Freeing the Foot

Effects of a 12-week intrinsic foot muscle strengthening training (STIFF) on gait in older adults: a parallel randomized controlled trial protocol

BACKGROUND

Falling is highly prevalent among older adults and has serious impact. Age-induced mobility impairments, such as gait modifications, are strongly associated with increased fall risk. Among fall prevention interventions, those including exercises are most effective. However, there is an urgent need to further improve these kinds of interventions. Strengthening the plantar intrinsic foot muscles might benefit mobility in older adults, which may contribute to the reduction of fall risk. The aim of this paper is to provide a protocol to investigate the effect of a plantar intrinsic foot muscle strengthening training versus no training on gait and intrinsic foot muscle function in older adults who are involved in a functional exercise program.

METHODS

For this assessor-blinded RCT, older adults (> 65 years) are recruited who are involved in a group-based functional exercise program. Eligibility criteria include: being able to ambulate 10 m barefoot without using a walking aid and reporting to have either fear of falling or experienced a fall in the previous 12 months or have difficulties with mobility, gait, or balance in daily life. Participants are randomly assigned to an intervention and a control group. The intervention group follows a 12-week plantar intrinsic foot muscle strengthening training. The training consists of isolated and functional foot exercises to be performed 5 times a week, each session lasting approximately 20 min. The training is supervised once a week and the intensity gradually increases based on the participant's progression. Both groups keep a diary to report physical activities, fall incidents and movement related discomfort. The control condition is limited to keeping this diary. Data are collected at baseline and post-intervention. The trial outcomes are the between group differences in the mean change from baseline in maximum gait speed (primary outcome measure), capacity and strength of the plantar intrinsic foot muscles, foot and ankle biomechanics during gait, and various other fall risk-related variables. ANCOVA's are used to analyze the trial outcomes.

DISCUSSION

The results of this RCT will offer recommendations, related to plantar intrinsic foot muscle strengthening, to existing fall preventive exercise programs.

TRIAL REGISTRATION

The trial is registered in the United States National Library of Medicine through ClinicalTrials.gov (NCT05531136, 07/26/2022).

Fatigue of the intrinsic foot core muscles had a greater effect on gait than extrinsic foot core muscles: A time-series based analyze

BACKGROUND

The Heel Rise endurance (HRE) which indicates the extrinsic foot core (ECO) muscle's performance and the paper grip endurance (PGE) which indicates the intrinsic foot core (ICO) muscle's performance are essential components of a healthy foot function. However, the foot core muscles' fatigue response on spatial and temporal gait parameters after the HRE and the PGE tests were not adequately investigated. The purpose of this study was to determine whether the fatigue of the ICO and the ECO muscles affect gait parameters.

MATERIAL AND METHODS

A prospective, cross-sectional study was conducted on 22 sedentary individuals (44 feet). Gait was investigated pre and after the Heel Rise (HR) endurance test and the paper grip (PG) endurance test by inertial sensors. At least 500 consecutive steps were collected for each individual. Spatial-temporal gait parameters were used as outcome measures.

RESULTS

ECO fatigue and ICO fatigue led to increases in the step length (p < 0.05) and the stride lengths (p < 0.05), the single support (p < 0.05), and the terminal stance durations (p < 0.05). It was also seen that ICO fatigue had a greater effect on gait than ECO fatigue. The ECO fatigue had a medium to large effect on the gait parameters (d=0.313-0.646). The ICO fatigue affected gait with a large effect (d=0.524-2.048).

CONCLUSION

The ECO fatigue and the ICO fatigue led to clinically important changes in long-range gait parameters and the ICO fatigue had a greater effect on gait than ECO fatigue. It was suggested that clinicians add ICO muscle endurance training to improve the physical performance of individuals.

Effects of integrated intrinsic foot muscle exercise with foot core training device on balance and body composition among community-dwelling adults aged 60 and above

BACKGROUND

Evidence on the effects of plantar intrinsic foot muscle exercise in older adults remains limited. This study aimed to evaluate the effect of an integrated intrinsic foot muscle exercise program with a novel three-dimensional printing foot core training device on balance and body composition in community-dwelling adults aged 60 and above.

METHODS

A total of 40 participants aged ≥ 60 years were enrolled in this quasi-experimental, single-group, pretest-posttest design; participants were categorized into two groups, those with balance impairment and those without balance impairment. The participants performed a 4-week integrated intrinsic foot muscle exercise program with a three-dimensional printing foot core training device. The short physical performance battery (SPPB) and timed up and go test were employed to evaluate mobility and balance. A foot pressure distribution analysis was conducted to assess static postural control. The appendicular skeletal muscle mass index and fat mass were measured by a segmental body composition monitor with bioelectrical impedance analysis. The Wilcoxon signed rank test was used to determine the difference before and after the exercise program.

RESULTS

Among the 40 enrolled participants (median age, 78.0 years; female, 80.0%; balance-impaired group, 27.5%), the 95% confidence ellipse area of the center of pressure under the eyes-closed condition was significantly decreased (median pretest: 217.3, interquartile range: 238.4; median posttest: 131.7, interquartile range: 199.5; P = 0.001) after the exercise. Female participants without balance impairment demonstrated a significant increase in appendicular skeletal muscle mass index and a decrease in fat mass. Participants in the balance-impaired group exhibited a significant increase in SPPB.

CONCLUSIONS

Integrated intrinsic foot muscle exercise with a three-dimensional printing foot core training device may improve balance and body composition in adults aged 60 and above.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT05750888 (retrospectively registered 02/03/2023).

Effect of Exercises for Strengthening the Intrinsic Muscles of the Foot and Improving Ankle Mobility on Patients of Diabetic Peripheral Neuropathy

Background and objectives The study aimed to compare the efficacy of standard home care versus structured ankle mobility exercises in enhancing ankle and foot joint range of motion (ROM) among individuals with diabetes mellitus (DM). Additionally, it investigated the impact of foot intrinsic muscle strengthening exercises on hallux grip force in those with Diabetic Peripheral Neuropathy (DN). Materials and methods In a study of 200 patients with Diabetic Neuropathy (DN), selected from 345 screened diabetics with stable glucose levels and routine monitoring at a tertiary care facility, the efficacy of structured exercises versus standard care was evaluated. Participants, aged 40-70 years with mild neuropathic symptoms (neuropathy disability score of 3 to 5), were divided into two groups. Group 1 received standard care per International Diabetic Foot guidelines, while Group 2 performed targeted foot intrinsic muscle strengthening and ankle mobility exercises over eight weeks. The range of motion (ROM) for ankle and first metatarsophalangeal (MTP) joints and hallux grip force were measured, showing significant improvements in Group 2. Analysis was done using IBM SPSS. Results The average age of the individuals in group 1 (n=100) was 53.87±5.42 years, whereas the average age of the subjects in group 2 (n=100) was 54.23±4.69 years. The study included a total of 97 male participants, with 48 in group 1 and 49 in group 2. The groups exhibited homogeneity in terms of age, gender, duration of DM, and BMI (p>,0.05). When comparing the ROM for ankle dorsiflexion between the groups, it was shown that subjects in group 2 had a substantially higher ROM following exercise for both the right (27.97°±5.3° Vs 19.24°±2.54°) and left (28.55°±4.61° Vs 18.22°±1.14°) ankles compared to the patients in group 1 (p<,0.01). Nevertheless, there were statistically insignificant differences (p>,0.05) observed within the groups, both before and after the exercises, for all the variables examined except for right and left ankle dorsiflexion, and right ankle plantarflexion in group 2. Group 2 subjects exhibited a considerably greater hallux grip force compared to group 1 subjects. The mean enhanced paper grip strength for the right and left big toe of group 2 was 44±3.58 N and 43.2±2.62 N respectively. The mean enhanced paper grip force for the right and left big toe of group 1 was 38±3.11 N and 37.92±2.13 N respectively. A statistically highly significant difference was observed for hallux grip force between the groups (p<,0.01). Conclusion The findings of this study suggest that performing the foot intrinsic muscle strengthening and ankle mobility exercises on the foot and ankle joints can potentially enhance ROM and hallux grip force in patient groups with DN.

Evidence for Intrinsic Foot Muscle Training in Improving Foot Function: A Systematic Review and Meta-Analysis

OBJECTIVE

To critically assess the literature focused on strength training of the intrinsic foot muscles (IFMs) and resulting improvements in foot function.

DATA SOURCES

A search of electronic databases (PubMed, CINAHL, Scopus, and SPORTDiscus) was completed between January 2000 and March 2022.

STUDY SELECTION

Randomized control trials with an outcome of interest and at least 2 weeks of IFM exercise intervention were included. Outcomes of interest were broadly divided into 5 categories of foot posture (navicular drop and Foot Posture Index), namely: balance, strength, patient-reported outcomes, sensory function, and motor performance. The PEDro scale was used to assess the methodologic quality of the included studies with 2 independent reviewers rating each study. Studies with a PEDro score greater than 4/10 were included.

DATA EXTRACTION

Data extracted by 2 independent reviewers were design, participant characteristics, inclusion and exclusion criteria, type of intervention, outcomes, and primary results. We performed a random-effects meta-analysis to analyze the difference between intervention and control groups for each outcome when at least 2 studies were available. Standardized mean differences (SMDs) describe effect sizes with 95% CIs (SMD ranges). When the CI crossed zero, the effect was not significant.

DATA SYNTHESIS

Thirteen studies were included, and IFM exercise interventions were associated with decreasing navicular drop (SMD range = 0.37, 1.83) and Foot Posture Index (SMD range = 1.03, 1.69) and improving balance (SMD range = 0.18, 1.86), strength (SMD range = 0.06, 1.52), and patient-reported outcomes for disability (SMD range = 0.12, 1.00), with pooled effect sizes favoring the IFM intervention over the control. The IFM exercises were not superior (SMD range = -0.15, 0.66) for reducing pain. We could not perform a meta-analysis for sensory function and motor performance, as only 1 study was available for each outcome; however, these results supported the use of IFM strength training.

CONCLUSIONS

Strength training of the IFMs was helpful for patients in improving foot and ankle outcomes.

Effects of intrinsic foot muscle strengthening on the medial longitudinal arch mobility and function: A systematic review

OBJECTIVE

To Investigate the effects of intrinsic foot muscle (IFM) strengthening on foot's medial longitudinal arch (MLA) mobility and function in healthy individuals. We also identified exercise type and resistance training characteristics (series and repetitions).

METHODS

Eight databases were searched, between October 2020 and February 2021 and updated in May 2021. We included randomized controlled trials involving IFM strengthening exercises compared with controls (no exercise or exercises not involving isolated intrinsic foot muscle strengthening). Methodological quality of the studies was assessed using PEDro scale and Cochrane Risk of Bias tool. Quality of evidence was evaluated using GRADE model (Grading of Recommendations, Assessment, Development and Evaluations).

RESULTS

Four randomized controlled trials (RCT) were included. IFM strengthening did not change MLA mobility in the short-term (4 weeks); however, it promoted medium-term effects (8 weeks - low quality of evidence). IFM exercises improved function in the short and medium-term (low quality of evidence). Most studies used the short-foot exercise and the toe-towel curl exercise with contractions of 5 s and load progression from sitting to standing.

CONCLUSION

IFM strengthening exercises change MLA mobility in the medium-term (8 weeks) and improve the dynamic balance of healthy individuals in short- (4 weeks) and medium-terms.

Effects of short foot exercise combined with lower extremity training on dynamic foot function in individuals with flexible flatfoot: A randomized controlled trial

BACKGROUND

Flexible flatfoot has demonstrated biomechanical linkages between distal and proximal lower extremities. However, supporting evidence is required to investigate the benefits of short foot exercise (SF) and short foot exercise in combination with lower extremity training (SFLE) on dynamic foot function.

RESEARCH QUESTION

This study aimed to determine the effects of a 6-week SF, 6-week SFLE, or control condition (no intervention) on dynamic foot function during gait in individuals with flexible flatfoot.

METHODS

Forty-five individuals with flexible flatfoot were randomly assigned into three conditions: (1) SF, (2) SFLE, and (3) control conditions. Participants in two intervention programs performed daily training via telerehabilitation and a home-based exercise program. Foot kinematics and center of pressure excursion index (CPEI) during the gait, intrinsic foot muscle test, and navicular drop test were assessed at baseline and after the 6-week intervention program.

RESULTS

Post-intervention participants in the SF and SFLE conditions showed a shorter time to the lowest medial longitudinal arch (MLA) and improved MLA motion during the stance phase compared with the baseline. In addition, participants in the SFLE conditions showed greater changes in CPEI than in the SF and control conditions. Improvements in intrinsic foot muscle and navicular drop tests were also observed in participants in both intervention programs post-intervention.

SIGNIFICANCE

A major finding of the study was the improvement in dynamic foot function during gait in individuals with flexible flatfoot after the six weeks of the SF and SFLE intervention programs. Both intervention programs appear to have the potential for inclusion in a corrective program for individuals with flexible flatfoot.

Comparison of intrinsic foot muscle morphology and isometric strength among runners with different strike patterns

This study aimed to compare the intrinsic foot muscle (IFM) morphology and isometric strength among runners with habitual rearfoot strike (RFS) and non-rearfoot strike (NRFS) patterns. A total of 70 recreational male runners were included in this study (32 RFS and 38 NRFS), an ultrasound device and hand-held dynamometry were used to measure IFM morphology and isometric strength. Results indicated that the RFS runners had significantly thicker tibialis anterior (P = 0.01, ES = 0.64, 95% CI [0.01-0.07]) in IFMs morphology and higher Toe2345 flexion strength in IFMs strength (P = 0.04, ES = 0.50, 95% CI [0.01-0.27]) than NRFS runners, the cross-sectional area of flexor digitorum brevis was positively correlated with T2345 flexion strength (r = 0.33, p = 0.04), T12345 (r = 0.37, p = 0.02) and Doming (r = 0.36, p = 0.03) for runners with NRFS. IFMs morphology and isometric strength were associated with foot strike pattern, preliminary findings provide new perspectives for NRFS runners through the simple measurement of IFMs morphological characteristics predicting IFMs strength, future studies could adopt IFMs training to compensate the muscle strength defects and prevent foot-related injuries.

Intrinsic Foot Muscle Exercises With and Without Electric Stimulation

CONTEXT

Exercising intrinsic foot muscles (IFMs) can improve dynamic balance and foot posture. The exercises are not intuitive and electrotherapy (neuromuscular electrical stimulation [NMES]) has been suggested to help individuals execute the exercises. The aim of this study was to evaluate the effects of training IFM program on dynamic balance and foot posture and compare traditional training methods (TRAIN) with traditional training plus NMES on the perceived workload of the exercises, balance, and foot posture.

DESIGN

Randomized controlled trial.

METHODS

Thirty-nine participants were randomized to control, TRAIN, or NMES. TRAIN and NMES performed IFM exercises daily for 4 weeks; NMES received electrotherapy during the first 2 weeks of training. The Y-Balance test and arch height index were measured in all participants at baseline. The training groups were measured again at 2 weeks; all participants were measured at 4 weeks and 8 weeks, after 4 weeks of no training. Perceived workload (National Aeronautics and Space Administration Task Load Index) of exercises was assessed throughout the first 2 weeks and at 4 weeks.

RESULTS

A 4-week IFM training program demonstrated increases in Y-Balance (P = .01) for TRAIN and in arch height index (seated P = .03; standing P = .02) for NMES, relative to baseline. NMES demonstrated improvement in Y-Balance (P = .02) and arch height index standing (P = .01) at 2 weeks. There were no significant differences between the training groups. Groups were similar in the number responding to exercises in excess of minimal detectable change on all clinical measures. Perceived workload of the exercises decreased during the first 2 weeks of training (P = .02), and more notably at 4 weeks (P < .001). The groups did not differ in how they perceived the workload.

CONCLUSIONS

A 4-week IFM training program improved dynamic balance and foot posture. Adding NMES in early phases of training provided early improvement in dynamic balance and foot posture, but did not affect perceived workload.

The effects of short foot exercises to treat flat foot deformity: A systematic review

BACKGROUND

Studies on the effects of performing short foot exercises (SFEs) on the medial longitudinal arch (MLA) have been inconclusive.

OBJECTIVE

This study aimed to conduct a systematic review of the effects of SFEs.

METHODS

'SFE' and 'intrinsic foot muscle' were keywords used to search for randomized controlled trials. One researcher screened relevant articles based on their titles and abstracts, and two independent researchers closely read the texts, accepting nine studies for inclusion. Outcomes, intervention duration, frequency, and the number of interventions were investigated.

RESULTS

Of 299 potential studies identified, the titles and abstracts of 211 studies were reviewed, and 192 were excluded. The full texts of 21 studies were obtained and evaluated according to inclusion and exclusion criteria. Nine studies met the inclusion criteria. Six studies concerning the MLA were identified, with four reporting MLA improvement. There was no consensus concerning the number and frequency of SFEs performed, and the mechanism of MLA improvement was unclear. MLA improvement was observed in participants who undertook ⩾ 5 weeks of interventions.

CONCLUSIONS

The results suggest that performing SFEs for ⩾ 5 weeks is effective in improving the MLA. Randomized controlled trials with details concerning the number and frequency of treatments are required.

Effects of a Single Electrical Stimulation Session on Foot Force Production, Foot Dome Stability, and Dynamic Postural Control

CONTEXT

Mounting evidence suggests neuromuscular electrical stimulation (NMES) as a promising modality for enhancing lower limb muscle strength, yet the functional effects of a single electrical stimulation session for improving the function of the intrinsic foot muscles (IFM) has not been evaluated.

OBJECTIVE

To investigate the immediate effects of an NMES session compared with a sham stimulation session on foot force production, foot dome stability, and dynamic postural control in participants with static foot pronation.

DESIGN

Randomized controlled clinical trial.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 46 participants (23 males, 23 females) with static foot pronation according to their Foot Posture Index (score ≥ 6) were randomly assigned to an NMES (n = 23) or control (n = 23) group.

INTERVENTION(S)

The NMES group received a single 15-minute NMES session on the dominant foot across the IFM. The control group received a 15-minute sham electrical stimulation session.

MAIN OUTCOME MEASURE(S)

All outcome measurements were assessed before and after the intervention and consisted of foot force production on a pressure platform, foot dome stability, and dynamic postural control. Statistical analysis was based on the responsiveness of the outcome measures and responder analysis using the minimum detectable change scores for each outcome measure.

RESULTS

In the NMES group, 78% of participants were classified as responders for at least 2 of the 3 outcomes, compared with only 22% in the control group. The relative risk of being a responder in the NMES group compared with the control group was 3.6 (95% CI = 1.6, 8.1]. Interestingly, we found that all participants who concomitantly responded to foot strength and navicular drop (n = 8) were also responders in dynamic postural control.

CONCLUSIONS

Compared with a sham stimulation session, a single NMES session was effective in immediately improving foot function and dynamic postural control in participants with static foot pronation. These findings support the role of NMES for improving IFM function in this population.

Effects of the Short-Foot Exercise on Foot Alignment and Muscle Hypertrophy in Flatfoot Individuals: A Meta-Analysis

This study aimed to conduct a meta-analysis of randomized controlled trials to examine the effects of the short-foot exercise (SFE) compared to foot orthosis or other types of interventions. Eligibility criteria involved participants with flatfoot engaging in the SFE compared to other forms of intervention or control groups without specific intervention. Relevant studies published before the end of June 2022 were identified from databases. A meta-analysis was performed by calculating the mean differences (MD) and standard MD (SMD) using the random effects model. Six trials with 201 patients (out of 609 records) that met selection criteria were reviewed. Five of the six trials implemented distinct interventions in the control group such as shoe insoles and muscle strengthening exercises, while in the remaining trial, controls received no intervention. The SFE group significantly reduced the navicular drop test (NDT) values (MD: -0.23; 95% confidence interval: -0.45 to -0.02; p = 0.04) and the foot posture index (FPI-6) score (MD: -0.67; 95% confidence interval: -0.98 to -0.36; p < 0.0001) when compared to the control group. The muscle hypertrophy did not differ significantly between the groups. The SFE may contribute more benefits than other intervention as it affects flatfoot individuals' foot alignment. Hence, the SFE is recommended as a beneficial dynamic support when facing flatfoot problems.

Effects of intervention combining transcranial direct current stimulation and foot core exercise on sensorimotor function in foot and static balance

Objective

This study aimed to examine the effects of combining transcranial direct current stimulation (tDCS) and foot core exercise (FCE) on the sensorimotor function of the foot (i.e., toe flexor strength and passive ankle kinesthesia) and static balance.

Methods

In this double-blinded and randomized study, 30 participants were randomly assigned into two groups: tDCS combined with FCE and sham combined with FCE (i.e., control group). The participants received 2 mA stimulation for 20 min concurrently with FCE over 4 weeks (i.e., three sessions per week). After the first two groups completed the intervention, a reference group (FCE-only group) was included to further explore the placebo effects of sham by comparing it with the control group. Foot muscle strength, passive ankle kinesthesia, and static balance were assessed at baseline and after the intervention.

Results

Compared with the control group and baseline, tDCS combined with FCE could increase toe flexor strength (p < 0.001) and decrease the passive kinesthesia threshold of ankle eversion (p = 0.002). No significant differences in static balance were observed between tDCS + FCE and control groups. The linear regression models showed an association towards significance between the percent changes in metatarsophalangeal joint flexor strength and the anteroposterior average sway velocity of the center of gravity in one-leg standing with eyes closed following tDCS + FCE (r2 = 0.286; p = 0.057). The exploratory analysis also showed that compared with FCE alone, the sham stimulation did not induce any placebo effects during FCE.

Conclusion

Participating in 4 weeks of intervention using tDCS in combination with FCE effectively enhances toe flexor strength and foot–ankle sensory function.

Effects of global postural reeducation on postural control, dynamic balance, and ankle range of motion in patients with hallux abducto valgus. A randomized controlled trial

Hallux abducto valgus (HAV) is a common musculoskeletal disorder that has been addressed surgically. Nevertheless, the manual therapy approach may play an important role in the management of this condition. The present study aimed to determine the effectiveness of global postural reeducation (GPR) in subjects with symptomatic mild to moderate HAV in static postural control, dynamic stability, and ankle dorsiflexion range of motion (DFROM). A total of 80 patients with mild to moderate symptomatic HAV were allocated to the intervention group (GPR) or control group (CG) (no treatment) for 8 weeks. Outcome measures were assessed at baseline at 4 and 8 weeks including static postural control (Romberg test), dynamic balance (Star Excursion Balance Test [SEBT]), and ankle DFROM (Weight-Bearing Lunge Test [WBLT]). No improvements were observed at 4 weeks, but there were improvements at 8 weeks in: static postural control mediolateral displacement (X) of center of pressure (CoP) in both eyes open (EO) and eyes closed (EC): XEO (t(36) = 2.892, p = .006, d = 0.67); XEC (t(68) = 2.280, p = .026, d = 054); and velocity (V) of CoP displacement: VEO (t(68) = 2.380, p = .020, d = 0.57); VEC (t(36) = 2.057, p = .047, d = 0.37). It were also improvements in: WBLT (t(36) = -2.869, p = .007, d = 0.54) and SEBT at three directions (anterior, ANT; posteromedial, PM; and posterolateral, PL): SEBT.ANT (t(36) = -2.292, p = .028, d = 0.23); SEBT.PM (t(36) = -4.075, p < .001, d = 0.43); SEBT.PL (t(62) = -3.506, p = .001, d = 0.34). The present study showed that GPR compared to the CG might be effective in enhancing ankle function including postural control, dynamic balance, and DFROM.

The mechanical role of the metatarsophalangeal joint in human jumping

This study investigated the mechanical role of metatarsophalangeal (MTP) joints in human jumping. Eighteen healthy young men performed three types of single-leg jumps (SJ: squat jump; CMJ: countermovement jump; HJ: standing horizontal jump) on a force plate under barefoot (BARE) and forefoot immobilisation (FFIM) conditions. For FFIM, the forefoot was immobilised around the MTP joints of the dominant leg by a custom-made splint. Force-time components and the centre of pressure (COP) trajectory were measured from the ground reaction force (GRF) in the take-off phase of jumping. The vertical jump heights calculated from the net vertical impulse were lower under FFIM than under BARE during the CMJ (p < 0.05). The HJ distance under FFIM was significantly shorter than that under BARE (p < 0.01). The relative net vertical impulse was lower under FFIM than under BARE during the CMJ (p < 0.05). During the HJ, all the horizontal GRF variables were significantly lower under FFIM than under BARE (p < 0.01), but none of the vertical GRF variables differed between the two conditions. The horizontal relative GRF in the 90–95% of the final take-off phase during the HJ was significantly lower under FFIM than under BARE (p < 0.01). Under FFIM, the COP range in the antero-posterior direction in the take-off phase of the HJ decreased (p < 0.05), whereas its range in the anterior direction for the SJ and CMJ increased (p < 0.05). The results of this study indicate that MTP joint motion can play an important role in regulating force-generating capacities of toe flexor muscles in the take-off phase of human jumping, especially in the horizontal direction of horizontal jumping.

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.

Effects of Foot-Core Training on Foot-Ankle Kinematics and Running Kinetics in Runners: Secondary Outcomes From a Randomized Controlled Trial

This study investigated the effectiveness of an 8-week foot-core exercise training program on foot-ankle kinematics during running and also on running kinetics (impact loads), with particular interest in biomechanical outcomes considered risk factors for running-related injuries in recreational runners. A single-blind, randomized, controlled trial was conducted with 87 recreational runners randomly allocated to either the control (CG) or intervention (IG) group and assessed at baseline and after 8 weeks. The IG underwent foot-core training 3 times/week, while the CG followed a placebo lower-limb stretching protocol. The participants ran on a force-instrumented treadmill at a self-selected speed while foot-segment motion was captured simultaneously with kinetic measurements. After the intervention, there were statistically significant changed in foot biomechanics, such as: IG participants strike the ground with a more inverted calcaneus and a less dorsiflexed midfoot than those in the CG; at midstance, ran with a less plantarflexed and more adducted forefoot and a more abducted hallux; and at push-off, ran with a less dorsiflexed midfoot and a less adducted and more dorsiflexed hallux. The IG runners also had significantly decreased medial longitudinal arch excursion (p = 0.024) and increased rearfoot inversion (p = 0.037). The 8-week foot-core exercise program had no effect on impact (p = 0.129) and breaking forces (p = 0.934) or on vertical loading rate (p = 0.537), but it was positively effective in changing foot-ankle kinematic patterns.”

The Effects of Electrical Stimulation Program on Navicular Height, Balance, and Fear of Falling in Community-Dwelling Elderly

INTRODUCTION

Intrinsic foot muscle weakness is a crucial cause of balance deficit in the elderly, which leads to a limited range of motion from the fear of falling and subsequently decreases the quality of life. Muscle strengthening via transcutaneous electrical stimulation (TENS) is an effective intervention; however, its effects on elderly people have rarely been reported. This study was conducted to investigate the effects of TENS on navicular height, balance, and fear of falling.

METHOD

In this study, forty-eight participants aged 65-75 years were included and were randomly divided into two groups: the TENS and control groups. Before and after 4 weeks of training, navicular height, balance, and fear of falling were measured.

RESULT

After 4 weeks of training, navicular height significantly increased in both groups (p < 0.05); however, the increase was higher in the TENS group (p = 0.035). The TENS group had a better improvement in balance in all four directions-front, back, left, and right (p < 0.05). However, postural balance improvements in the control group were observed in three directions only-front, back, and left (p < 0.05)-without any significant difference between the two groups. Furthermore, the TENS group decreased the scale of fear of falling after 4 weeks of training (p = 0.039).

CONCLUSION

In summary, the results of this study can be used as part of the muscle strengthening via ES for decreasing the risk of falls or fear of falling in the elderly.

Randomized Clinical Trial: The Effect of Exercise of the Intrinsic Muscle on Foot Pronation

Background: There is little scientific evidence regarding the effectiveness of strengthening exercises on the foot's intrinsic musculature in improving the lower limb on the statics and dynamics in healthy individuals. Method: To evaluate the effect on foot posture with regard to the reinforcement of the short foot exercise (SFE) compared to another without a recognized biomechanical action, which we called the "non-biomechanical function" (NBF) exercise. A randomized clinical trial was carried out with 85 asymptomatic participants with a bilateral Foot Posture Index (FPI) greater than 6 points. An experimental group (n = 42) did SFE training and a control group (n = 43) carried out NBF exercises. The foot posture was evaluated twice via the navicular drop (ND) test, and the FPI was assessed on the day of inclusion in the study (pre-intervention) and after four weeks of training (post-intervention). Results: Statistically significant values were not found in foot posture between the experimental and the control groups when comparing before and after the training. However, the foot posture was modified in both groups with respect to its initial state, and the ND value decreased. Conclusions: SFE could be considered a useful tool to deal with pathologies whose etiology includes excessive pronation of the foot.

The Effects of the Short Foot Exercise on Navicular Drop: A Critically Appraised Topic

Clinical Scenario: Deformation of the arch, as measured by navicular drop (ND), is linked to lower-extremity musculoskeletal injuries. The short foot exercise (SFE) has been used to strengthen the intrinsic foot muscles that support the arch. Clinical Question: Does the SFE decrease ND in healthy adults? Summary of Key Findings: Three studies that examined the use of the SFE on ND were included. A randomized control trial that compared the SFE to a towel-curl exercise and a control group found no significant differences between the 3 groups. A randomized control trial compared the SFE to the use of arch support insoles in individuals with a flexible flatfoot and found a significant improvement in the SFE group. A prospective cohort study, without a control group, reported a significant decrease in ND following a 4-week SFE intervention without a regression at an 8-week follow-up. Overall, two of the three studies reported a significant reduction in ND following an SFE. Clinical Bottom Line: There is preliminary data supporting the use of the SFE to decrease ND-particularly in individuals with a flexible flatfoot. However, issues with the study designs make it difficult to interpret the data. Strength of Recommendation: Due to limited evidence, there is grade B evidence to support the use of the SFE to decrease ND.

Acute Effects of High-Definition Transcranial Direct Current Stimulation on Foot Muscle Strength, Passive Ankle Kinesthesia, and Static Balance: A Pilot Study

This study aimed to examine the effects of single-session anodal high-definition transcranial direct current stimulation (HD-tDCS) on the strength of intrinsic foot muscles, passive ankle kinesthesia, and static balance. Methods: In this double-blinded self-controlled study, 14 healthy younger adults were asked to complete assessments of foot muscle strength, passive ankle kinesthesia, and static balance before and after a 20-minute session of either HD-tDCS or sham stimulation (i.e., control) at two visits separated by one week. Two-way repeated-measures analysis of variance was used to examine the effects of HD-tDCS on metatarsophalangeal joint flexor strength, toe flexor strength, the passive kinesthesia threshold of ankle joint, and the average sway velocity of the center of gravity. Results: All participants completed all study procedures and no side effects nor risk events were reported. Blinding was shown to be successful, with an overall accuracy of 35.7% in the guess of stimulation type (p = 0.347). No main effects of intervention, time, or their interaction were observed for foot muscle strength (p > 0.05). The average percent change in first-toe flexor strength following anodal HD-tDCS was 12.8 ± 24.2%, with 11 out of 14 participants showing an increase in strength, while the change following sham stimulation was 0.7 ± 17.3%, with 8 out of 14 participants showing an increase in strength. A main effect of time on the passive kinesthesia threshold of ankle inversion, dorsiflexion, and anteroposterior and medial–lateral average sway velocity of the center of gravity in one-leg standing with eyes closed was observed; these outcomes were reduced from pre to post stimulation (p < 0.05). No significant differences were observed for other variables between the two stimulation types. Conclusion: The results of this pilot study suggested that single-session HD-tDCS may improve the flexor strength of the first toe, although no statistically significant differences were observed between the anodal HD-tDCS and sham procedure groups. Additionally, passive ankle kinesthesia and static standing balance performance were improved from pre to post stimulation, but no significant differences were observed between the HD-tDCS and sham procedure groups. This may be potentially due to ceiling effects in this healthy cohort of a small sample size. Nevertheless, these preliminary findings may provide critical knowledge of optimal stimulation parameters, effect size, and power estimation of HD-tDCS for future trials aiming to confirm and expand the findings of this pilot study.

From barefoot hunter gathering to shod pavement pounding. Where to from here? A narrative review

Understanding the current prevalence and incidence of running injury from an evolutionary perspective has sparked great debate. Proponents of the evolutionary approach to understanding running injury suggest that humans ran using less injurious biomechanics prior to the invention of cushioned running shoes. Those who disagree with this view, point to the many runners, wearing cushioned running shoes, who do not get injured and suggest that the evolutionary approach is indulging in a 'natural fallacy'. This polarises the scientific debate into discrete categories such as 'shod' vs 'barefoot'. This review aims, first, to describe humans' innate impact moderating mechanisms which arise from our evolutionary legacy. Second, we discuss the impact of footwear on these mechanisms and the potential link to injury in some runners. Finally, we discuss the role of barefoot training in sports medicine and attempt to make some practical suggestions as to how it might be integrated in our modern urban environments.

Effects of a 4-Week Short-Foot Exercise Program on Gait Characteristics in Patients With Stage II Posterior Tibial Tendon Dysfunction

CONTEXT

Clinically, it has been suggested that increased activation of intrinsic foot muscles may alter the demand of extrinsic muscle activity surrounding the ankle joint in patients with stage II posterior tibial tendon dysfunction. However, there is limited empirical evidence supporting this notion.

OBJECTIVE

The purpose of this study was to investigate the effects of a 4-week short-foot exercise (SFE) on biomechanical factors in patients with stage II posterior tibial tendon dysfunction.

DESIGN

Single-group pretest-posttest.

SETTING

University laboratory.

PARTICIPANTS

Fifteen subjects (8 males and 7 females) with stage II posterior tibial tendon dysfunction who had pain in posterior tibial tendon, pronated foot deformity (foot posture index ≥+6), and flexible foot deformity (navicular drop ≥10 mm) were voluntarily recruited.

INTERVENTION

All subjects completed a 4-week SFE program (15 repetitions × 5 sets/d and 3 d/wk) of 4 stages (standing with feedback, sitting, double-leg, and one-leg standing position).

MAIN OUTCOME MEASURES

Ankle joint kinematics and kinetics and tibialis anterior and fibularis longus muscle activation (% maximum voluntary isometric contraction) during gait were measured before and after SFE program. Cohen d effect size (ES [95% confidence intervals]) was calculated.

RESULTS

During the first rocker, tibialis anterior activation decreased at peak plantarflexion (ES = 0.75 [0.01 to 1.49]) and inversion (ES = 0.77 [0.03 to 1.51]) angle. During the second rocker, peak dorsiflexion angle (ES = 0.77 [0.03 to 1.51]) and tibialis anterior activation at peak eversion (ES = 1.57 [0.76 to 2.39]) reduced. During the third rocker, the peak abduction angle (ES = 0.80 [0.06 to 1.54]) and tibialis anterior and fibularis longus activation at peak plantarflexion (ES = 1.34 [0.54 to 2.13]; ES = 1.99 [1.11 to 2.86]) and abduction (ES = 1.29 [0.50 to 2.08]; ES = 1.67 [0.84 to 2.50]) decreased.

CONCLUSIONS

Our 4-week SFE program may have positive effects on changing muscle activation patterns for tibialis anterior and fibularis longus muscles, although it could not influence their structural deformity and ankle joint moment. It could produce a potential benefit of decreased tibialis posterior activation.

The evalaution of the foot core system in individuals with plantar heel pain

OBJECTIVE

To compare foot posture, plantar sensation, plantar fascia thickness, intrinsic foot muscle performance, and abductor hallucis morphology in individuals with and without plantar heel pain (PHP).

DESIGN

Cross-Sectional.

SETTING

Laboratory.

PARTICIPANTS

Sixteen individuals with PHP and sixteen matched healthy participants.

MAIN OUTCOME MEASURES

Static foot posture, plantar sensation, plantar fascia thickness, intrinsic foot muscle performance and abductor hallucis morphology were evaluated. Foot posture was assessed with the Foot Posture Index-6. Abductor hallucis morphology and plantar fascia thickness were measured utilizing diagnostic ultrasound. Plantar foot sensation was assessed at the head of the first metatarsal and medial longitudinal arch using Semmes-Weinstein Monofilaments. Intrinsic foot muscle performance was assessed using the intrinsic foot muscle test (IFMT). Mann-Whitney U and independent t-tests were used to examine between group differences.

RESULTS

Individuals with PHP exhibited a more pronated foot posture and greater plantar fascia thickness at the proximal insertion compared to healthy controls. Plantar sensation thresholds were higher in the PHP compared to healthy controls at the head of the first metatarsal. There were no group differences in abductor hallucis morphology or IFMT performance.

CONCLUSIONS

Individuals with PHP exhibited a more pronated foot posture, thicker plantar fascia, and diminished plantar tactile sensation.

Effects of Short-Foot Exercises on Foot Posture, Pain, Disability, and Plantar Pressure in Pes Planus

CONTEXT

Pes planus is a prevalent chronic condition that causes foot pain, disability, and impaired plantar load distribution. Short-foot exercises are often recommended to strengthen intrinsic foot muscles and to prevent excessive decrease of medial longitudinal arch height.

OBJECTIVE

To investigate the effects of short-foot exercises on navicular drop, foot posture, pain, disability, and plantar pressures in pes planus.

DESIGN

Quasi-experimental study.

SETTING

Biomechanics laboratory.

PARTICIPANTS

A total of 41 participants with pes planus were assigned to the short-foot exercises group (n = 21) or the control group (n = 20).

INTERVENTION

Both groups were informed about pes planus, usual foot care, and appropriate footwear. Short-foot exercises group performed the exercises daily for 6 weeks.

MAIN OUTCOME MEASURES

Navicular drop, Foot Posture Index, foot pain, disability, and plantar pressures were assessed at the baseline and at the end of 6 weeks.

RESULTS

Navicular drop, Foot Posture Index, pain, and disability scores were significantly decreased; maximum plantar force of midfoot was significantly increased in short-foot exercises group over 6 weeks (P < .05). No significant differences were determined between the baseline and the sixth week outcomes in control group (P > .05).

CONCLUSIONS

Six-week short-foot exercises provided a reduction in navicular drop, foot pronation, foot pain, and disability and increment in plantar force of medial midfoot in pes planus.

How to Evaluate and Improve Foot Strength in Athletes: An Update

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 muscles lengthen eccentrically during the stance phase of running before shortening at the propulsion phase, as the arch recoils in parallel to the plantar fascia. They play a key role in supporting the medial longitudinal arch, providing flexibility, stability and shock absorption to the foot, whilst partially controlling pronation. Much of the foot rigidity in late stance has been attributed to the windlass mechanism – the dorsiflexion of the toes building tension up in the plantar aponeurosis and stiffening the foot. In addition, recent studies have shown that the IFM provide a necessary active contribution in late stance, in order to develop sufficient impedance in the metatarsal-phalangeal joints. This in turn 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, 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 to be transmitted efficiently to the ground. It may be of particular interest to strengthen foot muscles to maintain and improve an optimal capacity to generate and absorb these forces. The current evidence supports multiple exercises to achieve higher strength in the foot, such as the “short foot exercise,” doming, toes curl, towing exercises or the more dynamic hopping exercises, or even barefoot running. Their real impact on foot muscle strength remains unclear and data related to its assessment remains scarce, despite a recognized need for this, especially before and after a strengthening intervention. It would be optimal to be able to assess it. In this article, we aim to provide the track and field community with an updated review on the current modalities available for foot strength assessment and training. We present recommendations for the incorporation of foot muscles training for performance and injury prevention in track and field.

The effect of running on foot muscles and bones: A systematic review

Despite the widespread evidence of running as a health-preserving exercise, little is known concerning its effect on the foot musculature and bones. While running may influence anatomical foot adaptation, it remains unclear to what extent these adaptations occur. The aim of this paper is to provide a systematic review of the studies that investigated the effects of running and the adaptations that occur in foot muscles and bones. The search was performed following the PRISMA guidelines. Relevant keywords were used for the search through PubMed/MEDLINE, Scopus and SPORTDiscus. The methodological quality of intervention studies was assessed using the Downs and Black checklist. For cross-sectional studies, the Newcastle-Ottawa scale was used. Sixteen studies were found meeting the inclusion criteria. In general, the included studies were deemed to be of moderate methodological quality. Although results of relevant literature are limited and somewhat contradictory, the outcome suggests that running may increase foot muscle volume, muscle cross-sectional area and bone density, but this seems to depend on training volume and experience. Future studies conducted in this area should aim for a standard way of reporting foot muscle/bone characteristics. Also, herein, suggestions for future research are provided.

Does neuromuscular electrostimulation have the potential to increase intrinsic foot muscle strength?

PURPOSE

The purpose of this study was to investigate the effect of an eight-week neuromuscular electrostimulation program on the intrinsic foot muscle strength. The results were compared with those from a passive and an active control group.

METHODS

74 healthy participants were recruited and divided into three groups: a neuromuscular electrostimulation group (n=19), a passive control group (n=15) with no further intervention, and an active control group following a running protocol with minimal shoes (n=40). The electrostimulation and running groups followed a training protocol consisting of two sessions per week over a period of eight weeks. Three characteristics of intrinsic foot muscle strength were investigated: cross sectional area of the abductor hallucis muscle, longitudinal arch stability, and intrinsic foot muscle fatigue.

RESULTS

After eight weeks of intervention, the cross sectional area increased by 16.3% for the running group with a large effect size (0.801) according to Cohen's d. The electrostimulation group showed no such effect. The increase in the cross sectional area had no impact on longitudinal arch stability or intrinsic foot muscle fatigue results.

CONCLUSION

This study investigated neuromuscular electrostimulation as a prevention and rehabilitation strategy. The results indicate that, compared to minimally shod running, the effects of electrostimulation on healthy participants might be too small to be detected. Further, the results provide evidence that the static navicular drop test is not sensitive enough to indicate intrinsic foot muscle strength. This appears clinically relevant, as this test is often used by therapists to evaluate patients' longitudinal arch function.

Electromyographic analysis of balance exercises in single-leg stance using different instability modalities of the forefoot and rearfoot

PURPOSE

To investigate the activity of lower extremity muscles in response to single-leg stance on a training device, destabilizing the forefoot while the rearfoot stands on a fixed plate and vice versa compared with a balance pad and the floor.

DESIGN

Cross-sectional study.

SETTING

University's laboratory.

PARTICIPANTS

Twenty-seven healthy adults.

METHODS

Surface electromyography and 2D video analysis were used to record the activity of lower extremity muscles and to control sagittal knee joint angle during single-leg stance trials under one stable control condition and five unstable conditions.

RESULTS

The majority of lower extremity muscles were significantly more active when the forefoot was destabilized while the rearfoot remained stable compared with the stable condition and the conditions where the forefoot was stable and the rearfoot unstable (p <0 .001). Mean change of knee joint angle was significantly increased under the conditions rearfoot stable/forefoot unstable (p = 0.001). The soleus muscle activation was significantly increased when balancing on the balance pad (p < 0.001).

CONCLUSIONS

Increased activity in the majority of lower extremity muscles and sagittal knee joint angles indicate that destabilizing the forefoot while the rearfoot remains stable is the most challenging balance task. Soleus muscle activation increased when performing ankle plantarflexion on the soft balance pad.

Foot and Ankle Kinematics During Descent From Varying Step Heights

In the general population, one-third of incidences during step negotiation occur during the transition to level walking. Furthermore, falls during curb negotiation are a common cause of injury in older adults. Distal foot kinematics may be an important factor in determining injury risk associated with transition step negotiation. The purpose of this study was to identify foot and ankle kinematics of uninjured individuals during descent from varying step heights. A 7-segment foot model was used to quantify kinematics as participants walked on a level walkway, stepped down a single step (heights: 5 cm, 15 cm, 25 cm), and continued walking. As step height increased, landing strategy transitioned from the rearfoot to the forefoot, and the rearfoot, lateral and medial midfoot, and medial forefoot became more plantar flexed. During weight acceptance, sagittal plane range of motion of the rearfoot, lateral midfoot, and medial and lateral forefoot increased as step height increased. The changes in landing strategy and distal foot function suggest a less stable ankle position at initial contact and increased demand on the distal foot at initial contact and through the weight acceptance phase of transition step negotiation as step height increases.

Impact of foot pronation on postural stability: An observational study

OBJECTIVE

To investigate the effect of foot pronation on the postural stability through measuring the dynamic balance including overall stability index (OAI), anteroposterior stability index (APSI) and mediolateral stability index (MLSI).

METHODS

Forty participants from both sexes were selected from the Faculty of Physical Therapy, Cairo University, with a mean age of 23.55 ± 1.74 years. Subjects were divided into two groups: group A (8 males and 12 females) with foot pronation, and group B (9 males and 11 females) with normal feet. The Navicular Drop Test (NDT) was used to determine if the feet were pronated and Biodex Balance System was used to assess dynamic balance at level 8 and level 4 for both groups.

RESULTS

No significant difference was found in dynamic balance, including OAI, APSI and MLSI at stability level 8 (p> 0.05) but, there was a significant difference at stability level 4 (p< 0.05) between the two groups with lower stability in group A.

CONCLUSION

Foot pronation affects the postural stability at stability level four and not affects stability level eight compared with those in the control group.

Intrinsic Foot Muscle Activation During Specific Exercises: A T2 Time Magnetic Resonance Imaging Study

CONTEXT

The intrinsic foot muscles maintain the medial longitudinal arch and aid in force distribution and postural control during gait. Impaired intrinsic foot-muscle function has been linked to various foot conditions. Several rehabilitative exercises have been proposed to improve it; however, literature that identifies which individual muscles are activated during specific intrinsic foot-muscle exercises is lacking.

OBJECTIVE

To describe changes in activation of the intrinsic plantar foot muscles after 4 exercises as measured with T2 magnetic resonance imaging (MRI).

DESIGN

Descriptive laboratory study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Eight healthy National Collegiate Athletic Association Division I collegiate cross-country and track athletes (5 men and 3 women: age = 20 ± 0.93 years, height = 180.98 ± 10.84 cm, mass = 70.91 ± 7.82 kg).

INTERVENTION(S)

Participants underwent T2 MRI before and after each exercise. They completed 1 set of 40 repetitions of each exercise (short-foot exercise, toes spread out, first-toe extension, second- to fifth-toes extension).

MAIN OUTCOME MEASURE(S)

Percentage increases in muscle activation of the abductor hallucis, flexor digitorum brevis, abductor digiti minimi, quadratus plantae, flexor digiti minimi, adductor hallucis oblique, flexor hallucis brevis, and interossei and lumbricals (analyzed together) after each exercise were assessed using T2 MRI.

RESULTS

All muscles showed increased activation after all exercises. The mean percentage increase in activation ranged from 16.7% to 34.9% for the short-foot exercise, 17.3% to 35.2% for toes spread out, 13.1% to 18.1% for first-toe extension, and 8.9% to 22.5% for second- to fifth-toes extension. All increases in activation had associated 95% confidence intervals that did not cross zero.

CONCLUSIONS

Each of the 4 exercises was associated with increased activation in all of the plantar intrinsic foot muscles evaluated. These results may have clinical implications for the prescription of specific exercises to target individual intrinsic foot muscles.

Strength training for plantar fasciitis and the intrinsic foot musculature: A systematic review

The aim was to critically evaluate the literature investigating strength training interventions in the treatment of plantar fasciitis and improving intrinsic foot musculature strength. A search of PubMed, CINHAL, Web of Science, SPORTSDiscus, EBSCO Academic Search Complete and PEDRO using the search terms plantar fasciitis, strength, strengthening, resistance training, intrinsic flexor foot, resistance training. Seven articles met the eligibility criteria. Methodological quality was assessed using the modified Downs and Black checklist. All articles showed moderate to high quality, however external validity was low. A comparison of the interventions highlights significant differences in strength training approaches to treating plantar fasciitis and improving intrinsic strength. It was not possible to identify the extent to which strengthening interventions for intrinsic musculature may benefit symptomatic or at risk populations to plantar fasciitis. There is limited external validity that foot exercises, toe flexion against resistance and minimalist running shoes may contribute to improved intrinsic foot musculature function. Despite no plantar fascia thickness changes being observed through high-load plantar fascia resistance training there are indications that it may aid in a reduction of pain and improvements in function. Further research should use standardised outcome measures to assess intrinsic foot musculature strength and plantar fasciitis symptoms.

Impaired Foot Plantar Flexor Muscle Performance in Individuals With Plantar Heel Pain and Association With Foot Orthosis Use

Study Design Controlled laboratory study. Background Plantar heel pain is one of the most common foot and ankle conditions seen in clinical practice, and many individuals continue to have persisting or recurrent pain after treatment. Impaired foot plantar flexor muscle performance is a factor that may contribute to limited treatment success, but reliable methods to identify impairments in individuals with plantar heel pain are needed. In addition, foot orthoses are commonly used to treat this condition, but the implications of orthosis use on muscle performance have not been assessed. Objectives To assess ankle plantar flexor and toe flexor muscle performance in individuals with plantar heel pain using clinically feasible measures and to examine the relationship between muscle performance and duration of foot orthosis use. Methods The rocker-board plantar flexion test (RBPFT) and modified paper grip test for the great toe (mPGTGT) and lesser toes (mPGTLT) were used to assess foot plantar flexor muscle performance in 27 individuals with plantar heel pain and compared to 27 individuals without foot pain who were matched according to age, sex, and body mass. Pain ratings were obtained before and during testing, and self-reported duration of foot orthosis use was recorded. Results Compared to the control group, individuals with plantar heel pain demonstrated lower performance on the RBPFT (P = .001), the mPGTGT (P = .022), and the mPGTLT (P = .037). Longer duration of foot orthosis use was moderately correlated to lower performance on the RBPFT (r = -0.52, P = .02), the mPGTGT (r = -0.54, P = .01), and the mPGTLT (r = -0.43, P = .03). Conclusion Ankle plantar flexor and toe flexor muscle performance was impaired in individuals with plantar heel pain and associated with longer duration of self-reported foot orthosis use. J Orthop Sports Phys Ther 2016;46(8):681-688. Epub 3 Jul 2016. doi:10.2519/jospt.2016.6482.

Treatment of Progressive First Metatarsophalangeal Hallux Valgus Deformity: A Biomechanically Based Muscle-Strengthening Approach

Synopsis Hallux valgus is a progressive deformity of the first metatarsophalangeal joint that changes the anatomy and biomechanics of the foot. To date, surgery is the only treatment to correct this deformity, though the recurrence rate is as high as 15%. This clinical commentary provides instruction in a strengthening approach for treatment of hallux valgus deformity, by addressing the moment actions of 5 muscles identified as having the ability to counter the hallux valgus process. Unlike surgery, muscle strengthening does not correct the deformity, but, instead, reduces the pain and associated gait impairments that affect the mobility of people who live with the disorder. This review is organized in 4 parts. Part 1 defines the terms of foot motion and posture. Part 2 details the anatomy and biomechanics, and describes how the foot is changed with deformity. Part 3 details the muscles targeted for strengthening; the intrinsics being the abductor hallucis, adductor hallucis, and the flexor hallucis brevis; the extrinsics being the tibialis posterior and fibularis longus. Part 4 instructs the exercise and reviews the related literature. Instructions are given for the short-foot, the toe-spread-out, and the heel-raise exercises. The routine may be performed by almost anyone at home and may be adopted into physical therapist practice, with intent to strengthen the foot muscles as an adjunct to almost any protocol of care, but especially for the treatment of hallux valgus deformity. J Orthop Sports Phys Ther 2016;46(7):596-605. Epub 6 Jun 2016. doi:10.2519/jospt.2016.6704.