Peroneus Longus Activity Research Articles

Comparison of the influence of supportive and sensorimotor insoles in the muscle activity of tibialis anterior and peroneus longus in combat boots

IntroductionFlatfoot is a very common static deformity. It occurs frequently in soldiers and causes problems in the lower extremities. There is a lack of data regarding therapy with insoles, especially with sensorimotor insoles. The objective of this study was to investigate the influence in muscle activity of supporting/correcting and sensorimotor insoles in combat boots in the muscles of the lower limb and thus to draw conclusions according to the benefits of insole therapy in military footwear. Methods73 patients (12 female, 61 males; average age: 30.8 ± 7.9 years) with pes planovalgus deformity were included in this prospective randomized placebo-controlled study. For intervention supporting (N = 23), sensorimotor (N = 28) and placebo insoles (N = 22) were used.During gait analysis muscle activity was measured by means of surface electromyography (EMG) of the tibialis anterior and peroneus longus muscle in combat boots with and without insoles. Statistical evaluation was performed using two-factor ANOVA with repeated measures. ResultsEMG measures (amplitude, integral, maximum, mean) showed mainly activating effects in the peroneus longus muscle in the case of sensorimotor and activity reductions in supporting insoles. Comparing effects of different kinds of insoles to the peroneus longus muscle, significant differences could be shown. No significant differences in muscular activation were observed for the tibialis anterior muscle. ConclusionEven in combat boots effects of sensorimotor insoles on the peroneus longus muscle can be detected. The expected effects, attributed to the different kinds of insole, could be observed, too. While sensorimotor insoles had an activating kind of effect, supportive insoles reduced muscular activity of the peroneus longus. In contrast for the tibialis anterior muscle no clear conclusion could be drawn. Its muscular activity seems not to be influenced by insoles in combat boots. However, it remains unclear whether clinical long term effects, e.g. pain and function, can be improved.

Influence of Landing in Neuromuscular Control and Ground Reaction Force with Ankle Instability: A Narrative Review.

Ankle sprains are generally the most common injuries that are frequently experienced by competitive athletes. Ankle sprains, which are the main cause of ankle instability, can impair long-term sports performance and cause chronic ankle instability (CAI). Thus, a comprehensive understanding of the key factors involved in repeated ankle strains is necessary. During jumping and landing, adaptation to the landing force and control of neuromuscular activation is crucial in maintaining ankle stability. Ankle mobility provides a buffer during landing, and peroneus longus activation inhibits ankle inversion; together, they can effectively minimize the risk of ankle inversion injuries. Accordingly, this study recommends that ankle mobility should be enhanced through active and passive stretching and muscle recruitment training of the peroneus longus muscles for landing strategies should be performed to improve proprioception, which would in turn prevent ankle sprain and injury to neighboring joints.

Elucidation of abductor digiti minimi activity in chronic ankle instability.

[Purpose] This study aimed to compare the muscle activity around the foot and ankle joints, notably of the abductor digiti minimi, between affected and unaffected sides of individuals with chronic ankle instability. [Participants and Methods] Twelve adult males with chronic ankle instability in one ankle (age, 27.7 ± 5.4 years; height, 172.5 ± 8.1 cm; weight, 67.5 ± 8.1 kg) were included and underwent surface electromyography assessments in multiple positions on both affected and unaffected sides. Measurements were obtained for eight muscles including the abductor digiti minimi. Each measurement included a 5-s segment of the stable waveform, with the root mean square-processed and normalized to the resting position set to 1. [Results] Abductor digiti minimi activity on the affected side was significantly reduced during maximal toe extension/abduction with both ankle dorsiflexion and plantarflexion. Peroneus longus activity on the affected side was significantly greater during maximal toe extension/abduction with ankle plantarflexion; peroneus longus and tibialis anterior muscle activities were significantly greater on the affected side during maximal toe extension/abduction with ankle dorsiflexion. [Conclusion] In the absence of load, muscle imbalance in the intrinsic and extrinsic muscles of the foot was suggested. However, no significant differences were observed under loading conditions.

Effect of Peroneus Longus Muscle Release on Abductor Hallucis Muscle Activity and Medial Longitudinal Arch before Toe-Tap Exercise in Participants with Flexible Pes Planus.

Pes planus is a medical condition of the foot wherein there is a flattening or lowering of the medial longitudinal arch. The abductor hallucis muscle starts at the heel bone and attaches to the medial side of the first toe. Whenever it contracts, it plays a key role in elevating the medial longitudinal arch. Hence, the abductor hallucis muscle should be strong enough to control the depression on the medial longitudinal arch. The peroneus longus muscle plantarflexes the ankle and everts the ankle and subtalar joint. If this muscle contracts more than the abductor hallucis muscle does, the medial longitudinal arch of the foot is depressed. This study aimed to investigate the effect of myofascial release of the peroneus longus before performing the toe-tap exercise for strengthening the abductor hallucis muscle in participants with flexible pes planus. This cross-over study included 16 volunteers with flexible pes planus. The participants performed a toe-tap exercise before and after the myofascial release of the peroneus longus. During the toe-tap exercise, the muscle activity of the abductor hallucis and peroneus longus were measured using a Delsys Trigno Wireless Electromyography System. The angle of the medial longitudinal arch was measured using Image J software. Photos in the sagittal plane were used. The peroneus longus activity and medial longitudinal arch angles were significantly decreased. On the other hand, the activity of the abductor hallucis significantly increased after the myofascial release of the peroneus longus before performing the toe-tap exercise (p < 0.05). Individuals with flexible pes planus should be encouraged to perform myofascial release of the peroneus longus before the toe-tap exercise to improve the abductor hallucis activity and to elevate the medial longitudinal arch.

Assessment of a New Lateral Cushioned Casting Orthosis: Effects on Peroneus Longus Muscle Electromyographic Activity During Running

Background:Classical medial wedge (CMW) orthoses have been prescribed to treat overpronation foot pathologies in runners. The effects of a novel supination orthosis (NSO) on the surface electromyography (EMG) activity of the peroneus longus (PL) muscle during a complete cycle of running have yet to be tested.Purpose/Hypothesis:The purpose of this study was to compare the EMG activity of the PL in participants wearing CMW orthoses and NSOs versus neutral running shoes (NRS) during a full cycle of running gait. It was hypothesized that the PL muscle activity would be lower for the NSO compared with CMW or NRS.Study Design:Controlled laboratory study.Methods:Included were 31 healthy recreational runners of both sexes (14 male and 17 female; mean age, 38.58 ± 4.02 years) with a neutral Foot Posture Index and standard rearfoot-strike pattern. Participants ran on a treadmill at 9 km/h while wearing NSO (3-, 6-, and 9-mm thicknesses), CMW (3-, 6-, and 9-mm thicknesses), and NRS, for a total of 7 different conditions randomly selected, while the EMG signal activity of the PL was recorded for 30 seconds. Each trial was recorded 3 times, and the intraclass correlation coefficient (ICC) to test reliability of the measurements was calculated. The Wilcoxon pair to pair nonparametric test with Bonferroni correction was performed to analyze differences among the conditions.Results:The reliability of all assessments was almost perfect (ICC, >0.81). For both the CMW and NSO, regardless of thickness, the PL activity was statistically significantly lower compared with the NRS (P < .05 for all). For all CMW thicknesses, the PL activity was lower compared with the respective NSO thicknesses, with the 3-mm thickness having the largest difference (CMW3mm, 18.63 ± 4.64 vs NSO3mm, 20.78 ± 4.99 mV; P < .001).Conclusion:Both CMW and NSO produced reduced EMG activity of the PL muscle; therefore, they can be prescribed to treat overpronation pathologies without associated PL strain concerns. In addition, the NSO saved the enhancement material placed on the medial-rear side of CMW, making it easier to wear sports shoes.Clinical Relevance:Knowing the safety of CMW and NSO will aid in understanding treatments for overpronation pathologies.

Ankle muscles drive mediolateral center of pressure control to ensure stable steady state gait

During steady-state walking, mediolateral gait stability can be maintained by controlling the center of pressure (CoP). The CoP modulates the moment of the ground reaction force, which brakes and reverses movement of the center of mass (CoM) towards the lateral border of the base of support. In addition to foot placement, ankle moments serve to control the CoP. We hypothesized that, during steady-state walking, single stance ankle moments establish a CoP shift to correct for errors in foot placement. We expected ankle muscle activity to be associated with this complementary CoP shift. During treadmill walking, full-body kinematics, ground reaction forces and electromyography were recorded in thirty healthy participants. We found a negative relationship between preceding foot placement error and CoP displacement during single stance; steps that were too medial were compensated for by a lateral CoP shift and vice versa, steps that were too lateral were compensated for by a medial CoP shift. Peroneus longus, soleus and tibialis anterior activity correlated with these CoP shifts. As such, we identified an (active) ankle strategy during steady-state walking. As expected, absolute explained CoP variance by foot placement error decreased when walking with shoes constraining ankle moments. Yet, contrary to our expectations that ankle moment control would compensate for constrained foot placement, the absolute explained CoP variance by foot placement error did not increase when foot placement was constrained. We argue that this lack of compensation reflects the interdependent nature of ankle moment and foot placement control. We suggest that single stance ankle moments do not only compensate for preceding foot placement errors, but also assist control of the subsequent foot placement. Foot placement and ankle moment control are ‘caught’ in a circular relationship, in which constraints imposed on one will also influence the other.

Immediate effects of footwear with vibration applied to the swing phase of the gait cycle on dynamic balance in patients with diabetic peripheral neuropathy

Sensory and sub-sensory foot vibration have beneficial effects on the static and dynamic balance of patients with diabetic peripheral neuropathy (DPN). Previous foot vibration during walking was applied at sub-sensory threshold in both stance and swing phases of the gait cycle in DPN. This study aimed to investigate the effects of footwear with vibration above the sensory threshold applied to the swing phase of the gait cycle on the dynamic balance of DPN. Fifteen patients with DPN and 10 matched healthy control participants were enrolled in this study. Dynamic balance assessment was investigated by the sit to stand and turn tests while electromyography activity (root mean square, RMS) of the vastus lateralis (VL), tibialis anterior (TA), and peroneus longus (PL) muscles were recorded at baseline, after 10 min of wearing the vibratory sandal without vibration, and after 10 min of wearing the sandal with vibration. Repeated measure analysis of variance was conducted for data analysis. Wearing the vibratory sandal slightly increased the speed of weight transfer in both groups and COP sway in DPN (P > 0.05), and close to significant decrease of turn sway (P = 0.07) in both groups. There were significant differences of the PL RMS in turn test (P = 0.03) in DPN and peak RMS of the PL after 10 min of wearing the sandal with vibration in both groups (P < 0.05). The results of the present study demonstrated that PL activity was significantly influenced by the vibratory sandal as its tendon passing across the sole and in direct contact with the source of the vibration.

Six-Week Remodeled Bike Pedal Training Improves Dynamic Control of Lateral Shuffling in Athletes With Functional Ankle Instability.

Remodeled bicycle pedal training with multidirectional challenges through muscle strengthening and neuromuscular facilitation may increase dynamic postural control and performance during lateral shuffling for athletes with functional ankle instability (FAI). The 6-week remodeled bicycle pedal training is effective on the ankle joint control and muscle activation, and especially that of the ankle evertor muscle co-contraction to improve dynamic postural control during lateral shuffling for athletes with FAI. Laboratory randomized controlled trial. Level 2. Fourteen healthy athletes (healthy group) and 26 athletes with FAI aged 18 to 30 years were included in the study. The athletes with FAI were randomly assigned to either the training group (FAI-T group) or the nontraining group (FAI-NT group). The athletes in the FAI-T group underwent 6 weeks of remodeled bicycle pedal training, whereas those in the FAI-NT group did not undergo any intervention. Muscle co-contraction index and muscle activation in the initial contact (IC) and propulsion phases, and ankle joint angle in the IC and propulsion phases were measured during lateral shuffling before and after 6 weeks of training. After remodeled bicycle pedal training, the FAI-T group demonstrated greater muscle activation in the hamstring (P = 0.01), greater muscle coactivation of the tibialis anterior (TA) and the peroneus longus (P = 0.01), and greater ankle eversion angle in the IC phase. Significantly greater muscle activation of the TA (P = 0.01), greater coactivation of quadriceps and hamstring (P = 0.03), and a smaller ankle inversion angle (P = 0.04) in the propulsion phase were observed in the FAI-T group after training compared with those in the FAI-NT group. Remodeled bicycle pedal training facilitates the TA and peroneus longus activation and the coactivation of the quadriceps and hamstring muscles during lateral shuffling and resulted in enhanced ankle and knee joint stability. In addition, a better ankle movement strategy during a dynamic task can be achieved via a 6-week remodeled pedal training program. This remodeled bicycle pedal training can be effective for rehabilitating athletes with FAI to recover lateral dynamic movement capability.

Acute Effect of Ankle Kinesio™ Taping on Lower-Limb Biomechanics During Single-Legged Drop Landing.

Chronic ankle instability is documented to be followed by a recurrence of giving away episodes due to impairments in mechanical support. The application of ankle Kinesiotaping (KT) as a therapeutic intervention has been increasingly raised among athletes and physiotherapists. This study aimed to investigate the impacts of ankle KT on the lower-limb kinematics, kinetics, dynamic balance, and muscle activity of college athletes with chronic ankle instability. A crossover study design. Twenty-eight college athletes with chronic ankle sprain (11 females and 17 males, 23.46 [2.65]y, 175.36 [11.49]cm, 70.12 [14.11]kg) participated in this study. The participants executed 3 single-leg drop landings under nontaped and ankle Kinesio-taped conditions. Ankle, knee, and hip kinematics, kinetics, and dynamic balance status and the lateral gastrocnemius, medial gastrocnemius, tibialis anterior, and peroneus longus muscle activity were recorded and analyzed. The application of ankle KT decreased ankle joint range of motion (P = .039) and angular velocities (P = .044) in the sagittal plane, ground reaction force rate of loading (P = .019), and mediolateral time to stability (P = .035). The lateral gastrocnemius (0.002) and peroneus longus (0.046) activity amplitudes also experienced a significant decrease after initial ground contact when the participants' ankles were taped, while the application of ankle KT resulted in an increase in the peroneus longus (0.014) activity amplitudes before initial ground contact. Ankle lateral supports provided by KT potentially decreases mechanical stresses applied to the lower limbs, aids in dynamic balance, and lowers calf muscle energy consumption; therefore, it could be offered as a suitable supportive means for acute usage in athletes with chronic ankle instability.

보행 시 만성 발목 불안정성 환자의 근육 활성도 변화

The present study aimed to investigate differences in muscle activation of peroneus longus (PL) and tibialis anterior (TA) among individuals with chronic ankle instability (CAI), copers, and heatlhy controls during walking and running. A total of 54 participants were recruited for this study. 54 participants were equally assigned to the CAI, coper, and control groups based on eligibility criteria for each group. Two surface electromyography (sEMG) were attached to PL and TA of the affected leg and 33 reflective markers were also attached to the landmark of participants based on the Visual 3D marker set. All participants were instructed to walk and run at the speed of 1.34 m/s with a boundary of 0.07 m/s and 2.68 m.s with a boundary of 0.14 m/s along the 8 m walkway. Three valid gait trials were recorded and analyzed. The full gait cycle from initial contact (IC) of the affected leg to next IC of the same leg were normalized to 100%. All sEMG data were normalized by the amplitude during maximum voluntary contraction of each participant. Ensemble curve analyses with mean ± 90% confidence intervals were conducted to identify mean differences in the amplitude of two muscles among three groups. The CAI group showed the greater amplitude of PL during walking than the coper and control groups during walking. Individuals with CAI exhibited the altered muscle activation of TA compared with copers and controls during walking. In addition, our findings indicated that there were significantly different in muscle activation of both of PL and TA between the CAI and non-CAI groups during running. Given our results, individuals with CAI need to improve joint stability using pre-activation before IC during gait.

Effects of corrective insole on leg muscle activation and lower extremity alignment in rice farmers with pronated foot: a preliminary report

BackgroundExecution of strenuous activities in conjunction with slippery and viscous muddy working terrain in rice cultivation leads to a high prevalence of farmer musculoskeletal disorders and malalignments. Recommended intervention strategies originally designed for congenitally disabled individuals may also be applicable to farmers, including simple corrective wedges to reduce foot eversion. The objective of the present study was to conduct a preliminary investigation of the effects of corrective wedges on lower extremity muscle activity and alignment when subjects stood on flat rigid ground or muddy terrain, simulating typical work conditions encountered by the unique but populous Thai rice farming workforce. MethodsNine healthy farmers with pronated feet were recruited to participate and wedges were custom fabricated for each farmer based on physical therapy assessment and use of rapid prototyping techniques. Participants were asked to stand barefoot or with wedges on the two surface types. ResultsResults revealed foot pronation and knee valgus to improve (ranging, on average between 5.5 and 16.1 degrees) when participants were equipped with corrective wedges. The muscle activity of the peroneus longus and the tibialis anterior increased for muddy terrain, as compared with the rigid surface. In general, the wedges induced less tibialis anterior activity and greater peroneus longus activity, compared to when participants were standing barefoot. An elevation in evertor muscle activity may reflect stretching of the shortened muscle as a result of the reduced degree of foot pronation. ConclusionsFindings demonstrate potential benefits of corrective insole usage for farmers with pronated feet, including improved lower extremity alignment and invertor muscle activity reduction for both rigid and muddy terrains.

Ankle muscle activation during the limits of stability test in subjects with chronic ankle instability

ObjectiveTo study postural control and muscle activity during the limit of stability test (LOS) in subjects with chronic ankle instability. DesignObservational study. SettingUniversity laboratory. Participants10 healthy subjects were included in the control group and 10 subjects in the CAI group (age between 18 and 30 years, with history of the multiple ankle “giving way” episodes in the last six months and score ≤24 in the Cumberland Ankle Instability Tool). Main outcome measuresA computerized dynamic posturography equipment was used for assessing the LOS. The electromyography activity of tibialis anterior (TA), soleus (SOL), medial gastrocnemius (MG) and peroneus longus (PL) was registered. ResultsSubjects with CAI had a greater activation in TA to forward (p < .01), forward affected (p = .001), backward affected (p = .007) and backward directions (p < .01); in PL to forward affected (p < .01) and affected directions (p = .001); in MG to forward (p = .023) and affected directions (p < .01) and in SOL to the affected direction (p = .009). We observed restricted excursions and less directional control in subjects with CAI. ConclusionsSubjects with CAI exhibited poorer ability to move their center of gravity within stability limits. In addition, they have an altered ankle muscle activity during LOS test toward the affected ankle joint.

The influence of footwear on walking biomechanics in individuals with chronic ankle instability.

Background/PurposeThe effects of footwear on the walking kinematics, kinetics and electromyography (EMG) of individuals with chronic ankle instability (CAI) at different speeds are still unknown. The objective of this cross-sectional study was to evaluate the kinematic, kinetic and electromyography differences between shod and barefoot walking at comfortable (CW) and fast (FW) speeds in individuals with CAI.MethodsTwenty-one individuals with CAI walked on a 5-meter walkway shod and barefoot at CW and FW speeds. A force plate was used to record the ground reaction forces, a 3-D motion analysis system to record the lower limb kinematics and a surface EMG system to collect the gluteus medius, vastus lateralis, gastrocnemius lateralis, gastrocnemius medialis, peroneus longus and tibialis anterior muscles activity. The dependent variables were ankle and knee angles and moments and normalized muscle activity. The shod and barefoot data during CW and FW were compared using a one-dimensional non-parametric mapping analysis.ResultsThe main results of this study were that individuals with CAI exhibited more ankle dorsiflexion angle, knee extension and tibialis anterior muscle activation during the beginning of the stance phase during shod compared to barefoot walking. Also, the biomechanical effects of shoes are similar during walking at FW and CW.ConclusionThe biomechanical deficits associated with CAI were partly attenuated during the shod compared to the barefoot condition and these effects were similar at CW and FW. These findings are compatible with the concept that locomotor interventions using suitable shoes may enhance gait abilities in individuals with CAI.

Effect of non-elastic closed-basket weave ankle taping on muscle activity of tibialis anterior, peroneus longus, medial, and lateral gastrocnemius during jump landing on a hard, flat surface in healthy individuals: a pilot study

Effect of non-elastic closed-basket weave ankle taping on muscle activity of tibialis anterior, peroneus longus, medial, and lateral gastrocnemius during jump landing on a hard, flat surface in healthy individuals: a pilot study

Effect of Isometric Hip Abduction on Foot and Ankle Muscle Activity and Medial Longitudinal Arch During Short-Foot Exercise in Individuals With Pes Planus.

The improvement of hip joint stability can significantly impact knee and rearfoot mechanics. Individuals with pes planus have a weak abductor hallucis (AbdH), and the tibialis anterior (TA) may activate to compensate for this. As yet, no studies have applied isometric hip abduction (IHA) for hip stability during short-foot exercise (SFE). To compare the effects of IHA on the muscle activity of the AbdH, TA, peroneus longus (PL), and gluteus medius (Gmed), as well as the medial longitudinal arch (MLA) angle during sitting and standing SFE. Two-way repeated analyses of variance were used to determine the statistical significance of AbdH, TA, PL, and Gmed electromyography activity, as well as the change in MLA angle. University research laboratory. Thirty-two participants with pes planus. The participants performed SFE with and without isometric hip abduction in sitting and standing positions. Surface electromyography was used to measure the activity of the AbdH, TA, PL, and Gmed muscles, and Image J was used to measure the MLA angle. Significant interactions between exercise type and position were observed in terms of the PL muscle activity and in the change in MLA angle only, while other muscles showed significant main effects. The IHA during SFE significantly increased the AbdH muscle activity, while the TA muscle activity was significantly lower. The muscle activity of Gmed and PL was significantly increased in the standing position compared with sitting, but there was no significant difference with or without IHA. The change in the MLA angle was significantly greater in SFE with IHA in a standing position than in the other SFE conditions. IHA may be an effective method for reducing compensatory TA activity and increasing AbdH muscle activity during SFE for individuals with pes planus.

The effect of ankle Kinesio™ taping on ankle joint biomechanics during unilateral balance status among collegiate athletes with chronic ankle sprain

ObjectivesTo determine the effects of ankle Kinesio-taping (KT) on postural sway, lower limb ROM, and muscle activity during a unilateral balance tasks. DesignCase control study design. SettingData were collected at the human movement analysis laboratory. Participants30 collegiate athletes with chronic ankle sprain (11 females and 19 males, 23.91 ± 2.58 years). Main outcome measureHip, knee and ankle joints ranges of motion (ROMs); postural sway area and velocities in both anteroposterior and mediolateral directions; and muscular activity amplitudes (% peak) of lateral and medial gastrocnemius, tibialis anterior and peroneus longus in a 20s single leg balance test in two non-taped (control) and KT (intervention) conditions. ResultsSignificant decrease observed in ankle lateral ROM (p = 0.048, d = 0.52), mediolateral postural sway velocity (p = 0.029, d = 1.25), and peroneus longus activity amplitudes (p = 0.042, d = 0.55) after KT application. ConclusionAcute application of KT among athletes with chronic ankle instability could provide lateral mechanical support to the ankle, potentially decreasing the velocity of frontal plane sway, and decreasing the magnitude of muscle activation. These data suggest that KT may be beneficial for improving static joint stability among individuals with chronic ankle sprain, and thus could be considered an option to allow safe return-to-activity.

Effects of 4-week impairment-based rehabilitation on jump-landing biomechanics in chronic ankle instability patients

ObjectiveTo determine effects of 4-weeks of impairment-based rehabilitation on lower extremity neuromechanics during jump-landing. DesignDescriptive laboratory study. ParticipantsTwenty-six CAI subjects (age = 21.4 ± 3.1 sex=(M = 7,F = 19), height = 169.0 ± 8.8 cm, weight = 71.0 ± 13.8 kg) completed 15 jump-landing trials prior to and following 12 supervised rehabilitation sessions. Main outcome measuresFrontal and sagittal lower extremity kinematics and kinetics and sEMG amplitudes (anterior tibialis, peroneus brevis, peroneus longus, and medial gastrocnemius). Means and 90% confidence intervals (CIs) were calculated for 100 ms prior to and 200 ms following ground contact. Areas where pre- and post-rehabilitation CIs did not overlap were considered significantly different. Kinematic and kinetic peaks and kinematic excursion were compared with paired t-test (P ≤ 0.05). ResultsFollowing rehabilitation, CAI subjects exhibited less ankle (2.1° (0.8, 3.4), P < 0.01) and hip (2.0° (0.5, 3.7), P = 0.01) frontal plane excursion and lower peak hip abduction (2.5° (0.0, 5.0), P = 0.05). There was less ankle (5.0° (1.7, 8.3), P < 0.01) and knee (3.4° (0.8, 6.0), P = 0.01) sagittal plane excursion following rehabilitation. There was decreased peroneus longus activity from 9 ms to 135 ms post ground contact and decreased peak plantar flexion moment (0.08 N∗m/kg (0.01, 0.13), P = 0.02) following rehabilitation. ConclusionProgressive impairment-based rehabilitation resulted in reductions in kinematic excursion and peroneus longus muscle activity, suggesting a more efficient landing strategy.

The Effect of Hopping Exercises on the Feedforward and Feedback Activity and Start Time of Selected Lower Limb Muscles in Athletes with Functional Ankle Instability in Single Leg Jump Task

Introduction : The aim of this study was to investigate the effect of hopping exercises on the feedback and feedforward activity of selected lower limb muscles in single leg jump landing task in athletes with functional ankle instability. Materials and Methods: 24 male athletes (12 in the control group and 12 in the training group) with functional ankle instability participated in this randomized clinical trial. Hopping exercises were given for six weeks, three times a week to the experimental group. The control group continued their routine exercise three sessions per week. The electric activity of Peroneus Longus, Tibialis Anterior, Medial Gastrocnemius, gluteus medius, and gluteus maximus muscles in the jump landing, before and after the hopping exercises were collected. Results: The results of this study showed that after six weeks of hopping exercises, there was a significant effect on the onset of activity of the Peroneus Longus and gluteus medius muscles (P ≤ 0.001). There was a significant increase in the activity of Peroneus Longus (P ≤ 0.003), Medial Gastrocnemius (P ≤ 0.005), and gluteus medius (P ≤ 0.001) muscles in 100 milliseconds before the first contact of the foot on the ground. In addition, Peroneus Longus (P ≤ 0.001) and gluteus medius (P ≤ 0.001) activity increased significantly between 100-200 milliseconds after the first contact of the foot on the ground. However, no significant difference was observed in muscle activity of the untreated control group (P > 0.050). No significant change was recorded in the activity of the Tibialis Anterior, Medial Gastrocnemius, and gluteus maximus muscles (P > 0. 050). Conclusion : Six weeks of hopping exercises seem to reduce the time interval before the onset of activity and increase the activity amplitude for aforementioned muscles in single leg jump landing in athletes with functional ankle sprain. Therefore, while planning therapeutic exercise programs for athletes with functional ankle instability, it may be beneficial to have a look at hoping exercises.

THE EFFECTS OF MULTIPLE MODALITIES OF COGNITIVE LOADING ON DYNAMIC POSTURAL CONTROL IN INDIVIDUALS WITH CHRONIC ANKLE INSTABILITY

BackgroundEvidence of neuroplasticity after joint injury has suggested that individuals with chronic ankle instability (CAI) may have degraded movement when facing cognitive demand. To date, research into these effects have been limited to static balance models, and typically only incorporate a single type of cognitive demands. Research questionWe aimed to determine the effects of multiple modalities of cognitive load (quantitative, verbal-memory, visuospatial) on dynamic postural control strategies in a sample of patients with CAI compared to uninjured controls. MethodsThirty-two participants (16 CAI, 16 healthy) performed a series of 20 hops-to-stabilization while either under no cognitive load (CON), or while performing Benton’s judgment of line orientation (JLO), the symbol digit modalities test (SDM), or a serial seven task (SVN). Dynamic postural stability indices and mean muscle activation from the lower leg muscles were extracted and assessed via analysis of variance. ResultsHealthy subjects demonstrated better vertical and dynamic postural stability indices under JLO (P ≤ 0.017) and SVN (P ≤ 0.010) conditions compared to CON. Postural stability was unaffected in CAI (P > 0.050). Peroneus longus and lateral gastrocnemius activation was lowest in SVN across all subjects (P ≤ 0.033). Lateral gastrocnemius activation was greatest in SDM (P ≤ 0.033). SignificanceThese results suggest improvements in postural stability under cognitive demand in healthy individuals that did not occur in CAI, suggesting less movement optimization. Quantitative tasks appear to impede stabilizing muscle activation in the leg, while verbal-memory tasks result in a more protective landing strategy.

Effect of a task’s postural demands on medial longitudinal arch deformation and activation of foot intrinsic and extrinsic musculatur

It is not well established how motion and muscle activation of the medial longitudinal arch (MLA) of the foot vary under different loading conditions. Intrinsic and extrinsic foot muscles may play a role in postural control, which may be investigated by comparing loading tasks with differing postural demands. The objective of this study was to investigate the interaction of MLA flexibility and loading task on muscle activation. Twenty healthy adults completed two instrumented single-foot loading tasks: controlled external load of 50% body weight while sitting and bilateral standing. Fine-wire intramuscular and surface electromyography collected flexor hallucis brevis, abductor hallucis, tibialis posterior, flexor hallucis longus, tibialis anterior, and peroneus longus activation. MLA deformation was measured as a percent change in navicular height with loading. During seated external loading, greater MLA deformation was associated with greater muscle activation for all instrumented muscles (R² = 0.224-0.303, p < 0.05) except for tibialis anterior. During bilateral stance, there were no correlations between MLA deformation and muscle activation. Activation of all extrinsic muscles except for tibialis anterior were greater during bilateral standing than during external loading ( p = 0.002-0.013), indicating activation of these muscles was caused by postural demands of the standing task, not simply load. MLA deformation and muscle activation are strongly task-dependent.