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Biomechanical parameters are often analyzed independently, although running gait is a dynamic system wherein changes in one parameter are likely to affect another. Accordingly, the Volodalen® method provides a model for classifying running patterns into 2 categories, aerial and terrestrial, using a global subjective rating scoring system. We aimed to validate the Volodalen® method by verifying whether the aerial and terrestrial patterns, defined subjectively by a running coach, were associated with distinct objectively-measured biomechanical parameters. The running patterns of 91 individuals were assessed subjectively using the Volodalen® method by an expert running coach during a 10-min running warm-up. Biomechanical parameters were measured objectively using the OptojumpNext® during a 50-m run performed at 3.3, 4.2, and 5 m·s(-1) and were compared between aerial- and terrestrial-classified subjects. Longer contact times and greater leg compression were observed in the terrestrial compared to the aerial runners. The aerial runners exhibited longer flight time, greater center of mass displacement, maximum vertical force and leg stiffness than the terrestrial ones. The subjective categorization of running patterns was associated with distinct objectively-quantified biomechanical parameters. Our results suggest that a subjective holistic assessment of running patterns provides insight into the biomechanics of running gaits of individuals. © Georg Thieme Verlag KG Stuttgart · New York.
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IJSM/4752/1.10.2015/MPS Training & Testing
Gindre C et al. Aerial and Terrestrial Patterns. Int J Sports Med
Aerial and Terrestrial Patterns: A Novel Approach to
Analyzing Human Running
Authors C. Gindre1, T. Lussiana1, 2, K. Hebert-Losier3, L. Mourot2, 4
Aliations Aliation addresses are listed at the end of the article
Introduction
The subjective appreciation of sports movements
is an important quality for any coach seeking to
improve athletic performance [22]. However, to
be eective, observations must be centered on
the essential parameters of the activity [29].
Interviews with expert sprint coaches emphasize
that posture, hip position (i. e., center of mass and
pelvis position), arm action, as well as ground
contact are key parameters in running perfor-
mance [29]. The scientic literature supports
most of these beliefs. For instance, contact time is
suggested to be the most important kinematic
parameter for generating dierences between
elite sprinters, whereby faster sprinters exhibit
shorter contact times [6] and develop greater
mass-specic forces during that time [30]. Even
in endurance runners, contact time has been
related to 5-km time-trial performances
(r = 0.49, p < 0.05) [26]. Arm swing reduces the
energy cost of running [1], helping to minimize
trunk rotation and counterbalancing leg swing
[2]. In long-distance runners, the range of elbow
motion has been positively correlated to running
economy (r = 0.42, p < 0.25) [28], indicating value
in observing arm action while running.
Such biomechanical parameters, i. e., arm motion
and body posture, are usually assessed indepen-
dently. However, the running gait pattern is a
dynamic system in which the evolution of one
parameter is likely to aect another. For instance,
a decrease in contact time, without adjusting
step frequency, leads to an increase in ight time
that can promote vertical displacement of the
center of mass [9]. Alterations in step width and
arm motion has also been shown to alter running
gait, increasing the cost of running and challeng-
ing lateral balance [1]. Individuals with excessive
pronation demonstrate lower peak adduction
and greater peak exion at the knee during
stance, with rearfoot strikers also exhibiting
greater peak knee exion [16]. Taken together, all
biomechanical parameters generate a global run-
ning pattern or style that is specic to individuals
and can be used by coaches to dierentiate run-
ners from one another. It may even be possible
to categorize specic running styles in which
accepted after revision
June 26, 2015
Bibliography
DOI http://dx.doi.org/
10.1055/s-0035-1555931
Published online: 2015
Int J Sports Med
© Georg Thieme
Verlag KG Stuttgart · New York
ISSN 0172-4622
Correspondence
Thibault Lussiana
Laboratoire C3S Culture Sport
Santé Société
Université de Franche Comté
31, avenue de l'épitaphe
25000 Besançon
France
Tel.: + 33/632/424 343
Fax: + 33/383/355 288
thibault.lussiana@gmail.com
Key words
training
coaching
biomechanics
subjective scale
Abstract
Biomechanical parameters are often analyzed
independently, although running gait is a
dynamic system wherein changes in one param-
eter are likely to aect another. Accordingly, the
Volodalen® method provides a model for classify-
ing running patterns into 2 categories, aerial and
terrestrial, using a global subjective rating scor-
ing system. We aimed to validate the Volodalen®
method by verifying whether the aerial and ter-
restrial patterns, dened subjectively by a run-
ning coach, were associated with distinct
objectively-measured biomechanical parame-
ters. The running patterns of 91 individuals were
assessed subjectively using the Volodalen®
method by an expert running coach during a
10-min running warm-up. Biomechanical
parameters were measured objectively using the
OptojumpNext® during a 50-m run performed at
3.3, 4.2, and 5 m · s − 1 and were compared between
aerial- and terrestrial-classied subjects. Longer
contact times and greater leg compression were
observed in the terrestrial compared to the aerial
runners. The aerial runners exhibited longer
ight time, greater center of mass displacement,
maximum vertical force and leg stiness than
the terrestrial ones. The subjective categorization
of running patterns was associated with distinct
objectively-quantied biomechanical parame-
ters. Our results suggest that a subjective holistic
assessment of running patterns provides insight
into the biomechanics of running gaits of indi-
viduals.
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Gindre C et al. Aerial and Terrestrial Patterns. Int J Sports Med
runners display similar movement patterns. For example,
McMahon et al. [20] termed running with excessive knee exion
"Groucho running", which is typically associated with increased
contact time and step length and decreased ight time and ver-
tical oscillation of the body. On the other hand, Ardense et al. [3]
investigated "Pose running", characterized by mid-forefoot
striking, short contact times and step lengths, and less knee ex-
ion during stance.
Our laboratory has been using a holistic approach, the Volodalen®
method, to classify running patterns subjectively for several
years. The Volodalen® method considers runners to be a global
and dynamic system. Running patterns are subdivided into 2
main groups according to 5 subjectively-evaluated criteria.
Using a standardized grid and rating system, coaches can classify
running patterns as being aerial or terrestrial to assist in better
understanding and training individuals. Overall, the aerial pat-
tern is characterized by a more spring-like vertical bouncing
gait, and the terrestrial pattern by a more grounded horizontal
gait. Considering the entire running pattern of individuals
allows coaches to adapt their instructions and address decien-
cies by implementing targeted exercise programs on the basis of
a holistic approach.
Thus, the purpose of this study was to validate the Volodalen®
method by verifying whether the 2 subjectively-classied run-
ning patterns are in fact associated with distinct objectively-
measured biomechanical parameters. We hypothesized that
aerial runners would exhibit shorter contact times, greater leg
stiness, and longer ight times than terrestrial runners.
Materials and Methods
Subjects
91 active individuals in good self-reported general health
[mean ± standard deviation (SD): females (n = 14): age
31.9 ± 12.7 y, height 166.2 ± 6.3 cm, body mass 59.6 ± 8.6 kg, and
training time: 9.1 ± 4.6 h · week − 1; males (n = 77): age 29.2 ± 11.0 y,
height 178.0 ± 6.3 cm, body mass 71.9 ± 8.4 kg, and training time:
6.7 ± 4.3 h · week − 1] voluntarily participated in this study. All par-
ticipants were free from lower-extremity injuries and had been
injury-free for the previous year. The university’s Institutional
Review Board approved the study protocol prior to subject
recruitment, which was conducted in accordance with Interna-
tional Journal of Sports Medicine ethical standards [10].
Design
Each subject participated in an experimental session lasting
30 min. After providing written informed consent, subjects ran
for 10 min as a warm-up at a self-selected speed (range: 2.5–
3.5 m · s − 1). For testing, subjects then ran 3 × 50 m from stand-
still on an indoor athletic track at 3.3, 4.2, and 5 m · s − 1 in a rand-
omized order, interspersed with 2-min rest periods during
which participants were permitted to walk. Speed of trials was
monitored using photoelectric cells (Racetime2, MicroGate,
Timing and Sport, Bolzano, Italy) placed at the 20th and 40th
meter of the 50-m trial. A running trial was accepted when its
speed was within ± 5 % of the specied speed. Otherwise, it was
disregarded and repeated after a 2-min rest period, which
occurred in less than 20 % of the trials and no more than twice
per subject.
Subjective assessment
During the 10-min warm-up and independently of the objective
analysis, subjects’ running patterns were observed by an expert
running coach (coaching experience > 20 years at a national
level) and scored using the Volodalen® method (
Fig. 1). The
coach, who was familiar with this method (more than 10 years of
use), focused on the global movement patterns of subjects with
particular attention given to 5 key elements (A–E in
Fig. 1),
similar to those sourced by Thomson et al. [29]. Each element
was scored from 1 to 5. A global score (V®score) was then com-
puted by summing the individual scores of each element. A
V®score ≤ 15 indicated a terrestrial runner and > 15, an aerial
runner. The reliability of the Volodalen® method has been previ-
ously examined (unpublished data). Both intra- and inter-rater
(expert and novice regarding use of the Volodalen® method)
absolute reliabilities of V®scores were adequate, with coecient
of variations being 6.1 ± 7.0 % and 6.6 ± 6.5 %, respectively, with no
large systematic bias between V®scores detected (paired t-test:
p = 0.927 and 0.250, respectively).
Objective assessment
An optical measurement system (Optojump Next®, MicroGate
Timing and Sport, Bolzano, Italy) sampling at 1 000 Hz was used
to record contact (tc, ms) and ight (tf, ms) times for 20 m from
the 20th to the 40th meter of the 50-m running trials. As described
by Morin et al. [23], the spring-mass characteristics of the lower
extremity were estimated using a sine-wave model employing
tc, tf, velocity (v), body mass (m), and leg length (L, the distance
between the greater trochanter and the ground measured in
barefoot upright stance). Vertical stiness (kvert, kN · m − 1) was
calculated as the ratio between the maximal vertical force (Fmax,
kN) and center of mass displacement (Δz, m) using the following
equations:
kF
vert z
= ⋅Δ
max
1
(1)
F mg tf
tc
max
=+
π
2
1
(2)
(3)
Δ =− +
z
F
m
tc gtc
max
22
28
π
Fig. 1 Subjective grid of the Volodalen® method to assess the individual
running pattern. The asterisks ( * ) indicate a signicant dierence
(p < 0.05) between aerial and terrestrial running patterns.
AVertical oscillation
of the head Lo
wP
ronounced
By elbows
High and anteverted
Below the CG
Forefoot
Aerial runner
Terrestrial runner
12345
By shoulders
Low and retroverted
In front of the CG
Rearfoot
Arms movement
Pelvis position at
ground contact
Foot position at
ground contact
Strike pattern
B
C
D
E
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Gindre C et al. Aerial and Terrestrial Patterns. Int J Sports Med
Leg stiness (kl eg, in kN · m − 1) was calculated as the ratio between
the Fmax and the maximal leg length deformation, i. e., leg spring
compression (ΔL, m), using the following equations:
kF
leg L
=⋅
max Δ1
(4)
ΔΔ
L=− −
+LL vtc d
z
2
2
2 (5)
where d represents the distance of the point of force application
translation, estimated for each individual to equal 18 % of their
leg length [18].
Analysis
Descriptive statistics of the data are presented as mean ± SD val-
ues. Since all data were normally distributed on the basis of the
Kolmogorov-Smirnov test, parametric statistical methods were
employed for data analysis. Student t-tests were used to com-
pare the overall V®score, scores for each element of the V®score,
and baseline characteristics between aerial and terrestrial run-
ning groups. 2-way (running group × speed) repeated measures
analyses of variance, and Holm-Sidak procedures for post-hoc
pair-wise comparisons, were used to identify the main eect of
running group (aerial vs. terrestrial) on the biomechanical
parameters, considering interactions between running group
and speed. Statistical signicance was accepted when the overall
p-value was < 0.05, with all analyses performed in SigmaStat 12
for Windows (Systat Software Inc., San Jose, CA, USA).
Results
Of the 91 subjects, 48 (n = 5 females) were categorized as being
aerial runners and 43 (n = 9 females) as terrestrial runners.
Accordingly, the former group had signicantly higher V®scores
than the latter group (18.4 ± 2.0 vs. 12.1 ± 2.3), as well as higher
scores in each of the 5 key elements assessed. In agreement with
the classication schemes presented in
Fig. 1, rearfoot striking
(scale criteria E), foot-ground contact ahead of the centre of
gravity (criteria D), retroversed pelvis position (criteria C), arm
movement led by the shoulders (criteria B), and low vertical
oscillations (criteria A) were more readily observed in terrestrial
than aerial runners (
Fig. 2). Otherwise, the 2 groups were simi-
lar in terms of baseline characteristics regarding age, height,
body mass, and training time (all p > 0.05).
Values of tc, tf, f, ΔL, Δz, Fmax, kvert and kleg are reported in
Table 1,
and were not inuenced by the interaction eect (group × speed,
all p ≥ 0.569). On the other hand, group inuenced several
parameters. Aerial runners exhibited lower tc and ΔL with greater
tf, Δz, Fmax, and kleg than terrestrial runners.
Discussion
The Volodalen® method is a practical tool used by running
coaches to classify the running patterns of individuals into aerial
or terrestrial ones according to visual observations. Here we
demonstrate that the subjective classication is in fact associ-
ated with specic biomechanical parameters at 3 dierent run-
ning speeds (3.3, 4.2, and 5 m · s − 1). According to our hypothesis,
running with an aerial pattern was associated with shorter con-
tact times, greater leg stiness, and longer ight times than with
a terrestrial pattern. The former running style also demon-
strated greater center of mass displacements and maximal verti-
cal forces than terrestrial runners. In the absence of tools that
objectively quantify running gait, the Volodalen® method may
provide coaches insight into the biomechanical preferences of
individuals (i. e., quick contact time with high leg stiness).
It is not always clear in the literature what biomechanical
parameters lead to a better running performance and economy,
especially when only one parameter is considered in isolation.
For instance, both short [26] and long [31] contact times have
been linked to enhanced running economy, while other studies
report no marked relationship between these variables [27].
Similarly, both rearfoot [25] and mid/forefoot [21] strike pat-
terns are suggested to be more economical. However, several
studies also report no marked dierences in running economy
between rearfoot and forefoot strikers [8], with self-selections of
running gait repeatedly reported as the most ecient [1, 8]. Dif-
ferences in running mechanics between studies and individuals
can be attributed to several factors [11], including running
speed, surface, and training level [11, 12]. Even amongst the top-
nishers of a race, stride mechanics dier. It is possible that
inherent characteristics of individuals, including neuromuscular
[19, 24] and architectural [19] attributes, contribute to dier-
ences in fundamental movement patterns and global motor
coordination of runners.
Using a simple, eld-based, subjective scale, the Volodalen®
method considers several criteria that seem independent (e. g.,
foot strike and arm swing) and combines them to classify run-
ning patterns into aerial and terrestrial. This approach agrees
with previous suggestions that a runner needs to be considered
as a dynamic system, wherein the alteration in one aspect of the
running gait is likely to alter another [21]. Pilot testing suggests
acceptable intra- and inter-experimenter reliability of the
V®score with a CV of 6.1 ± 7.0 % and 6.6 ± 6.5 %, respectively.
Although a more extensive reliability study is warranted to con-
rm results, it appears that the Volodalen® method can be reli-
ably used by both novice and expert coaches to better understand
and train runners on the basis of biomechanical observations. A
more detailed biomechanical analysis that investigates each of
the criteria presented in
Fig. 1, their inter-dependence, and
their relationship to the Volodalen® classication system is also
warranted to further validate this approach. Then, the next step
would be to investigate whether coaches need to address the
entire running pattern of individuals (e. g., vertical oscillation of
Fig. 2 Subjective scores for each technical criteria included in the
Volodalen® method.
5.0
*****
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0 Vertical
oscillation
of the head
Arms
movement
Pelvis
position at
ground
contact
Foot
position at
ground
contact
Strike
pattern
Aerial runnersTerrestrial runners
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Gindre C et al. Aerial and Terrestrial Patterns. Int J Sports Med
the head, pelvis position, and foot strike) simultaneously and
base recommendations according the Volodalen® classication
system rather than focusing on a single parameter (e. g., foot
strike) to enhance performance.
The aerial pattern was objectively associated with a shorter con-
tact time and a higher leg stiness than the terrestrial pattern,
and subjectively associated with a mid-forefoot strike pattern.
All these characteristics are proposed to increase the ability of
the lower-extremity to store and release elastic energy via the
spring-mass model during running [7], engaging the plantar
arch and Achilles tendon dierently than when using a rearfoot
strike pattern [14]. Kyröläinen et al. [17] have suggested that
stier muscles around the ankles and the knees during touch-
down can enhance force potentiation during push-o, and
increase the mechanical eciency of runners. Theoretically, the
aerial pattern could rely on a better utilization of the stretch-
shortening cycle compared to the terrestrial pattern to optimize
running performance and reduce energy cost.
In contrast, the terrestrial pattern was objectively associated
with a shorter ight time, longer ground contact time, and a
higher leg compression than the aerial pattern, and subjectively
associated with a rearfoot strike pattern and a low vertical oscil-
lation. These parameters do not promote the store and release of
elastic energy through the mechanisms suggested above.
Instead, the mechanical eciency of terrestrial runners theo-
retically relies on their ability to generate forces over a longer
period of time and minimize vertical displacements. Indeed,
longer contact times permit forces to be generated over a longer
period of time, with an inverse relationship existing between
the energy cost of running and ground contact time [15]. Shorter
ight times are usually associated with decreased vertical oscil-
lations of the center of mass [13], which is recognized as being
more economical [9, 31]. In summary, the terrestrial pattern
could utilize energy to propel the body forward rather than
upward to a greater extent than the aerial pattern.
The above presents a paradox whereby aerial and terrestrial run-
ning both presents with advantages regarding running econo my
and performance. Based on biomechanical analysis, we hypoth-
esized that the aerial pattern relies on the stretch-shortening
cycle and the return of elastic energy to minimize energy
expenditure, whereas the terrestrial pattern minimizes energy
expenditure through reduced vertical oscillation and external
work. Consequently, we believe that there may be a generally
benecial set of mechanical parameters for aerial runners and
another for terrestrial runners.
Yet, in agreement with previous studies [1, 7], we also believe
that runners select movement patterns that optimize their own
running economy and that there may be an optimal set of
parameters at an individual level. To a certain extent, the
Volodalen® method can be perceived as a sliding scale, whereby
adjusting dierent parameters would lead to enhanced perfor-
mance based on preferred running style. Athletes and coaches
can use the Volodalen® method to evaluate and modify the run-
ning technique, favoring either the aerial or terrestrial pattern
depending on what might benet the athlete the most. Here, the
training prescription would rely on the subjective evaluation of
the coach, with the training aiming to either encourage certain
characteristics of an individual's pattern (e. g., promote forefoot
strike in aerial runners) or promote the alternate pattern when
characteristics are overly expressed (e. g., reduce vertical oscilla-
tion in an aerial runner with excessive vertical displacements).
Furthermore, it could be that aerial and terrestrial runners
respond preferentially to dierent types of training interven-
tions geared towards improving their performance. For instance,
integrating plyometric training in aerial runners might enhance
their running economy, but minimally inuence terrestrial run-
ners. In contrast, resistance training that improves leg strength
and power might further benet terrestrial rather than aerial
runners, which would need to be veried through a standard-
ized intervention study.
Age has been shown to inuence self-selected running strategies
and might have confounded our results. More precisely, Cavagna
et al. [5] observed that older vs. younger subjects (mean age:
73.6 vs. 20.8 years) run with lower vertical oscillations of the
center of mass and shorter ight times, implying lesser storage-
and-release of elastic energy during the gait cycle. According to
the Volodalen® classication, older individuals might preferen-
tially adopt a terrestrial running pattern, whereas younger indi-
viduals might self-select an aerial one. However, this assumption
requires a more precise investigation given that no dierence in
the mean age of our terrestrial and aerial runners was observed.
Contact and ight time were the only 2 parameters measured in
this study and employed to model the spring-mass variables.
Although the use of a force platform would have been desirable,
Morin et al. [23] have validated the computational approaches
that we employed here, reporting low bias (from 0.1 to 6.9 %)
between force platform and modeled values for leg stiness, ver-
tical stiness, leg length changes, maximal force, and centre of
gravity displacements during running. As such, we can be rela-
tively condent that our modeled results would approximate
those measured directly from a force platform. Another limita-
tion of this study was the focus on temporal and spring-mass
variables without quantication of joint biomechanics or ener-
getic cost. Of course, running economy and mechanics rely on
complex interactions between the metabolic, cardiorespiratory,
biomechanical, and neurological systems [4]. More comprehen-
Running
group
3.3 m · s−1 4.2 m · s− 1 5 m · s− 1 ANOVA running
groupeect
Aerial Terrestrial Aerial Terrestrial Aerial Terrestrial
tc (ms) 257 ± 18 273 ± 20 * 222 ± 16 236 ± 18 * 198 ± 13 209 ± 16 * < 0.001
tf (ms) 111 ± 19 91 ± 20 * 134 ± 17 116 ± 17 * 143 ± 17 127 ± 16 * < 0.001
f (step.s − 1) 2.73 ± 0.12 2.76 ± 0.17 2.81 ± 0.12 2.84 ± 0.17 2.95 ± 0.14 3.00 ± 0.21 NS
Δz (cm) 6.7 ± 0.6 6.3 ± 0.8 * 6.3 ± 0.5 6.2 ± 0.7 5.7 ± 0.5 5.6 ± 0.7 0.020
ΔL (cm) 13.5 ± 1.3 14.2 ± 1.8 14.5 ± 1.6 15.5 ± 2.0 * 15.0 ± 1.6 16.3 ± 2.2 * < 0.001
Fmax (kN) 1.54 ± 0.21 1.47 ± 0.22 * 1.73 ± 0.23 1.62 ± 0.23 * 1.86 ± 0.25 1.74 ± 0.23 * < 0.001
kvert (kN.m − 1) 23.3 ± 3.4 23.0 ± 3.5 27.6 ± 4.2 26.5 ± 3.8 31.4 ± 5.0 31.4 ± 4.7 NS
kleg (kN.m − 1) 11.6 ± 2.0 10.4 ± 2.0 * 12.2 ± 2.4 10.6 ± 2.0 * 12.6 ± 2.5 10.9 ± 1.8 * < 0.001
Values are mean ± SD. The asterisks ( * ) indicate a signicant dierence (p < 0.05) between aerial and terrestrial running patterns at a
given speed identied using Holm Sidak procedures during post-hoc analysis
Table 1 Contact (tc) and ight
(tf) times, step frequency (f),
displacement of the centre of
mass (Δz), leg compression during
stance (ΔL), maximal force (Fmax),
and vertical (kvert) and leg (kleg)
stiness in aerial and terrestrial
runners at the 3 speeds
investigated.
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Gindre C et al. Aerial and Terrestrial Patterns. Int J Sports Med
sive biomechanical and bioenergetics investigations are needed
to validate the underlying premises to the Volodalen® method
and conrm whether subjective parameters of the classication
system (e. g., vertical head displacements) are associated with
objective biomechanical measures (e. g., measured head dis-
placement using linear transducers or motion analysis).
Conclusion
The aerial and terrestrial patterns determined subjectively by an
expert coach using the Volodalen® method demonstrated dis-
tinct running biomechanics parameters, providing preliminary
validation of the usefulness of this method. The terrestrial pat-
tern was associated with a longer contact time and greater leg
compression than the aerial pattern, while the latter was associ-
ated with greater ight time, center of mass displacement, max-
imal vertical force, and leg stiness. These ndings highlight
that qualitative assessments of running patterns using a holistic
subjective approach provides insight into the biomechanics of
running gait of individuals in absence of objective measurement
tools. Understanding the running preference of individuals
might assist in individualizing their training programs.
Acknowledgements
This study was supported by the University of Franche Comté
(France) and the Exercise, Performance, Health, and Innovation
platform of Besançon and Volodalen Company. The results of the
current study do not constitute endorsement of the product by
the authors or the journal. The authors thank the subjects for
their time and cooperation.
Conictof interest: The authors have no conict of interest to
declare.
Aliations
1 Research and Development department, Volodalen Compagny, Chaveria,
France
2 Research unit EA4660, Culture Sport Health Society and Exercise Perfor-
mance Health Innovation platform, Franche-Comté University, Besançon,
France.
3 National Sports Institute of Malaysia, National Sports Complex, Kuala
Lumpur, Malaysia
4 Clinical Investigation Centre, INSERM CIT 808, CHRU, Besançon, France
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... Objective (Hoerzer et al., 2015;Lussiana et al., 2019;Phinyomark et al., 2015) and subjective (Lussiana et al., 2017b) kinematic and spatio-temporal differences between endurance runners have then been revealed. The terms Terrestrial (TER) and Aerial (AER) runners have been proposed to characterize these different running forms (Gindre et al., 2016). These TER and AER runners have been shown to have the same running economy (Lussiana et al., , 2017a. ...
... Two running coaches with several years of experience using the Volodalen® scale focused on the overall movement form of participants as they ran. The coaches paid attention to five key elements: vertical oscillation of the head, antero-posterior motion of the elbows, pelvis position at ground contact, antero-posterior foot position at ground contact, and foot strike pattern (Gindre et al., 2016;Lussiana et al., 2017a). The intra-and inter-rater reliability of this method has been shown recently . ...
... (Buckthorpe and Roi, 2018;Buckthorpe and Roi, 2018;Buckthorpe and Roi, 2018;Buckthorpe and Roi, 2018;Buckthorpe and Roi, 2018;Buckthorpe and Roi, 2018;Buckthorpe and Roi, 2018) a close link between plantar flexors RFD and musculo-tendinous stiffness has been observed (Driss et al., 2012). Hence, our previous observations of greater leg stiffness in AER as compared to TER (Gindre et al., 2016;Lussiana et al., 2017a) could partly explain this greater RFD in AER. But more importantly, several neural aspects, such as the synchronicity of motor unit recruitments and the efficiency of the neural drive, could also significantly impact RFD performance (Maffiuletti et al., 2016). ...
Article
Two main types of endurance runners have been identified: aerial runners (AER), who have a larger flight time, and terrestrial runners (TER), who have a longer ground contact time. The purpose of this study was to assess the neuromuscular characteristics of plantar flexors between AER and TER runners. Twenty-four well-trained runners participated in the experiment. They were classified either in a TER or AER group according to the Volodalen® scale. Plantar flexors’ maximal rate of force development (RFD) and maximal voluntary contraction force (MVC) were assessed. Percutaneous electrical stimulation was delivered to the posterior tibial nerve to evoke maximal M-waves and H-reflexes of the triceps surae muscles. These responses, as well as voluntary activation, muscle potentiation, and V-waves, were recorded by superimposing stimulations to MVCs. RFD was significantly higher in AER than in TER, while MVC remained unchanged. This was accompanied by higher myoelectrical activity recorded in the soleus muscle. While M-waves and other parameters remained unchanged, maximal H-reflex was significantly higher in AER than in TER, still in soleus only. The present study raised the possibility of different plantar flexors’ neuromuscular characteristics according to running profile. These differences seemed to be focused on the soleus rather than on the gastrocnemii.
... Moreover, the longitudinal monitoring of these parameters allows the follow-up of functional outcomes after rehabilitation treatments [11][12][13]. Qualitative gait analysis identifies specific running features (e.g., foot strike pattern, presence of cross-over, and low gait harmony) that are associated with increased risk of overuse injuries [13] or global movement scores (e.g., Volodalen Scale) indicative of running economy and inversely related to the risk of overuse injuries [14]. ...
... Limitations of the use of gold-standard methods are a not fully ecological walking or running style, due to the use of a treadmill, and the high costs and complexity in terms of experimental setup [15][16][17][18]. In recent years, more low-cost, easy-to-use, and marker-less alternatives to gold-standard methods have been developed for large-scale gait evaluation [6,8,13,14]. The most frequently used alternative technologies for quantitative gait analysis are optical timing systems and inertial sensors. ...
... Qualitative analysis of running is traditionally performed by clinicians or expert coaches using evaluation scales during direct observation of gait or offline video analysis [13,14,22]. Objective methods have been proposed to overcome the limitations of the above subjective approach, the most frequently used alternative being inertial sensors. ...
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Quantitative and qualitative running gait analysis allows the early identification and the longitudinal monitoring of gait abnormalities linked to running-related injuries. A promising calibration- and marker-less video sensor-based technology (i.e., Graal), recently validated for walking gait, may also offer a time- and cost-efficient alternative to the gold-standard methods for running. This study aim was to ascertain the validity of an improved version of Graal for quantitative and qualitative analysis of running. In 33 healthy recreational runners (mean age 41 years), treadmill running at self-selected submaximal speed was simultaneously evaluated by a validated photosensor system (i.e., Optogait-the reference methodology) and by the video analysis of a posterior 30-fps video of the runner through the optimized version of Graal. Graal is video analysis software that provides a spectral analysis of the brightness over time for each pixel of the video, in order to identify its frequency contents. The two main frequencies of variation of the pixel's brightness (i.e., F1 and F2) correspond to the two most important frequencies of gait (i.e., stride frequency and cadence). The Optogait system recorded step length, cadence, and its variability (vCAD, a traditional index of gait quality). Graal provided a direct measurement of F2 (reflecting cadence), an indirect measure of step length, and two indexes of global gait quality (harmony and synchrony index). The correspondence between quantitative indexes (Cadence vs. F2 and step length vs. Graal step length) was tested via paired t-test, correlations, and Bland-Altman plots. The relationship between qualitative indexes (vCAD vs. Harmony and Synchrony Index) was investigated by correlation analysis. Cadence and step length were, respectively, not significantly different from and highly correlated with F2 (1.41 Hz ± 0.09 Hz vs. 1.42 Hz ± 0.08 Hz, p = 0.25, r2 = 0.81) and Graal step length (104.70 cm ± 013.27 cm vs. 107.56 cm ± 13.67 cm, p = 0.55, r2 = 0.98). Bland-Altman tests confirmed a non-significant bias and small imprecision between methods for both parameters. The vCAD was 1.84% ± 0.66%, and it was significantly correlated with neither the Harmony nor the Synchrony Index (0.21 ± 0.03, p = 0.92, r2 = 0.00038; 0.21 ± 0.96, p = 0.87, r2 = 0.00122). These findings confirm the validity of the optimized version of Graal for the measurement of quantitative indexes of gait. Hence, Graal constitutes an extremely time- and cost-efficient tool suitable for quantitative analysis of running. However, its validity for qualitative running gait analysis remains inconclusive and will require further evaluation in a wider range of absolute and relative running intensities in different individuals.
... In addition, nonrearfoot strikers respond less favourably to the VP4 shoe than rearfoot strikers (H ebert-Losier et al., 2020;Hoogkamer et al., 2019). These observations might partly be explained by the fact that each runner adopts a spontaneous running style (Gindre et al., 2016;van Oeveren et al., 2021) and hence responds differently to footwear, but this warrant further investigation. ...
... Keeping in mind that the running pattern is a dynamic system with several interconnected variables (Novacheck, 1998), the energy savings might be due to the combination of many but small biomechanical adaptations. Moreover, as large interindividual variations were reported in terms of running economy in response to the VP4 shoe (Barnes & Kilding, 2019;H ebert-Losier et al., 2020), pooling all runners together might mask an effect that would be observed when only considering high responders, e.g., runners with an improvement in running economy greater than 2.6% (Barnes & Kilding, 2015), or subgroups of runners determined using their spontaneous running style (Gindre et al., 2016;van Oeveren et al., 2021). Hence, we suggest that the relation between the VP4-specific biomechanical adaptations and improvement in running economy should be multifactorial, consider only high responders, and take into account the running style. ...
Article
In a recent article published in Footwear Science, the teeter-totter effect was indirectly observed with the Nike Vaporfly 4% (VP4) running shoe. This mechanism was attributed to the presence of a curved carbon-fibre (stiff) plate, and potentially causes runners to propel forward during push-off. It was suggested that such mechanism should explain the 4% improvement of performance of the VP4 compared to regular shoes. However, there was, to the best of the authors' knowledge, no attempt to associate this VP4-specific mechanism to the change in running economy and personal best time yet. Furthermore, a recent article published in the Journal of Sport and Health Science observed that the stiffening effect of the curved carbon-fibre plate plays a limited role in the energy savings, which therefore questions the presence of the teeter-totter effect in the VP4 shoe. In our view, the better running economy and personal best time obtained with the VP4 shoe cannot be currently explained from a biomechanical standpoint. With this letter, we would like to (1) summarise the specificities of the VP4 shoe, (2) report the observed improvements in running economy and personal best time, and (3) point out the absence of any biomechanical explanation to the better performance yet. ARTICLE HISTORY
... The participants performed their warm-up which consisted, according to Whelan et al. recommendation, of a 3 min jog followed by sprint-specific dynamic exercises of the lower limbs [18,19]. The total warm-up time was 15 minutes. ...
... The participants were required to perform 3 trials of each jump in random order separated by 10 s rest between trials and 2 min rest between sets [19]. The best trial of each jump variant was recorded and further statistically analyzed. ...
Article
Background: The purpose of the current study was to investigate: (1) differences between three types of countermovement jumps (CMJ), (2) development of lower-body strength during training periods, and (3) relationship between 200m personal best results and jumping ability in sprinters. Material and methods: A total of 14 male sprinters from local university academic sport club participated in the study. Athletes performed three variants of CMJ: with arm swing (AS), without AS, and from a maximal squat position. We took measures two times: during the active rest period and the final phase of the preparatory period. For measurements the Optojump photoelectric cell system was used. Statistical significance was set at p ≤ 0.05. Results: Effect of the training period and jump variant was shown on all jump parameters (height, total energy, and specific energy; p<0.001). Personal best 200m time was significantly correlated only with total energy in both training periods in all jump variants. Conclusions: According to the results obtained in this study, we conclude that: (1) jumping parameters depends on CMJ variants, (2) jumping abilities improved during sprinter training, (3) 200m-sprint PB are related to total energy, but not with specific energy and jump height.
... Other authors suggested that the higher prevalence of soft tissue injuries and lacerations observed in cerebral palsy athletes compared to other disabled athletes could be explained by their moving and walking patterns (4). Herein, we suggest an approach using the preferred running form assessed through the Volodalen R method (5) to guide injury prevention, rehabilitation, and retraining exercise prescription. The approach is based on biomechanical concepts from the scientific literature, as well as our clinical experiences, and evaluates potential discrepancies between spontaneously chosen running forms, biomechanical abnormalities, and the natural tendency for biological systems to self-optimize (6). ...
Article
Full-text available
Despite the wealth of research on injury prevention and biomechanical risk factors for running related injuries, their incidence remains high. It was suggested that injury prevention and reconditioning strategies should consider spontaneous running forms in a more holistic view and not only the injury location or specific biomechanical patterns. Therefore, we propose an approach using the preferred running form assessed through the Volodalen ® method to guide injury prevention, rehabilitation, and retraining exercise prescription. This approach follows three steps encapsulated by the PIMP acronym. The first step (P) refers to the preferred running form assessment. The second step (I) is the identification of inefficiency in the vertical load management. The third step (MP) refers to the movement plan individualization. The answers to these three questions are guidelines to create individualized exercise pathways based on our clinical experience, biomechanical data, strength conditioning knowledge, and empirical findings in uninjured and injured runners. Nevertheless, we acknowledge that further scientific justifications with appropriate clinical trials and mechanistic research are required to substantiate the approach.
... L'augmentation des hautes fréquences de vibrations a été expliquée par l'augmentation conjointe de la fréquence d'impact et des activations musculaires avec la vitesse de course (Boyer & Nigg, 2004;Nilsson & Thorstensson, 1989;Tsuji et al., 2015). En ce qui concerne les différents mouvements, une combinaison spécifiques d'activations musculaires et d'angles articulaires pourrait expliquer la spécificité de chaque mouvement en terme de vibrations (Gindre et al., 2016;Gruber et al., 2014;Müller et al., 2012). Un amortissement plus important pour ce type de mouvement en comparaison à la course à pied pourrait s'expliquer par une adaptation du système neuromusculaire cherchant à limiter les vibrations induites par ces types de mouvements. ...
Thesis
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La course à pied et les différentes pratiques sportives induisent des chocs et des vibrations transitoires au niveau des tissus mous à chaque impact. Ces impacts et vibrations peuvent générer un stress mécanique important, qui accroit le risque de fatigue et de blessure de sur-sollicitation. Le premier objectif de la thèse était consacré au développement de méthodes de traitement du signal d’accélération et d’analyse statistique afin de mieux caractériser les impacts et vibrations subies par le sportif. Le second objectif était de définir les facteurs externes, tels que le type de mouvement, le matériel sportif, ou la fatigue neuromusculaire, qui faisaient varier le comportement vibratoire en pratique écologique. Avec le développement de méthodes de traitement du signal (transformée en ondelettes continue) et statistiques (Statistical Parametric Mapping), nous avons montré que la vibration des tissus mous était différente de la vibration musculaire. Ainsi, les accéléromètres ne permettaient de caractériser que partiellement la vibration du muscle par rapport à une échographe ultra rapide. De plus, l’augmentation de la vitesse de course et les mouvements effectués lors de la pratique de sports collectifs génèrent des impacts à plus grande amplitude et à plus haute fréquence, ainsi que des vibrations des tissus mous plus amples que la course en ligne droite. Parmi le matériel sportif évalué, seul un revêtement sportif coulissant a permis de réduire l’amplitude de l’impact au sol. Une identification du type de mouvement a été rendu possible grâce à la mesure des impacts et l’usage d’un réseau de neurones convolutifs, permettant de franchir une première étape dans l’évaluation de la dose vibratoire subie par un sportif lors de sa pratique. Enfin, une étude réalisée lors des courses de l’UTMB a permis d’observer une stratégie de protection de l’organisme après des efforts de type trail en diminuant l’amplitude et la fréquence des vibrations des muscles les plus sollicités. Il reste nécessaire d’améliorer la caractérisation de la vibration musculaire avec des accéléromètres fixés sur la peau et de déterminer l’effet de l’exposition répétée à des vibrations transitoires sur le système neuromusculaire et musculo-squelettique.
... It is also possible to change (decrease) leg and vertical stiffness by running with different (increased) knee flexion (the so-called "Groucho running"). This type of running technique lowers ground reaction forces and reduces flight time, but requires increased metabolic power (oxygen consumption) [82][83][84][85]. The above phenomenon should be taken into account in particular by team sport games coaches, where technique like "Groucho running" is often used. ...
Article
Full-text available
Stiffness, the resistance to deformation due to force, has been used to model the way in which the lower body responds to landing during cyclic motions such as running and jumping. Vertical, leg, and joint stiffness provide a useful model for investigating the store and release of potential elastic energy via the musculotendinous unit in the stretch-shortening cycle and may provide insight into sport performance. This review is aimed at assessing the effect of vertical, leg, and joint stiffness on running performance as such an investigation may provide greater insight into performance during this common form of locomotion. PubMed and SPORTDiscus databases were searched resulting in 92 publications on vertical, leg, and joint stiffness and running performance. Vertical stiffness increases with running velocity and stride frequency. Higher vertical stiffness differentiated elite runners from lower-performing athletes and was also associated with a lower oxygen cost. In contrast, leg stiffness remains relatively constant with increasing velocity and is not strongly related to the aerobic demand and fatigue. Hip and knee joint stiffness are reported to increase with velocity, and a lower ankle and higher knee joint stiffness are linked to a lower oxygen cost of running; however, no relationship with performance has yet been investigated. Theoretically, there is a desired “leg-spring” stiffness value at which potential elastic energy return is maximised and this is specific to the individual. It appears that higher “leg-spring” stiffness is desirable for running performance; however, more research is needed to investigate the relationship of all three lower limb joint springs as the hip joint is often neglected. There is still no clear answer how training could affect mechanical stiffness during running. Studies including muscle activation and separate analyses of local tissues (tendons) are needed to investigate mechanical stiffness as a global variable associated with sports performance.
... L'augmentation des hautes fréquences de vibrations a été expliquée par l'augmentation conjointe de la fréquence d'impact et des activations musculaires avec la vitesse de course (Boyer & Nigg, 2004;Nilsson & Thorstensson, 1989;Tsuji et al., 2015). En ce qui concerne les différents mouvements, une combinaison spécifiques d'activations musculaires et d'angles articulaires pourrait expliquer la spécificité de chaque mouvement en terme de vibrations (Gindre et al., 2016;Gruber et al., 2014;Müller et al., 2012). Un amortissement plus important pour ce type de mouvement en comparaison à la course à pied pourrait s'expliquer par une adaptation du système neuromusculaire cherchant à limiter les vibrations induites par ces types de mouvements. ...
Presentation
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Soutenance de thèse - 09/07/2021 - Etude et caractérisation des vibrations dans la pratique sportive
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Research has demonstrated the existence of two 'natural preference' profiles in running. The objective of this study was to determine the influence of the natural preferences of ground (with a "posterior and flexion" movement) and air (with an "anterior and extension" movement) on the ball speed and impact position during the service of 19 professional players. The results allow to propose a new reading grid of the service technique to consider the preferential motricity of each player while respecting the biomechanical principles
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Exercise-related lower leg pain (ERLLP) is one of the most prevalent running-related injuries, however little is known about injured runners’ mechanics during outdoor running. Establishing biomechanical alterations among ERLLP runners would help guide clinical interventions. Therefore, we sought to a) identify defining biomechanical features among ERLLP runners compared to healthy runners during outdoor running, and b) identify biomechanical thresholds to generate objective gait-training recommendations. Thirty-two ERLLP (13 M, age: 21± 5 years, BMI: 22.69±2.25 kg/m²) and 32 healthy runners (13 M, age: 23± 6 years, BMI: 22.33±3.20 kg/m²) were assessed using wearable sensors during one week of typical outdoor training. Step-by-step data were extracted to assess kinetic, kinematic, and spatiotemporal measures. Preliminary feature extraction analyses were conducted to determine key biomechanical differences between healthy and ERLLP groups. Analyses of covariance (ANCOVA) and variability assessments were used compare groups on the identified features. Participants were split into 3 pace bands, and mean differences across groups were calculated to establish biomechanical thresholds. Contact time was the key differentiating feature for ERRLP runners. ANCOVA assessments reflected that the ERLLP group had increased contact time (Mean Difference [95% Confidence Interval] =8 ms [6.9,9.1], p<.001), and approximate entropy analyses reflected greater contact time variability. Contact time differences were dependent upon running pace, with larger between-group differences being exhibited at faster paces. In all, ERLLP runners demonstrated longer contact time than healthy runners during outdoor training. Clinicians should consider contact time when assessing and treating these ERLLP runner patients.
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Running economy (RE) represents a complex interplay of physiological and biomechanical factors that is typically defined as the energy demand for a given velocity of submaximal running and expressed as the submaximal oxygen uptake (VO2) at a given running velocity. This review considered a wide range of acute and chronic interventions that have been investigated with respect to improving economy by augmenting one or more components of the metabolic, cardiorespiratory, biomechanical or neuromuscular systems. Improvements in RE have traditionally been achieved through endurance training. Endurance training in runners leads to a wide range of physiological responses, and it is very likely that these characteristics of running training will influence RE. Training history and training volume have been suggested to be important factors in improving RE, while uphill and level-ground high-intensity interval training represent frequently prescribed forms of training that may elicit further enhancements in economy. More recently, research has demonstrated short-term resistance and plyometric training has resulted in enhanced RE. This improvement in RE has been hypothesized to be a result of enhanced neuromuscular characteristics. Altitude acclimatization results in both central and peripheral adaptations that improve oxygen delivery and utilization, mechanisms that potentially could improve RE. Other strategies, such as stretching should not be discounted as a training modality in order to prevent injuries; however, it appears that there is an optimal degree of flexibility and stiffness required to maximize RE. Several nutritional interventions have also received attention for their effects on reducing oxygen demand during exercise, most notably dietary nitrates and caffeine. It is clear that a range of training and passive interventions may improve RE, and researchers should concentrate their investigative efforts on more fully understanding the types and mechanisms that affect RE and the practicality and extent to which RE can be improved outside the laboratory.
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Although the mechanical function is quite clear, there is no consensus regarding the metabolic benefit of arm swing during human running. We compared the metabolic cost of running using normal arm swing with the metabolic cost of running while restricting the arms in three different ways: (1) holding the hands with the arms behind the back in a relaxed position (BACK), (2) holding the arms across the chest (CHEST) and (3) holding the hands on top of the head (HEAD). We hypothesized that running without arm swing would demand a greater metabolic cost than running with arm swing. Indeed, when compared with running using normal arm swing, we found that net metabolic power demand was 3, 9 and 13% greater for the BACK, CHEST and HEAD conditions, respectively (all P<0.05). We also found that when running without arm swing, subjects significantly increased the peak-to-peak amplitudes of both shoulder and pelvis rotation about the vertical axis, most likely a compensatory strategy to counterbalance the rotational angular momentum of the swinging legs. In conclusion, our findings support our general hypothesis that swinging the arms reduces the metabolic cost of human running. Our findings also demonstrate that arm swing minimizes torso rotation. We infer that actively swinging the arms provides both metabolic and biomechanical benefits during human running.
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PURPOSE: To analyze the influence of foot strike pattern on running economy and biomechanical characteristics in sub-elite runners with a similar performance level. METHODS: Twenty sub-elite long-distance runners participated and were divided into two groups according to their foot strike pattern: rearfoot (RF, n= 10) and midfoot strikers (MF, n= 10). Anthropometric characteristics were measured (height, body mass, BMI, skinfolds, circumferences and lengths); physiological (V˙O2max, anaerobic threshold and running economy) and biomechanical characteristics (contact and flight times, step rate and step length) were registered during both incremental and submaximal tests on a treadmill. RESULTS: There were no significant intergroup differences in anthropometrics, V˙O2max or anaerobic threshold measures. RF strikers were 5.4, 9.3 and 5.0% more economical than MF at submaximal speeds (11, 13 and 15 km·h respectively, though the difference was not significant at 15 km·h, p=0.07). Step rate and step length were not different between groups, but RF showed longer contact time (p<0.01) and shorter flight time (p<0.01) than MF at all running speeds. CONCLUSIONS: The present study showed that habitually rearfoot striking runners are more economical than midfoot strikers. Foot strike pattern affected both contact and flight times, which may explain the differences in running economy.
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In this study, we analyzed the relationship between running economy (RE) and biomechanical parameters in a group running at the same relative intensity and same absolute velocity. Sixteen homogeneous male long-distance runners performed a test to determine RE at 4.4 m.s⁻¹, corresponding to 11.1% below velocity at the ventilatory threshold. We found significant correlations between RE and biomechanical variables (vertical oscillation of the center of mass, stride frequency, stride length, balance time, relative stride length, range of elbow motion, internal knee, ankle angles at foot strike, and electromyographic activity of the semitendinosus and rectus femoris muscles). In conclusion, changes in running technique can influence RE and lead to improved running performance. © 2012 by the American Alliance for Health, Physical Education, Recreation and Dance.
Article
Abstract To determine if unilateral measures of muscle architecture in the rectus femoris (RF) and vastus lateralis (VL) were related to (and predictive of) sprinting speed and unilateral (and bilateral) force (FRC) and power (POW) during a 30 s maximal sprint on the Woodway Curve 3.0(TM) non-motorized treadmill (TM). Twenty-eight healthy, physically active men (n = 14) and women (n = 14) (age = 22.9 ± 2.4 years; body mass = 77.1 ± 16.2 kg; height = 171.6 ± 11.2 cm; body-fa t = 19.4 ± 8.1%) completed one familiarization and one 30-s maximal sprint on the TM to obtain maximal sprinting speed, POW and FRC. Muscle thickness (MT), cross-sectional area (CSA) and echo intensity (ECHO) of the RF and VL in the dominant (DOM; determined by unilateral sprinting power) and non-dominant (ND) legs were measured via ultrasound. Pearson correlations indicated several significant (p < 0.05) relationships between sprinting performance [POW (peak, DOM and ND), FRC (peak, DOM, ND) and sprinting time] and muscle architecture. Stepwise regression indicated that POWDOM was predictive of ipsilateral RF (MT and CSA) and VL (CSA and ECHO), while POWND was predictive of ipsilateral RF (MT and CSA) and VL (CSA); sprinting power/force asymmetry was not predictive of architecture asymmetry. Sprinting time was best predicted by peak power and peak force, though muscle quality (ECHO) and the bilateral percent difference in VL (CSA) were strong architectural predictors. Muscle architecture is related to (and predictive of) TM sprinting performance, while unilateral POW is predictive of ipsilateral architecture. However, the extent to which architecture and other factors (i.e. neuromuscular control and sprinting technique) affect TM performance remains unknown.
Article
Purpose: Orienteering athletes must adapt to running on various surfaces, with biomechanics likely contributing to performance. Here, our aims were to identify the effect of athletic status and of surface on the running biomechanics of orienteers. Methods: Seven elite and seven amateur male orienteers ran 20 m on road, path, and forest surfaces at maximal, 3.8 m·s, and 85% of maximal speeds. A three-dimensional motion capturing system monitored temporal gait and lower extremity kinematic parameters. Data were analyzed using mixed effects models that considered surface (road-path-forest), group (elite-amateur), and surface-group interaction effects. Results: Forest running at maximal speed was slower and involved longer step and cycle times, greater knee extension at foot strike, smaller peak hip flexion and dorsiflexion during stance, and increased ranges of vertical pelvis motion compared with those observed on the road. Elites specifically exhibited greater hip extension at foot strike, larger dorsiflexion at toe-off, and lower pelvis at foot strike and toe-off, whereas amateurs displayed longer stance, greater plantarflexion at foot strike, and greater knee with lesser ankle motion. At the slowest speed, subjects exhibited greater knee flexion at foot strike, greater dorsiflexion at toe-off, shorter strides, smaller peak dorsiflexion during stance, and greater hip, knee, and vertical pelvis motions on forest than on road surfaces. Elites specifically demonstrated shorter stance, step, and cycle times whereas amateurs did not. Conclusions: Orienteering athletes adjusted their running biomechanics when off-road, with distinct adaptations observed in elite versus amateur competitors. The vertical pelvis motion was consistently greater when running off-road, coherent with reported increases in energy expenditure. However, our athletes did not exhibit more crouched lower limb postures when sprinting in the forest, indicating alternative responses to off-road running to that previously proposed by "Groucho" running.
Article
We compared the reduction in running velocities from road to off-road terrain in eight elite and eight amateur male orienteer athletes to investigate whether this factor differentiates elite from amateur athletes. On two separate days, each subject ran three 2-km time trials and three 20-m sprints “all-out” on a road, on a path, and in a forest. On a third day, the running economy and maximal aerobic power of individuals were assessed on a treadmill. The elite orienteer ran faster than the amateur on all three surfaces and at both distances, in line with their better running economy and aerobic power. In the forest, the elites ran at a slightly higher percentage of their 2-km (∼3%) and 20-m (∼4%) road velocities. Although these differences did not exhibit traditional statistical significance, magnitude-based inferences suggested likely meaningful differences, particularly during 20-m sprinting. Of course, cognitive, mental, and physical attributes other than the ability to run on different surfaces are required for excellence in orienteering (e.g., a high aerobic power). However, we suggest that athlete-specific assessment of running performance on various surfaces and distances might assist in tailoring training and identifying individual strengths and/or weaknesses in an orienteer.
Article
Running economy is a key determinant of endurance performance, and understanding the biomechanical factors that affect it is of great theoretical and applied interest. This study aimed to analyse how the ground-contact time and strike pattern used by competitive runners concurrently affect running economy. Cross-sectional. Fourteen sub-elite male competitive distance runners completed a 6-min submaximal running trial at 14kmh(-1) on an outdoor track using their habitual strike pattern (n=7 rearfoot strikers: average age, 25.3 years old (SD=2.4); average weight, 64.7kg (SD=5.6); average height, 175.3cm (SD=5.2); n=7 midfoot strikers: average age, 25.0 years old (SD=2.8); average weight, 69.6kg (SD=4.0); average height, 180.1cm (SD=5.1). During the run, the oxygen uptake and ground-contact time were measured. Midfoot strikers showed a significantly shorter (p=0.015) mean contact time (0.228s (SD=0.009)) compared with rearfoot strikers (0.242s (SD=0.010)). Conversely, there was no significant difference (p>0.05) between the groups with respect to mean oxygen uptake (midfoot strikers: 48.4mlmin(-1)kg(-1) (SD=5.3); rearfoot strikers: 49.8mlmin(-1)kg(-1) (SD=6.4)). Linear modelling analysis showed that the effect of contact time on running economy was very similar in the two groups, with a 1ms longer contact time involving an approximately 0.51mlmin(-1)kg(-1) lower oxygen uptake. In contrast, when controlling for contact time, midfoot striking involved an approximately 8.7mlmin(-1)kg(-1) lower oxygen uptake compared with rearfoot striking. When adjusting the foot-ground contact biomechanics of a runner with the aim of maximising running economy, a trade-off between a midfoot strike and a long contact time must be pursued.
Article
Purpose: Knee pain and Achilles tendinopathies are the most common complaints among runners. The differences in the running mechanics may play an important role in the pathogenesis of lower limb overuse injuries. However, the effect of a runner's foot strike pattern on the ankle and especially on the knee loading is poorly understood. The purpose of this study was to examine whether runners using a forefoot strike pattern exhibit a different lower limb loading profile than runners who use rearfoot strike pattern. Methods: Nineteen female athletes with a natural forefoot strike (FFS) pattern and pair-matched women with rearfoot strike (RFS) pattern (n = 19) underwent 3-D running analysis at 4 m·s⁻¹. Joint angles and moments, patellofemoral contact force and stresses, and Achilles tendon forces were analyzed and compared between groups. Results: FFS demonstrated lower patellofemoral contact force and stress compared with heel strikers (4.3 ± 1.2 vs 5.1 ± 1.1 body weight, P = 0.029, and 11.1 ± 2.9 vs 13.0 ± 2.8 MPa, P = 0.04). In addition, knee frontal plane moment was lower in the FFS compared with heel strikers (1.49 ± 0.51 vs 1.97 ± 0.66 N·m·kg⁻¹, P =0.015). At the ankle level, FFS showed higher plantarflexor moment (3.12 ± 0.40 vs 2.54 ± 0.37 N·m·kg⁻¹; P = 0.001) and Achilles tendon force (6.3 ± 0.8 vs 5.1 ± 1.3 body weight; P = 0.002) compared with RFS. Conclusions: To our knowledge, this is the first study that shows differences in patellofemoral loading and knee frontal plane moment between FFS and RFS. FFS exhibit both lower patellofemoral stress and knee frontal plane moment than RFS, which may reduce the risk of running-related knee injuries. On the other hand, parallel increase in ankle plantarflexor and Achilles tendon loading may increase risk for ankle and foot injuries.