Intrinsic vs. Combined Foot Muscle Strengthening for Paediatric Pes Planovalgus | Find Your Stride | Edinburgh Podiatrist

Introduction

Flexible pes planovalgus (flatfoot) remains one of the most common presentations in paediatric podiatry, thought to account for nearly 90% of pediatric podiatry visits (according to the authors). For clinicians managing young athletes, the real question isn’t whether flat feet exist, it’s whether early intervention improves long-term outcomes in:

• Running performance

• Balance and neuromuscular control

• Injury risk (e.g., tibial stress, patellofemoral pain, Achilles overload)

• Kinetic chain development

A 2025 randomized controlled trial by Tuncer et al., published in the European Journal of Pediatrics, attempts to answer a clinically important question:

Does adding extrinsic muscle strengthening to intrinsic foot exercises produce superior outcomes in children aged 4–7 with pes planovalgus?

Tuncer et al. (2025) suggest that Flexible pes planovalgus (flatfoot) accounts for nearly 90% of pediatric podiatry visits

Study Overview

Design: Prospective randomized controlled trial

Participants: 36 children (4–7 years old) with bilateral flexible pes planovalgus

Intervention duration: 8 weeks

Groups: 1. IMSG – Intrinsic muscle strengthening only. 2. IEMSG – Combined intrinsic + extrinsic strengthening

Both groups received weekly supervised sessions plus 4 days/week home exercises. Compliance was high (77% full adherence)  .

Outcome Measures

Primary:

• Single Leg Stance Test (SLST)

• Timed Up and Go (TUG)

Secondary:

• Navicular Drop Test (NDT)

• Foot Posture Index-6 (FPI-6)

• Sit-to-Stand (STS)

• 6-Minute Walk Test (6MWT)

Intention-to-treat analysis was used, strengthening internal validity  .

Key Findings

1️⃣ Both programs improved foot posture, balance, and mobility.

All outcomes improved significantly within both groups.

2️⃣ The combined program (intrinsic + extrinsic) was superior for:

• Navicular Drop Test

• Foot Posture Index

• Static balance (SLST)

Effect sizes were moderate to large (ηp² up to 0.27 for balance)  .

3️⃣ No significant between-group differences in:

• TUG

• STS

• 6MWT

Functional mobility improved, but whole-body dynamic tasks did not show superiority for the combined approach.

Clinical Interpretation for Podiatry & Sports Medicine

The Foot Core Concept—Expanded

The study reinforces what many sports clinicians already suspect: The medial longitudinal arch is not maintained by intrinsic muscles alone.

The addition of:

• Tibialis posterior strengthening

• Tibialis anterior strengthening

• Supination-based drills

• Tiptoe stance training

Produced greater structural change. For young runners, this is critical. The tibialis posterior is arguably the most important dynamic stabiliser of the medial arch during midstance. Weakness here may contribute to:

• 'Excessive pronation'

• Delayed resupination

• Increased tibial internal rotation

• Patellofemoral stress

• Plantar fascia overload

If we only prescribe toe curls and short-foot exercises, we may be under-dosing the system.

Implications for Running Performance

Although this population was preschool-aged (not competitive runners) the neuromuscular foundations are being laid during this stage. Improved static balance and arch posture may translate into:

• Better force transfer in stance phase

• Improved single-leg stability

• Reduced frontal plane collapse

• More efficient propulsion mechanics

However, the absence of dynamic performance differences (TUG, 6MWT) suggests: Foot strengthening alone may not be enough to improve global movement efficiency. For youth athletes, foot rehab likely needs integration with:

• Hip control work

• Proximal stability training

• Plyometric progression

• Gait retraining

Strengths of the Study

✔ Randomized controlled design

✔ Intention-to-treat analysis

✔ Clearly defined inclusion/exclusion criteria

✔ High adherence

✔ Practical, clinic-friendly outcome measures

✔ First pediatric RCT comparing intrinsic vs combined strengthening

Limitations That Matter Clinically

❗ Small Sample Size - 36 participants total. Effect sizes were large, but small studies can overestimate magnitude.

❗ Short Duration (8 Weeks) - No long-term follow-up to determine:

• Sustainability of arch change

• Injury reduction

• Impact on sport participation

❗ No Blinding of Assessors - Potential measurement bias.

❗ No Running-Specific Metrics, the study didn't look at:

• Plantar pressure analysis

• Gait biomechanics

• Jump landing control

• Sport injury tracking

❗ Natural Arch Development Confounder - Children aged 4–7 are still in a developmental window. Some improvements may reflect maturation rather than intervention alone.

Should We Intervene in 4–7-Year-Olds?

This remains controversial. Some literature argues most flexible flatfeet resolve spontaneously. However, this study supports early intervention when:

• Arch development lags

• Balance is impaired

• Activity-related symptoms exist

• Family history suggests persistence

From a sports injury prevention standpoint, early neuromuscular conditioning likely carries minimal downsides.

Practical Takeaways for Clinicians

If managing pediatric flatfoot in active children, do not rely on intrinsic exercises alone. Include:

• Tibialis posterior resistance band work

• Controlled supination drills

• Tiptoe gait training

• Progressive single-leg loading

For young runners:

Foot strengthening could be integrated into:

• Warm-up routines

• Barefoot balance circuits

• Youth conditioning programs

Orthotics vs Exercise?

This study excluded orthotics. It suggests: Active muscular rehabilitation may be foundational, not optional. For athletes, orthoses may support, but not replace foot strength development.

Bottom Line

This RCT strengthens the case for combined intrinsic and extrinsic foot muscle strengthening in pediatric pes planovalgus. For podiatrists and sports clinicians:

• The medial arch is a system.

• Tibialis posterior matters.

• Early neuromuscular training may shape long-term biomechanics.

But we still lack evidence that early strengthening:

• Prevents running injuries

• Improves athletic performance

• Alters long-term foot structure into adolescence

Future research should include longitudinal injury tracking and biomechanical gait analysis.

Citation

Tuncer D, Erekdag A, Senaran H, Uzer G. Intrinsic vs. combined foot muscle strengthening for pes planovalgus in children aged 4–7 years: a randomized controlled trial. European Journal of Pediatrics. 2025;184:636.

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