REVIEW
published: 11 October 2019
doi: 10.3389/fspor.2019.00046
How to Evaluate and Improve Foot
Strength in Athletes: An Update
Romain Tourillon 1,2,3*, Boris Gojanovic 3* and François Fourchet 3*
1
Faculty of Sport Sciences, University of Nantes, Nantes, France, 2 School of Physical Therapy and Rehabilitation,
IFM3R, Saint-Sébastien sur Loire, France, 3 Motion Analysis Lab, Physiotherapy and Sports Medicine Department,
Swiss Olympic Medical Center, La Tour Hospital, Meyrin, Switzerland
The foot is a complex system with multiple degrees of freedom that play an essential role
in running or sprinting. The intrinsic foot muscles (IFM) are the main local stabilizers of the
foot and are part of the active and neural subsystems that constitute the foot core. These
Edited by:
muscles lengthen eccentrically during the stance phase of running before shortening at
Olivier Girard,
Murdoch University, Australia the propulsion phase, as the arch recoils in parallel to the plantar fascia. They play a
Reviewed by: key role in supporting the medial longitudinal arch, providing flexibility, stability and shock
Alexandre Igor Araripe Medeiros, absorption to the foot, whilst partially controlling pronation. Much of the foot rigidity in
Universidade Federal Do Ceará, Brazil
Helen Bayne,
late stance has been attributed to the windlass mechanism – the dorsiflexion of the toes
University of Pretoria, South Africa building tension up in the plantar aponeurosis and stiffening the foot. In addition, recent
*Correspondence: studies have shown that the IFM provide a necessary active contribution in late stance,
Romain Tourillon
in order to develop sufficient impedance in the metatarsal-phalangeal joints. This in turn
Boris Gojanovic facilitates the propulsive forces at push-off. These factors support the critical role of the
foot in providing rigidity and an efficient lever at push-off. During running or sprinting,
François Fourchet
athletes need to generate and maintain the highest (linear) running velocity during a
single effort in a sprinting lane. Acceleration and sprinting performance requires forces
Specialty section: to be transmitted efficiently to the ground. It may be of particular interest to strengthen
This article was submitted to
Elite Sports and Performance
foot muscles to maintain and improve an optimal capacity to generate and absorb these
Enhancement, forces. The current evidence supports multiple exercises to achieve higher strength in the
a section of the journal foot, such as the “short foot exercise,” doming, toes curl, towing exercises or the more
Frontiers in Sports and Active Living
dynamic hopping exercises, or even barefoot running. Their real impact on foot muscle
Received: 17 July 2019
Accepted: 24 September 2019 strength remains unclear and data related to its assessment remains scarce, despite
Published: 11 October 2019 a recognized need for this, especially before and after a strengthening intervention. It
Citation: would be optimal to be able to assess it. In this article, we aim to provide the track
Tourillon R, Gojanovic B and
and field community with an updated review on the current modalities available for foot
Fourchet F (2019) How to Evaluate
and Improve Foot Strength in strength assessment and training. We present recommendations for the incorporation of
Athletes: An Update. foot muscles training for performance and injury prevention in track and field.
Front. Sports Act. Living 1:46.
doi: 10.3389/fspor.2019.00046 Keywords: intrinsic foot muscles, foot strengthening, assessment, track and field athletics, exercises
Frontiers in Sports and Active Living | www.frontiersin.org 1 October 2019 | Volume 1 | Article 46
, Tourillon et al. Foot Strength in Athletes: An Update
INTRODUCTION acceleration phase are not those who produce the highest total
force, but those who manage to orient the forces horizontally
The foot is a complex joint system with multiple degrees of (Morin and Samozino, 2016).
freedom that play an important role in athletic tasks such as To achieve this, the sprinter must accomplish a series of
running or sprinting. The compliance of the foot is remarkable segment rotations (Krell and Stefanyshyn, 2006) and gross
and its spring-like properties—in the medial longitudinal arch moment generation about the lower limb joints, including hip,
(MLA) – allow mechanical energy to be stored and returned at knee, and ankle (Tanaka et al., 2019). The small MTP joints (via
each step (Ker et al., 1987). Previous studies have shown that dorsiflexion) may be related to sprint performance, as several
this spring mechanism was provided by the elastic components studies have shown (Krell and Stefanyshyn, 2006; Bezodis et al.,
of the plantar fascia or aponeurosis (PA). This may account 2012). Stefanyshyn and Nigg (1997) investigated the energy
for 8–17% of the mechanical energy required for a stride (Ker patterns at the foot level during sprinting and found a large
et al., 1987; Stearne et al., 2016) and it increases stiffness negative net energy balance (a lot of energy absorbed, whilst
via the windlass mechanism. Recent studies showed however little produced) in the MTP joint during early to late stages of
that this spring cannot simply be passive, as it cannot explain stance phase. These authors concluded that performance may
the ability of the foot to adapt to the mechanical loads of be improved through a reduction in the energy loss at the
running or sprinting (Riddick et al., 2019). Kelly et al. (2018) MTP joint, but the question of how to achieve a better energy
showed during running that as speed increases, so does the balance, hence better performance at push-off, remains. For
dissipation of mechanical energy within the foot. This can example, Smith et al. (2014) found that varying the stiffness
be modulated by the muscular capacity of the intrinsic foot of spikes resulted in a significant decrease in MTP joint range
muscles (IFM). of motion as well as dorsiflexion velocity when compared to
The IFM are the main local stabilizers of the foot and are barefoot. Spikes enable the MTP joint to plantar flex during push-
part of the active and neural subsystems that constitute the foot off without affecting the windlass mechanism, which in turn
core (McKeon et al., 2015). With their anatomical insertions facilitates propulsion by increasing the length of the moment
located under the foot, these muscles lengthen eccentrically arm (Smith et al., 2014).
during the early stance phase of running, producing negative This longer lever arm requires increased strength from the
work before they shorten during the late stance phase as the arch plantar flexors, and running athletes can benefit from it: a larger
recoils to produce positive work (Fourchet and Gojanovic, 2016). and more efficient horizontal force production may enhance
This active contraction aids propulsion and is enabled by the performance (Morin and Samozino, 2016). A recent study
following three muscle-tendon units: abductor hallucis (AbH), showed that IFM activity in late stance is needed to generate
flexor digitorum brevis (FDB), and quadratus plantae (QP) (Kelly sufficient impedance at the MTP joints, which in turn provides
et al., 2015). an efficient push-off (Farris et al., 2019).
Because the IFM are usually neglected in assessment and Finally the MTP joint plays a key role during sprinting
treatment, a key component of foot core stability is not and that may result in the development of very strong foot
considered. We aim to provide the track and field community muscles in sprinters population. However, Tanaka et al. (2019)
an updated review on the current modalities available for foot demonstrated that although elite sprinters have thicker foot
strength assessment and training. Running or sprinting is a muscles compared with non-sprinters, AbH thickness correlates
cyclic activity involving all joints and muscles groups in the positively with their 100 m personal best. In other words a
lower limbs, including the IFM, and the metatarsophalangeal bigger AbH might be a negative factor for superior sprint
(MTP) joint. We believe that it is of interest to assess performance. On the contrary, Yuasa et al. (2018) showed a
the MTP joint’s role during sprinting, especially looking at significant correlation in collegiate American football players
the link between midfoot and plantar flexors’ torque before between maximal toe flexors strength with a dorsiflexed MTP
considering the various strengthening modalities and protocols. and the ability to change direction in pro-agility and 3-cone
We will present recommendations for the incorporation of foot tests. Abe et al. (2016) found in active subjects that fourth
muscles training or performance and injury prevention in track and fifth toe flexor strength was correlated positively with
and field. walking speed in men (r = 0.584) and women (r = 0.553),
whereas Hashimoto and Sakuraba (2014) found that 8 weeks
of toe flexors exercises decreased 50 m best personal time
THE FOREFOOT REGION AND RUNNING in 12 men.
OR SPRINTING Although toe flexors strength is generated by a simultaneous
action of both intrinsic and extrinsic foot muscles, the IFM
During running or sprinting, athletes need to generate and seem most likely to be the main contributors to MTP joints
maintain the highest (linear) running velocity during a single torque (Farris et al., 2019). Again, we should not underestimate
effort in a sprinting lane. Acceleration and sprinting performance the role of the MTP joints in strength training. In summary,
requires forces to be transmitted efficiently to the ground. strengthening interventions should not be limited to extrinsic
In particular, the production of horizontal force during the foot and ankle muscles (e.g., flexor digitorum longus, triceps
acceleration, more than vertical force, is related to sprinting surae, flexor hallucis longus), but should also target intrinsic
performance. Indeed, the fastest runners at the end of the foot muscles.
Frontiers in Sports and Active Living | www.frontiersin.org 2 October 2019 | Volume 1 | Article 46
published: 11 October 2019
doi: 10.3389/fspor.2019.00046
How to Evaluate and Improve Foot
Strength in Athletes: An Update
Romain Tourillon 1,2,3*, Boris Gojanovic 3* and François Fourchet 3*
1
Faculty of Sport Sciences, University of Nantes, Nantes, France, 2 School of Physical Therapy and Rehabilitation,
IFM3R, Saint-Sébastien sur Loire, France, 3 Motion Analysis Lab, Physiotherapy and Sports Medicine Department,
Swiss Olympic Medical Center, La Tour Hospital, Meyrin, Switzerland
The foot is a complex system with multiple degrees of freedom that play an essential role
in running or sprinting. The intrinsic foot muscles (IFM) are the main local stabilizers of the
foot and are part of the active and neural subsystems that constitute the foot core. These
Edited by:
muscles lengthen eccentrically during the stance phase of running before shortening at
Olivier Girard,
Murdoch University, Australia the propulsion phase, as the arch recoils in parallel to the plantar fascia. They play a
Reviewed by: key role in supporting the medial longitudinal arch, providing flexibility, stability and shock
Alexandre Igor Araripe Medeiros, absorption to the foot, whilst partially controlling pronation. Much of the foot rigidity in
Universidade Federal Do Ceará, Brazil
Helen Bayne,
late stance has been attributed to the windlass mechanism – the dorsiflexion of the toes
University of Pretoria, South Africa building tension up in the plantar aponeurosis and stiffening the foot. In addition, recent
*Correspondence: studies have shown that the IFM provide a necessary active contribution in late stance,
Romain Tourillon
in order to develop sufficient impedance in the metatarsal-phalangeal joints. This in turn
Boris Gojanovic facilitates the propulsive forces at push-off. These factors support the critical role of the
foot in providing rigidity and an efficient lever at push-off. During running or sprinting,
François Fourchet
athletes need to generate and maintain the highest (linear) running velocity during a
single effort in a sprinting lane. Acceleration and sprinting performance requires forces
Specialty section: to be transmitted efficiently to the ground. It may be of particular interest to strengthen
This article was submitted to
Elite Sports and Performance
foot muscles to maintain and improve an optimal capacity to generate and absorb these
Enhancement, forces. The current evidence supports multiple exercises to achieve higher strength in the
a section of the journal foot, such as the “short foot exercise,” doming, toes curl, towing exercises or the more
Frontiers in Sports and Active Living
dynamic hopping exercises, or even barefoot running. Their real impact on foot muscle
Received: 17 July 2019
Accepted: 24 September 2019 strength remains unclear and data related to its assessment remains scarce, despite
Published: 11 October 2019 a recognized need for this, especially before and after a strengthening intervention. It
Citation: would be optimal to be able to assess it. In this article, we aim to provide the track
Tourillon R, Gojanovic B and
and field community with an updated review on the current modalities available for foot
Fourchet F (2019) How to Evaluate
and Improve Foot Strength in strength assessment and training. We present recommendations for the incorporation of
Athletes: An Update. foot muscles training for performance and injury prevention in track and field.
Front. Sports Act. Living 1:46.
doi: 10.3389/fspor.2019.00046 Keywords: intrinsic foot muscles, foot strengthening, assessment, track and field athletics, exercises
Frontiers in Sports and Active Living | www.frontiersin.org 1 October 2019 | Volume 1 | Article 46
, Tourillon et al. Foot Strength in Athletes: An Update
INTRODUCTION acceleration phase are not those who produce the highest total
force, but those who manage to orient the forces horizontally
The foot is a complex joint system with multiple degrees of (Morin and Samozino, 2016).
freedom that play an important role in athletic tasks such as To achieve this, the sprinter must accomplish a series of
running or sprinting. The compliance of the foot is remarkable segment rotations (Krell and Stefanyshyn, 2006) and gross
and its spring-like properties—in the medial longitudinal arch moment generation about the lower limb joints, including hip,
(MLA) – allow mechanical energy to be stored and returned at knee, and ankle (Tanaka et al., 2019). The small MTP joints (via
each step (Ker et al., 1987). Previous studies have shown that dorsiflexion) may be related to sprint performance, as several
this spring mechanism was provided by the elastic components studies have shown (Krell and Stefanyshyn, 2006; Bezodis et al.,
of the plantar fascia or aponeurosis (PA). This may account 2012). Stefanyshyn and Nigg (1997) investigated the energy
for 8–17% of the mechanical energy required for a stride (Ker patterns at the foot level during sprinting and found a large
et al., 1987; Stearne et al., 2016) and it increases stiffness negative net energy balance (a lot of energy absorbed, whilst
via the windlass mechanism. Recent studies showed however little produced) in the MTP joint during early to late stages of
that this spring cannot simply be passive, as it cannot explain stance phase. These authors concluded that performance may
the ability of the foot to adapt to the mechanical loads of be improved through a reduction in the energy loss at the
running or sprinting (Riddick et al., 2019). Kelly et al. (2018) MTP joint, but the question of how to achieve a better energy
showed during running that as speed increases, so does the balance, hence better performance at push-off, remains. For
dissipation of mechanical energy within the foot. This can example, Smith et al. (2014) found that varying the stiffness
be modulated by the muscular capacity of the intrinsic foot of spikes resulted in a significant decrease in MTP joint range
muscles (IFM). of motion as well as dorsiflexion velocity when compared to
The IFM are the main local stabilizers of the foot and are barefoot. Spikes enable the MTP joint to plantar flex during push-
part of the active and neural subsystems that constitute the foot off without affecting the windlass mechanism, which in turn
core (McKeon et al., 2015). With their anatomical insertions facilitates propulsion by increasing the length of the moment
located under the foot, these muscles lengthen eccentrically arm (Smith et al., 2014).
during the early stance phase of running, producing negative This longer lever arm requires increased strength from the
work before they shorten during the late stance phase as the arch plantar flexors, and running athletes can benefit from it: a larger
recoils to produce positive work (Fourchet and Gojanovic, 2016). and more efficient horizontal force production may enhance
This active contraction aids propulsion and is enabled by the performance (Morin and Samozino, 2016). A recent study
following three muscle-tendon units: abductor hallucis (AbH), showed that IFM activity in late stance is needed to generate
flexor digitorum brevis (FDB), and quadratus plantae (QP) (Kelly sufficient impedance at the MTP joints, which in turn provides
et al., 2015). an efficient push-off (Farris et al., 2019).
Because the IFM are usually neglected in assessment and Finally the MTP joint plays a key role during sprinting
treatment, a key component of foot core stability is not and that may result in the development of very strong foot
considered. We aim to provide the track and field community muscles in sprinters population. However, Tanaka et al. (2019)
an updated review on the current modalities available for foot demonstrated that although elite sprinters have thicker foot
strength assessment and training. Running or sprinting is a muscles compared with non-sprinters, AbH thickness correlates
cyclic activity involving all joints and muscles groups in the positively with their 100 m personal best. In other words a
lower limbs, including the IFM, and the metatarsophalangeal bigger AbH might be a negative factor for superior sprint
(MTP) joint. We believe that it is of interest to assess performance. On the contrary, Yuasa et al. (2018) showed a
the MTP joint’s role during sprinting, especially looking at significant correlation in collegiate American football players
the link between midfoot and plantar flexors’ torque before between maximal toe flexors strength with a dorsiflexed MTP
considering the various strengthening modalities and protocols. and the ability to change direction in pro-agility and 3-cone
We will present recommendations for the incorporation of foot tests. Abe et al. (2016) found in active subjects that fourth
muscles training or performance and injury prevention in track and fifth toe flexor strength was correlated positively with
and field. walking speed in men (r = 0.584) and women (r = 0.553),
whereas Hashimoto and Sakuraba (2014) found that 8 weeks
of toe flexors exercises decreased 50 m best personal time
THE FOREFOOT REGION AND RUNNING in 12 men.
OR SPRINTING Although toe flexors strength is generated by a simultaneous
action of both intrinsic and extrinsic foot muscles, the IFM
During running or sprinting, athletes need to generate and seem most likely to be the main contributors to MTP joints
maintain the highest (linear) running velocity during a single torque (Farris et al., 2019). Again, we should not underestimate
effort in a sprinting lane. Acceleration and sprinting performance the role of the MTP joints in strength training. In summary,
requires forces to be transmitted efficiently to the ground. strengthening interventions should not be limited to extrinsic
In particular, the production of horizontal force during the foot and ankle muscles (e.g., flexor digitorum longus, triceps
acceleration, more than vertical force, is related to sprinting surae, flexor hallucis longus), but should also target intrinsic
performance. Indeed, the fastest runners at the end of the foot muscles.
Frontiers in Sports and Active Living | www.frontiersin.org 2 October 2019 | Volume 1 | Article 46
