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Effect of intrinsic foot muscles training on foot function and dynamic postural balance: A systematic review and meta-analysis


This systematic review aimed to analyse the effects of intrinsic foot muscle (IFM) training on foot function and dynamic postural balance. Keywords related to IFM training were used to search four databases (PubMed, CINAHL, SPORTDiscus and Web of Science databases.) for relevant studies published between January 2011 and February 2021. The methodological quality of the intervention studies was assessed independently by two reviewers by using the modified Downs and Black quality index. Publication bias was also assessed on the basis of funnel plots. This study was registered in PROSPERO (CRD42021232984). Sixteen studies met the inclusion criteria (10 with high quality and 6 with moderate quality). Numerous biomechanical variables were evaluated after IFM training intervention. These variables included IFM characteristics, medial longitudinal arch morphology and dynamic postural balance. This systematic review demonstrated that IFM training can exert positive biomechanical effects on the medial longitudinal arch, improve dynamic postural balance and act as an important training method for sports enthusiasts. Future studies should optimise standardised IFM training methods in accordance with the demands of different sports.

1 Introduction

Whilst running, the feet act as the starting body part of the lower limb kinetic chain. Aside from functioning as shock absorbers, weight support structures and locomotive effectors [1, 2], the feet can resist deformation, provide a stable base of support and lever the arms to propel the body efficiently [3]. Given that the feet are the most distal aspect of the lower limb and the first part touching the ground [4], many studies have explored their potential mechanism in transmitting ground reaction force and established that impact forces can be distributed through the active modulation of the activity of muscles, such as the plantar flexor, tibialis anterior and calf muscles [3, 57].

The main Intrinsic foot muscles (IFMs) are abductor hallucis (ABH), flexor digitorum brevis (FDB) and quadratus plantae (QP). Their principal function is to provide foot stability and flexibility for shock absorption [8]; improve dynamic alignment; stiffen the foot arches and stimulate proprioceptors on the sole of the feet [912]. IFMs are also categorised as active subsystems in the foot core system and play an important role in static posture and dynamic activities [1, 13]. During the early stance phase of rearfoot strike running, IFMs are passively stretched as the rearfoot initially touches the ground, and the arch of the foot is slowly compressed to absorb impact energy, which is stored in the relevant plantar elastic structure [6, 12, 14]. In the terminal stance phase, the compressed arch begins to rebound, releasing previously stored elastic energy and providing improved propulsion to runners in the push-off phase [12]. This spring-like mechanism of foot muscles provides 8%–17% of the mechanical energy to the body during every step [2, 15, 16].

IFMs can be trained by using several methods, such as short foot exercise (SFE), toe-posture exercises, towel curl exercises and metatarsophalangeal joint (MPJ) muscle training [1721]. Amongst these methods, SFE is the most studied because it utilises the IFMs to draw the metatarsal heads back towards the heel whilst minimising distal interphalangeal flexion [18, 22, 23]. Through IFM training, weakened or inhibited IFMs are activated and foot–ankle neuromuscular control is improved [24], which may help prevent running-related injuries, such as plantar fasciitis [25], foot pronation [26], hallux valgus [27] and chronic ankle instability [28].

While a number of isolated studies have shown benefits of IFM, the applicability of these findings is still limited, to date, no previous study has systematically studied these effects nor has a meta-analysis been applied to get an overall estimate of the effect of IFM training. Therefore, the current study aims to identify and determine the effect of IFM training on foot function and dynamic postural balance.

2 Methods

2.1 Search strategy

This systematic review was conducted in accordance with the PRISMA guidelines [29] and registered in PROSPERO (CRD42021232984). PubMed, CINAHL, SPORTDiscus and Web of Science bibliographic databases were searched by 2 independent authors to identify potentially relevant articles from January 2011 to February 2021. The following search terms were applied in the database search: (‘foot muscle’ OR ‘intrinsic foot muscle’ OR ‘plantar muscle’ OR ‘intrinsic flexor foot’ OR ‘toe muscle’ OR ‘hallux muscle’) AND (‘training’ OR ‘exercise’ OR ‘strength’ OR ‘strengthening’) AND (‘foot function’ OR ‘foot morphology’ OR ‘foot structure’ OR ‘foot posture’) AND (‘dynamic postural balance’ OR ‘dynamic balance’ OR ‘posture stability’ OR ‘posture control’ OR ‘postural’ OR ‘balance’). The Scottish Intercollegiate Guidelines Network criteria were used to describe the include studies [30]. An example of the search strategy for the PubMed database is attached in the supporting information. The search strategy was limited to publications in English.

2.2 Study selection

After duplicate articles were removed, the search results were screened independently by 2 authors based on titles, abstracts and full texts on the basis of the following criteria:1) research specific to IFM training as an intervention (treatments, such as SFE, that emphasise the neuromuscular recruitment of the plantar intrinsic foot muscles), 2) having at least 1 desired foot biomechanical parameters (such as navicular drop, foot posture index) and 3) randomised controlled trials (RCTs) or pre-/postintervention studies assessing the effectiveness of an intervention.

2.3 Data extraction and analyses

The following data were extracted: (i) author (year), (ii) study design, (iii) population characteristics (e.g. sample size), (iv) interventions (e.g. exercise prescription [sets/repetitions]), (v) outcome characteristics (e.g. foot posture index to describe the parameters of foot function) and (vi) main findings. When the information was unclear, the corresponding author of the study was contacted via email for clarification.

2.4 Quality assessment

The methodological quality of the included intervention studies were evaluated by two researchers independently using the Physiotherapy Evidence Database (PEDro) scale [31], which is found to be a reliable and valid measure to evaluate the quality of intervention trials [32], with higher scores indicating lower risk of bias. Each item scoring “yes” contributes 1 point to the total score, except for the first item, which relates to external validity. The total PEDro score thus ranges from 0 to 10 points. Studies with a total score of at least 6 points are considered to be of adequate quality [32, 33]. Notably, if the trials/studies were listed in the PEDro database (, those scores were used in this review.

2.5 Quantitative data synthesis and analysis

The training effects were calculated and illustrated based on difference between the pre-intervention and post- intervention parameters using forest plots with Review Manager version 5.3. Random effects models were used to calculate standardised mean differences and 95% confidence intervals (CIs) for the control and experimental groups. The I2 statistic was used to verify heterogeneity (χ2) between the included studies. The risk of publication bias was also assessed by using funnel plots.

3 Results

The electronic database search yielded 249 articles. After duplicates were removed (29 excluded), a total of 220 eligible articles were included. Then, 203 articles were excluded after reviewing the titles and abstracts, reducing the number of articles to 17. After full text screening, 1 article was excluded [34]. Finally, the remaining 16 articles met all the inclusion criteria and were included in this systematic review (Fig 1).

3.1 Methodological quality

The results of the risk of bias assessment using the PEDro scale can be found in Table 1. The total scores for the methodological quality ranged from 1 to 8 points. Eight studies [11, 16, 18, 2223, 26, 35, 36] were moderate quality (PEDro score ≥5) and the others [10, 17, 19, 3741] were poor quality (PEDro score < 5). The following items were most commonly reported in the articles: random allocation (69%), concealed allocation groups (19%), similar at baseline (63%), blinding of the therapist/subject reported in none of the articles, and blinding of the assessor in ten articles (63%), follow-up > 85% (38%), intention-to-treat analysis (25%), between-group comparison (88%), Point measures and measures of variability (100%).

Table 1. Results of the risk of bias assessment using the PEDro scale.

3.2 Study characteristics

The studies included 14 RCTs with sample sizes ranging from 14 to 118 [11, 1619, 22, 23, 26, 37, 3941] and 2 pre-/post-test designs with sample sizes of n = 12 and n = 21 [10, 36]. The intervention time of the 16 studies varied: 4 weeks [10, 16, 26], 5 weeks [39], 6 weeks [17, 18, 35, 41], 7 weeks [19], 8 weeks [11, 22, 36, 38], 9 weeks [40], 10 weeks [37] and 16 weeks [23]. The details of the study and participant characteristics are presented in Table 2.

3.2.1 Sample characteristics.

The 16 studies included a total of 627 participants. Seven studies included elite long-distance runners (n = 348) [17, 18, 22, 23, 3739]. Three studies explored the IFMs in patients with pes planus (n = 75) [11, 39, 41], and 6 other studies included only healthy or asymptomatic subjects (n = 207) [10, 16, 19, 26, 36, 40]. The sample sizes of the included studies ranged from 12 to 118 (mean = 39). The validity and statistical conclusions of the study by Hashimoto and Sakuraba (n = 12) were the lowest [38]. Overall, the proportion of males was slightly higher than that of females (54.10%). The age of the runners ranged on average from 20 years old to 45 years old (mean = 27.78), and the body weight of the runners ranged from 50 kg to 76 kg (mean = 67.17). For the foot morphology characteristics, the foot posture indexes in the existing studies ranged from 1 to 10 (mean = 6). Table 3 shows the details of the sample population characteristics.

Table 3. Sample sizes and participant characteristics for each included study.

3.2.2 IFM foot interventions.

All included studies have various differences in IFM foot interventions. The interventions varied in terms of training methods, exercise prescriptions and timeframes. In broad terms of the training approaches, the included interventions can be categorised as 1. SFE [10, 11, 26, 39, 41], 2. series of foot–ankle muscle training exercises [22, 23, 36, 40], 3. SFE and stability training of the foot [17, 18, 35], 4. SFE and toe/hallux-extension exercises [16, 37] and 5. interphalangeal joint and MPJ loading exercises [19, 38].

3.3 Outcome measures

For the characteristics of IFMs before and after training, the included studies measured the muscle activation ratio (contracted measurement/resting measurement) [16] through ultrasonographic imaging and the thickness [11], cross-sectional areas [22, 36] and volume [22] of the foot muscles by using magnetic resonance imaging (Table 2). Additionally, IFM training was measured directly through the hallux or toe muscle strength test [19, 22, 23, 36, 37, 41] and intrinsic foot musculature test [10] by using a custom-made dynamometer.

Medial longitudinal arch morphology was evaluated on the basis of the navicular drop [10, 11, 26, 39, 41] and arch height index [10]. These parameters were verified to provide accurate changes in the medial longitudinal arch. Six studies (n = 326) used the multidimensional and comprehensive evaluation of the foot posture index for the pronation/supination of the feet [11, 17, 23, 26, 40, 41]. This index has been verified to have clinical applications in assessing the risk of injury in athletes (Table 2).

Dynamic postural balance was evaluated by using some function tests, such as the functional movement screen test [17, 18], the star excursion balance test [10, 39] and clinician-assessed motor performance [16] (Table 2). Additionally, Fraser and Hertel [16] explored the participants’ perceived difficulty during the toe-spread-out, hallux-extension and lesser-toe-extension tests.

3.4 Data analysis

The results of cross-sectional area indicated no significant effect on the muscle characteristics of the Abductor hallucis (ABH) (P = 0.07), Abductor digiti minimi (ADM) (P = 0.08), Flexor digitorum brevis (FDB) (P = 0.22) and Flexor hallucis brevis (FHB) (P = 0.20).

IFM training was observed to have a significant effect on the medial longitudinal arch. The navicular drop (P = 0.02) and foot posture index (P = 0.0003) after IFM intervention had significantly decreased relative to those after the control treatment. The mean difference was −1.97 (95% CI: -3.57–-0.36) for the navicular drop (Fig 2) and -0.69 (95% CI: -1.06–-0.32) for the foot posture index (Fig 3). No significant heterogeneity was observed amongst studies (navicular drop: I2 = 40%, P = 0.17; FPI: I2 = 35%, P = 0.18). The bias funnel plots of the navicular drop (Fig 4) and foot posture index (Fig 5) did not suggest evidence of publication bias in the studies included in this meta-analysis.

Fig 2. Forest plot illustrating navicular drop of meta-analysis comparing IFMs training with control group.

Fig 3. Forest plot illustrating foot posture index of meta-analysis comparing IFMs training with control group.

Fig 4. Funnel plots showing publication bias among studies used to compare IFMs training and control groups.

Fig 5. Funnel plots showing publication bias among studies used to compare IFMs training and control groups.

A significant difference was found for dynamic postural balance after intervention. Although various function tests were included and were difficult to synthesise, the included studies all demonstrated that IFM training can exert positive effects on dynamic postural balance.

4 Discussion

This systematic review performed a meta-analysis to summarise the current studies that explored the effect of IFM training on foot biomechanical outcomes. Although potential differences in IFM intervention type, time or frequency may contribute to the potential heterogeneity of the included studies, the current studies verified that IFM training would bring positive biomechanical effects and ameliorate dynamic postural balance.

Four included studies (n = 102) explored the effects of IFM training on muscle morphology [11, 16, 22, 36]. However, no significant difference was found in terms of the parameters of IFM thickness, cross-sectional area and volume. Possible explanations for these discrepancies maybe explained by previous studies indicating that small volumes of IFMs are covered by plantar fascia, which would bring barrier to detect the slight changes in foot muscles [11]. Additionally, Taddei et al. [22, 36] also established proposed that ABH, FDB and FHB have various origins and insertions, different lever arm lengths and may be trained from different degrees during the intervention. Thus, the strength change of single IFMs may be different and hard to detect. In light of the difficulty in measuring the small cross-sectional area of IFMs, future studies should utilise advanced technology, such as magnetic resonance imaging, to measure the IFM fat infiltration and cross-sectional area after training.

Another direct parameter used to describe muscle characteristics is IFM strength. Considering that no gold standard for measuring IFM strength exists [42], the studies included in this review measured IFM strength by applying various approaches, such as pressure platforms [22, 23, 36, 41] or the intrinsic foot musculature test [10]. Although Day and Hahn [37] verified the positive effect of IFM training on muscle strength, no significant difference was found after pooling the data of the included studies. One possible reasons for this conflicting result might be related to the compensation of extrinsic muscles, such as the tibial posterior muscle [43, 44]. Although studies have attempted to avoid possible interference factors by placing the lower limb in a special position, external muscles are still involved during the test. Unlike previous results reported that enhanced IFM strength can provide additional propulsive impulses, making the foot similar to a stiffened spring during late stance [44, 45], the current study also did not observe any differences. Hence, the actual effect of strength training on IFMs needs to be studied further.

The navicular drop and arch height index are 2 common parameters that describe medial longitudinal arch morphology and dynamic function. IFM exercise is believed to activate weakened IFMs and increase IFM recruitment by intensifying and optimising the tension of the medial longitudinal arch, thereby preventing the excessive lowering of the medial longitudinal arch [10, 46] and related running injuries. This systematic review included 4 studies (n = 80) that utilised the navicular drop [10, 11, 26, 41] and 1 study (n = 21) that utilised the arch height index [10] to explore the changes in the medial longitudinal arch. The included studies all demonstrated that the morphology and function of the medial longitudinal arch significantly improved after several weeks of intervention. Even though IFM morphology and single muscle strength showed no significant difference, the overall effect of the medial longitudinal arch was improved. This finding indicated that IFM training can be recommended as an effective measure to improve medial longitudinal arch function and might provide further benefits to people with pes planus. Moreover, the foot posture index is a validated measure for quantifying foot posture. Five studies (n = 103) demonstrated that foot posture index can rectify abnormal lower extremity alignment and stress on the foot and related structures [11, 17, 26, 40, 41].

Amongst the included studies, several measured the dynamic postural balance after IFM training by utilising the functional movement screen [17, 18], star excursion balance test [10], clinician-assessed motor performance and 1-legged long jumping [18]. Although various methods can be applied to assess dynamic postural balance, the results of the included studies established that IFM training has significant positive effects compared with other interventions. Additionally, of the 2 included studies that subjectively assessed IFM training difficulty and foot pain in different situations, the difficulty in motor function perceived by the participants seemed uncomplicated, and the pain in the pes planus was alleviated.

The main limitation of this systematic review is that the included studies varied in terms of their interventions’ approaches, time and frequency and their participants’ characteristics, this variation might compromise this study. In addition, the included studies utilised different methods for assessing IFM strength and dynamic postural balance. Potential heterogeneity and slight publication bias in the analysis may exist. Therefore, caution is warranted when interpreting the findings of this study.

5 Conclusion

Although the interventions of the included studies seemed inconsistent, this systematic review demonstrated that IFM training can exert positive biomechanical effects on the medial longitudinal arch, improve the postural balance of the lower limbs and act as an important training method. Future studies should optimise standardised training methods in accordance with the demands of different sports.

Supporting information

S3 Table. International prospective register of systematic reviews (CRD42021232984).



We would like to express our gratitude to those who helped us during the process of this article. I gratefully acknowledge the help of my supervisor Lin Wang, who have offered me valuable suggestions in this article.


  1. 1. McKeon PO, Hertel J, Bramble D, Davis I. The foot core system: a new paradigm for understanding intrinsic foot muscle function. Br J Sports Med 2015; 49(5): 290. pmid:24659509
  2. 2. Welte L, Kelly LA, Lichtwark GA, Rainbow MJ. Influence of the windlass mechanism on arch-spring mechanics during dynamic foot arch deformation. J R Soc Interface, 2018; 15(145): 20180270. pmid:30111662
  3. 3. Seneli RM, Beschorner KE, O’Connor KM, et al. Foot joint coupling variability differences between habitual rearfoot and forefoot runners prior to and following an exhaustive run. J Electromyogr Kines, 2021; 57:102514. pmid:33476861
  4. 4. Lieberman DE, Venkadesan M, Werbel WA, Daoud AI, D’Andrea S, Davis IS, et al. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature, 2010; 463(7280): 531–535. pmid:20111000
  5. 5. Ceyssens L, Vanelderen R, Barton C, Malliaras P, Dingenen B. Biomechanical Risk Factors Associated with Running-Related Injuries: A Systematic Review. Sports Med, 2019; 49(7): 1095–1115. pmid:31028658
  6. 6. Holowka NB, Richards A, Sibson BE, Lieberman DE. The human foot functions like a spring of adjustable stiffness during running. J Exp Biol, 2021; 224(Pt 1). pmid:33199449
  7. 7. Hart N, Nimphius S, Rantalainen T, Ireland A, Siafarikas A, Newton RU. Mechanical basis of bone strength: influence of bone material, bone structure and muscle action. J Musculoskel Neuron, 2017; 17(3): 114–139. pmid:28860414
  8. 8. Kelly LA, Cresswell AG, Racinais S, Whiteley R, Lichtwark G. Intrinsic foot muscles have the capacity to control deformation of the longitudinal arch. J R Soc Interface, 2014; 11(93): 20131188. pmid:24478287
  9. 9. Garofolini A, Taylor S. The effect of running on foot muscles and bones: A systematic review. Hum Mov Sci, 2019; 64:75–88. pmid:30682645
  10. 10. Mulligan EP, Cook PG. Effect of plantar intrinsic muscle training on medial longitudinal arch morphology and dynamic function. Man Ther, 2013; 18(5): 425–430. pmid:23632367
  11. 11. Okamura K, Fukuda K, Oki S, Ono T, Tanaka S, Kanai S. Effects of plantar intrinsic foot muscle strengthening exercise on static and dynamic foot kinematics: A pilot randomized controlled single-blind trial in individuals with pes planus. Gait Posture, 2020; 75:40–45. pmid:31590069
  12. 12. Riddick R, Farris DJ, Kelly LA. The foot is more than a spring: human foot muscles perform work to adapt to the energetic requirements of locomotion. J R Soc Interface, 2019; 16(150): 20180680. pmid:30958152
  13. 13. McKeon PO, Fourchet F. Freeing the foot: integrating the foot core system into rehabilitation for lower extremity injuries. Clin Sports Med, 2015; 34(2): 347–361. pmid:25818718
  14. 14. Chen TL, Wong DW, Wang Y, Lin J, Zhang M. Foot arch deformation and plantar fascia loading during running with rearfoot strike and forefoot strike: A dynamic finite element analysis. J Biomech, 2019; 83:260–272. pmid:30554818
  15. 15. Ker RF, Bennett MB, Bibby SR, Kester RC, Alexander RM. The spring in the arch of the human foot. Nature, 1987; 325(6100): 147. pmid:3808070
  16. 16. Fraser JJ, Hertel J. Effects of a 4-Week Intrinsic Foot Muscle Exercise Program on Motor Function: A Preliminary Randomized Control Trial. J Sport Rehabil, 2019; 28(4): 339–349. pmid:29364026
  17. 17. Sulowska I, Oleksy L, Mika A, Bylina D, Sołtan J. The Influence of Plantar Short Foot Muscle Exercises on Foot Posture and Fundamental Movement Patterns in Long-Distance Runners, a Non-Randomized, Non-Blinded Clinical Trial. PLoS One, 2016; 11(6): e0157917. pmid:27336689
  18. 18. Sulowska-Daszyk I, Mika A, Oleksy Ł. Impact of Short Foot Muscle Exercises on Quality of Movement and Flexibility in Amateur Runners. Int J Environ Res, 2020; 17(18): 6534. pmid:32911733
  19. 19. Goldmann JP, Sanno M, Willwacher S, Heinrich K, Brüggemann GP. The potential of toe flexor muscles to enhance performance. J Sports Sci, 2013; 31(4): 424–433. pmid:23106289
  20. 20. Ferreira JSSP Cruvinel Junior RH, Silva EQ Veríssimo JL, Monteiro RL Pereira DS, et al. Study protocol for a randomized controlled trial on the effect of the Diabetic Foot Guidance System (SOPeD) for the prevention and treatment of foot musculoskeletal dysfunctions in people with diabetic neuropathy: the FOotCAre (FOCA) trial I. Trials, 2020; 21(1):73–87. pmid:31931855
  21. 21. Matias AB, Taddei UT, Duarte M, Sacco IC. Protocol for evaluating the effects of a therapeutic foot exercise program on injury incidence, foot functionality and biomechanics in long-distance runners: a randomized controlled trial. BMC Musculoskelet Disord. 2016;17:160–171. pmid:27075480
  22. 22. Taddei UT, Matias AB, Ribeiro FI, Bus SA, Sacco ICN. Effects of a foot strengthening program on foot muscle morphology and running mechanics: A proof-of-concept, single-blind randomized controlled trial. Phys Ther Sport, 2020; 42:107–115. pmid:31962191
  23. 23. Taddei UT, Matias AB, Duarte M, Sacco ICN. Foot Core Training to Prevent Running-Related Injuries: A Survival Analysis of a Single-Blind, Randomized Controlled Trial. Am J Sports Med, 2020; 48(14): 3610–3619. pmid:33156692
  24. 24. Maeda N, Hirota A, Komiya M, Morikawa M, Mizuta R, Fujishita H, et al. Intrinsic foot muscle hardness is related to dynamic postural stability after landing in healthy young men. Gait Posture, 2021; 86:192–198. pmid:33756408
  25. 25. Huffer D, Hing W, Newton R, Clair M. Strength training for plantar fasciitis and the intrinsic foot musculature: A systematic review. Phys Ther Sport, 2017; 24:44–52. pmid:27692740
  26. 26. Pabon-Carrasco M, Castro-Mendez A, Vilar-Palomo S, Jiménez-Cebrián AM, García-Paya I, Palomo-Toucedo IC. Randomized Clinical Trial: The Effect of Exercise of the Intrinsic Muscle on Foot Pronation. Int J Environ Res, 2020; 17(13):4882. pmid:32645830
  27. 27. Kim MH, Kwon OY, Kim SH, Jung DY. Comparison of muscle activities of abductor hallucis and adductor hallucis between the short foot and toe-spread-out exercises in subjects with mild hallux valgus. J Back Musculoskelet, 2013; 26(2): 163–168. pmid:23640317
  28. 28. Lee DR, Choi YE. Effects of a 6-week intrinsic foot muscle exercise program on the functions of intrinsic foot muscle and dynamic balance in patients with chronic ankle instability. J Exer Rehab, 2019; 15(5):709–714. pmid:31723561
  29. 29. Moher D, Liberati A, Tetzlaff J, Altman DG; PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ, 2009; 172–181. pmid:19622551
  30. 30. Scottish Intercollegiate Guidelines Network (SIGN) Methodology Review Group, editor. Report on the review of the method of grading guideline recommendations. Edinburgh: SIGN 1999
  31. 31. Macedo LG, Elkins MR, Maher CG, Moseley AM, Herbert RD, Sherrington C. There was evidence of convergent and construct validity of Physiotherapy Evidence Database quality scale for physiotherapy trials. J Clin Epidemiol. 2010; 63(8):920–925. pmid:20171839.
  32. 32. Maher CG, Sherrington C, Herbert RD, Moseley AM, Elkins M. Reliability of the PEDro scale for rating quality of randomized controlled trials. Phys Ther. 2003; 83: 713–721. pmid:12882612.
  33. 33. Armijo-Olivo S, da Costa BR, Cummings GG, Ha C, Fuentes J, Saltaji H, et al. PEDro or Cochrane to Assess the Quality of Clinical Trials? A Meta-Epidemiological Study. PLoS One. 2015; 10: e0132634. pmid:26161653.
  34. 34. Vincent KR, Vincent HK. Use of Foot Doming for Increasing Dynamic Stability and Injury Prevention in Runners and Athletes. Curr Sports Med Rep. 2018;17(10):320–321. pmid:30300191.
  35. 35. Sulowska I, Mika A, Oleksy L, Stolarczyk A. The Influence of Plantar Short Foot Muscle Exercises on the Lower Extremity Muscle Strength and Power in Proximal Segments of the Kinematic Chain in Long-Distance Runners. Biomed Res Int, 2019, 2019:6947273. pmid:30719446
  36. 36. Taddei UT, Matias AB, Ribeiro FI, Inoue RS, Bus SA, Sacco ICN. Effects of a therapeutic foot exercise program on injury incidence, foot functionality and biomechanics in long-distance runners: Feasibility study for a randomized controlled trial. Phys Ther Sport, 2018, 34: 216–226. pmid:30388670
  37. 37. Day EM, Hahn ME. Increased toe-flexor muscle strength does not alter metatarsophalangeal and ankle joint mechanics or running economy. J Sports Sci. 2019;37(23):2702–2710. pmid:31608832.
  38. 38. Hashimoto T, Sakuraba K. Strength Training for the Intrinsic Flexor Muscles of the Foot: Effects on Muscle Strength, the Foot Arch, and Dynamic Parameters Before and After the Training. J Phys Ther Sci, 2014; 26(3): 373–376. pmid:24707086
  39. 39. Kim EK, Kim JS. The effects of short foot exercises and arch support insoles on improvement in the medial longitudinal arch and dynamic balance of flexible flatfoot patients. J Phys Ther Sci. 2016, 28(11):3136–3139. pmid:27942135
  40. 40. Sánchez-Rodríguez R, Valle-Estévez S, Fraile-García PA, Martínez-Nova A, Gómez-Martín B, Escamilla-Martínez E. Modification of Pronated Foot Posture after a Program of Therapeutic Exercises. Int J Environ Res, 2020, 17(22): 8406. pmid:33202893
  41. 41. Unver B, Erdem EU, Akbas E. Effects of Short-Foot Exercises on Foot Posture, Pain, Disability, and Plantar Pressure in Pes Planus. J Sport Rehabil, 2019, 29(4): 436–440. pmid:30860412
  42. 42. Soysa A, Hiller C, Refshauge K, Burns J. Importance and challenges of measuring intrinsic foot muscle strength. J Foot Ankle Res, 2012, 5(1): 29. pmid:23181771
  43. 43. van der Merwe C, Shultz SP, Colborne GR, Fink PW. Foot Muscle Strengthening and Lower Limb Injury Prevention. Res Q Exerc Sport, 2020, 1–8. pmid:32633706
  44. 44. Farris DJ, Kelly LA, Cresswell AG, Lichtwark GA. The functional importance of human foot muscles for bipedal locomotion. Proc Natl Acad Sci U S A, 2019, 116(5): 1645–1650. pmid:30655349
  45. 45. Alexander J, Willy RW, Napier C, Bonanno DR, Barton CJ. Infographic. Running myth: switching to a non-rearfoot strike reduces injury risk and improves running economy. Brit J Sport Med, 2020, bjsports-2020-102262. pmid:32423913
  46. 46. Sauer LD, Beazell J, Hertel J. Considering the Intrinsic Foot Musculature in Evaluation and Rehabilitation for Lower Extremity Injuries: A Case Review. Athletic Training & Sports Health Care, 2011, 2(1): 43–47.