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Increasing Running Shoe Traction can Enhance Performance

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The outsole of a running shoe must provide enough traction for the athlete to avoid slipping during running. What is unknown is whether there is any point to designing running shoe outsoles with traction above this minimum required traction. The purpose of this study was to investigate whether performance could be enhanced by increasing the outsole traction of a running shoe. A commercially available running shoe (Control) was compared against the same shoe model with the outsole modified with a higher traction rubber (High Traction). The available traction of each shoe was measured with a traction testing system. Twenty male athletes completed a maximal effort timed running course in both shoes on two different surfaces. When wearing the Control running shoe, the athletes were able to complete the course on an asphalt road surface at maximal effort without slipping. When completing the same course wearing the High Traction shoe, the subjects were able to perform the course even faster. Therefore, the results show that the role of running shoe outsole traction is not to merely provide adequate traction to avoid large scale slips, but can also help athletes enhance performance of high-traction tasks such as accelerations and changes in direction.
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RJTA Vol. 18 No. 2 2014
17
Increasing Running Shoe Traction can Enhance Performance
Jay T. Worobets
1
*, Fausto Panizzolo
2
, Steve Hung
1
, John W. Wannop
1
and Darren J. Stefanyshyn
1
1
Human Performance Lab, Faculty of Kinesiology, University of Calgary, Canada
2
School of Sport Science, Exercise and Health, University of Western Australia, Australia
ABSTRACT
The outsole of a running shoe must provide enough traction for the athlete to avoid
slipping during running. What is unknown is whether there is any point to designing
running shoe outsoles with traction above this minimum required traction. The purpose of
this study was to investigate whether performance could be enhanced by increasing the
outsole traction of a running shoe. A commercially available running shoe (Control) was
compared against the same shoe model with the outsole modified with a higher traction
rubber (High Traction). The available traction of each shoe was measured with a traction
testing system. Twenty male athletes completed a maximal effort timed running course in
both shoes on two different surfaces. When wearing the Control running shoe, the athletes
were able to complete the course on an asphalt road surface at maximal effort without
slipping. When completing the same course wearing the High Traction shoe, the subjects
were able to perform the course even faster. Therefore, the results show that the role of
running shoe outsole traction is not to merely provide adequate traction to avoid large
scale slips, but can also help athletes enhance performance of high-traction tasks such as
accelerations and changes in direction.
Keywords: Footwear, Running Shoe, Outsole, Traction, Performance
1. Introduction
Footwear properties can enhance athletic
performance. For instance, researchers have
shown that reducing running shoe mass can
increase running economy (Catlin &
Dressendorfer, 1979; Divert et al., 2008;
Frederick, 1984), and incorporating properly
engineered carbon fiber insole plates into
footwear can positively affect jump height and
sprint time (Stefanyshyn & Fusco, 2004;
Stefanyshyn & Nigg, 2000; Tinoco et al., 2010;
Toon et al., 2009; 2011).
An aspect of running shoes that could potentially
affect performance is the outsole. The outsole, or
‘tread’, of the shoe is the bottom part of the shoe
that directly contacts the ground. As such, one
important role of the outsole is to provide the
athlete with traction. Clearly, if the outsole of a
shoe provides insufficient traction, the athlete
may slip during running, thus negatively affecting
performance. However, if the outsole traction of a
shoe already provides sufficient traction to avoid
slipping, it is not clear whether there is any
performance benefit if the traction is increased
even further.
Previous published research on running shoe
traction has focused on measuring the traction
(the translational friction coefficient) between
different running shoes and different surfaces
(Haberl & Prokop, 1973; Morehouse & Morrison,
1975; Nigg 1980; Cavanagh & Williams, 1981).
While this information has been invaluable in
furthering the basic knowledge on the topic, a
description is missing in the literature on how
running shoe traction and running performance
are related.
From a biomechanical standpoint, outsole traction
provides a runner with the ability to manipulate
the direction of the resultant ground reaction force
vector. As it is this ground reaction force that
accelerates the runner in the intended direction, it
is theoretically plausible that providing a runner
with more grip could allow the runner to direct
the ground reaction force more advantageously,
* Corresponding author. Tel.: 1 (403) 220 2704
E-mail address: worobets@ucalgary.ca (Jay Worobets)
RJTA Vol. 18 No. 2 2014
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facilitating faster accelerations and changes in
direction (as when running along a curved path).
Therefore, the purpose of this study was to
investigate whether performance of a maximal
effort running course composed of accelerations
and changes in direction could be enhanced by
increasing the outsole traction of a running shoe.
2. Methods
Twenty male recreational athletes with either
distance or track running experience were
recruited for this study (age 32.6 ± 10.2 yr, height
176.1 ± 2.7 cm, mass 73.6 ± 7.5 kg). All subjects
were a US 9 shoe size and free from recent injury
or pain. Informed written consent was obtained
from all subjects prior to data collection in
accordance with the University of Calgary’s
Conjoint Health Research Ethics Board.
The two shoes tested in the study were obtained
from adidas AG. The control shoe was the
commercially available adidas adiZERO adios
racing flat, which had a stiff polymer outsole
material under the forefoot (Figure 1). The
experimental ‘High Traction’ shoe was the same
adiZERO adios model, however, during the
manufacturing process the forefoot outsole was
built with a soft rubber material obtained from the
tire manufacturer Continental AG (Figure 1). This
rubber from the tire manufacturer was softer,
heavier, and was purported to have higher traction
than the outsole material found on the
commercially available shoe. Therefore, the two
shoes tested in the study varied only in forefoot
outsole material and tread pattern, and the overall
shoe mass (Control 202 g, High Traction 209g).
Fig. 1. Photographs of the Control shoe (left) and
High Traction shoe (right).
The available traction of each of the test shoes
was quantified by using a custom portable
footwear traction testing system. The system
consisted of a foot last mounted under a moveable
load cell. The foot last was mounted at an angle of
20° of plantar-flexion such that only the forefoot
of the shoe would be in contact with the ground.
A shoe was placed on the foot last, a vertical load
of 580 N was applied on top of the load cell to
contact the shoe with the ground, and then the
shoe was dragged across the ground at a speed of
250 mm s-1 by an automated electrical motor.
During this movement, horizontal forces were
collected by the load cell at a frequency of 2000
Hz. These forces were then used to calculate the
peak translational traction coefficient between the
shoe and ground. A more detailed description of a
similar system can be found in Kuhlman et al.
(2010), where traction coefficients were measured
between cleated shoes and artificial turf surfaces.
Prior to the study, the portable footwear traction
testing system was validated in-lab with the use of
a Kistler force platform embedded in the ground
sampling at 2000 Hz. With the traction tester
positioned over the force platform, forces were
simultaneously measured by both systems as a
shoe was dragged across the force platform
(Figure 2). The calculated peak traction
coefficients from the two systems were found to
be in good agreement (differences were less than
1.0%).
Fig. 2. Traction coefficients obtained from the
portable traction tester and force plate
during validation. Each curve is the
average of 5 trials
A short duration maximal effort timed running
course was used to evaluate athletic performance
(Figure 3). The course was designed to
incorporate a curved acceleration, an abrupt
change in direction, and a straight acceleration.
RJTA Vol. 18 No. 2 2014
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The subjects started from rest, then after tripping
a first set of infra-red timing lights sprinted with
maximal effort along an 8 meter radius quarter
circle to a second set of timing lights. The
subjects were instructed to come to a stop as
quickly as possible once they heard the ‘beep’
from the second set of timing lights, then turn
around and sprint straight towards a third set of
timing lights 8 meters away. The total time to
complete the course was recorded.
Fig. 3. The timed running course. Dotted lines
indicate timing light gates
Testing occurred outdoors on two different
surfaces under dry conditions; an asphalt road
surface, and a tartan track and field surface. In
order to quantify the available traction between
the shoes and surfaces, ten trials per shoe were
collected with the traction tester on each surface.
Each subject completed two performance testing
sessions, one session per surface. The two test
sessions for any subject were not completed on
consecutive days, and the order that the surfaces
were tested in was randomized for each subject.
During a test session, after a warm up to get used
to the course, each subject completed five trials in
each shoe condition on each surface, for a total of
ten trials. The shoe condition worn for the first
trial was randomized, then after each trial the
subject changed shoes. The subjects were allowed
as much time between trials to recover as they
required in order to minimize effects of fatigue.
The averages of the five trials for each shoe were
calculated for analysis.
Additionally, each subject’s perceived
performance in each shoe condition was
quantified using visual analog scales (VASs). The
VAS was a 14 cm horizontal line, with the left end
of the line stating “Worst traction imaginable”,
and the right end of the line stating “Best traction
imaginable”. After every trial, the subjects were
required to indicate their perceived performance
by marking a vertical line on the VAS. The VAS
scores were quantified by measuring the distance
from the left end of the scale to the subject’s mark
in centimeters. These values were then
normalized to the total length of the scale by
dividing by 14 cm and multiplied by 100 to be
expressed as a percentage. During testing, the
course times of the subjects were not revealed to
them.
Independent t-tests were used to identify any
statistically significant differences in available
traction between shoes, and paired t-tests were
used to compare course times and VAS scores
between shoes. The level of significance was set
at α=0.05.
3. Results
The average values for the peak available traction
coefficients, course completion times, and VAS
scores for the two surfaces are shown in Table 1.
Statistically significant differences between shoe
conditions are indicated with bold p-values.
Table 1. Average (SD) values of the variables of
interest.
Control
High
Traction
p-value
Asphalt Surface
Traction Coeff. 1.25
(0.05)
1.41
(0.05)
< 0.01
Course Time [s]
5.78
(0.47)
5.73
(0.43)
< 0.01
VAS Score [cm]
7.2
(2.8) 9.0
(1.9) 0.01
Tartan Surface
Traction Coeff. 1.38
(0.05) 1.40
(0.05) 0.54
Course Time [s]
5.73
(0.52)
5.75
(0.47)
0.29
VAS Score [cm]
8.6
(1.9)
9.2
(1.6)
0.06
On the asphalt road surface, the available traction
of the High Traction shoe was statistically
significantly higher than that of the Control shoe
(1.41 vs. 1.25). The subjects completed the course
significantly faster in the High Traction shoe
compared to the Control shoe (5.73 s vs. 5.78 s).
The VAS scores were statistically significantly
higher (indicating more perceived traction) for the
RJTA Vol. 18 No. 2 2014
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High Traction shoe than the Control shoe (7.2 cm
vs. 9.0 cm).
On the tartan track surface, there were no
statistically significant differences identified
between the High Traction and Control shoes for
any of the three analyzed variables. On this
surface, the High Traction shoe did not have more
traction than the Control, and the subjects
performed the same in both shoe conditions.
4. Discussion
The purpose of this investigation was to
investigate whether performance could be
enhanced by increasing the outsole traction of a
running shoe. Intuitively, decreasing traction
could cause an athlete to slip. However, it is not
clear if providing a runner with increased traction
could allow the athlete to move faster. Currently,
the published opinion on the role of running shoe
outsole traction is to provide sufficient grip to
avoid slipping during running (Frederick, 1984).
It may be that if the traction was increased
beyond this ‘sufficient’ value, an additional role
may be to allow the athlete to perform
high-traction tasks better (such as accelerating
and changing direction).
The results of this study suggest that the role of
running shoe traction is not to merely provide
adequate traction to avoid large scale slipping, but
can also help athletes maximize performance. The
subjects were able to complete the running course
on a dry asphalt road surface statistically
significantly faster when wearing the High
Traction shoe compared to the Control shoe. The
running course was composed of high-traction
tasks; curved acceleration, abrupt deceleration,
and linear acceleration, all at maximal effort. The
Control shoe provided enough traction to allow
the subjects to complete the course at maximal
effort without large scale slipping. However,
when the High Traction shoe was worn, the
subjects were able to perform the course even
faster.
Similar results that relate footwear traction to
performance in other sports have been recently
reported. Luo & Stefanyshyn (2011) showed that
increasing the available traction of basketball
shoes up to a point allowed athletes to accelerate
faster both along curved and straight paths on an
indoor surface. Müller et al. (2010) showed that
soccer cleat traction affected the performance of
soccer players who executed a running/cutting
slalom course on synthetic turf. In both of these
studies, athletes were able to perform
high-traction maneuvers faster due to increased
footwear traction. The present study found the
same result, but this time with running shoes on a
dry outdoor asphalt road surface.
The mechanism by which the increased traction
allowed the subjects to perform better is unknown
and warrants further study. It could be that greater
traction allows an athlete to direct the ground
reaction force more horizontally, which would
increase accelerations and decelerations in the
transverse plane. Or, it could be that even though
large scale slipping in the Control shoe did not
happen, micro-slipping between the shoe and
surface was occurring. If this was the case, the
higher traction outsole may have reduced this
amount of micro-slipping. However, this is
merely speculation and was not verified in this
experiment.
The experimental High Traction shoe condition
used in this study was constructed by integrating
rubber obtained from a tire manufacturer
(Continental AG) into the outsole. This rubber
was purported by the manufacturer to have
enhanced traction characteristics. When the
available traction of the two shoe conditions were
measured on the asphalt road surface with the
traction tester, this was in fact found to be the
case; the High Traction shoe had statistically
significantly higher traction than the Control shoe.
However, when tested on the tartan track surface,
no difference in traction was found between the
two shoes.
It is unknown exactly why the soft rubber used in
the High Traction shoe increased traction on the
asphalt road surface but did not on the tartan track
surface. One possible explanation could be that on
a smooth hard surface such as asphalt, the outsole
of the shoe dictates the traction characteristics,
but on a rough soft surface such as a tartan track,
it is the surface that dictates the traction
characteristics. Or, it could be that the rubber
obtained from the tire manufacturer was
specifically designed to enhance traction on the
type of surface that the tires would be driven on; a
hard surface similar to asphalt. Nevertheless, the
RJTA Vol. 18 No. 2 2014
21
results on both surfaces support the main finding
of the study; on asphalt the High Traction shoe
provided more traction and the athletes performed
faster, while on the tartan track surface the High
Traction shoe did not provide more traction, and
the performance of the athletes was not affected.
Although the increase in performance found in
this study was real (i.e. statistically significant),
the average magnitude of the increase was
relatively small (0.05 s). It is unknown whether
this improvement in performance would translate
to a meaningful advantage for an athlete
competing in a race over an asphalt surface.
However, it is important to note that the VAS
results showed that the subjects were actually able
to perceive the extra traction offered by the High
Traction shoe, despite being blinded to the shoe
conditions. This should not be discounted as a
potential important benefit to an athlete; there
may be positive psychological implications when
a user is wearing footwear that s/he is more
confident in, although this is merely speculation.
On the asphalt surface, the rubber in the High
Traction shoe increased the available traction
from 1.25 to 1.41. It may be that the course
performance could have been further improved if
the traction was increased even higher. However,
there is evidence that increasing footwear traction
only enhances athletic performance up to a point;
if traction is further increased above a certain
critical threshold, no additional improvements are
made to performance (Luo & Stefanyshyn, 2011).
However, without further testing, it is unknown
how close the High Traction shoe was to this
critical traction threshold. It must be noted that
the traction coefficients measured in this study are
not absolute values; they are specific to the
measurement method employed. Previous studies
have documented how the boundary conditions of
a traction test can influence the value of the
traction coefficient obtained (Kuhlman et al. 2010;
Rheinstein et al. 1978; Valiant, 1987; 1993;
1994).
5. Conclusion
The role of running shoe outsole traction was
previously thought to be important only for
avoiding large scale slipping during running. In
this study, when wearing a control running shoe
athletes were able to complete a course composed
of high-traction maneuvers on a dry asphalt
surface at maximal effort without slipping. When
the subjects completed the same course wearing a
shoe with increased outsole traction, the subjects
were able to perform the course even faster.
Therefore, these results show that the role of
running shoe outsole traction is not to merely
provide adequate traction to avoid large scale
slips, but can also help athletes enhance
performance of high-traction tasks such as
accelerations and changes in direction.
The results of this study suggest that if the goal of
a running shoe manufacturer is to help an athlete
maximize performance, the outsole of the shoe
should be designed to offer more traction than is
sufficient to just avoid slipping. It is currently
unknown at what point increasing traction no
longer has a positive effect on performance.
Future work employing similar methods to this
study could help establish a minimum outsole
traction value (a value required to avoid slipping)
and a maximum outsole traction value (a value
above which performance is no longer increased).
This information would serve as a useful
guideline for footwear manufacturers during
outsole design and development.
Acknowledgements
The authors would like to thank adidas AG for
providing the test shoes for the study.
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Reproduced with permission of the copyright owner. Further reproduction prohibited without
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... Running is among the most popular global sports (van Dyck, Cardon, de Bourdeaudhuij, de Ridder, & Willem, 2017). Therefore, there is research need focussing on running motion (McClay & Manal, 1998;Stacoff, Nigg, Reinschmidt, van den Bogert, & Lundberg, 2000) and running shoe features like comfort, performance and injury prevention (Dinato et al., 2015;Theisen et al., 2014;Worobets, Panizzolo, Hung, Wannop, & Stefanyshyn, 2014). ...
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Running and running shoe biomechanics are usually measured in laboratory settings, capturing discontinuous running trials. Continuous running measured outdoors doesn’t allow comprehensive measurement equipment due to limited technology. This research compared biomechanical effects of continuous loop and discontinuous runway running on locomotion and running shoe characterisation. Twenty-two runners performed eight trials in three shoe conditions in a runway and a loop laboratory setting, while capturing ground reaction forces and lower limb kinematics. Running mode and shoe variable magnitudes and intra-participant variability, means were compared for main and interaction effects (p < 0.05) by a 2 × 3 within-participants repeated measures analysis of variance, and effect size estimation. Kinetic and kinematic variables indicated biomechanical effects induced by running mode. Continuous loop running significantly decreased ground contact time (241.31–234.47 ms), and braking force (0.37–0.35 bw). It showed a significantly flatter and inverted foot-strike at touchdown by reducing sagittal shoe ground angle (20.27–16.69°), and increasing ankle inversion angle (5.50–6.67°). Continuous loop running significantly increased intra-participant variability in ankle dorsiflexion (9.49–12.78) and maximal eversion angle (12.70–17.36). Kinetic and kinematics indicated biomechanical effects induced by running shoes, shoe classification was similar between modes. Running mode influences biomechanics, whilst shoe classification remains similar. Anterior-posterior braking force is overestimated in discontinuous runway running, combined with increased variability suggesting an inconsistent foot-strike. Variability at the ankle joint was seen to increase during continuous loop running, indicating a more rigid ankle complex during discontinuous runway running. Our findings suggest that continuous loop running should be used when precise absolute variable magnitudes are required while runway running tests appear sufficient for general comparative shoe evaluation.
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The aim of this study was to determine whether increasing the stiffness of the shoe midsole supporting the metatarsophalangeal (MTP) joint could induce a better jumping and lateral cutting movement performance. Twelve young team-sports players used two different shoe models (commercialized), with different sole bending stiffnesses. Two tests were performed: a multi-directional (Multi-D) sprint test including rapid lateral braking and cutting movements, and a fatigue test including drop jumps (DJs) and countermovement jumps (CMJs) in pre- and post-fatigue conditions. A significant (p< 0.05) improvement was observed in the Multi-D test times with the stiffer midsole. Further, in fatigued conditions, the group with the stiffer midsole shoe showed a non-significant 9 per cent performance decrease in CMJs, while this decrease was higher and significant (16.1 per cent; p<0.05) for the compliant midsole group. Compared with the stiffer midsole, the compliant midsole yielded a significant decrease in the jump performance, highlighting the fact that a higher MTP midsole stiffness helped subjects to limit the effects of fatigue on jumping performance. Therefore, a higher midsole MTP stiffness is associated with better performance in indoor-sport-specific movements including fatigued conditions, which could be explained by a preserved dynamic interaction with the ground in these specific sport situations.
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The purpose of this study was to evaluate the traction characteristics of four different stud configurations on Fédération Internationale de Football Association (FIFA) 2-Star, third-generation artificial soccer turf. The investigated stud configurations were hard ground design, firm ground design, soft ground design, and an experimental prototype. The concept of this study combines performance, perception, biomechanical, and mechanical testing procedures. Twenty-five soccer players took part in the different testing procedures. Variables of this study were: running times, subjective rankings/ratings, ground reaction forces, and mechanical traction properties. Statistical discrimination between the four stud configurations was shown for performance, perception, and biomechanical testing (p < 0.05). Unsuited stud configurations for playing on artificial turf are characterized by less plain distributed and pronounced studs.
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ASTM F2333 is a test method for quantifying traction characteristics between an athletic shoe and a sports surface. This standard calls for normal loads of 500-3000 N to be applied between a footform and a playing surface. To assess the effect of varying the normal load on the traction coefficients between cleated athletic shoes and artificial turf surfaces, a new testing device was developed and used to collect traction data. Four different models of cleated athletic shoes were tested on FieldTurf at normal loads ranging from 222 N to 1776 N. Static, dynamic, and peak traction coefficient values were calculated for each condition. There was a significant difference in the slope of the load versus traction coefficient curve for loads below and above 888 N for all three variables measured. No significant differences in traction characteristics were found between shoes for loads below 888 N. Significant differences between the shoes were seen with loads above 888 N. However, buckling and potential permanent damage to the turf surface was seen at loads of 1776 N. The results suggest that traction data obtained on FieldTurf at loads below one body weight are not sensitive to different shoe designs. Therefore, the measurement of traction between cleated shoes and FieldTurf should be conducted at a load of at least 888 N which is, in part, consistent with the default normal load of 1000 N in ASTM F2333. However, a normal force of 3000 N defined in the standard for studying stopping may not be feasible without permanently damaging the turf surface.
Article
It has been demonstrated that, by varying the mechanical properties of footwear, the sprinting performance can be improved. It has been hypothesized that, for maximal performance, tuning the shoe stiffness to the requirements of the athlete is necessary. The aim of this study was to investigate the feasibility of using sprint shoes constructed with selective-laser-sintered Nylon 12 sole units for sprint-related jump tasks and to examine whether adaptations to the mechanical properties of the footwear were sufficient to elicit changes to lower-limb dynamics during athletic performance. An internationally competitive sprinter completed sprint-related jump metrics in various selective-laser-sintered shoes with bending stiffnesses of 9 N, 24.5 N, and 38 N in flexion and 7.4 N, 14.7 N, and 26.1 N in extension. The participant performed best in the medium-stiffness shoe for squat jumps and the maximum-stiffness shoe for bounce drop jumps. This investigation has demonstrated that selective laser sintering can produce high-integrity footwear with markedly different mechanical properties. Such footwear, coupled with an appropriate test method, has been shown to be suitable for investigating the relationship between lower-limb dynamics and shoe stiffness.
Article
The primary kinematic factors relating to sprinting performance may be influenced by the mechanical properties of the footwear worn. It was hypothesized that, compared with the barefoot condition, sprint spikes would influence sole angle to the ground, and metatarsophalangeal joint (MPJ) extension and flexion. High-speed video recording was used to analyse key kinematic variables of the foot segments and the MPJ in barefoot and shod running conditions. The stance phases of four sprinters (two male) were captured in the blocks, at 10 m and at 50 m into a maximal effort sprint. Angular range and angular velocity during MPJ flexion at 10 m and 50 m were reduced significantly when wearing sprint spikes. The mean angular range at 10 m was reduced by 11°, 13°, and 5° for the initial flexion phase, the extension phase, and the final phase of flexion respectively. This effect was larger during ground contact at 10 m versus 50 m. Sole angle to the ground at take-off was lower in the sprint spike shod condition than in the barefoot condition. Performance-related parameters such as degree of MPJ extension, MPJ extension velocity, and sole angle to the ground are influenced by sprint spikes when compared with the barefoot condition.
Article
The purpose of this study was to investigate the relationship between mechanically available footwear traction and performance in top-speed curved sprint running and maximum effort linear acceleration. Based on results from previous studies, it was hypothesized that performance would increase as available traction increased but only to a point after which performance would plateau and further increases in available traction would not affect performance. The goal of this study was to identify such critical traction values. Thirty-two recreational athletes performed maximum effort 2.3 m radius curve sprints and linear accelerations from a standing start using four identical mid-cut basketball shoes differing only in outsole traction. Available traction was modified by manipulating the outsole material. The traction coefficients of the test shoes, quantified with a portable traction tester on the actual test surface, were 0.26, 0.54, 0.82 and 1.13. Ground reaction forces and three-dimensional kinematics were quantified during the tests. Greater amounts of traction (both peak and average) were utilized as the mechanically available traction increased. Increases in available traction from 0.26 to 0.54 to 0.82 provided systematic performance advantages for both curved sprinting and linear acceleration. However, no further performance enhancements were detected when the available traction increased beyond 0.82. Increases in the use of available traction beyond a threshold of 0.82 were reflected in the peak but not the average utilized traction or overall ground reaction impulse generation.
Article
The purposes of this investigation were to determine if increasing the bending stiffness of sprint shoes increases sprinting performance and to determine whether simple anthropometric factors can be used to predict shoe bending stiffness for optimal performance. Thirty-four athletes were tested using four different shoe conditions--a standard condition consisting of their currently used footwear and three conditions where the bending stiffness was increased systematically. The sprinters performed maximal effort 40 m sprints and their sprint times were recorded from 20 to 40 m. On average, increasing the shoe bending stiffness increased sprint performance. The stiffness each athlete required for his or her maximal performance was subject specific but was not related to subject mass, height, shoe size or skill level. It is speculated that individual differences in the force-length and force-velocity relationships of the calf muscles may influence the appropriate shoe stiffness for each athlete to obtain their maximal performance.
Article
The purposes of this investigation were to determine the effects of outsole composition and hardness, playing surfaces and player weight on the dynamic torque, traction forces and static drag developed at the shoe-surface interface. Basketball shoes of polyurethane and elastomer outsoles, each of three different hardnesses, were tested on clean and dusty hardwood floor samples, and on a sample of an artificial gymnasium flooring. The tests were conducted using a laboratory apparatus which included a player leg assembly with simulation of two player weights. Dynamic torque, traction forces from side and rear impacts and static drag were measured at the shoe surface interface. The results indicated that in basketball the magnitude of the resistance forces and torques are influenced by the outsole material and outsole hardness of the shoes, the playing surface and player weights.