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Tuesday, June 6, 2023

The Role of Tibialis Posterior Fatigue on Foot Kinematics During Walking

Brent Brookbush

Brent Brookbush


Research Review: The Role of Tibialis Posterior Fatigue on Foot Kinematics During Walking

By David Chessen DPT, PT, OCS, MBA

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Pohl, M. B., Rabbito, M., and Ferber, R. (2010). The role of tibialis posterior fatigue on foot kinematics during walking. Journal of Foot and Ankle Research, 3(1), 6. ABSTRACT

Why the Study Is Relevant: The tibialis posterior serves as an invertor of the rear foot and provides dynamic arch support for the mid foot (1). The effect of tibialis posterior dysfunction on the mechanics of ambulation has been well documented (2,3). However, the effect of tibialis posterior  fatigue on foot kinematics in healthy individuals has received little attention. This 2010 study investigated the effect of fatiguing the tibialis posterior  through resisted foot adduction on foot kinematics during walking.

Tibialis Posterior Tendon Source: https://brentbrookbush.com/articles/anatomy-articles/muscular-anatomy/tibialis-posterior/

Study Summary

Study Design Single-group quasi experimental
Level of EvidenceIIB evidence from at least one other type of quasi-experimental study
Participant CharacteristicsDemographics
  • Age: 27.3 ± 8.1 yrs
  • Mass: 68.8 ± 13.5 kg
  • Gender: 18 females and 11 males

Inclusion Criteria:

  • Recreationally active and currently free from lower extremity injury, familiar with treadmill walking

Exclusion Criteria:

  • History of surgery to the foot and lower leg; not familiar with treadmill walking
  • One investigator measured the relaxed standing rear foot angle on all participants
  • 3-D data was collected while participants walked on a treadmill both prior to, and following fatigue-inducing exercise of the tibialis posterior.
  • Pre-fatigue condition was established by treadmill walking before the fatigue protocol.
  • Within 15 seconds after completing the fatigue protocol, participants returned to the treadmill to complete kinematic data collection for the post-fatigue (POST) condition
  • Fatigue protocol:
    • The tibialis posterior was fatigued using a closed chain resisted foot adduction motion.
    • The participant's right foot was placed in a custom built device that allowed concentric/eccentric foot adduction.
    • A dynamometer on the device measured maximal isometric voluntary contraction (MVIC).
    • The mean of three MVIC trials was used to represent the PRE condition.
    • With the ankle positioned in 20° plantar flexion, the participant's performed 50 concentric/eccentric contractions at 50% MVIC through a 30° range of motion.
      • The participant rested 10 seconds between each set after every four sets MVICs were performed.
      • This continued until the MVICs were <70% of the PRE values or the participants were unable to complete two consecutive sets.

    • A final set of three MVICs was taken within 2 minutes after the post-fatigue walk and then averaged for the post-fatigue (POST) condition.

Data Collection and Analysis
  • Paired sample t-tests for kinematic variables for between-condition comparison
  • Pearson-product moment correlation for the relationship between the standing rear foot angle and changes in rear foot kinematics
Outcome MeasuresKinematic variables of interest:
  • Rear foot peak eversion (EVE)
  • Rear foot EVE excursion
  • Time to peak rear foot EVE
  • Forefoot peak dorsiflexion (DF)
  • Forefoot DF excursion
  • Time to peak forefoot DF
  • Forefoot peak abduction (ABD)
Results Force output:
  • The mean baseline isometric force was 66.2 Newtons (N) ± 28.3
  • After fatiguing exercise the mean MVC force was 44.6 N ± 21.8 which equals 67% of the baseline value


  • Following fatigue protocol, there was significantly greater rear foot EVE excursion (0.7°)
    • Pre-fatigue -6.5° (1.9)
    • Post-fatigue -7.2° (1.8)

  • No significant difference in rear foot peak EVE or the time to peak EVE following fatigue protocol
  • No significant changes in forefoot peak DF, DF excursion, or time to peak DF
  • 22 out of 29 (76%) had greater rear foot EVE excursion following fatigue protocol
    • Of those 22, only 12 demonstrated changes that exceeded the magnitude of precision error

  • 17 of 29 (58%) had an increase in peak forefoot ABD following fatigue protocol
    • Of the 17, only 5 had increases that exceeded the magnitude of precision error

Structure and Kinematics:

  • The mean anatomical standing rear foot angle for all subjects was 6.8° ± 2.7° of eversion
  • Standing rear foot angle was poorly correlated with the kinematic changes in peak rear foot eversion (standard error of measurement, r = -0.19, P = 0.32) and excursion (r = -0.28, P = 0.15) following fatigue protocol
Our ConclusionsThis study found no significant changes in rear foot eversion during walking following a fatiguing exercise protocol for the tibialis posterior. This study has influenced the Brookbush Institute (BI) model for lower extremity dysfunction (LED); resulting in consideration of labeling pronation as the osteokinematic change correlated with "feet flatten" rather than eversion.
Researchers' Conclusions

An exercise protocol aimed at fatiguing the tibialis posterior produced no substantial changes in rear foot eversion during walking. No significant changes in forefoot kinematics were observed after the fatiguing protocol. (Note: medial longitudinal arch height was not measured)

Dr. Brent Brookbush instructs a patient on how to perform Tibialis Posterior Activation with toe extension to reciprocally inhibit the long toe flexors.
Caption: Dr. Brent Brookbush instructs a patient on how to perform Tibialis Posterior Activation with toe extension to reciprocally inhibit the long toe flexors.

Tibialis Posterior Activation

Tibialis posterior activation exercise from the Brookbush Institute. Source: https://brentbrookbush.com/articles/corrective-exercise-articles/activation/tibialis-posterior-activation/

Review & Commentary:

This study found that a fatiguing exercise protocol for the tibialis posterior did not alter peak rear foot and forefoot kinematics with walking; however, greater excursion of the rear foot was noted.

The study had many methodological strengths, including:

  • The study used a clinically relevant exercise in foot adduction to fatigue the tibialis posterior .
  • The timeline for the fatiguing protocol was well documented and explained allowing future replication of the study methods.
  • To our knowledge this is the first study to measure the effect of a fatiguing protocol for the tibialis posterior  on gate.

Weaknesses that should be noted prior to clinical integration of the findings include:

  • No electromyographic (EMG) analysis was performed making it difficult to determine whether the tibialis posterior was directly affected by the fatiguing exercise protocol (and what effect fatigue has on activity).
  • The contribution of other structures or muscles was not analyzed which may have affected the results of this study.
  • Structural measures of the participants' medial longitudinal arch and forefoot were not measured.

How This Study is Important:

The findings of this study suggest that other muscles may support the rear foot, and/or that the tibialis posterior  does not have a significant influence over rear foot mechanics. Further studies should consider EMG of synergistic muscles and inclusion of the navicular drop test to assess forefoot mechanics.

How the Findings Apply to Practice:

Rear foot mechanics (eversion) may not be a reliable assessment of tibialis posterior  activity and strength. Human movement professionals should assess (and intervene when appropriate) the entire ankle/foot complex and consider all potential structures contributing to the altered mechanics notes.

How does it relate to Brookbush Institute Content?

The tibialis posterior is noted as being long and under active in the Brookbush Institute (BI) predictive model of lower extremity dysfunction (LED) . Activation techniques are suggested by the BI to enhance the functioning of the tibialis posterior and improve movement dysfunctions such as "feet flatten ." The study did not find significant changes in foot mechanics or rear foot eversion with fatiguing of the tibialis posterior , which suggests that other structures may support and compensate for the fatigued tibialis posterior . The tibialis anterior  also provides muscular support for the medial longitudinal arch, acting as a powerful supinator of the foot (4), which may imply that "feet flatten " is the result of forefoot pronation and not rear foot eversion. It is important to note that this study investigated asymptomatic individuals with no history of LED . It is unknown whether similar results would have occurred in symptomatic individuals.

The following videos illustrate common assessment techniques and interventions used to affect the tibialis posterior :

Tibialis Posterior Manual Muscle Testing

Tibialis Posterior Activation

Tibialis Posterior Activation Progression 2


  1. Tome, J., Nawoczenski, D. A., Flemister, A., & Houck, J. (2006). Comparison of foot kinematics between subjects with posterior tibialis tendon dysfunction and healthy controls. Journal of Orthopaedic & Sports Physical Therapy, 36(9), 635-644.
  2. Ness, M. E., Long, J., Marks, R., & Harris, G. (2008). Foot and ankle kinematics in patients with posterior tibial tendon dysfunction. Gait & posture, 27(2), 331-339.
  3. Ringleb, S. I., Kavros, S. J., Kotajarvi, B. R., Hansen, D. K., Kitaoka, H. B., & Kaufman, K. R. (2007). Changes in gait associated with acute stage II posterior tibial tendon dysfunction. Gait & posture, 25(4), 555-564.
  4. Klein, P., Mattys, S., & Rooze, M. (1996). Moment arm length variations of selected muscles acting on talocrural and subtalar joints during movement: An in vitro study. Journal of biomechanics, 29(1), 21-30.

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