Intrinsic foot muscle strengthening exercises with electromyographic biofeedback achieve increased toe flexor strength in older adults: A pilot randomized controlled trial.

BACKGROUND: Toe flexor strength is important for preventing older adults from falling. Although intrinsic foot muscles are the main determinants of toe flexor strength, exercises for strengthening these muscles are difficult for older adults. This study therefore aimed to determine whether the use of electromyographic biofeedback helps older adults to perform intrinsic foot muscle strengthening exercises. METHODS: This randomized controlled trial had two parallel arms. Participants were randomly allocated to the control group or the electromyographic biofeedback group. Control participants performed two progressive intrinsic foot muscle strengthening exercises twice a week for 6 weeks. Participants in the other group performed these exercises assisted by electromyographic biofeedback. Primary outcome measures were changes in toe flexor strength and the timed up-and-go and functional reach tests (the latter two being balance tests). FINDINGS: Altogether, 23 older adults were randomized to the control group (n = 12) or the electromyographic biofeedback group (n = 11). After the 6-week intervention, toe flexor strength on the dominant side increased in both groups (P < 0.017). However, toe flexor strength on the nondominant side increased only in the electromyographic biofeedback group (P < 0.017), with a large effect size of 1.5. There were no changes in the two balance tests. Three of the control group and two of the electromyographic biofeedback group were lost to follow- up. INTERPRETATION: Our results indicate that, the use of electromyographic biofeedback can enhance the effect of intrinsic foot muscle strengthening exercises on the nondominant side in older adults. CLINICAL TRIAL REGISTRATION NUMBER: UMIN000036521.

Effect of electromyographic biofeedback on learning the short foot exercise.

BACKGROUND: The short foot (SF) exercise is a strengthening exercise for the intrinsic foot muscles that is difficult to master. OBJECTIVE: To examine the effect of three different electromyographic (EMG) biofeedback methods on learning the SF exercise. METHODS: Thirty-six healthy subjects were randomly allocated to the control group (CTG), EMG-controlled electrical stimulation group (ESG), visual EMG biofeedback group (VSG), and combination EMG-controlled electrical stimulation with visual EMG biofeedback group (CBG). The CTG practiced the SF exercise for 5 minutes using the conventional method. The other groups each used the EMG biofeedback method and the conventional method. The EMG activity of the abductor hallucis (ABH), the medial longitudinal arch (MLA) angle, and the foot length during the SF exercise were measured before and after 5 minutes of practice. RESULTS: The EMG activity of the ABH in the VSG and CBG was significantly higher than that before practice. There were no intergroup differences in MLA morphology. CONCLUSIONS: These results suggest that visual EMG biofeedback is an effective method of increasing the EMG activity of the ABH during the SF exercise in a short practice time.

The effect of additional activation of the plantar intrinsic foot muscles on foot kinematics in flat-footed subjects.

BACKGROUND: Strengthening exercises of the plantar intrinsic foot muscles (PIFMs) are often prescribed to flat-footed subjects because of the capacity of the PIFMs to support the medial longitudinal arch (MLA). However, it is unclear whether the capacity of the PIFMs to support the MLA is enough to change the foot kinematics in flat-footed subjects. To confirm this, the current study examined changes in foot kinematics in flat-footed subjects during standing and gait accompanied by changes in the activity of the PIFMs. METHODS: Eighteen flat-footed subjects were randomly assigned to an electrical stimulation group (ESG) or a control group (CG). In the ESG, electrical stimulation to the PIFMs was applied during standing and gait to simulate reinforcement of the PIFMs. Then, foot kinematics were measured using 3D motion analysis, and the amount of change from baseline (when no electrical stimulation was applied) was compared between the groups. RESULTS: In the gait analysis, the time at which the MLA height reached its minimum value was significantly later in the ESG, with no reduction in the MLA height at that time. Moreover, forefoot inversion angle and tibial external rotation angle were significantly increased in the ESG at that time. In the standing analysis, there were no significant differences between the groups. CONCLUSION: The results revealed that in flat-footed subjects, the PIFMs have the capacity to support the MLA enough to change foot kinematics during gait. Strengthening these muscles may be effective in preventing or treating lower extremity overuse injuries related to flat-foot alignment.