Influence of age, body mass index and leg dominance on functional ankle stability

Influence of age on static postural control in adults with type 2 diabetes mellitus: a cross-sectional study

Aim

It was the aim of this study to assess static postural control characteristics in people with type 2 diabetes mellitus (T2D) of different ages using a force platform. A relationship was also established between static postural control parameters and age in this study.

Methods

A total of 706 participants with T2D were included in this study. The participants were stratified into three age groups: Group 1 (<60 years old), Group 2 (60-70 years old), and Group 3 (>70 years old). Static postural control assessment during two-leg stance was performed on a force platform by all participants. The center of pressure (CoP)-related parameters were measured under two stance conditions (eyes open and closed). Kruskal-Wallis tests were applied to explore the difference among the different age groups. Multivariate regression analysis was performed to determine the relation between age and static postural control parameters.

Results

Group 1 (<60 years old) had significantly less CoP total tracking length (TTL), sway area (SA), and CoP velocity along the Y direction (V-Y) under both eyes-open and eyes-closed conditions compared with Group 2 (60-70 years old) and Group 3 (>70 years old). Group 1 (<60 years old) had significantly less CoP maximum sway length along the X direction (MSL_X) and longer tracking length each area unit (TTL/SA) under the eyes-open condition compared with Group 2 (60-70 years old) and Group 3 (>70 years old). There was a significantly positive correlation between age and the most static postural parameters such as CoP TTL, SA, MSL-X, MSL-Y, and V-Y. There was a significantly negative correlation between age and TTL/SA.

Conclusion

This study suggested that older T2D participants had worse static postural control ability than younger ones. Most static postural parameters presented a significant correlation with age; the higher the age, the worse the static postural control.

An association between excessive valgus hindfoot alignment and postural stability during single-leg standing in adolescent athletes

BACKGROUND

Diminished balance is associated with the incidence of ankle and lower extremity injuries in adolescents. Although flexible flatfoot is a common foot condition in pediatric and adolescent populations, the association between balance control and foot morphology remain unclear in adolescent athletes.

METHODS

Rearfoot angle in the double-limb standing position, body mass index (BMI), and isometric muscle strength related to the knee joint were retrospectively reviewed in 101 adolescent athletes (75 boys and 26 girls) with a mean age of 14.0 years (range 12-17). Postural stability during single-leg standing on static and dynamic platforms was investigated using Balance System SD in 119 feet without functional ankle instability. The participants were divided according to their rearfoot angle into control (less than 7°) and valgus (greater than or equal to 7°) groups. The measured parameters were compared between the control and valgus groups using Welch's t-test, and P values < 0.05 were considered statistically significant. Multiple regression analysis was conducted to identify the factors that significantly influenced postural control.

RESULTS

The average rearfoot angle was 4.6° in all participants. An excessive valgus rearfoot angle was detected in 53 feet (26.2%). No significant difference was found between the groups in terms of BMI and isometric knee muscle strength. Although no statistical differences were observed in postural stability on the static platform between the control and valgus groups, the valgus group demonstrated poorer postural stability for single-leg standing on the dynamic platform. Multiple regression analysis revealed that BMI and rearfoot angle were significantly associated with a poor postural control on the dynamic platform.

CONCLUSIONS

Our findings suggest that excessive rearfoot valgus specifically contributes to the deterioration of postural stability in adolescent athletes, and that rearfoot alignment should be evaluated for the adolescent population to prevent sports-related lower extremity injury.

Influence of the medial longitudinal arch of the foot in adult women in ankle isokinetic performance: a cross-sectional study

BACKGROUND

Maintenance of the medial longitudinal arch (MLA) of the foot is fundamental during functional tasks and disorders can lead to clinical alterations. Studies have demonstrated that deficits in ankle isokinetic performance can predispose an individual to lower limb injuries.

OBJECTIVES

To evaluate the muscular performance of cavus, planus, and normal feet by means of torque/body mass and the isokinetic phases, to generate 3D surface map analysis, and to verify whether there is a relationship between MLA height and arch height flexibility with isokinetic performance.

METHODS

The sample consisted of 105 healthy adult women, divided into three groups: normal, cavus, and planus. Assessment in concentric mode at 30, 60, and 90 °/s in the dorsiflexion and plantarflexion of the ankle joint were analyzed during the three isokinetic phases (acceleration, sustained velocity, and deceleration). The variables total range of motion, peak of torque (PT), and angle of PT were extracted within the sustained velocity.

RESULTS

In dorsiflexion at 60 °/s, the phase where the velocicty is sustained (load range phase) was higher in the planus group (M_eanD_ifference=10.9 %; ω²_p = 0.06) when compared with the cavus group. Deficits in the peak torque/body mass in dorsiflexion at 60 °/s (cavus feet: MD=-3 N.m/kg; ω²_p = 0.06; and planus feet: MD=-1.1 N.m/kg; ω²_p = 0.06) were also observed as well as in the 3D surface maps, when compared with the normal group. The flexibility of MLA had a negative correlation of PT at 30 °/s in cavus group. The heigth of MLA had a postive correlation with the PT for the cavus and planus group ate 60 °/s. All other results did not show differences between the groups.

CONCLUSIONS

The planus groups showed a better capacity of attain and sustained the velocity in dorsiflexion in relation the cavus group. The cavus and planus group had deficts in torque in relation the normal. The correlations were weak between the measures of MLA and PT. Thereby, in general the differences between foot types showed small effect in isokinetic muscle performance measures of the plantar and dorsi flexores.

TRIAL REGISTRATION

Study design was approved by the IRB (#90238618.8.0000.5231).

Immediate effects of myofascial release maneuver applied in different lower limb muscle chains on postural sway

BACKGROUND

There is little evidence about the myofascial release maneuver (MLM) targeting the fascial tissue and its effect on postural balance. This study investigated the immediate effects of the MLM in different lower limb muscle chains on the postural sway of healthy men.

METHODS

Sixty-three healthy men (27.2 ± 4.7 years) were randomly assigned to 7 groups (n = 9 each) to receive MLM applied to the lower limb muscle chains (anterior, posterior, medial, lateral, anterior/posterior, and medial/lateral) or placebo intervention. Skin pressure during the 3-min MLM was determined by the visual analog scale between 5 and 7 as previously assessed on participants. Posturography analysis of the elliptical area (Area) and average velocity (Vavg) of the center-of-pressure displacement was performed before and immediately after the MLM in single-leg support and with eyes closed.

RESULTS

A two-way repeated measures analysis of variance showed no interaction effect of factors group and time (Area: p = 0.210, ω² = 0.004; Vavg: p = 0.358, ω² < 0.001). Within-factor main effect of time was observed for both Area (p < 0.001, ω² = 0.038) and Vavg (p < 0.001, ω² = 0.028), with decreased Area and Vavg after all interventions. No between-factor main effect of group was observed for Area or Vavg (MLM or placebo, p = 0.188 or higher).

CONCLUSION

MLM applied to the lower limb muscle chains showed no immediate specific effects on postural sway in healthy men. Pre-post effects of MLM were not different from those elicited by a superficial massage. MLM in lower limb muscle chains is not advocated for an immediate improvement of postural balance in this population.

The role of the dominant leg while assessing balance performance. A systematic review and meta-analysis

BACKGROUND

Good balance is a pre-requisite for various activities of daily life and sports. Physiotherapists thus regularly assess and train patient's balance capacities. In order to interpret the test results of unilateral balance tests, a comparison with normative data is common. In patients who had an injury or a surgery, the performance of the injured leg is often compared with performance of the non-injured leg. Nevertheless, it remains unclear if unilateral balance performance differs between the dominant and non- dominant legs. If so, this should take into consideration when interpreting test results.

RESEARCH QUESTION

This meta-analysis summarized the current evidence to determine if the balance performance of healthy adults was influenced by the leg's dominance.

METHODS

Articles were searched in PubMed, CINAHL, Cochrane and Embase. Data from studies meeting the pre-defined inclusion criteria were extracted in a standardized form. A meta-analysis was conducted using a random effect model.

RESULTS

Forty-six studies were included. Their data were allocated in 7 categories of balance tests. Significant differences between the dominant and the non-dominant legs were not found in any of the categories (surface stable, eyes open: -0.04, 95 % CI -0.12 to 0.05, surface stable eyes closed: -0.06, 95 % CI -0.22 to 0.11, surface unstable, eyes open: -0.15, 95 % CI -0.38 to 0.07, surface unstable, eyes closed: -0.06, 95 % CI -0.27 to 0.15, BESS (Balance Error Scoring System): 0.03, 95 % CI -1.09 to 1.14, SEBT (Star Excursion Balance Test)/YBT (Y Balance Test): 0.06, 95 % CI -0.04 to 0.16, jump: 0.04, 95 % CI -0.28 to 0.36).

SIGNIFICANCE

Results indicate that balance performance is not influenced by the leg's dominance. This means that performances of both legs can be used as reference. Evidence is strong for the one leg stance. However, future studies are needed to confirm our results for stabilization tasks after a jump landing.

Hop Performance After Return to Sport in Anterior Cruciate Ligament-Reconstructed Gaelic Football and Hurling Athletes

PURPOSE

Anterior cruciate ligament (ACL) injuries are among the most severe injuries in the Gaelic Athletic Association. Hop tests measure functional performance after ACL reconstruction as they replicate the key requirements for a match situation. However, research examining functional recovery of ACL-reconstructed Gaelic athletes is lacking. The objective of this study is to determine if athletes restore normal hop symmetry after ACL reconstruction and to examine if bilateral deficiencies persist in hop performance following return to sport.

METHODS

A cross-sectional design was used to evaluate hop performance of 30 ACL-reconstructed Gaelic athletes who had returned to competition and 30 uninjured controls in a battery of hop tests including a single, 6-m, triple, and triple-crossover hop test.

RESULTS

In each test, the mean symmetry score of the ACL reconstruction group was above the cutoff for normal performance of 90% adopted by this study (98%, 99%, 97%, and 99% for the single, 6-m, triple, and triple-crossover hop, respectively). No significant differences in absolute hop scores emerged between involved and control limbs, with the exception of the single-hop test where healthy dominant limbs hopped significantly further than ACL-reconstructed dominant limbs (P = .02). No significant deficits were identified on the noninvolved side.

CONCLUSIONS

The majority of ACL-reconstructed Gaelic athletes demonstrate normal levels of hop symmetry after returning to competition. Suboptimal hop performance can persist on the involved side compared with control limbs. Targeted rehabilitation may be warranted after returning to competition to restore performance to levels of healthy uninjured athletes.

The effect of foot type, body length and mass on postural stability

BACKGROUND

Poor postural stability is associated with chronic ankle instability. Previous research showed an effect of foot type on postural stability. However, the specific effect of supinated feet remains unclear.

RESEARCH QUESTION

Our study aimed to assess the effect of foot type on postural stability, while taking potential confounding effects of body mass and body height into account.

METHODS

Forty-three healthy participants between 18 and 40 years old performed barefooted single leg stance tests with eyes open (EO) and closed (EC) on solid ground, and on a balance board (BB). Foot type was determined from pressure recordings during gait, using the arch index. Ground reaction forces were measured using a force plate. Outcome measures were Center of Pressure Velocity (COPV) divided by body height, and the Horizontal Ground Reaction Force (HGRF) divided by body mass. Generalized Estimating Equations models assessed the differences between supinated, normal and pronated feet during EO, EC and on a BB.

RESULTS

During EO an interaction between supinated feet and body mass showed an increase of COPV with 0.03 × 10^-2 1/s per kilogram of mass relative to normal feet (p = .03). During EC this interaction was more pronounced with 0.22 × 10^-2 1/s increase per kilogram mass (p < .01). The HGRF did not differ between foot types in any of the conditions.

SIGNIFICANCE

Supinated feet have a larger increase in COPV compared to normal feet with increasing mass when standing on solid ground during EO and EC. This indicates that people with supinated feet and a higher mass are less stable during single leg stance.

LEVEL OF EVIDENCE

Level 3, associative study.

Leg asymmetry and muscle function recovery after anterior cruciate ligament reconstruction in elite athletes: a pilot study on slower recovery of the dominant leg

The aim of this study was to examine performance in hopping tests in male athletes after anterior cruciate ligament reconstruction (ACLR) in the 4-to-6 months post-surgery period. A total of 36 athletes (24 ACLR and 12 controls) participated in this study. The ACLR group consisted of athletes who had undergone an ACLR on their dominant side (ACL DG n=16) or non-dominant side (ACL NDG n=8). Participants completed the following functional tests: a single-leg hop (SLH), single-leg triple hop (SL3H) and single-leg counter movement jump (SLCMJ), then the limb symmetry index (LSI) was calculated. There were no significant differences between the dominant and the non-dominant legs for all functional tests when comparing the ACL DG and the ACL NDG at 6 months after surgery. At 6 months after ACLR, the LSI of the two legs was within acceptable values, whether the athlete had the operation on their dominant or non-dominant leg (except the mean LSI for the ACL DG in the SLCMJ test). Furthermore, the control group showed higher performances as compared to the ACL group for all variables at 6 months after surgery, despite acceptable LSI. We concluded that an early return to “full participation to training” is not recommended in participants who have undergone an ACLR with patellar tendon grafts.

Weight, BMI and stability are risk factors associated with lateral ankle sprains and chronic ankle instability: a meta-analysis

IMPORTANCE

Lateral ankle sprains (LAS) are common in the general population and may lead to chronic ankle instability (CAI). If patients at risk could be identified, they could receive adequate and on-time treatment.

OBJECTIVE

The purpose of the current review was to identify all reported intrinsic factors associated with sustaining a LAS or progressing to CAI after an initial sprain.

EVIDENCE REVIEW

PubMed, Embase, MEDline, Cochrane and PEDro were searched for studies published until July 2019. Articles were selected if they included intrinsic factors related to LAS or CAI, subjects of at least 16 years old, and contained a minimum of 10 patients and 10 controls. Studies were excluded if they concerned reviews or case reports, included patients with previous surgical interventions, concomitant injuries or joint pathology other than ankle instability. Quality of included studies was assessed using the Quality in Prognostic Studies tool and quality of evidence was assessed using the GRADEpro tool. In case outcomes were described by at least three studies, data were pooled and assessed by performing a meta-analysis. Based on the pooled data, either a fixed-effects model or random-effects model was selected to correct for the degree of heterogeneity.

FINDINGS

The search resulted in a total of 4154 studies. After title and abstract screening and subsequent full-text screening, 80 relevant studies were included. Results of the meta-analyses indicated that, compared with healthy controls, patients with LAS had a higher mean body mass index (BMI). In patients with CAI, a higher weight and a longer time to stabilise after performing a task (eg, jumping) were found compared with healthy controls. Other outcomes could not be compared using a meta-analysis due to heterogeneity in outcome measurement and the great number of different outcomes reported. Identification of the risk factors when patients present themselves after a LAS may help to determine which patients are at risk of recurrent sprains or developing CAI.

CONCLUSIONS AND RELEVANCE

Based on the findings in this review, a higher BMI, and a higher weight and neuromuscular stability deficits may be regarded risk factors for sustaining a LAS or developing CAI, respectively.

LEVEL OF EVIDENCE

III.

Evaluation of functional ankle instability assessed by an instrumented wobble board

OBJECTIVES

Ankle sprains often lead to a history of recurrent injuries and functional joint instability. This study evaluated a new method for assessing functional impairment in patients with chronic ankle instability.

DESIGN

Case-control study for construct validation purpose.

SETTING

The participants were tested during one-leg standing for 20 s on an instrumented wobble board and on a balance platform.

PARTICIPANTS

Twenty-five young people with previous ankle sprain and an instability score >11 in the "Identification of Functional Ankle Instability questionnaire" and an age-matched control group of 25 healthy individuals.

MAIN OUTCOME MEASURES

Wobble board variation of tilt angle measured by two accelerometers placed horizontally in the board.

RESULTS

The variation in angular tilt of the wobble board in the medio-lateral direction (standard deviation of tilt angle) was higher in the group with perceived ankle instability than in the control group: 1.5 (0.7) versus 1.1 (0.3). ICC for intra-tester reliability: 0.87 and correlation with COP area measures from the stable balance platform: 0.64.

CONCLUSIONS

People with functional ankle instability display poorer postural stability in the medio-lateral direction when challenged on an unstable surface. The instrumented wobble board may serve as a relevant tool in the clinical evaluation of functional ankle stability.

Measuring the 3D motion space of the human ankle

BACKGROUND

The 3D motion space of the human ankle is an important area of study in medicine. The 3D motion space can provide significant information for establishing more reasonable rehabilitation procedures and standards of ankle injury care.

OBJECTIVE

This study aims to measure the 3D motion space of the human ankle and to use mathematical methods to quantify it.

METHODS

A motion capturing system was used to simultaneously capture the 3D coordinates of points marked on the foot, and convert these coordinate values into rotation angles through trigonometric functions and vectors. The mathematical expression of the ankle's motion space was obtained by screening, arranging, and fitting the converted data.

RESULTS

The mathematical expression of the 3D motion space of the participants was obtained. We statistically analyzed the data and learned that, in terms of 3D motion space, the right foot is more flexible than the left foot and the female foot is more flexible than the male foot.

CONCLUSIONS

The adduction and abduction rotation ranges are affected by the plantar flexion or dorsal flexure rotation angles. This relationship can be expressed mathematically, which is significant in the study of the ankle joint.

Postural sway in single-limb and bilateral quiet standing after unilateral total knee arthroplasty

AIM

To investigate whether total knee arthroplasty (TKA) was associated with stability in single-limb stance and whether reduced stability in single-limb stance was associated with increased postural sway in bilateral quiet standing.

METHODS

3D kinematics for center of mass was used to assess postural sway in 23 subjects with TKA and 23 controls. Tests included bilateral quiet standing with and without vision and on a compliant surface, and single-limb stance.

RESULTS

30% of the subjects in the TKA group were unable to maintain single-limb stance for 20s on any leg. Of the 70% in the TKA group able to stand on one leg, mean sway velocity in the medio-lateral direction was marginally higher for the prosthetic side (p=.02), but no differences were found between the TKA and the control group in single-limb stance. Performance in bilateral quiet standing was similar in TKA-subjects, able as well as unable to stand on one leg, and controls. Reduced quadriceps strength in the contralateral leg, higher BMI, and older age predicted failure to maintain single-limb stance.

CONCLUSION

In subjects able to stand on one leg, performance was considered comparable between the prosthetic and contralateral side and between groups. Inability to stand on one leg did not affect postural sway in bilateral quiet standing. The results suggest that inability to maintain single-limb stance is explained by reduced physical capacity rather than the knee condition in itself. The present study emphasizes the importance of physical activity to improve strength and functional capacity.

A large-scale study on epidemiology and risk factors for chronic ankle instability in young adults

Up to 40% of ankle sprains can result in chronic ankle instability (CAI). The prevalence of CAI and its association with body mass index (BMI) and height in the general young adult population has not been reported. The database records of young adults before recruitment into mandatory military service were studied. Information on the disability codes associated with CAI was retrieved. Logistic regression models were used to assess the association between the BMI and body height with various grades of CAI severity. The study cohort included 829,791 subjects (470,125 males and 359,666 females). The prevalence was 0.7% for mild CAI and 0.4% for severe instability in males and 0.3% and 0.4%, respectively, for females (p < .001). An increased BMI was associated with ankle instability in males (overweight, odds ratio [OR] 1.249, p < .001; obese, OR 1.418, p < .001) and females (overweight, OR 1.989 p < .001; obese, OR 2.754, p < .001). The body height was associated with an increased risk of CAI when the highest height quintile was compared with the lowest height quintile in both males (OR 2.443, p < .001) and females (OR 1.436, p < .001) for all levels of instability severity. The present study has shown a greater prevalence of CAI among males than females in a general healthy young adult population. CAI was associated with an increased BMI and greater body height for all grades of instability severity.

One-Leg Standing Performance and Muscle Activity: Are There Limb Differences?

The purpose of this study was to compare static balance performance and muscle activity during one-leg standing on the dominant and nondominant leg under various sensory conditions with increased levels of task difficulty. Thirty healthy young adults (age: 23 ± 2 years) performed one-leg standing tests for 30 s under three sensory conditions (ie, eyes open/firm ground; eyes open/foam ground [elastic pad on top of the balance plate]; eyes closed/firm ground). Center of pressure displacements and activity of four lower leg muscles (ie, m. tibialis anterior [TA], m. soleus [SOL], m. gastrocnemius medialis [GAS], m. peroneus longus [PER]) were analyzed. An increase in sensory task difficulty resulted in deteriorated balance performance (P< .001, effect size [ES] = .57−2.54) and increased muscle activity (P< .001, ES = .50−1.11) for all but two muscles (ie, GAS, PER). However, regardless of the sensory condition, one-leg standing on the dominant as compared with the nondominant limb did not produce statistically significant differences in various balance (P> .05, ES = .06−.22) and electromyographic (P> .05, ES = .03−.13) measures. This indicates that the dominant and the nondominant leg can be used interchangeably during static one-leg balance testing in healthy young adults.

The association between body composition and foot structure and function: a systematic review

The aim of this systematic review was to investigate the relationship between body composition and foot structure and function. Six electronic databases (Ovid MEDLINE, Ovid EMBASE, Ovid AMED, CINAHL, Scopus and The Cochrane Library) and reference lists from relevant papers were searched on 2 September 2013. Sixteen papers that reported on the association between body composition and foot structure and function met our inclusion criteria and were reviewed. The evidence indicates that obesity is strongly associated with planus (low-arched) foot posture, pronated dynamic foot function and increased plantar pressures when walking. However, there is limited evidence to support an association between other body composition measures, such as fat mass, with foot structure or function.

Muscular responses to handle perturbation with different glove condition

Effect of wearing gloves on timely muscle reaction to stabilize handle perturbation was investigated. Thirteen adults gripped a horizontal overhead handle to which an upward force was applied at a random time. Muscle reaction time, integrated EMGs for eight muscles, and handle displacement were compared among three glove conditions affecting the coefficient of friction (COF=0.32, 0.50, and 0.74 for the polyester glove, bare hand, and latex glove, respectively). Lower COF increased the integrated EMGs and handle displacement until stabilization of the perturbed handle. The low-friction glove resulted in 16% (p=.01) greater muscular effort and 20% (p=.002) greater handle displacement, compared to the high-friction glove. Muscle reaction time was not influenced by glove condition. Cutaneous sensation and reflex eliciting forearm muscle activity appear to play an important role in detecting and responding to the perturbation initially, while the forearm and latissimus dorsi muscles primarily contribute to stabilizing the perturbed handle compared to other shoulder and upper arm muscles. Therefore, low-friction gloves, cutaneous sensory dysfunction, and weakened forearm and latissimus dorsi muscles may jeopardize persons' ability to stabilize a grip of a handle after perturbation.

Comparative analysis of inter- and intraligamentous distribution of sensory nerve endings in ankle ligaments: a cadaver study

BACKGROUND

The aim of this study was to analyze the inter-, intraligamentous, and side-related patterns of sensory nerve endings in ankle ligaments.

METHODS

A total of 140 ligaments from 10 cadaver feet were harvested. Lateral: calcaneofibular, anterior-, posterior talofibular; sinus tarsi: lateral- (IERL), intermediate-, medial-roots inferior extensor retinaculum, talocalcaneal oblique and canalis tarsi (CTL); medial: tibionavicular (TNL), tibiocalcaneal (TCL), superficial tibiotalar, anterior/posterior tibiotalar portions; syndesmosis: anterior tibiofibular. Following immunohistochemical staining, the innervation and vascularity was analyzed between ligaments of each anatomical complex, left/right feet, and within the 5 levels of each ligament.

RESULTS

Significantly more free nerve endings were seen in all ligaments as compared to Ruffini, Pacini, Golgi-like, and unclassifiable corpuscles (P ≤ .005). The IERL had significantly more free nerve endings and blood vessels than the CTL (P ≤ .001). No significant differences were seen in the side-related distribution, except for Ruffini endings in right TCL (P = .016) and unclassifiable corpuscles in left TNL (P = .008). The intraligamentous analysis in general revealed no significant differences in mechanoreceptor distribution.

CONCLUSIONS

The IERL at the entrance of the sinus tarsi contained more free nerve endings and blood vessels, as compared to the deeper situated CTL. Despite different biomechanical functions in the medial and lateral ligaments, the interligamentous distribution of sensory nerve endings was equal.

CLINICAL RELEVANCE

The intrinsic innervation patterns of the ankle ligaments provides an understanding of their innate healing capacities following injury as well as the proprioception properties in postoperative rehabilitation.

Characteristics of human knee muscle coordination during isometric contractions in a standing posture: the effect of limb task

Different functional roles for the hands have been demonstrated, however leg control is not as well understood. The purpose of the present study was to evaluate bilateral knee neuromuscular control to determine if the limb receiving greater attention would have more well-tuned control compared to an unattended limb. Surface electrodes were placed on seven muscles of each limb, before standing on two force platforms. Visual feedback was given of the forces and moments of the "focus limb," but not the "unattended limb." Static isometric forces were matched with their focus limb, requiring their unattended limb to push in the opposite direction, using a combination of forward-backward-medial-lateral shear forces while muscle activity was collected bilaterally. There was a significant main effect for limb task (p = 0.02), with the medial hamstrings being more specific (p = 0.001) while performing the unattended limb and the lateral hamstring being more well-tuned (p = 0.007) while performing the focus limb task. The focus limb's medial and lateral gastrocnemius were principally active in the forwards direction, but only the unattended limb's lateral gastrocnemius was active in the backwards direction. Findings suggest unique neuromuscular control strategies are used for the legs depending on limb task.

[Neuromuscular deficits in chronic ankle instability. Frequency and significance - multicenter study]

The peroneal reaction time (PRT) is used in the assessment of neuromuscular deficits in chronic functional ankle instability. Powered by the Editorial Manager and Preprint Manager from Aries Systems Corporation the present study was conducted to determine the PRT in a large collective of patients with chronic ankle instability because it is unclear if this parameter of neuromuscular deficit is prolonged. In this study 186 patients underwent a diagnostic algorithm consisting of anamnesis, clinical examination, X-ray and determination of the PRT on a tilting platform. A prolonged PRT as a manifestation of a neuromuscular deficit could be detected in the majority of the patients (n = 143, 77%). Comparing the affected and healthy legs 77 patients (41%) showed a significant difference in talar shift (p = 0.002) and talar tilt (p = 0.04) in the radiological stress views. Of these 77 patients only 15 (8%) showed radiological evidence of a mechanical problem. As a consequence of recurring ankle sprains a post-traumatic deficit in proprioception has to be expected in most cases. In general a conservative therapy approach should be followed including specific training to improve neuromuscular and proprioceptive deficits.

The influence of playing level on functional ankle stability in soccer players

OBJECTIVE

The aim of this study was to compare the functional ankle stability between professional and amateur soccer players as well as controls.

MATERIALS AND METHODS

Thirty professional soccer players, 30 amateur soccer players and 30 controls were evaluated. All participants completed a questionnaire. Range of motion (ROM), peroneal reaction time (PRT) and ankle position sense were measured. Balance control was investigated with the Biodex Stability System, measuring the stable level 8 and the unstable level 2.

RESULTS

Professional soccer players cited significantly more frequent ankle sprains than all other groups (P = 0.002). They showed a significantly decreased dorsiflexion of the right foot (amateur: P = 0.017; controls: P = 0.004), an increased pronation of both feet (amateurs: right: P = 0.0048, left: P = 0.006; controls: right: P = 0.017, left: P = 0.007) and a decreased supination of the left foot in comparison to all other groups (amateurs: P = 0.003; controls: P = 0.004). Balance control showed no significant differences among all groups. Significant differences in angle reproduction were observed between professionals and amateurs for the left ankle joint at the positions of 105° (P = 0.0018) and 140° (P = 0.013). Professionals (P = 0.004) and amateurs (P = 0.001) showed a significantly delayed PRT of the right peroneus longus muscle compared to controls. In addition, the PRT of the right peroneus brevis muscle was significantly increased in professional soccer players in comparison to controls (P = 0.017).

CONCLUSIONS

Professional soccer players have shown more frequent ankle sprains, limited ROM, and delayed PRT of the right leg which reflects the higher risk of functional ankle instability due to intensified work-related use of feet. Therefore, proprioceptive exercises of the ankle in daily training programs are recommended in order to minimize the risk of ankle injuries and improve functional ankle stability.