Sudden Inversion Research Articles

Avaliação do tempo de resposta eletromiográfica em atletas de voleibol e não atletas que sofreram entorse de tornozelo

A proposta deste estudo foi examinar o tempo de resposta eletromiográfica dos músculos fibulares, na inversão repentina do pé, em tornozelos com presença de lesão e saudáveis. Três grupos foram testados, um de atletas normais (grupo 1), um de atletas com história recente de entorse de tornozelo (grupo 2) e o outro de não atletas com história recente de entorse de tornozelo (grupo 3). Para cada sujeito dos três grupos, ambos os tornozelos foram testados. Os sujeitos que sofreram entorse de tornozelo (grupos 2 e 3) não apresentavam sintomas de lesão durante os últimos dois meses antes do teste. Uma plataforma capaz de produzir uma inversão repentina lateral de 20° do tornozelo no plano frontal simulava um evento de entorse de tornozelo. Eletrodos de eletromiografia de superfície foram colocados na pele sobre os músculos fibulares. Os tempos de resposta eletromiográfica dos músculos fibulares foram obtidos e comparados entre os grupos. Para o grupo 1, a média dos tempos de resposta eletromiográfica foi de 71ms para a perna direita e 69ms para a perna esquerda. Para o grupo 2, a média dos tempos de resposta eletromiográfica foi de 72ms para o tornozelo sem lesão e 74ms para o tornozelo com a lesão. Para o grupo 3, a média dos tempos de resposta eletromiográfica foi de 72ms para o tornozelo sem lesão e 73ms para o tornozelo com a lesão. Os resultados indicaram que não houve diferença estatisticamente significante entre as pernas direita e esquerda no grupo 1 e entre os tornozelos sem lesão e com lesão dos grupos 2 e 3 para os músculos fibulares. Os achados do presente estudo sugerem que a resposta eletromiográfica dos músculos fibulares, durante o deslocamento angular repentino do tornozelo, não foi influenciada pela entorse de tornozelo.

Joint Stabilizing Response to Expected and Unexpected Tilts

The results found in the literature regarding functional ankle joint stabilization are controversial possibly because of the testing methods used. The responses of 22 subjects to unexpected and expected sudden inversions of the foot were compared for all subjects together, as well as grouped by their self-perceived stability. A three-dimensional foot model was used to describe ankle and foot motion. Electromyographic signals of six muscles of the lower limb as well as the horizontal ground reaction forces were recorded. Whereas unexpected and expected trials did not show significant differences (p > 0.05) in kinematics, higher activation and horizontal force integrals were found for the unexpected trials. In addition, no differences in electromyographic or ground reaction force parameters were found between stable and unstable ankles; however, the kinematics revealed higher amplitudes and velocities for the stable group. The awareness of the instant of tilt enhances stabilization in that the same motion is achieved with a lower muscle activation. Evidence suggests that this is triggered at supraspinal levels. We found that timing of the EMG signal is not as relevant to stabilization as the amplitude (which has often been disregarded in the literature).

The effect of different ankle brace–skin interface application pressures on the electromyographic peroneus longus reaction time

Electromyographic peroneal reaction time measurements is a well established and reliable method of assessing the dynamic defence mechanism of the ankle joint against ankle sprains. Ankle bracing has been proved to be an effective prophylactic measure against injury since it restricts joint ROM. However, its role in improving the dynamic defence mechanism of the ankle according to the skin–brace interface application pressure, is unclear. The aim of this study was to investigate the effect of different pressures of ankle brace application in the peroneus longus reaction time. Thirty-three young, male, uninjured, physical education students were measured under three conditions: (1) without brace, (2) with brace and 30 kPa application pressure and (3) with brace and 60 kPa application pressure, as measured by a pressure sensitive sensor. Peroneal reaction time was assessed with surface electromyography, during a sudden inversion stress test on a trapdoor. The results demonstrated significant differences between the control (no brace condition) and the two brace conditions, with a significant increase of the peroneal reaction time, with increasing ankle brace application pressures, more pronounced in the 60 kPa pressure. The findings of this study show that prophylactic ankle bracing when applied tightly, seems to have a detrimental effect in the dynamic defence mechanism of the ankle joint, since it delays the peroneous longus activation onset during a simulated ankle sprain. Whether different brace application pressures introduced in this study can affect the incidence of ankle sprains remains to be examined.

The Peroneal Reaction Time (PRT) - Reference Data in a Healthy Sample Population

Acute ankle sprains can result in severe residual symptoms, such as chronic ankle instability from weakness of the ligamentous complex or neuromuscular deficits. Measuring peroneal reaction time (PRT) has become a commonly accepted procedure for evaluating proprioceptive deficits. The present experimental study was conducted to determine the effects of anthropometric factors on PRT in 120 healthy volunteers. The patients were asked to stand on a platform with a tilting mechanism. Surface electrodes were used to record peroneal muscle activity in response to sudden inversion stress. The reaction of the peroneal muscles was analyzed using electromyography. The statistical analysis showed similar intra-individual and inter-individual values for PRT. The results for the muscle groups measurements, however, varied considerably. PRT seems to increase significantly with age (long peroneal muscle: p < 0.0001, short peroneal muscle: p = 0.004). PRT was found to be an objective parameter that is unaffected by extrinsic and intrinsic factors. The present study, however, also showed that PRT significantly increases with age. As for studies on PRT, as well as for clinical routine, it is important to consider the patients' ages.

Intrinsic Risk Factors for Inversion Ankle Sprains in Male Subjects: A Prospective Study

Background Many variables have been retrospectively associated with ankle sprains. However, very little is known about factors predisposing people to these injuries. Hypothesis Measurable intrinsic factors might predispose male athletes to ankle sprains. Study Design Cohort study; Level of evidence, 2. Methods A total of 241 male physical education students were evaluated for possible intrinsic risk factors for inversion sprains at the beginning of their academic study. The evaluated intrinsic risk factors included anthropometrical characteristics, functional motor performances, ankle joint position sense, isokinetic ankle muscle strength, lower leg alignment characteristics, postural control, and muscle reaction time during a sudden inversion perturbation. Subjects were followed prospectively for 1 to 3 years. Results A total of 44 (18%) of the 241 male subjects sustained an inversion sprain; 4 sprained both ankles. Cox regression analysis revealed that male subjects with slower running speed, less cardiorespiratory endurance, less balance, decreased dorsiflexion muscle strength, decreased dorsiflexion range of motion, less coordination, and faster reaction of the tibialis anterior and gastrocnemius muscles are at greater risk of ankle sprains. Conclusion Based on our findings, it is suggested that running speed, cardiorespiratory endurance, balance, dorsiflexion strength, coordination, muscle reaction, and dorsiflexion range of motion at the ankle are associated with the risk of ankle inversion sprains in male subjects.

Intrinsic risk factors for inversion ankle sprains in females – a prospective study

Ankle sprains are extremely common. However, very little is known about the variables that predispose individuals to these injuries. The purpose of this study was to examine prospectively intrinsic risk factors for inversion sprains in a young physically active female population. One hundred and fifty-nine female physical education students were evaluated for several possible intrinsic risk factors for inversion sprains at the beginning of their academic study. The evaluated intrinsic risk factors included anthropometrical and physical characteristics, ankle joint position sense, isokinetic ankle muscle strength, lower leg alignment characteristics, postural control and muscle reaction time during a sudden inversion perturbation. All sports injuries were registered during 1-3 years and exposure to sport was recorded (mean: 15.33+/-4.33 h a week). Thirty-two (20%) of the 159 females sprained their ankle. The number of ankle sprains per 1000 h of sports exposure was 0.75. The Cox regression analysis revealed that females with less accurate passive joint inversion position sense [hazard ratio (HR): 1.08, 95% confidence interval (CI): 1.02-1.14 for absolute error at 15 degrees inversion], a higher extension range of motion at the first metatarsophalangeal joint (HR: 1.03, 95% CI: 1.00-1.06) and less coordination of postural control (HR: 0.96, 95% CI: 0.93-1.00 for endpoint excursion; HR: 0.94, 95% CI: 0.89-0.99 for maximal endpoint excursion) are at greater risk of an ankle sprain. The findings of this study suggest that effective prevention and conservative rehabilitation of ankle inversion sprains should include attention to these variables.

Delayed Latency of Peroneal Reflex to Sudden Inversion with Ankle Taping or Bracing

The purpose of the present study was to examine the effects of ankle taping and bracing based on the peroneal reflex in the hypermobile and normal ankle joints with and without history of ankle injury. Thirty-six ankle joints of 18 collegiate American football athletes with and without previous history of injury were studied. The angle of talar tilt (TT) was measured by stress radiograph for classifying normal (TT</=5 degrees ) or hypermobile (TT>5 degrees ) ankles. They were tested with taping, bracing, and without any supports as a control. The latency of peroneus longus muscle was measured by a sudden inversion of 25 degrees using surface EMG signals. The results of the present study show no significant three-way Group (hypermobile or normal ankles) by History (previously injured or uninjured ankles) by Condition (control, taping, or bracing) interaction, while Condition main effect was significant (p<0.05). There were significant differences between control (80.8 ms) and taping (83.8 ms, p<0.01), between control and bracing (83.0 ms, p<0.05), but not between taping and bracing (p>0.05). In conclusion, ankle taping and bracing delayed the peroneal reflex latency not only for hypermobile ankles and/or injured ankle joints but also for intact ankle joints.

Ankle eversion torque response to sudden ankle inversion: Torque response in unbraced, braced, and pre-activated situations

In 13 young ankle stable subjects, ankle eversion torque and peroneal EMG were simultaneously recorded in response to sudden ankle inversion. The eversion torque response was bi-phasic. The initial development of torque, which was responsible for 30% of the maximal eversion torque response, was observed 135 ms after the start of platform rotation and correlated well with the onset of the automatic postural peroneal EMG response. The remaining eversion torque response commenced after 305 ms, strongly correlating with the onset of the peroneal long latency voluntary EMG activity. With the ankle unbraced, 66% of the maximal torque level was reached in 326 ms. While braced, the same torque magnitude was reached using 230 ms ( p < 0.02), and pre-activation of the peroneal muscles allowed the subjects to reach the same level of torque in 89 ms ( p < 0.0005). Prior to the study, a common reaction pattern to sudden inversion was expected in an ankle stable population, but review of the eversion torque and EMG data from the 13 subjects revealed three different voluntary reaction patterns: 10 subjects showed an efficient activation of evertor muscles; two subjects stiffened their ankles with activation of both in- and evertor muscles; and one subject showed a marginal voluntary activation of the ankle evertors. The results of the study indicate that the reaction to sudden ankle inversion is not solely automatic. The main part of the torque response is voluntarily mediated and inter-individual differences in strategy seem to exist in healthy subjects.

A Comparison of Ankle Muscle Activity Following Sudden Ankle Inversion During Walking and Standing

A Comparison of Ankle Muscle Activity Following Sudden Ankle Inversion During Walking and Standing

A Comparison of Ankle Muscle Activity Following Sudden Ankle Inversion During Walking and Standing

A Comparison of Ankle Muscle Activity Following Sudden Ankle Inversion During Walking and Standing

Intrinsic Risk Factors for Inversion Sprains

2126 PURPOSE: to prospectively examine intrinsic risk factors for inversion sprains in a young physical active population. METHODS: 400 physical education students (241 men, 159 women; mean age: 18.4 ± 1.1 years), who were freshman in 2000–2001, 2001–2002 and 2002–2003 at the Ghent University, Belgium were evaluated for several possible risk factors at the beginning of their academic study. Anthropometric data were collected. Physical characteristics were evaluated using the European Test of Physical Fitness. Active and passive ankle joint position sense were assessed using the Biodex System 2 Isokinetic Dynamometer. The Biodex System 3 Isokinetic Dynamometer was used to determine isokinetic peak torque and peak torque/body weight values for concentric and eccentric eversion-inversion movements of the ankle and for concentric plantar-dorsiflexion. Lower leg alignment characteristics were measured. Postural control was assessed using the Neurocom Balance Master. Muscle reaction time was measured with EMG from the mm. peronei, m. tibialis anterior and m. gastrocnemius during a sudden inversion perturbation. All sports injuries were registered by the same sports physician throughout three, two and one academic year, for the three groups. A Cox regression was used to test the effect of each variable on the hazard of injury, taking into account differences in the length of time that the athletes were at risk. This was accomplished by computing time at risk as the total number of lessons, practices for lessons, practices for recreational or competition sports and games in which each subject participated until injury or, if uninjured, the end of the period followed. RESULTS: Of the 400 subjects, 162 did have no injuries at the lower leg, ankle or foot. 76 subjects had one or more inversion sprains, of whom five bilaterally. Statistical analysis revealed that subjects who scored less on the flamingo balance test, were at greater risk of ankle sprains. Less accurate passive joint position sense at 15° of inversion is also a risk factor for inversion sprains. Our results also show that a higher extension range of motion at the metatarsophalangeal I joint increases the risk of an ankle sprain. CONCLUSIONS: In order to reduce ankle sprains, a prevention program should include balance and proprioception training and limitation of the extension in the metatarsophalangeal I joint. Supported by BOF-RUG 01109001

Intrinsic Risk Factors for Inversion Sprains

2126 PURPOSE: to prospectively examine intrinsic risk factors for inversion sprains in a young physical active population. METHODS: 400 physical education students (241 men, 159 women; mean age: 18.4 ± 1.1 years), who were freshman in 2000–2001, 2001–2002 and 2002–2003 at the Ghent University, Belgium were evaluated for several possible risk factors at the beginning of their academic study. Anthropometric data were collected. Physical characteristics were evaluated using the European Test of Physical Fitness. Active and passive ankle joint position sense were assessed using the Biodex System 2 Isokinetic Dynamometer. The Biodex System 3 Isokinetic Dynamometer was used to determine isokinetic peak torque and peak torque/body weight values for concentric and eccentric eversion-inversion movements of the ankle and for concentric plantar-dorsiflexion. Lower leg alignment characteristics were measured. Postural control was assessed using the Neurocom Balance Master. Muscle reaction time was measured with EMG from the mm. peronei, m. tibialis anterior and m. gastrocnemius during a sudden inversion perturbation. All sports injuries were registered by the same sports physician throughout three, two and one academic year, for the three groups. A Cox regression was used to test the effect of each variable on the hazard of injury, taking into account differences in the length of time that the athletes were at risk. This was accomplished by computing time at risk as the total number of lessons, practices for lessons, practices for recreational or competition sports and games in which each subject participated until injury or, if uninjured, the end of the period followed. RESULTS: Of the 400 subjects, 162 did have no injuries at the lower leg, ankle or foot. 76 subjects had one or more inversion sprains, of whom five bilaterally. Statistical analysis revealed that subjects who scored less on the flamingo balance test, were at greater risk of ankle sprains. Less accurate passive joint position sense at 15° of inversion is also a risk factor for inversion sprains. Our results also show that a higher extension range of motion at the metatarsophalangeal I joint increases the risk of an ankle sprain. CONCLUSIONS: In order to reduce ankle sprains, a prevention program should include balance and proprioception training and limitation of the extension in the metatarsophalangeal I joint. Supported by BOF-RUG 01109001

The lagos La Plata and Fontana fold-and-thrust belt: long-lived orogenesis at the edge of western Patagonia

Extensive fieldwork carried out in the inner sectors of the Cordillera Patagónica has revealed evidence of alternate of periods of crustal extension and orogen formation since the Jurassic. The Patagonian lithosphere was extended during the Mesozoic and fractured and collapsed into numerous depocenters within the arc and retroarc. The last pulse of extension during this period occurred in the Early Cretaceous, related to a series of Pacific transgressions that formed the embayment of the Rı́o Mayo basin, north of the Austral basin. The Rı́o Mayo basin is part of a widespread Early Cretaceous synrift episode found throughout the Patagonian region between 155 and 140 Ma. The last part of this rifting episode, between 140 and 125 Ma, was spatially more limited, restricted to the arc and inner retroarc. The area of extension can be related to an early Paleozoic suture between the Somuncura Massif and the hanging wall of the Deseado Massif. The correct identification of this suture zone helps delimit distinctive volcanic provinces, as well as metallogenic ore districts. Thermal subsidence ceased as a consequence of a sudden tectonic inversion related to a major lithospheric reorganization at 120 Ma, during the breakup of southern Gondwana. The closure of the small Rı́o Mayo intra-arc-retroarc basin occurred as a result of a fold-and-thrust belt, mainly by tectonic inversion of previous normal faults, and was partially related to thin-skinned deformation. The emplacement of the Eastern Patagonian batholith between 100 and 80 Ma destroyed the inner sectors of the fold-and-thrust belt. During this time, the collapse of the inner sectors allowed for the development of a second, more limited intra-arc basin. The orogenic wedge grew through the inversion of progressively deeper decollements and out-of-sequence thrusts and lasted until the Late Paleogene, with a period of probable quiescence during the highly oblique subduction of the Aluk (Phoenix) Plate in the early Paleogene.

Choosing EMG parameters: comparison of different onset determination algorithms and EMG integrals in a joint stability study

Objective. The aim was to test various algorithms for onset determination and compare onset repeatability to that from integrals of the EMG signal. The information contained in both parameters is discussed. Design. Onset times were calculated using six different algorithms. The integral of the EMG signal was calculated for seven intervals: from tilt start and from each of the resulting onsets to 200 ms after tilt start. Background. EMG onset times are often utilised, especially regarding co-ordination patterns or joint stability. There are almost as many different procedures for onset determination as authors dealing with it. Results in the literature are contradictory. The determination and usage of onset times remains controversial. Methods. EMG signals from six muscles of the lower leg of 23 subjects were recorded during three consecutive, expected and unexpected sudden inversion and eversion trials while standing on a tilting platform. Results. In most cases the repeatability of the onset times was considerably lower than that of the integrals of the EMG for all studied algorithms. In some cases earlier onset times corresponded to lower integral values and constant onsets to variable integrals. Conclusions. In many cases onset times alone are not sufficient for describing onset phenomena. The additional calculation of the integrated EMG might provide relevant information regarding the quality of early activation. Relevance The findings are evidencing that care should be taken when interpreting onset times alone. The additional use of the integral of the EMG signal is suggested to provide more meaningful information.

Peroneus longus stretch reflex amplitude increases after ankle brace application

Background: The use of external ankle support is widespread throughout sports medicine. However, the application of ankle bracing to a healthy ankle over a long period has been scrutinised because...

Mechanically induced ankle inversion during human walking and jumping

A new method to study sudden ankle inversions during human walking and jumping is presented. Ankle inversions of 25° were elicited using a box containing a trap door. During the gait task, subjects walked at a speed of 4 km/h. At a pre-programmed delay after left heel strike, an electromagnet released the box on the treadmill. This delay enabled the subject to step on the box without having to change the walking cadence. During the jumping task, subjects jumped from a 30 cm high platform on the box in a standardised way. In both tasks 20 stimulus and 20 control trials were presented randomly. The average tilting velocity of the trap door during the stimulus trials was 403°/s during the walking task and 595°/s during the jumping task. For the control trials a tilting of 0° was used. With this method it is possible to evoke reproducible ankle inversions causing characteristic EMG responses in six lower leg muscles.

Sensori-motor control of the uninjured and injured human ankle

This review focuses on the role of sensori-motor function in the healthy as well as the functionally unstable ankle. The concept functional ankle instability—a widely used term, which has no universally agreed upon definition—as well as the sources of peripheral afferent information measured with different sensori-motor tests are discussed. The protective mechanisms against sudden ankle inversion are reviewed, and models that directly connect deficits in kinaesthesia and peroneal reflex reaction to an increased risk of sustaining unprovoked ankle inversion injuries are presented.

Peroneal reaction time: study of a normal sample

Chronic functional instability is a residual problem after acute ankle sprain. Reasons may be weak ligaments and/or a deficit in the proprioceptive system. Studies have shown that peroneal reaction time (PRT) can be used to quantify proprioceptive performance. To test the influence of anthropometric data on PRT, an experimental study with 120 healthy volunteers was performed. Surface electrodes recorded the activity of the peroneal muscles after a sudden inversion on a tilting platform. It was found that PRT is not influenced by extrinsic or anthropometric data. Furthermore, the results prove a significant slackening in PRT with increasing age. Therefore, the patient's age must to be considered in judging the PRT.

ANKLE BRACING DOES NOT AFFECT PERONEUS LONGUS RESPONSE FOLLOWING MUSCLE FATIGUE

The potential effects of ankle bracing on joint proprioception have not been well established. In our laboratory, we have recently showed a facilitation in peroneus longus (PL) stretch reflex amplitude after immediate application of a ankle brace. There is evidence that suggests that ankle bracing may enhance proprioception by increasing afferent input from various mechanoreceptors. It has been shown that diminished joint force output, and impaired motor control occurs following muscular fatigue. Therefore, the purpose of this research was to establish if ankle bracing can minimize the negative consequences of muscular fatigue by enhancing neuromuscular function of the peroneus longus (PL) during sudden foot inversion. Fifteen healthy collegiate volunteers (age = 21.7 ± 3.2 yrs, ht = 172.5 ± 11.1 cm, and mass = 73.7 ± 12.0 kg) free from lower extremity pathology 12 months prior to the study and not engaged in a strength training program served as subjects. All subjects had PL neuromuscular function {magnitude (% of max amplitude) and latency (ms)} assessed during sudden foot inversion during two ankle brace conditions (control & lace-up) before and after a standardized isokinetic muscular fatigue protocol. A repeated measures ANOVA revealed that PL stretch reflex magnitude was unaffected (P > 0.05) by brace condition (control = 86.8 ± 1.3; lace-up = 86.3 ± 1.1) and fatigue (pre = 85.6 ± 1.4; post = 87.6 ± 1.4). Similarly, PL stretch reflex latency remained unchanged (P > 0.05) by brace condition (control = 52.9 ± 2.9; lace-up = 50.2 ± 2.3) and fatigue (pre = 51.5 ± 2.4; post = 51.6 ± 2.2). It appears from these data that muscle fatigue does not influence the reactive response of the PL during sudden foot inversion. Additionally, application of a lace-up style ankle brace does not affect PL latency and magnitude following an inversion perturbation.

Peroneal reaction times for diagnosis of functional ankle instability

In order to differentiate between functional and mechanical chronic ankle instability, peroneal muscle function was examined in sudden inversion movements produced by a 30° tilting platform. Surface electromyographic (EMG) signals were recorded from the peroneus brevis and longus, tibialis anterior, and soleus muscles. An electrogoniometer was used to record rearfoot motion. Sixty-five subjects were assigned either to a functional (n = 35) or a mechanical instability group (n = 30) based on radiographic and mechanical stability measurements. Mechanical instability was characterized by a greater talar tilt and anterior drawer in the unstable leg. The groups did not differ significantly in the stability characteristics of the unaffected leg. Functional instability was reflected in significantly longer reaction times of the peroneus brevis (65 versus 57 ms, P = 0.002) and longus muscle (60 versus 54 ms, P = 0.01) in comparison with the mechanical instability group. Therefore, in those unstable patients without a clear mechanical insufficiency, the problem appears to be caused by a neuromuscular instability. Peroneal reaction times may help to distinguish between different causes of chronic ankle instability.