflict of interest.
1. Alcaraz, PE, Palao, JM, and Elvira, JLL. Determining the optimal
load for resisted sprint training with sled towing. J Strength Cond Res
23: 480–485, 2009.
Journal of Strength and Conditioning Research
VOLUME 28 | NUMBER 7 | JULY 2014 | 1873
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
2. Alcaraz, PE, Palao, JM, Elvira, JLL, and Linthorne, NP. Effects of
three types of resisted sprint training devices on the kinematics of
sprinting at maximum velocity. J Strength Cond Res 22: 890–897,
3. Bosco, C, Rusko, H, and Hirvonen, J. The effect of extra-load
conditioning on muscle performance in athletes. Med Sci Sports
Exerc 18: 415–419, 1986.
4. Brughelli, M, Cronin, J, and Chaouachi, A. Effects of running
velocity on running kinetics and kinematics. J Strength Cond Res 25:
933–939, 2011.
5. Cissik, JM. Means and methods of speed training, part I. Strength
Cond J 26: 24–29, 2004.
6. Clark, KP, Stearne, DJ, Walts, CT, and Miller, AD. The longitudinal
effects of resisted sprint training using weighted sleds vs. weighted
vests. J Strength Cond Res 24: 3287–3295, 2010.
7. Cronin, J and Hansen, KT. Resisted sprint training for the
acceleration phase of sprinting. Strength Cond J 28: 42–51, 2006.
8. Cronin, J, Hansen, K, Kawamori, N, and Mcnair, P. Effects of
weighted vests and sled towing on sprint kinematics. Sports Biomech
7: 160–172, 2008.
9. Delecluse, C. Influence of strength training on sprint running
performance. Sports Med 24: 147–156, 1997.
10. Drinkwater, EJ, Hopkins, WG, McKenna, MJ, Hunt, PH, and
Pyne, DB. Modelling age and secular differences in fitness between
basketball players. J Sports Sci 25: 869–878, 2007.
11. Faccioni, A. Assisted and resisted methods for speed development:
Part 2. Mod Athlete Coach 32: 8–12, 1994.
12. Highton, JM, Lamb, KL, Twist, C, and Nicholas, C. The reliability
and validity of short-distance sprint performance assessed on
a nonmotorized treadmill. J Strength Cond Res 26: 458–465, 2012.
13. Hopker, JG, Coleman, DC, Wiles, JD, and Galbraith, A.
Familiarisation and reliability of sprint test indices during laboratory
and field assessment. J Sports Sci Med 8: 528–532, 2009.
14. Hughes, M, Doherty, M, Tong, R, Reilly, T, and Cable, N. Reliability
of repeated sprint exercise in non-motorised treadmill ergometry. Int
J Sports Med 27: 900–904, 2006.
15. Hunter, JP, Marshall, RN, and McNair, PJ. Relationships between
ground reaction force impulse and kinematics of sprint-running
acceleration. J Appl Biomech 21: 31–43, 2005.
16. Kawamori, N, Newton, RU, Hori, N, and Nosaka, K. Effects of
weighted sled towing with heavy versus light load on sprint
acceleration ability. J Strength Cond Res. Accessed 30, 2013: Epub
ahead print.
17. Kram, R. Carrying loads with springy poles. J Appl Physiol (1985) 71:
1119–1122, 1991.
18. Kugler, F and Janshen, L. Body position determines propulsive
forces in accelerated running. J Biomech 43: 343–348, 2010.
19. Lakomy, HKA. The use of a non-motorized treadmill for analysing
sprint performance. Ergonomics 30: 627–637, 1987.
20. Lim, JM and Chia, MYH. Reliability of power output derived from
the nonmotorized treadmill test. J Strength Cond Res 21: 993–996,
21. Lockie, RG, Murphy, AJ, Schultz, AB, Knight, TJ, and Janse de
Jonge, XAK. The effects of different speed training protocols on
sprint acceleration kinematics and muscle strength and power in
field sport athletes. J Strength Cond Res 26: 1539–1550, 2012.
22. Lockie, RG, Murphy, AJ, and Spinks, CD. Effects of resisted sled
towing on sprint kinematics in field-sport athletes. J Strength Cond
Res 17: 760–767, 2003.
23. Morin, JB, Bourdin, M, Edouard, P, Peyrot, N, Samozino, P, and
Lacour, JR. Mechanical determinants of 100-m sprint running
performance. Eur J Appl Physiol 112: 3921–3930, 2012.
24. Morin, JB, Edouard, P, and Samozino, P. Technical ability of force
application as a determinant factor of sprint performance. Med Sci
Sports Exerc 43: 1680–1688, 2011.
25. Ross, RE, Ratamess, NA, Hoffman, JR, Faigenbaum, AD, Kang, J,
and Chilakos, A. The effects of treadmill sprint training and
resistance training on maximal running velocity and power.
J Strength Cond Res 23: 385–394, 2009.
26. Sirotic, AC and Coutts, AJ. The reliability of physiological and
performance measures during simulated team-sport running on
a non-motorised treadmill. J Sci Med Sport 11: 500–509, 2008.
27. Tong, RJ, Bell, W, Ball, G, and Winter, EM. Reliability of power
output measurements during repeated treadmill sprinting in rugby
players. J Sports Sci 19: 289–297, 2001.
28. Young, W, Benton, D, and John Pryor, MHS. Resistance training for
short sprints and maximum-speed sprints. Strength Cond J 23: 7–13,
Vest Sprinting Kinetics and Kinematics
Journal of Strength and Conditioning Research
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
... Optimal loads for RST to target the maximum velocity phase (high-speed training) have been reported as loads that induce < 10% velocity decrement (or < 13% BM) compared to the maximum velocity achieved in control sprints (Cahill et al., 2019;Macadam et al., 2019), which has been suggested to be translatable to WV sprinting. Previous studies with WV loads between 5 and 9% BM have demonstrated velocity decrements, compared to control sprints, ranging from 1.2 to 4.7% (Alcaraz et al., 2008;Carlos-Vivas et al., 2019a;Carlos-Vivas et al., 2019b;Cross et al., 2014;Simperingham and Cronin, 2014). Previous kinematic results (studies with WV loads between 5 and 9% BM) have demonstrated that WV trials increase support time (ST) (range 4.7-5.6%) ...
... compared to control sprints, which change to larger extents than decreased step length (SL) (range 2.5-4.4%) and frequency (SF) (range 0.8-3.8%) trends during the maximum velocity phase (Cross et al., 2014;Macadam et al., 2019;Simperingham and Cronin, 2014). In terms of kinetics, two previous treadmill studies elucidated changes due to WVs, compared to control sprints, demonstrating no vertical peak force differences with loads of 5% BM (Simperingham and Cronin, 2014) or 9 kg absolute (Cross et al., 2014). ...
... trends during the maximum velocity phase (Cross et al., 2014;Macadam et al., 2019;Simperingham and Cronin, 2014). In terms of kinetics, two previous treadmill studies elucidated changes due to WVs, compared to control sprints, demonstrating no vertical peak force differences with loads of 5% BM (Simperingham and Cronin, 2014) or 9 kg absolute (Cross et al., 2014). ...
This study elucidated kinetic and kinematic changes between control and weighted vest sprinting with a load of 7% body mass. Fourteen male sprinters completed 60 m control and vest sprints over a long force platform system. Step-to-step ground reaction force and spatiotemporal variables were grouped, representing the initial acceleration (1st–4th steps), middle acceleration (5th–14th steps), later acceleration (15th step–step before maximum velocity reached) and maximum velocity (stride where maximum velocity reached) phase during each trial. Two-way ANOVA with post hoc Tukey HSD and a Cohen’s d effect size with 95% confidence intervals elucidated the difference between trials and phases. Between control and vest trials the velocity decreased (3.41–3.78%) through trivial–small step length (1.95–2.72%) and frequency (0.87–1.54%) decreases. Vertical impulse increased (6.46–6.78%) through moderate support time increases (4.84–6.00%), coupled with no effective vertical mean force differences during the vest trial, compared to the control. There was no significant interaction between trials and phases. Therefore, although weighted vest trials did not increase vertical mean force production, vests did induce an increased vertical force application duration during the support phase step-to-step while supporting a larger total load (body mass plus vest mass).
... In respect of sprinting, a review reported that acute trunk WR loading significantly reduced velocity (-3.6%) during treadmill sprinting as WR load increased beyond a threshold of 11% BM, while over-the-ground sprinting velocity were significantly reduced (-6.9%) with WR loads more than 8% BM (Macadam et al., 2016). Acute decrement in contact time of stance phase (3.8% to 24.5%) and the flight time (8.4% to 26.7%) were found during sprinting with 5 ~ 21.8%BM attached to the trunk Cross et al., 2014;Simperingham & Cronin, 2014). And 21% BM trunk WR loading significantly increase the peak vertical force (8.2%) during the maximal velocity phase of sprinting on a non-motorized treadmill (Cross et al., 2014). ...
... Acute decrement in contact time of stance phase (3.8% to 24.5%) and the flight time (8.4% to 26.7%) were found during sprinting with 5 ~ 21.8%BM attached to the trunk Cross et al., 2014;Simperingham & Cronin, 2014). And 21% BM trunk WR loading significantly increase the peak vertical force (8.2%) during the maximal velocity phase of sprinting on a non-motorized treadmill (Cross et al., 2014). Moreover, 5% BM limb WR loading (thigh or shank) significantly increased the contact time (4.3% to 4.7%) and peak vertical GRF (4% to 4.6%) as well as decreased the step frequency (3.6% to 3.5%) during the treadmill sprinting (Simperingham & Cronin, 2014). ...
... However, these results were different from loaded sprint study conducted by Simperingham and Cronin which reported the peak vertical force significantly decreased during the 5%BM weight vest loaded condition (Simperingham & Cronin, 2014). In this regard, the additional load significantly decreased flight time and subsequently decreased the rise and fall of the centre of mass (-15%, p < 0.05) during the flight phase (Simperingham & Cronin, 2014), which affected the momentum of COM when initial contact with ground and reduce the vertical GRF (Cross et al., 2014). It seems that the effect of the additional load is countered by the reduction in flight time (rise and fall of COM) (Cross et al., 2014). ...
This study determined the acute changes in kinematics and kinetics when an additional load equivalent to 5% body mass was attached to the torso during change of direction (COD). In this within-subject repeated measures study, 14 male soccer players (age: 18.29 ± 0.32 years) volunteered to participate. Subjects performed COD under two conditions in randomized order: (1) no WR, and (2) with WR. No significant differences between the loaded and unloaded conditions in actual COD angle, approach speed, braking time, propulsive time, contact time, COD completion time (all p > 0.05, ES = 0.05–0.11), and all measured kinematic parameters (all p > 0.05, ES = 0–0.18). Nonetheless, ankle plantar/dorsi flexion ROM had possibly small increase in the loaded condition (ES = 0.24). Kinetics analysis has shown that the loaded condition was likely to have small increase in relative peak vertical propulsive ground reaction force (GRF, p = 0.11, ES = 0.41), and possible small increases in relative peak braking GRF (vertical: p = 0.21, ES = 0.42; total: p = 0.22, ES = 0.38), relative peak total propulsive GRF (p = 0.24, ES = 0.26), and relative braking impulse (horizontal, vertical, and total; p = 0.27–0.41, ES = 0.26–0.28). WR did not significantly change the acute movement techniques, meanwhile induced small increases in important kinetic stimuli for potential adaptation in COD.
... All variables were collected at a sampling rate of 200 Hz, using a hardwired system interface (XPV7 PCB; Fitness Technology, Adelaide, Australia). Methods similar to previous research (Brughelli, Cronin, & Chaouachi, 2011;Cross, Brughelli, & Cronin, 2014) were used to calculate peak step velocity, step frequency, step length, contact time, flight time, peak horizontal force, peak vertical force, and peak power output. ...
... During this time, the subjects were encouraged to vary their pace to familiarise themselves with the feeling of accelerating on the foreign running surface. Two build-up sprints of 60% and 80% of the subjects' expected maximum velocity were then performed based on the findings of previous NMT sprint studies (Brughelli et al., 2011;Cross et al., 2014). This consisted of a 3-second submaximal acceleration to the determined velocity, holding that velocity for 5 s, and then decelerating. ...
... Therefore, greater leg WR loading is required to overload vertical force during NMT sprinting. This was certainly the case with trunk worn WR during NMT sprint-running, where loads of ∼20% BM were required to significantly overload vertical force (Cross et al., 2014). It may be proposed that thigh WR appears to be more of a rotational and horizontal overload than vertical overload to sprinting. ...
Full-text available
The aim of this study was to investigate the load effects of thigh attached wearable resistance (WR) on linear and angular kinematics and linear kinetics during sprint-running. Fourteen recreational active subjects performed a series of maximal sprints with and without WR of 1, 2, and 3% body mass (BM) in a randomised order. Sprints were performed on a non-motorised treadmill which collected velocity, and linear step kinematics and kinetics. Angular kinematics of the thigh were collected from an inertial measurement unit attached to the left thigh. Trivial decreases were found in peak velocity with all WR loads (-0.9 to -.2.4%, effect size [ES] 0.09-0.17, p > 0.05). The WR conditions resulted in significantly decreased average step frequency (-2.0% to -3.0%, ES 0.35-0.44, p < 0.05) with loads of ≥ 2% BM, whereas average step length was statistically unchanged (1.9-2.8%, ES 0.20-0.33). Average angular displacement was significantly decreased (-7.0% to -10.3%, ES 0.88-1.10, p 0.00-0.03) with loads of ≥ 2% BM. Average angular flexion velocity (-10.2%, ES 1.07, p 0.02) and extension velocity (-12.0%, ES 0.85, p 0.01) were significantly decreased with 3% BM. Trivial to small ES changes (p > 0.05) were found in the linear kinetic measures of interest. Thigh WR provides a sprint-specific rotational form of resistance resulting in greater changes to angular kinematics than linear properties of sprint-running. For practitioners who wish to target thigh angular kinematics and step frequency without decreasing step length, thigh WR of ≥ 2% BM offers a sprint-specific resistance training tool
... The muscular work for running takes place through the contraction of quadriceps and hamstrings [20]. However, the past studies mentioned that characterized the kinematics of RSA running are generally restricted to common variables such as T C , flight time (T F ), T S , S F , and stride length (S L ) [17,[21][22][23] which are considered the final product of muscle contractions. Based on this preliminary information, we, therefore, hypothesized that these variables alone could not show the whole effects of muscle work during running performance [21][22][23]. ...
... However, the past studies mentioned that characterized the kinematics of RSA running are generally restricted to common variables such as T C , flight time (T F ), T S , S F , and stride length (S L ) [17,[21][22][23] which are considered the final product of muscle contractions. Based on this preliminary information, we, therefore, hypothesized that these variables alone could not show the whole effects of muscle work during running performance [21][22][23]. The steps toward acceptance of this hypothesis depend on: ...
Full-text available
Summary Purpose The objectives of the present study were to analyze possible changes in biomechanical patterns during a repeated sprint protocol and identify the mechanical factors that could influence performance. Methods Sixteen male athletes (22.1 ± 3.1 years old, 78.6 ± 22.9 kg and 186.1 ± 10.1 cm in height) participated in this study. Warm-up exercises were performed. Thereafter, the subjects carried out the Running Anaerobic Sprint Test (RAST), composed of six explosive effort sprints of 35 m separated by 10 s of passive recovery. During the protocol, performed on an official indoor court (rigid surface), two cameras recorded performance parameters (time) while twelve cameras (OptiTrack™ Natural Point Inc. - USA) adjusted to 120 Hz, monitored the 3-D running kinematics. Results The time length of effort (+11.6%; P < 0.05) increased from the first (4.67 ± 0.39 s) to the sixth (5.28 ± 0.36 s) repetitions. Significant changes were identified in stride frequency, contact time, stride time, horizontal speed of core body mass (BCM), and angle of thigh at touchdown (−14.9%; 19.1%; 8.2%; 17.0%; −18.8%; P < 0.05). Correlations were found between common step variables (i.e., SF and TS) and complex variables of the ankle, hips, and center of mass (BCM) kinematics (i.e., φthighTD, φthighTO, STDzH, ωkneeTD, θankleTD, and θankleTO) with the minimum Time (4.43 ± 0.37 s) and mean Time (4.91 ± 0.23 s) in the RAST. Conclusion We can conclude that RAST performed on-court modify the mechanics of running and both, common and advanced kinematic measures such as derived from ankle, hips, and BCM motion are mechanical outputs linked with performance in this repeated sprint model. KEYWORDS: 3-D Kinematics; Running; Fatigue; Team sports.
... Literature shows there is a strong and significant relationship between maximal strength (MSt) performance in the squat and acceleration or movement velocity, 3,7,16 whereby acceleration and movement velocity are both dependent on speed strength. While MSt can be seen as important for the starting phase during sprints, [17][18][19] speed strength is needed to produce force in a very short unit time during accelerations 20 since ground contact times reduce to <200 ms 21 to the end of the acceleration phase. This points out the importance of rate of force development (RFD) as part of speed strength next to MSt for effective sprinting performance. ...
Practical Question: Is high-load squat training beneficial in improving sprinting performance in junior elite-level soccer players? Clinical Bottom Line: There is Level 3 evidence to support the validity of high-load squat training as a measure to improve sprinting performance in junior male elite-level soccer players. All three studies included showed significant increases in soccer-related sprinting performance.
... In the literature kinematic parameters during weighted running are generally limited to step variables and contact or flight times. Therefore, a direct comparison of the assessed joint angle parameters in the present study is difficult (Couture et al., 2020;Cross et al., 2014). However, it has been stated that less leg extension at toe off is beneficial for the running economy (Moore, 2016). ...
Full-text available
Wearable resistance allows individualized loading for sport specific movements and can lead to specific strength adaptations benefiting the athlete. The objective was to determine biomechanical changes during running with lower limb light-weight wearable resistance. Fourteen participants (age: 28±4 years; height: 180±8 cm; body mass: 77±6 kg) wore shorts and calf sleeves of a compression suit allowing attachment of light loads. Participants completed four times two mins 20-m over-ground shuttle running bouts at 3.3m*s⁻¹ alternated by three mins rest. The first running bout was unloaded and the other three bouts were under randomised loaded conditions (1%, 3% and 5% additional loading of the individual body mass). 3D motion cameras and force plates recorded kinematic and kinetic data at the midpoint of each 20-m shuttle. Friedman-test for repeated measures and linear mixed effect model analysis were used to determine differences between the loading conditions (α=0.05). Increased peak vertical ground reaction force (2.7N/kg to 2.74N/kg), ground contact time (0.20s to 0.21s) and decreased step length (1.49m to 1.45m) were found with additional 5 % body mass loading compared to unloaded running (0.001>p<0.007). Marginally more knee flexion and hip extension and less plantarflexion was seen with higher loading. Differences in the assessed parameters were present between each loading condition but accompanied by subject variability. Further studies, also examining long term effects, should be conducted to further inform use of this training tool.
... For example, vertical forces have a greater relative contribution to the V max phase [136,137]. Acute kinematic differences suggest vertical force production when sprinting could be developed by undertaking training strategies utilising weighted vests by providing a greater load on the eccentric braking phase at the beginning of the stance phase [185,186], whereas sled towing is expected to provide a superior adaptation in horizontal force production [185,187,188]. Further research is required to determine the optimal load, loading strategy, and dose for performance enhancement, particularly for V max development. ...
Full-text available
Background Within the football codes, medium-distance (i.e., > 20 m and ≤ 40 m) and long-distance (i.e., > 40 m) sprint performance and maximum velocity sprinting are important capacities for success. Despite this, no research has identified the most effective training methods for enhancing medium- to long-distance sprint outcomes. Objectives This systematic review with meta-analysis aimed to (1) analyse the ability of different methods to enhance medium- to long-distance sprint performance outcomes (0–30 m, 0 to > 30 m, and the maximum sprinting velocity phase [ V max ]) within football code athletes and (2) identify how moderator variables (i.e., football code, sex, age, playing standard, phase of season) affected the training response. Methods We conducted a systematic search of electronic databases and performed a random-effects meta-analysis (within-group changes and pairwise between-group differences) to establish standardised mean differences (SMDs) with 95% confidence intervals and 95% prediction intervals. This identified the magnitude and direction of the individual training effects of intervention subgroups (sport only; primary, secondary, tertiary, and combined training methods) on medium- to long-distance sprint performance while considering moderator variables. Results In total, 60 studies met the inclusion criteria (26 with a sport-only control group), totalling 111 intervention groups and 1500 athletes. The within-group changes design reported significant performance improvements (small–moderate) between pre- and post-training for the combined, secondary (0–30 and 0 to > 30 m), and tertiary training methods (0–30 m). A significant moderate improvement was found in the V max phase performance only for tertiary training methods, with no significant effect found for sport only or primary training methods. The pairwise between-group differences design (experimental vs. control) reported favourable performance improvements (large SMD) for the combined (0 to > 30 m), primary ( V max phase), secondary (0–30 m), and tertiary methods (all outcomes) when compared with the sport-only control groups. Subgroup analysis showed that the significant differences between the meta-analysis designs consistently demonstrated a larger effect in the pairwise between-group differences than the within-group change. No individual training mode was found to be the most effective. Subgroup analysis identified that football code, age, and phase of season moderated the overall magnitude of training effects. Conclusions This review provides the first systematic review and meta-analysis of all sprint performance development methods exclusively in football code athletes. Secondary, tertiary, and combined training methods appeared to improve medium-long sprint performance of football code athletes. Tertiary training methods should be implemented to enhance V max phase performance. Nether sport-only nor primary training methods appeared to enhance medium to long sprint performance. Performance changes may be attributed to either adaptations specific to the acceleration or V max phases, or both, but not exclusively V max . Regardless of the population characteristics, sprint performance can be enhanced by increasing either the magnitude or the orientation of force an athlete can generate in the sprinting action, or both. Trial Registration OSF registration .
... Indeed, weighted vests are associated with an increased training load, evidenced through increased oxygen consumption, increased relative exercise intensity (Puthoff et al. 2006), and increased blood lactate accumulation during steady-state exercise (Rusko and Bosco 1987). Further, the use of a weighted vest as a training overload stimulus appears to have a beneficial effect on sprinting (Macadam, Cronin, and Feser 2019), although caution has been proposed regarding technical execution while wearing the vest (Cross et al., 2014). The vast majority of literature having utilised weighted activities has been based on body mass (e.g. ...
Full-text available
This study quantified the physiological and biomechanical effects of the 20lb (9.07kg, males) and 14lb (6.35kg, females) weighted vest used in CrossFit, and whether they predisposed to injury. Twenty subjects (10 males, 10 females) undertook walking (0%, 5% and 10% gradient) and running trials in two randomised study visits (weighted vest/no weighted vest). Physiological demand during walking was increased with the vest at 10% but not 5% or 0% with no change in gait variables. In the running trial, the weighted vest increased oxygen uptake (males; females) (+0.22L/min, p < 0.01; +0.07L/min, p < 0.05), heart rate (+11bpm, p < 0.01; +11bpm, p < 0.05), carbohydrate oxidation (+0.6g/min, p < 0.001; +0.2g/min, p < 0.01), and energy expenditure (+3.8kJ/min, p < 0.001; +1.5kJ/min, p < 0.05) whilst blood lactate was increased only in males (+0.6mmol/L, p < 0.05). There was no change in stride length or frequency. Weighted vest training increases physiological stress and carbohydrate oxidation without affecting measured gait parameters. Practitioner Summary We examined the effect of weighted vest training prescribed in CrossFit (20 lb/9.07kg, males and 14 lb/6.35kg, females) in a randomised controlled trial. We found that physiological stress is increased in both sexes, although three-fold greater in males, but with no change in biomechanical gait that predisposes to lower-limb injury.
Full-text available
PURPOSE: This study aimed to examine the relationship between performance-related factors and physical abilities in Korean national bobsled and skeleton athletes.METHODS: Sixteen bobsled and skeleton athletes who participated in the 2018 Pyeongchang Winter Olympics as a Korean national team volunteered to participate in this study. The participants were evaluated in terms of performance-related factors, including anaerobic power, 5 bound jump (5 BJ), and sprinting speed by sections, and physical abilities, including isokinetic strength, 1 repetition maximum (1 RM) strength, body composition, anthropometry, and agility. Stepwise selection of multiple regression analyses was used to investigate the relationship between performance-related factors and physical ability.RESULTS: Statistically significant correlations were observed between anaerobic power, sprinting speed by sections, 5 BJ and chest, isokinetic strength (knee, 180°/s), deadlift, and side-step.CONCLUSIONS: The results of this study show that the performance of Korean national bobsled and skeletal athletes is related to upper and lower body strength and agility. Thus, future training programs for bobsled and skeletal athletes should focus on improving strength and agility for performance enhancement.
In pole vaulting, take-off speed is considered as a major determinant of performance. Pole carriage could affect the speed acquired during the approach and at the take-off. This study investigated different types of runs performed randomly by young male and female expert athletes: maximal sprint, maximal pole carriage run, maximal run-up with simulated pole plant and competition situation. Speed profile was determined with a radar gun and spatiotemporal parameters were recorded for the last 20 m of the approach with the Optojump Next system. For both genders, mechanical variables were compared using two-way ANOVAs with repeated measurements. Pole carriage represents the main cause of speed decrease for both men (−5.8%) and women (−6.2%). A step rate decrease during pole carriage was pointed out with an increase of contact time for both men and women. Significant speed decrease was observed for women at the take-off compared to pole plant simulation (−4.3%), while not for men. Those results provide a new insight for pole vault training allowing to update training process with specific exercises leading to reduce speed loss at take-off.
Full-text available
Weighted sled towing is a common resisted sprint training technique even though relatively little is known about the effects that such practice has on sprint kinematics. The purpose of this study was to explore the effects of sled towing on acceleration sprint kinematics in field-sport athletes. Twenty men completed a series of sprints without resistance and with loads equating to 12.6 and 32.2% of body mass. Stride length was significantly reduced by similar to10 and similar to24% for each load, respectively. Stride frequency also decreased, but not to the extent of stride length. In addition, sled towing increased ground contact time, trunk lean, and hip flexion. Upper-body results showed an increase in shoulder range of motion with added resistance. The heavier load generally resulted in a greater disruption to normal acceleration kinematics compared with the lighter load. The lighter load is likely best for use in a training program.
Full-text available
Adrian Faccioni, a lecturer at the Centre of Sports Studies, University of Canberra, Australia, presents a detailed evaluation of assisted and resisted speed development methods and their implications to coaching. See part 2 of this text (resisted methods) on the Canadian Athletics Coaching Centre Website. Re-printed with permission from Modern Athlete and Coach. Running velocity is determined by stride rate and stride length, (Running velocity = stride rate x stride length). However, as velocity increases from submaximal to supramaximal, stride rate and stride length do not increase linearly. Mero & Komi (1986) detailed how stride length plateaued as stride rate continued to increase to supramaximal velocity. Therefore, in order to improve maximal speed of running, attention should be directed towards increased speed of limb movement. This can be achieved by performing a variety of specific exercises that are movement specific and close to the competition rate. The goals of speed training are to increase physical, metabolic and neurological components t h a t a r e e s s e n t i a l t o i n c r e a s e a n a t h l e t e ' s r u n n i n g s p e e d . Maximal speed training (100%) must be performed regularly, but even this training modality, if performed too regularly, can lead to speed plateaus, making continued speed improvement very difficult. To ensure these plateaus do not occur, the athlete should use specific speed development exercises that can be divided into two major groups, those of assisted speed exercises that allow the athlete to increase speed or frequency of movement, and resisted methods to increase the force required to run at speed. The assisted method allows all the systems of the body to adapt to high speed movements that are then transferred to non-assisted competitive movements. The resisted speed exercises recruit more muscle fibers and greater neural activation that is then transferred to the competitive situation.
Full-text available
The aim of the study was to assess the reliability of sprint performance in both field and laboratory conditions. Twenty-one male (mean ± s: 19 ± 1 years, 1.79 ± 0.07 m, 77.6 ± 7.1 kg) and seventeen female team sport players (mean ± s: 21 ± 4 years, 1.68 ± 0.07 m, 62.7 ± 4.7 kg) performed a maximal 20-metre sprint running test on eight separate occasions. Four trials were conducted on a non-motorised treadmill in the laboratory; the other four were conducted outdoors on a hard-court training surface with time recorded by single-beam photocells. Trials were conducted in random order with no familiarisation prior to testing. There was a significant difference between times recorded during outdoor field trials (OFT) and indoor laboratory trials (ILT) using a non-motorised treadmill (3.47 ± 0.53 vs. 6.06 ±1.17s; p < 0.001). The coefficient of variation (CV) for time was 2.55-4.22% for OFT and 5.1-7.2% for ILT. During ILT peak force (420.9+87.7N), mean force (147.2+24.7N), peak power (1376.8 ± 451.9W) and mean power (514.8 ± 164.4W), and were measured. The CV for all ILT variables was highest during trial 1-2 comparison. The CV (95% confidence interval) for the trial 3-4 comparison yielded: 9.4% (7.7-12.1%), 7.9% (6.4-10.2%), 10.1% (8.2-13.1%) and 6.2% (5.1-8.0%) for PF, MF, PP and MP and respectively. The results indicate that reliable data can be derived for single maximal sprint measures, using fixed distance protocols. However, significant differences in time/speed over 20-m exist between field and laboratory conditions. This is primarily due to the frictional resistance in the non-motorised treadmill. Measures of force and power during ILT require at least 3 familiarisations to reduce variability in test scores.
Full-text available
This study examined the interday and intraday reliabilities and validities of various sprint performance variables on a nonmotorized treadmill (NMT) over distances of 10, 20, and 30 m. After habituation, 12 male team-sport players performed 3 sprints on the NMT on 2 separate days and an assessment of overground running performance, separated by 24 hours. Measurements included sprint times, mean and peak sprint speeds, and step length and frequency. Data analysis revealed no significant mean differences (p > 0.05) between NMT variables recorded on the same day or between days. Ratio limits of agreement indicated that the best levels of agreement were in 20-m (1.02 ×/÷ 1.09) and 30-m (1.02 ×/÷ 1.07) sprint times, peak (1.00 ×/÷ 1.06) and mean (0.99 ×/÷ 1.07) running speed, and step length (0.99 ×/÷ 1.09) and frequency (1.01 ×/÷ 1.06). The poorest agreement was observed for time to peak running speed (1.10 ×/÷ 1.47). These reliability statements were reinforced by coefficients of variation being <5% for all the variables except time to peak running speed (11%). Significant differences (p < 0.05) were observed between NMT and overground sprint times across all distances, with times being lower (faster) by approximately 25-30% overground. The correlations between NMT and overground variables were generally modest (0.44-0.67), and optimal for time to cover 30 m on day 2. Our data support NMT ergometry as a reliable tool for most of the sprint performance variables measured and reveal that the fastest 30-m overground sprinters were likely to be identifiable via NMT ergometry.
Full-text available
Sprint mechanics and field 100-m performances were tested in 13 subjects including 9 non-specialists, 3 French national-level sprinters and a world-class sprinter, to further study the mechanical factors associated with sprint performance. 6-s sprints performed on an instrumented treadmill allowed continuous recording of step kinematics, ground reaction forces (GRF), and belt velocity and computation of mechanical power output and linear force-velocity relationships. An index of the force application technique was computed as the slope of the linear relationship between the decrease in the ratio of horizontal-to-resultant GRF and the increase in velocity. Mechanical power output was positively correlated to mean 100-m speed (P < 0.01), as was the theoretical maximal velocity production capability (P < 0.011), whereas the theoretical maximal force production capability was not. The ability to apply the resultant force backward during acceleration was positively correlated to 100-m performance (r (s) > 0.683; P < 0.018), but the magnitude of resultant force was not (P = 0.16). Step frequency, contact and swing time were significantly correlated to acceleration and 100-m performance (positively for the former, negatively for the two latter, all P < 0.05), whereas aerial time and step length were not (all P > 0.21). Last, anthropometric data of body mass index and lower-limb-to-height ratio showed no significant correlation with 100-m performance. We concluded that the main mechanical determinants of 100-m performance were (1) a "velocity-oriented" force-velocity profile, likely explained by (2) a higher ability to apply the resultant GRF vector with a forward orientation over the acceleration, and (3) a higher step frequency resulting from a shorter contact time.
summary: This article covers factors affecting speed, describes sprinting technique, distinguishes between acceleration and maximum speed, and covers technique drills. Common faults and coaching cues are also discussed.
Weighted sled towing is used by athletes to improve sprint acceleration ability. The typical coaching recommendation is to use relatively light loads, as excessively heavy loads are hypothesized to disrupt running mechanics and be detrimental to sprint performance. However, this coaching recommendation has not been empirically tested. This study compared the effects of weighted sled towing with two different external loads on sprint acceleration ability. Twenty-one physically active men were randomly allocated to heavy- (n = 10) or light-load weighted sled towing (n = 11) groups. All subjects participated in two training sessions per week for 8 weeks. The subjects in the heavy and light groups performed weighted sled towing using external loads that reduced sprint velocity by ∼30% and ∼10%, respectively. Before and after the training, the subjects performed a 10-m sprint test, in which split time was measured at 5 and 10 m from the start. The heavy group significantly improved both the 5- and 10-m sprint time by 5.7 ± 5.7% and 5.0 ± 3.5%, respectively (P < 0.05), whereas only 10-m sprint time was improved significantly by 3.0 ± 3.5% (P < 0.05) in the light group. No significant differences were found between the groups in the changes in 5-m and 10-m sprint time from pre- to post-training. These results question the notion that training loads that induce greater than 10% reduction in sprint velocity would negatively affect sprint performance, and point out the potential benefit of using a heavier load for weighted sled towing.
The measurement of human power output and anaerobic capacity in high-intensity exercise has traditionally been made using cycle ergometers. The assessment of power output during running has proved difficult because previous approaches have limited themselves to using motorized treadmills. In the present study the problems associated with motorized treadmills were overcome by using a non-motorized treadmill which was instrumented so as to allow the measurement of power output during sprint running. A non-motorized treadmill (Woodway model AB) was used because it allows rapid changes in running velocity normally found in sprinting to be monitored. In order to calculate the horizontal component of the applied power the instantaneous values of both the horizontal component of applied force and the treadmill belt speed were measured, and their product determined. A harness, attached to a force transducer, was passed around the waist securing the subject to the crossbar without restricting the movement of the limbs. The force measured was assumed to be the same as that horizontally applied to the treadmill belt.The outputs from the speed detector, force transducer and heart rate monitor were continuously monitored by a microcomputer.The results of the study showed that:(1)the peak speed attained on the treadmill is approximately 80% of that achieved in free-sprinting.(2)peak force is attained earlier than peak power and in turn peak power occurs before peak speed.(3)the force and power required to propel the treadmill belt at a constant speed increase with body weight.(4)the power required to propel the treadmill belt increases with speed.(5)stride length and frequency could be monitored.(6)elasticity in the tethering system acted as a low pass filter on the force profile.
summary: This article covers means used in speed training, including stride-length and stride-frequency drills, sprints of varying distances and intensity, varied-speed training, resisted sprinting, and assisted sprinting. Program design guidelines and a sample program are also presented. (C) 2005 National Strength and Conditioning Association