Acute effect of foot orthoses on frequency domain of ground reaction forces in male children with flexible flatfeet during walking

Effect of foot orthoses on dynamic balance in taekwondo athletes with flexible flatfoot: A randomized controlled trial

BACKGROUND

Flexible flatfoot (FFF) cause biomechanical and sensorimotor disorders of the foot and ankle complex and reduce of postural stability. Postural stability is an important movement skill that affects the performance of taekwondo (TKD) athletes and can lead to fall injuries. The purpose of this study is the effect 12-week application of foot orthosis (FOs) on dynamic balance in TKD athletes with FFF.

METHOD

In this trial, 30 girls of the TKD athletes with FFF were recruited. They were randomly assigned to experimental and control groups (15 subjects in each group). The experimental group used FOs with medial longitudinal arch support for 12 weeks, and the control group did not have any intervention. The outcome measures include navicular drop and balance in three directions: anterior-posterior, medial-lateral and overall stability. Covariance analysis was used to compare the results between two groups.

RESULTS

The covariance results showed that the experimental group compared to the control group with a high effect size had a significant difference in reducing of navicular drop (P = 0.000, ηp2 =0.512), anterior-posterior sway (P = 0.000, (ηp2 =0.397) medial-lateral sway (P = 0.019, ηp2 = 0.186) and overall stability sway (P = 0.008, ηp2 = 0.232).

CONCLUSIONS

The FOs with medial longitudinal arch support leads to FFF correction and provides mechanical stability of the foot and ankle complex. Also, the impulses sent from plantar receptors are increased and a better understanding of postural sway is transmitted to the central nervous system and balance strategies are improved.

The effect of arch-support insole on knee kinematics and kinetics during a stop-jump maneuver

BACKGROUND

Anterior cruciate ligament injuries commonly occur during sports that involve sudden stops or direction changes. Although athletes often use arch-support insoles in competition and training, little is known about the effect of foot insoles on knee biomechanics and jump take-off performances.

OBJECTIVE

This study aimed to investigate the effects of arch-support insoles on knee kinematics and kinetics during the stop-braking phase and the subsequent jump take-off performances.

STUDY DESIGN

That is a quasi-experimental study, repeated-measures design.

METHODS

Twenty male healthy recreational university basketball athletes performed stop-jump with maximum effort in both arch-support and flat insole conditions. Paired t -tests were performed on knee kinetics and kinematics and jump performance variables to determine whether there were significant differences between insole conditions.

RESULTS

Wearing arch-support insoles experienced larger ground reaction forces (GRFs), loading rates of peak vertical and posterior GRFs, peak knee adduction and rotation moments, and knee flexion angular velocity than the flat insoles ( P < 0.05).

CONCLUSIONS

The increased GRFs and knee loading in arch-support insoles are indicative of a higher risk of anterior cruciate ligament injuries. The findings could be insightful to the knee mechanics that are related to performance and injury potential during stop-jump maneuvers.

Long-term training on sand changes lower limb muscle activities during running in runners with over-pronated feet

BACKGROUND

Running on sand could be a promising exercise intervention for the treatment of over-pronated feet. However, there is a lack of knowledge about the effects of running on sand on muscle activities. Therefore, this study aims to evaluate the long-term effects of running on sand on the activities of selected lower limb muscles in individuals with OPF compared with healthy controls.

METHODS

Sixty recreational adult male runners with over-pronated feet (foot posture index > 10) were divided into two equal groups (intervention and control). Participants ran barefoot at a pre-defined speed (⁓3.3 m/s) over level stable ground both before and after long-term training on the sand. Muscle activities were recorded using a surface bipolar electromyography system.

RESULTS

For the intervention group, we found a reduced foot posture index (p < 0.001; d = 2.00) and significant group-by-time interactions for gluteus medius activity during the mid-stance phase (p < 0.028; d = 0.59). Significantly higher gluteus medius activity (p = 0.028, d = 0.569) was found during the post-test. We also observed significant group-by-time interactions for medial gastrocnemius activity during the push-off phase (p < 0.041; d = 0.54). Significantly larger medial gastrocnemius activity (p = 0.041; d = 0.636) was found during the post-test compared to the pre-test.

CONCLUSIONS

Long-term running on sand resulted in reduced pronation, increased medial gastrocnemius activity, and improved frontal plane pelvic stability due to higher gluteus medius activity.

TRIAL REGISTRATION

IRCT20191211045704N1. Registered 25 February 2020. Retrospectively registered.

Effects of foot orthoses on dynamic balance and basketball free-throw accuracy before and after physical fatigue

While it is not uncommon for athletes to use foot orthoses to relieve pain and improve sports performance, little has been known about their effects on basketball performance. Free-throw basketball shooting is very important. However, fatigue deteriorates postural balance which might decrease free-throw shooting performance. This study investigated the effects of foot orthoses on dynamic balance and accuracy performance during free-throw shooting before and after physical fatigue was induced. Thirteen male recreational basketball players were tested with two foot orthoses (medial-arch support versus flat control) and fatigue conditions (before and after fatigue), when they performed standard free-throw shooting on a force platform. Results revealed that fatigue significantly increased coefficient of variance of medial-lateral center of pressure (CoP) excursion when participants worn flat control orthoses (p < 0.05). Meanwhile, foot orthoses improved dynamic balance during shooting as they significantly reduced total resultant and anterior-posterior sway excursions as well as resultant and anterior-posterior CoP velocities, and base of support area. Although this study found that fatigue and orthoses did not significantly affect the scores gained by free-throw shooting, the significant improvements in dynamic balance during shooting with the use of foot orthoses could have considerable impact on motor control during basketball shooting.