Impact of various foot arches on dynamic balance and speed performance in collegiate short distance runners: A cross-sectional comparative study

Morphological and mechanical characteristics of the intrinsic and extrinsic foot muscles under loading in individuals with flat feet

BACKGROUND

The intrinsic and extrinsic foot softtissue structures that apply force and support the medial longitudinal arch (MLA) have been implicated in the development of flat feet. However, the relationship between the changes in MLA height under increasing load and the morphological and mechanical properties of individual intrinsic and extrinsic foot soft tissue structures is not fully understood.

RESEARCH QUESTION

To examine the morphological and mechanical characteristics of the foot soft tissue structures in flat feet when subjected to loading.

METHODS

This study consisted of two studies focusing on the extrinsic foot muscles (10 normal feet/11 flat feet) and intrinsic foot muscles (14 normal feet/13 flat feet). Images of the extrinsic and intrinsic foot muscles and plantar fascia (PF) under 10%, 50%, and 90% body weight conditions were obtained using ultrasound-based shear-wave elastography.

RESULTS

The cross-sectional area (CSA) of the peroneus brevis was larger in the flat-foot group than in the normal-foot group under all loading conditions. The CSAs of the intrinsic foot muscles (abductor hallucis, flexor digitorum brevis, and quadratus plantae) and thickness of the PF in the flat-foot group decreased significantly with increasing load. As for mechanical characteristics, the stiffness of the flexor digitorum longus and abductor hallucis was higher in the flat-foot group than in the normal group under high loading conditions. In addition, flat feet with greater flexibility tended to exhibit a greater decrease in PF thickness and smaller increase in stiffness.

SIGNIFICANCE

Excessive stretching of the intrinsic foot muscles and PF occurs in flat feet, and excessive contraction of the flexor digitorum longus may counteract the excessive lowering of the foot arch. Therefore, it is necessary to promote the contraction of the intrinsic foot musculature in feet with greater flexibility of the MLA during loading.

Return to Play Following Achilles Tendon Rupture in NFL Players Based on Position

BACKGROUND

The purpose of this study was to determine the return-to-play (RTP) rate and postinjury performance after Achilles tendon (AT) ruptures in National Football League (NFL) skill position players.

METHODS

The study included NFL skill positions with an AT rupture between the 2009-2010 and 2015-2016 seasons. Performance data were collected and compared against a matched control group. RTP was defined as playing in at least 1 game after repair.

RESULTS

RTP rate was 57% for the study cohort. The tight ends (TEs) had the highest RTP rate at 71% while the wide receivers (WRs) had the lowest RTP rate at 38%. Compared with the control group, WRs with successful RTP had significantly less receptions per game (P = .01). For defensive players with RTP there were significant decreases in postrepair performance in tackles, passes defended, and fumbles forced/recovered compared with the control group.

CONCLUSION

A total of 57% of players achieved RTP with WRs and running backs (RBs) having the lowest RTP rates and TEs and linebackers (LBs) having the highest RTP rates. RBs, defensive backs (DBs), and LBs with successful RTP had decreased performance in all categories. This updated information may be helpful for athletes, physicians, scouts, and coaches in evaluating players with a history of AT rupture.

LEVELS OF EVIDENCE

Analytic, level 3, retrospective cohort study, Epidemiologic study.

Comparison of static balance and gait between subjects with plantar fasciitis and age-matched controls

BACKGROUND

Plantar fasciitis (PF) is a common condition amongst athletes as well as in non-sporting population. It is characterised by a sharp pain under the calcaneus during walking. The impact of pain due to PF on gait and static balance is examined in this observational study.

OBJECTIVE

To compare gait and balance between individuals with PF and age-matched controls without PF.

METHOD

A cross-sectional observational study was executed in an Outpatient Rehabilitation Centre. Twenty-nine participants were included, 14 with PF, and 15 age-matched healthy asymptomatic individuals. Main outcome measures were foot pain, foot function index (FFI), static balance measured with modified Romberg test, static balance measured on the TYMO® system, and gait with the G-Walk System.

RESULTS

Foot pain and FFI were adversely related to balance and gait parameters in subjects with PF. Static balance with eyes open and eyes closed on firm and soft surface measured on the TYMO® balance platform as well as gait parameters measured with the G-Walk system, were significantly lower in subjects with PF compared to age-matched healthy controls.

CONCLUSION

PF negatively affects parameters of static balance measured with TYMO® system and gait parameters measured with the G-Walk System. However, the Romberg balance test did not detect differences between subjects with PF and age-matched healthy controls.

Elite Tennis Players Experiencing High-Arched Supination and Cuboids Dropped Foot Syndromes in Daily Normal Gait

Many studies have focused on the plantar pressure characteristics of specific movements and footwork in tennis. However, little research has been conducted for exploring the foot characteristics among tennis professionals’ daily habitual paces. This study aims to examine the pressure profiles associated with foot posture and balance abilities of elite tennis players during normal gait to understand how foot loading patterns result from habitual paces that may be derived from intensive tennis training and competition. A cross-sectional comparative study is conducted on 95 male college elite tennis players (mean age: 20.2 ± 1.2 years) and 100 male recreational tennis players (mean age: 19.8 ± 0.9 years). Bipedal plantar pressure distributions (PPDs) associated with arch index (AI) and centers of gravity balance are explored through the plantar pressure device. The foot posture is estimated to determine the rearfoot postural alignment. During the midstance phase of walking with a normal gait, the bipedal AI values of the elite group are significantly lower, indicating that they have high-arched feet. Additionally, the elite group experienced higher PPDs at the lateral regions of their longitudinal arches and heels and relatively lower PPDs at the medial portions of both feet. Rearfoot postural alignment resonance analysis of the PPDs suggests that the elite group experienced foot supination associated with cuboid dropped. Moreover, the right foot bears heavier centers of gravity balance in the present study. The elite tennis players in the study are categorized as having high-arched supination with cuboids dropped when performing daily habitual paces. This finding warrants further investigation into the correlation between possible injuries and daily habitual paces that may result from tennis’ intensive training and competition.

Effects of Plyometric Exercises versus Flatfoot Corrective Exercises on Postural Control and Foot Posture in Obese Children with a Flexible Flatfoot

BACKGROUND

Obesity contributes to the acquired flatfoot deformity which in turn impairs balance.

AIM

The purpose of the current study was to compare the effect of plyometric exercises with flatfoot corrective exercises on balance, foot posture, and functional mobility in obese children with a flexible flatfoot.

METHODS

Forty-seven children participated in the study. Their age ranged from 7 to 11 years. Participants were randomly divided into 3 groups: experimental group I (EGI), experimental group II (EGII), and the control group (CG). The EGI received plyometric exercises and the EGII received corrective exercises, 2 sessions weekly for 10 weeks. The control group did not perform any planned physical activities. The Prokin system was used to assess balance, the timed up and go test (TUG) was used to assess functional mobility, and the navicular drop test (NDT) was used to assess foot posture.

RESULTS

EGI showed significant improvement in all balance parameters, foot posture, and TUG. EGII showed improvement in the ellipse area and perimeter in addition to foot posture and TUG.

CONCLUSION

Plyometric exercises and foot correction exercises had a positive effect on foot posture, balance, and functional mobility in obese children with flatfeet.

Effects of Typical Athletic Shoes on Postural Balance According to Foot Type

BACKGROUND

The effects of shoes and foot type on balance are unclear. We aimed to investigate the differences between static and dynamic balance among three foot types and the changes in postural balance while wearing typical athletic shoes.

METHODS

Based on the Foot Posture Index, the feet of 39 participants were classified as pronated, neutral, or supinated by a physiatrist. Static and dynamic balance function were assessed by center of gravity (COG) sway velocity with eyes open and eyes closed and a modified Star Excursion Balance Test in a random order with participants either barefoot or wearing shoes.

RESULTS

The COG sway velocity was significantly higher in the supinated foot group than in the neutral foot group (barefoot: eyes open, P = .004, eyes closed, P = .001). Normalized composite reach distance (NCRD) was significantly lower in the pronated and supinated foot groups (barefoot: P = .039, P = .008; shoes: P = .018, P = .018). In all three foot type groups, COG sway velocity was significantly decreased (P < .05) and NCRD was significantly increased (P < .05) while wearing typical athletic shoes.

CONCLUSIONS

The medial longitudinal arch of the foot affects postural balance. Typical athletic shoes improve postural balance regardless of foot type. However, the pronated and supinated foot groups still had lower dynamic postural balance compared with the neutral foot group, even when wearing athletic shoes. People with pronated and supinated feet may need additional interventions, such as foot orthoses or balance training.

Effects of medial longitudinal arch flexibility on propulsion kinetics during drop vertical jumps

This study examined the effects of medial longitudinal arch (MLA) flexibility on kinetics during the eccentric and concentric subphases of a drop vertical jump (DVJ). Physically active adults with flexible (n = 16) and stiff (n = 16) MLA completed DVJs onto a force platform from a height of 30 cm. Eccentric and concentric subphases of the DVJ were identified from the vertical ground reaction force (GRF) data. Jump height, ground contact time, reactive strength index (RSI), vertical center-of-mass depth, vertical stiffness and time of the eccentric and concentric subphases were evaluated. Amortization force, peak vertical GRF and vertical impulse were also obtained for the eccentric and concentric subphases of the DVJ. Dependent variables were compared between groups using independent samples t-tests (p < 0.05). Significantly greater vertical stiffness (p = 0.048; ES = 0.63) was found in the stiff arch group (-173.91 ± 99.73 N/kg/m) compared to the flexible arch group (-122.95 ± 63.42 N/kg/m). A moderate-magnitude difference (ES = 0.58) was observed for RSI between flexible (0.89 ± 0.39) and stiff arch (1.20 ± 0.70) groups, but was not significant (p = 0.063). The active and passive structures supporting the MLA may be used differently to achieve similar vertical jump height during a DVJ. Additional research is warranted to further understand the contributions of MLA flexibility to jumping performance.