Toe flexor strength is not related to postural stability during static upright standing in healthy young individuals

Mechanical drivers of intrinsic foot muscle for maximum toe flexor strength in upright standing across different body size

This study aimed to evaluate maximum toe flexor strength, foot arch height, intrinsic toe flexor muscle size and foot arch stiffness among individuals with different body sizes, and to compare these variables between sitting and standing positions. Maximum toe flexor strength in sitting and standing, and intrinsic foot muscle thicknesses (flexor hallucis brevis: FHB, flexor digitorum brevis: FDB, abductor hallucis: AH and quadratus plantae: QP), were measured using a toe grip dynamometer and a B-mode ultrasound in healthy young men. FHB was thicker than AH, FDB and QP, AH was thicker than FDB and QP, and no significant difference was found between FDB and QP. Toe flexor strength was correlated with FHB and AH, and foot arch height was correlated with FHB. Toe flexor strength was greater in standing than in sitting. Stepwise multiple regression analysis identified FHB and AH as determinants of toe flexor strength in standing, and the relative muscle strength values per body weight in standing were determined by QP, foot arch index and foot arch stiffness. Overweight individuals had a decreased rate of increase in relative toe flexor strength compared to normal individuals. These results suggest that a large muscle thickness of intrinsic foot muscle a key contributor to toe flexor strength. Moreover, toe flexor muscle in upright standing could have the potential to generate force independently of intrinsic foot muscle size, but obese individuals who chronically put weight on their feet might impair the force amplification mechanism in upright standing.

Age-Related Reduction of Foot Intrinsic Muscle Function and the Relationship with Postural Stability in Old Adults

Introduction

The risk of falls among the elderly significantly increases, which has become a serious public health concern. Falls can not only lead to serious complications such as fractures and brain injuries but also limit their mobility function, reducing quality of life. Foot intrinsic muscles (FIMs) are an essential part of foot core stability even overall postural stability. This study aimed to investigate the effects of aging on the function of FIMs and to explore the influence of FIMs on postural control in the elderly.

Materials and Methods

56 healthy old participants (60-75 years) and 57 healthy young participants (18-29 years) joined this study. An ergoFet dynamometer was used to determine foot muscle strength (Doming, T1, T23 and T2345), and ankle muscle strength (plantarflexion and dorsiflexion). The morphology of FIMs and extrinsic foot muscle was determined using a Doppler ultrasound system, whereas the postural stability was assessed through Limits of Stability test. Independent samples t-test was used to determine the differences in strength and morphological parameters and Spearman correlation analysis was used to determine whether an association existed between muscle strength and postural stability parameters in the elderly.

Results

Compared with young adults, foot muscle strength and ankle muscle strength (Doming, T1, T23, T2345, dorsiflexion, and plantarflexion, all p <0.05) and the morphology of foot muscles (all p <0.05) were significantly reduced in the elderly. The strength of FIMs and the limit of stability (r = 0.302-0.424, all p <0.05) were significantly correlated in the elderly.

Conclusion

Compared with young adults, the weakness of strength as well as the morphological decline of the intrinsic and extrinsic foot muscles were found in the elderly. In addition, a correlation was observed between FIM's strength and postural stability in the elderly, suggesting their potential role in posture stability.

Difference in the recruitment of intrinsic foot muscles in the elderly under static and dynamic postural conditions

Background

The effect of foot, especially intrinsic muscles, on postural control and its related mechanisms remain unclear due to the complex structure. Therefore, this study aims to investigate the activation of intrinsic foot muscles in the elderly under static and dynamic postural tasks.

Methods

Twenty-one elderly participants were included to perform different postural tests (sensory organization test (SOT), motor control test (MCT), limit of stability test (LOS), and unilateral stance test) by a NeuroCom Balance Manager System. The participants were instructed to maintain postural stability under conditions with combined different sensory inputs (vision, vestibular, and proprioception) in SOT as well as conditions with translation disturbance in MCT, and to perform an active weight-shifting tasks in LOS. During these tasks, muscle activation were simultaneously acquired from intrinsic foot muscles (abductor halluces (AbH) and flexor digitorum brevis (FDB)) and ankle muscles (anterior tibialis, medial head of gastrocnemius, lateral head of gastrocnemius, and peroneus longus). The root-mean-square amplitude of these muscles in postural tasks was calculated and normalized with the EMG activity in unilateral stance task.

Results

The activation of intrinsic foot muscles significantly differed among different SOT tasks (p < 0.001). Post-hoc tests showed that compared with that under normal condition 1 without sensory interference, EMGs increased significantly under sensory disturbance (conditions 2-6). By contrast, compared with that under the single-sensory disturbed conditions (conditions 2-4; 2 for disturbed vision, 3 for disturbed vestibular sensation, 4 for disturbed proprioception), activation was significantly greater under the dual-sensory disturbed postural tasks (conditions 5 and 6; 5 for disturbed vision and proprioception, 6 for disturbed vestibular sensation and proprioception). In MCT, EMGs of foot muscles increased significantly under different translation speeds (p < 0.001). In LOS, moderate and significant correlations were found between muscle activations and postural stability parameters (AbH, r = 0. 355-0.636, p < 0.05; FDB, r = 0.336-0.622, p < 0.05).

Conclusion

Intrinsic foot muscles play a complementary role to regulate postural stability when disturbances occur. In addition, the recruitment magnitude of intrinsic foot muscles is positively correlated with the limit of stability, indicating their contribution to increasing the limits of stability in the elderly.

Association between toe pressure strength in the standing position and postural control capability in healthy adults

BACKGROUND

A method has been developed to assess toe pressure strength in the standing position, taking into account concerns about toe grip strength.

RESEARCH QUESTION

Which is more associated to postural control capability, the conventional toe grip strength or the newly devised toe pressure strength in the standing position, which is close to the actual movement?

METHODS

This study is a cross-sectional study. This study included 67 healthy adults (mean age, 19 ± 1 years; 64% male). The postural control capability was measured using the center-of-pressure shift distance in the anterior-posterior axis. Toe pressure strength in the standing position was assessed using a toe pressure measuring device to evaluate the force of pressure on the floor surface by all toes. During measurement, care is taken to ensure that the toes do not flex. However, toe grip strength in the sitting position was measured using muscle strength for toe flexion in a conventional manner. Statistical analysis was conducted by performing a correlation analysis between each of the measured items. Additionally, multiple regression analysis was used to examine the functions associated with postural control capability.

RESULT

Pearson's correlation analysis revealed that the postural control capability was correlated with toe pressure strength in the standing position (r = 0.36, p = 0.003). Multiple regression analysis demonstrated that only toe pressure strength in the standing position was significantly associated with the postural control capability, even after adjusting for covariates (standard regression coefficient: 0.42, p = 0.005).

SIGNIFICANCE

The results of this study indicated that toe pressure strength in the standing position was more strongly associated with the postural control capability in healthy adults than toe grip strength in the sitting position. It has been suggested that a rehabilitation program for toe pressure strength in the standing position would help improve postural control capability.

Comparison of toe pressure strength in the standing position and toe grip strength in association with the presence of assistance in standing up: a cross-sectional study in community-dwelling older adults

PURPOSE

We believe that toe pressure strength in the standing position, which is closer to the actual movement, is more associated with standing up in the older adults than the conventional toe grip strength. Therefore, the purpose of this study is to examine the association between toe pressure strength in the standing position and the presence of assistance in standing up in the older adults.

METHODS

Ninety-five community-dwelling older adults (82 ± 8 years old, 72% female) were included in this study. The patients were evaluated based on their need for assistance in standing up. Physical functions, including toe pressure strength in the standing position, toe grip strength, hand grip strength, knee extension strength, one-leg standing time with eyes open, and maximal walking speed, were measured.

RESULTS

When compared with and without assistance to stand up, the group requiring assistance had weaker toe pressure strength in the standing position than the group without assistance (p = 0.015, ES = 0.53). After adjusting for confounding factors, the final model revealed that toe pressure strength in the standing position was associated with the use of assistance in standing up (odds ratio 0.94 [0.88-0.99, p = 0.025]).

CONCLUSION

Toe pressure strength in the standing position was associated with the use of assistance in standing up in older adults. Improving toe pressure strength in the standing position may facilitate the ability of older adults to stand up.

Determination of light pressing pressure for improving foot skin blood flow in type 2 diabetic patients

OBJECTIVE

Traditional Thai massage is one of the alternative treatments for diabetic feet. However, the specific amount of pressing pressure applied to the foot during Thai foot massage is unknown. This study aimed to evaluate the effect of light pressing pressure on foot skin blood flow in type 2 diabetic patients.

METHODES

A single-arm repeated measures was conducted. Forty-three participants were recruited via the subjective examination and screening using the Michigan Neuropathy Screening Instrument. To obtain foot skin blood flow by laser doppler blood flowmetry, a probe was pasted on the 1st distal phalange of the big toe. Light pressure at a single point was applied on the plantar skin fold between the bases of the second and third toes by using the digital algometer. The pressure was applied gently, then increased slightly until the participant started to feel some minor discomfort. Patients were asked to rate their pain intensity using the visual analogue scale.

RESULTS

The average pressing pressure without discomfort was 3.55 ± 1.04 kg/cm². The foot skin blood flow increased significantly immediately after the pressing pressure, and this increase represented about 1.9 times when compared with the baseline (p < 0.001).

CONCLUSION

The application of light pressing pressure could be used as a basic standard criterion for massage to improve the foot skin blood flow in type 2 diabetic patients.

The Influence of Gender and the Specificity of Sports Activities on the Performance of Body Balance for Students of the Faculty of Physical Education and Sports

A sense of balance is required in sports activities, conditioning the quality of movements and physical performance. (1) The purpose of the study is to investigate the influence of gender and the specificity of sports activities on body balance. The investigated participants are 157 students of the Faculty of Physical Education and Sports/Bachelor’s degree: 109 men (age = 20.49 ± 2.03, body mass index, BMI = 22.96 ± 3.20), and 48 women (age = 20.21 ± 1.51, BMI = 21.05 ± 2.78). (2) Design: Cross-sectional study, with the definition of the variables gender and sport activity with three stages (non-athletes/NA, team sports games/TSG, and individual sports/IS). The evaluation was based on four dynamic balance tests (Bass test/points, Functional reach test/cm, Fukuda test/degrees of rotation, and Walk and turn field sobriety test/errors) and three static balance tests (Flamingo test/falls, Stork test, and One-leg standing test with eyes closed/s). (3) Results: The variance analysis (multivariate and univariate tests) indicates the superiority of women in most tests applied, but with significantly better values (p < 0.05) only for the Flamingo test and Bass test. Men have superior results only for vestibular stability (Fukuda test) and One-leg standing test, but it is statistically insignificant (p > 0.05). The TSG group has slightly better values than the IS group for the whole set of tests conducted, but these are not statistically significant (p > 0.05), so we cannot highlight the certain superiority of TSG practitioners over those involved in IS. Both the TSG and the IS group outperformed all tests compared to the NA group, with significant differences (p < 0.05), especially for the TSG. Conclusion: Women have better values than men on most tests, and performance sports students have higher average scores than those in the NA group, which demonstrates the beneficial influence of specific training on static and dynamic postural stability.

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.

Increased toe flexor strength does not relate to altered postural sway during static upright standing after 12 weeks of multicomponent exercise training

AbstractThis study investigated whether an increase in toe flexor strength influenced postural control during static upright standing after 12 weeks of multicomponent exercise training in healthy young men. Twelve men (18-23 yrs) performed multicomponent exercise 3 days per week for 12 weeks. Twelve additional age-matched men were recruited for the untrained control group. The multicomponent exercise training consisted of strengthening and balance exercises for the foot and leg muscles. Toe flexor strength, foot arch height and postural control were assessed before, during, and after exercise training. Postural control was evaluated using the path of the centre of pressure, which was obtained with a force plate under three standing conditions: double-leg standing with eyes open, double-leg standing with eyes closed, and single-leg standing with eyes open. The dominant leg was used for single-leg standing. After exercise training, toe flexor strength increased by approximately 32% (p < 0.01), whereas the foot arch height did not change. The centre of pressure variables during double-leg standing did not change after exercise training; however, these variables decreased during single-leg standing. None of the variables in the control group changed after exercise training. The relative increase in toe flexor strength was not correlated with the relative improvement in the centre of pressure variables during single-leg standing after 12 weeks of exercise training (total length, r = 0.1734; mean velocity, r = 0.1734; sway area, r=-0.1372). These findings suggest that increased toe flexor strength has no significant effect on static postural control ability after exercise training in young men.

The Effect of Toe-grasping Exercises on Balance Ability in Home-based Rehabilitation: A Randomized Controlled Trial by Block Randomization

OBJECTIVE

The purpose of the study was to clarify the causal effect of toe-grasping exercises on the improvement of static or dynamic balance ability in home-based rehabilitation users.

METHOD

Our study included 34 subjects who met the criteria and were evaluable out of 98 rehabilitation service users at home nursing stations. This study was a randomized controlled trial. The intervention group performed towel gathering exercises in addition to the regular home-based rehabilitation program. The primary outcome was one-leg standing time, and the secondary outcomes were two-step test and toe grip strength.

RESULTS

Seventeen subjects were assigned to the intervention group and seventeen to the control group by block randomization. Data from 15 and 12 subjects in the intervention group and control group, respectively, who were able to complete the initial evaluation and the evaluation after 3 months, were analyzed. We compared the amount of change after 3 months of evaluation in the intervention group with the change in the control group. The results showed that the left/right mean value of oneleg standing time in the intervention group was significantly greater than that in the control group. In terms of the amount of change in the intervention period (T2-T1) within each assessment, there were significant improvements in both the toe-grip strength and the two-step values in the intervention group.

CONCLUSION

We found that toe-grasping exercises could improve the balance ability of home-based rehabilitation users. This suggests the clinical significance of toe function in rehabilitation programs.

Effects of standing and walking on plantar pressure distribution in recreational runners before and after long-distance running

With marathon-running grew in popularity, the effect of long-distance running on plantar pressure has been more attractive. It has been proposed that long-distance running influences the deviation in the center of pressure (COP) during standing and the changes to plantar pressure during walking. The objective of this study was to observe the effects on the COP motion amplitude of static standing and the plantar pressure distribution of walking after long-distance running. The influence of a 10-km run on changes to plantar pressure was assessed during standing and walking. Plantar pressure was measured before and immediately after running. In the study, seven males and five females participated in barefoot tests of static standing and dynamic walking. In the static standing tests, COP was measured under the following four ordered conditions: (1) bipedal, eyes open, standing; (2) bipedal, eyes closed, standing; (3) unipedal, eyes open, standing and (4) unipedal, eyes closed, standing. Under each condition, the data was collected while a stable standing posture for 10 s. In the dynamic walking tests, the contact duration and plantar pressure were recorded. The standing tests results revealed no significant differences between males and females while slight differences before vs. after running. Running for a single time had no effect on COP deviation during standing. The walking tests results revealed an initial landing on the lateral heel. After landing on the lateral heel, the females quickly transferred to the medial heel. The movement of the pressure to the medial heel was slower in males than females. After running, the pressure of females was more inward, while that of males was more outward under the metatarsal zones in the propulsion phase.

Importance of toe flexor strength in vertical jump performance

This study investigated whether toe flexor strength and foot arch height were related to force components during the ground contact phase in vertical jump performance. The toe flexor strength, foot arch height and vertical jump performance were studied in 31 healthy young men. For the measurement of toe flexor strength, participants explosively exerted maximum force on a toe grip dynamometer. The maximum isometric force (Fmax) and the rate of force development (RFD) of the toe flexor strength were evaluated. Foot arch height was assessed as the distance between the navicular tuberosity and the floor. Fmax and foot arch height were normalized by body mass (rFmax) and height, respectively. Three types of vertical jumps without arm swing were performed on a force plate: a squat jump (SJ), a countermovement jump (CMJ), and a rebound jump (RJ). Fmax, rFmax and RFD of the toe flexor strength were positively correlated with the vertical jump height in the SJ (r = 0.408, r = 0.452, r = 0.514) and CMJ (r = 0.377, r = 0.444, r = 0.548) and the rebound jump index in the RJ (r = 0.549, r = 0.582, r = 0.575); however, foot arch height was not correlated with the vertical jump performance, and it was only significantly correlated with the minimum ground reaction force relative to body weight during the unloading phase of the CMJ (r = -0.366). These results suggest that the toe flexor strength is an important parametre for enhancing the jump performance.

Immediate Effects of Self-Thai Foot Massage on Skin Blood Flow, Skin Temperature, and Range of Motion of the Foot and Ankle in Type 2 Diabetic Patients

Objectives: The purpose of this study was to investigate the immediate effects of self-Thai foot massages (STFMs) on the foot skin blood flow, the foot skin temperature, and range of motion (ROM) of the foot and ankle in type 2 diabetic patients with peripheral neuropathy. Design: A randomized crossover study. Subjects: Twenty five diabetic patients with peripheral neuropathy were recruited. Interventions: Participants were randomly assigned to either STFM or Thai foot massage (TFM) performed by a massage therapist; then, they were switched to the other group after a 1-week washout period. In both groups, the foot massage was performed in a seated position on the dominant lower leg and foot for 25 min. Outcome measures: Before and immediately after treatment, foot skin blood flow, foot skin temperature, and ROM of the foot and ankle were evaluated. Heart rate was measured throughout the treatment. Results: After a single treatment of the massage, foot skin blood flow and ROM of the foot and ankle significantly improved in both groups (p < 0.05). Foot skin temperature did not change in STFM, whereas it significantly increased in TFM. Heart rate significantly increased in STFM, whereas it tended to decrease in TFM. Conclusions: Both STFM and TFM by a massage therapist could improve foot skin blood flow and ROM of the foot and ankle in diabetic patients with peripheral neuropathy. An STFM could be a promising alternative treatment that patients can perform at home.

Relationships between Foot Morphology and Foot Muscle Strength in Healthy Adults

The purpose of this study was to investigate if measurements of foot morphology in sitting and standing positions can predict foot muscle strength. Twenty-six healthy male adults were recruited, and their foot morphology and foot muscle strength were measured. Foot morphological variables, toe flexor strength, and metatarsophalangeal joint flexor strength were measured by using a digital caliper, Ailitech-AFG500 dynameter and metatarsophalangeal joint flexor strength tester, respectively. Partial correlation and multivariate stepwise regression were used to explore the relationships between foot morphology and toe/metatarsophalangeal joint strength. Results adjusted by age and body mass index were as follows: (1) truncated foot length in sitting and standing positions and foot width in standing position were positively correlated with the flexor strength of the first toe; (2) foot length, foot width, and truncated foot length in both positions were positively related to the flexor strength of the other toes; (3) arch height index in sitting position and differences in navicular height were negatively associated with the flexor strength of the other toes; (4) differences in foot width were negatively associated with metatarsophalangeal joint flexor strength; and (5) the multivariate stepwise regression model showed that truncated foot length in sitting position, navicular height in standing position, differences in navicular height, foot width in sitting position, and differences in foot width were significantly correlated with toe/metatarsophalangeal joint flexor strength. Simple measurements of foot morphological characteristics can effectively predict foot muscle strength. Preliminary findings provided practical implications for the improvement of the foot ability by making specific foot muscle training sessions in professional sports and by compensating the predicted muscle strength defects to prevent foot injury.