Comparison of plantar pressure distribution in adolescent runners at low vs. high running velocity.

Abstract

This study aimed to compare foot plantar pressure distribution while jogging and running in highly trained adolescent runners. Eleven participants performed two constant-velocity running trials either at jogging (11.2 ± 0.9 km/h) or running (17.8 ± 1.4 km/h) pace on a treadmill. Contact area (CA in cm(2)), maximum force (F(max) in N), peak pressure (PP in kPa), contact time (CT in ms), and relative load (force time integral in each individual region divided by the force time integral for the total plantar foot surface, in %) were measured in nine regions of the right foot using an in-shoe plantar pressure device. Under the whole foot, CA, F(max) and PP were lower in jogging than in running (-1.2% [p<0.05], -12.3% [p<0.001] and -15.1% [p<0.01] respectively) whereas CT was higher (+20.1%; p<0.001). Interestingly, we found an increase in relative load under the medial and central forefoot regions while jogging (+6.7% and +3.7%, respectively; [p<0.05]), while the relative load under the lesser toes (-8.4%; p<0.05) was reduced. In order to prevent overloading of the metatarsals in adolescent runners, excessive mileage at jogging pace should be avoided.

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Short communication
Comparison of plantar pressure distribution in adolescent runners
at low vs. high running velocity
Franc ¸ois Fourcheta,*, Luke Kellyb, Cosmin Horobeanua, Heiko Loepelta, Redha Taiarc, Gre ´goire P. Milletd
aASPIRE Health Centre – ASPETAR, National Sports Medicine Programme, Doha, Qatar
bSport Science Department, ASPETAR – Qatar Orthopaedic and Sports Medicine Hospital, P.O. Box 29222, Doha, Qatar
cSport Science Department, Group of Research in Sciences for Engineer Laboratory Reims-Champagne, Reims, France
dISSUL Institute of Sport Sciences, Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Ba ˆtiment Vidy, CH-1015 Lausanne, Switzerland
1. Introduction
Running contributes to maintain health and cardiopulmonary
fitness [1]. Nevertheless, numerous overuse injuries have been
reported (i.e. at the metatarsals level) when running regularly
[2,3], especially in immature adolescent distance runners [4,5].
Nagel et al. explained this phenomenon by the increased peak
pressure under the metatarsal bones during running [6]. Kernozek
and Zimmer and Ho et al. reported that maximum force and
pressure increased under all foot regions with increasing pace
[1,7]. Ho et al. also observed increased foot inversion during stance
phase (e.g. peak pressure increase at the lateral foot side) when
jogging faster, among young non-trained females tested at 1.5, 2.0
and 2.5 m/s on a treadmill with 0% slope [1]. Unfortunately, the
differences in the relative load for each region between different
running velocities have never been reported. Therefore, the
purpose of this study was to compare foot plantar pressure
distribution between jogging and running in highly trained
adolescents (e.g. around 14 h/week of training). We hypothesised
that plantar pressure distribution would be affected by running
velocity.
2. Methods
2.1. Participants and experimental protocol
Eleven male adolescent distance runners (age: 16.9 ? 2.0 years, body mass:
54.6 ? 8.6 kg, height: 170.6 ? 10.9 cm, maximal aerobic speed: 18.7 ? 1.5 km/h)
performed two constant-velocity running trials either at 60% of their maximal aerobic
speed (MAS) (jogging; 11.2 ? 0.9 km/h) or at 95% MAS (running; 17.8 ? 1.4 km/h) on a
treadmill (h/p/Cosmos, Nussdorf-Traunstein, Germany) at 1% slope. Prior to
participation in the study, six participants were identified as rear-foot strikers and
the remaining five as mid/forefoot strikers, using the procedure described by
Hasegawa et al. [8]. All participants were healthy during the testing period. Prior to
testing, informed consent was obtained from all participants, and the study was
conformed to the guidelines of the local Ethical Committee and to the recommenda-
tions of the Declaration of Helsinki.
2.2. Plantar pressure distribution measures
Insole plantar pressure distribution was recorded for 30 s after a minute of
running at either 60% MAS or at 95% MAS, using the X-Pedar Mobile System (Novel
GmbH, Munich, Germany). Before commencement of data collection, the insoles
were calibrated according to the manufacturer’s guidelines. One insole was placed
under the right foot of all participants, wearing the same type of neutral running
shoes. The data logger for data storage was in a harness on the back of the
participant. Plantar pressures were sampled at 50 Hz. A regional analysis was
performed utilising nine separate ‘‘masks’’ or areas of the foot (Groupmask
Evaluation, Novel GmbH, Munich, Germany) (Fig. 1). Contact area (CA in cm2),
Gait & Posture 35 (2012) 685–687
A R T I C L E
I N F O
Article history:
Received 23 July 2011
Received in revised form 20 November 2011
Accepted 1 December 2011
Keywords:
Jogging
Pressure
Metatarsals
Foot
A B S T R A C T
This study aimed to compare foot plantar pressure distribution while jogging and running in highly
trained adolescent runners. Eleven participants performed two constant-velocity running trials either at
jogging (11.2 ? 0.9 km/h) or running (17.8 ? 1.4 km/h) pace on a treadmill. Contact area (CA in cm2),
maximum force (Fmaxin N), peak pressure (PP in kPa), contact time (CT in ms), and relative load (force time
integral in each individual region divided by the force time integral for the total plantar foot surface, in %)
were measured in nine regions of the right foot using an in-shoe plantar pressure device. Under the whole
foot, CA, Fmaxand PP were lower in jogging than in running (?1.2% [p < 0.05], ?12.3% [p < 0.001] and ?15.1%
[p < 0.01] respectively) whereas CT was higher (+20.1%; p < 0.001). Interestingly, we found an increase in
relative load under the medial and central forefoot regions while jogging (+6.7% and +3.7%, respectively;
[p < 0.05]), while the relative load under the lesser toes (?8.4%; p < 0.05) was reduced. In order to prevent
overloading of the metatarsals in adolescent runners, excessive mileage at jogging pace should be avoided.
? 2011 Elsevier B.V. All rights reserved.
* Corresponding author at: ASPIRE, Academy for Sports Excellence, 2006 Asian
Games Road, Doha, Qatar. Tel.: +974 44 13 61 07; fax: +974 44 13 69 89.
E-mail address: francois.fourchet@aspire.qa (F. Franc ¸ois).
Contents lists available at SciVerse ScienceDirect
Gait & Posture
jo u rn al h om ep age: ww w.els evier.c o m/lo c ate/g aitp os t
0966-6362/$ – see front matter ? 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.gaitpost.2011.12.004

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maximum force (Fmaxin N), peak pressure (PP in kPa), contact time (CT in ms), and
relative load (RL(FTI): force time integral [FTI] in each individual region divided by
FTI of the total plantar foot surface, in %) were determined for the nine selected
regions. In addition, as RL(FTI) does not take into account the size of an area it is
applied to, a more meaningful calculation of the relative load (RL(PTI)) was
performed while replacing FTI by (FTI/CA) in the above mentioned calculation of
RL(FTI), and where PTI means pressure time integral [9].
2.3. Statistical analysis
All data are presented as mean ? SD. A one way repeated measures analysis of
variance was used to examine the differences in plantar loading parameters for the
whole foot and for each region between jogging and running conditions. When
significant main effects were observed, Tukey post hoc analyses were used to identify
differences among means. Statistical analysis of the relationships between the foot-
strike patterns and the differences in plantar running patterns between running
velocities was not possible due to the small subgroups’ sample size. The statistical
analyses were performed using SigmaStat software (Jandel Corporation, San Rafael,
CA). Statistical significance was accepted at p < 0.05.
3. Results
RL(FTI) was higher under M5 and M6 (+6.7% and +3.7%
respectively,
p < 0.05)
but
was
p < 0.05) in jogging than in running. The differences in RL were
exactly in the same areas for RL calculated from FTI and from PTI
(Fig. 2). However, the differences between jogging and running
were statistically larger by using the alternative approach: +6.5%
(p < 0.01) and +3.3% (p < 0.05) under M5 and M6 respectively, and
?11.0% (p < 0.01) under M9. Under the whole foot, CA, Fmaxand PP
were lower in jogging than in running (?1.2% [p < 0.05], ?12.3%
lower
under
M9
(?8.4%;
Fig. 1. Regions of interest at the foot were masked to the size of the Pedar insole
(Groupmask Evaluation, Novel GmbH, Munich, Germany). The regions consisted of
the following: M1 medial heel, M2 lateral heel, M3 medial midfoot, M4 lateral
midfoot, M5 medial forefoot, M6 central forefoot, M7 lateral forefoot, M8 hallux and
M9 lesser toes.
Fig. 2. Mean (?SD) relative load (%) calculated from (A) the force time integral (FTI) and (B) the pressure time integral (PTI) for each foot region during jogging and running. *p < 0.05,
**p < 0.01 for significant differences between jogging and running.
F. Franc ¸ois et al. / Gait & Posture 35 (2012) 685–687
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[p < 0.001] and ?15.1% [p < 0.01] respectively) whereas CT was
higher (+20.1%; p < 0.001) (Table 1).
4. Discussion
Regarding the whole foot, CA, Fmaxand PP were lower in jogging
than in running whereas CT was higher, which is in line with the
well-known biomechanical features [1,7,10]. Interestingly, we
found an increase in relative load under the medial and central
forefoot regions while jogging, while the relative load under the
lesser toes was reduced. These findings expanded those of Ho et al.
[1], which focused only on peak pressures and maximum force and
showed an increased foot inversion during the stance phase when
running at 2.5 m/s compared to 1.5 m/s. Contrary to Melai et al.
findings [9], RL(PTI) only confirmed the results provided by RL(FTI)
but did not provide any additional information on the cumulative
mechanical loading. This study is limited by the fact that it was
conducted on a treadmill and not in a ‘‘natural running
environment’’. Differences in running mechanics between tread-
mill and natural running (e.g. different stride patterns and shock
absorption modalities) have been described previously [11,12]. In
order to prevent overloading of the metatarsals in adolescent
runners [4,5], excessive mileage at jogging pace should be avoided.
Also some jogging sessions may be implemented on a compliant
surface as natural grass, in order to reduce the plantar pressure
under the forefoot [13]. Finally, we recommend strengthening
exercises of the foot musculature which has been shown to protect
the first three metatarsals from overload during sprinting [14].
Acknowledgements
The authors wish to thank Dr Matthieu Sailly and Mr Carlos
Cavalheiro for their availability during these experiments.
Conflict of interest
We affirm that we have no financial affiliation (including
research funding) or involvement with any commercial organisa-
tion that has a direct financial interest in any matter included in
this manuscript.
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Table 1
Means (?SD) for contact area (cm2), maximum force (N), peak pressure (kPa), contact
time (ms), relative load calculated from the force time integral (%) for the whole foot
and for the medial forefoot, the central forefoot and the lesser toes during jogging and
running.
Foot region
Parameter
Jogging
Running
p
Whole foot
Contact area (cm2)
Maximum force (N)
Peak pressure (kPa)
Contact time (ms)
168.2 ? 4.6
1430.8 ? 287.4
284.0 ? 67.5
225.8 ? 21.3
15.9 ? 3.2
19.4 ? 3.3
16.8 ? 4.0
18.8 ? 3.8
11.0 ? 2.7
9.5 ? 2.2
170.2 ? 3.8
1607.3 ? 275.4
327.0 ? 72.9
180.4 ? 13.1
14.9 ? 3.4
18.2 ? 3.2
16.2 ? 3.9
18.2 ? 3.9
12.0 ? 2.3
10.5 ? 2.2
<0.05
<0.001
<0.01
<0.001
5
5
6
6
9
9
RL(FTI) (%)
RL(PTI) (%)
RL(FTI) (%)
RL(PTI) (%)
RL(FTI) (%)
RL(PTI) (%)
<0.05
<0.01
<0.05
<0.05
<0.05
<0.01
RL(FTI), relative load calculated from the force time integral. ‘‘Whole foot’’ means
that each variable changed significantly between jogging and running not only for
the whole foot but also for each region of the mask.
F. Franc ¸ois et al. / Gait & Posture 35 (2012) 685–687
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