Reliability of peroneal reaction time measurements

Peroneal reaction time delayed but dynamic single-legged stability retained in collegiate footballers during a simulated prolonged football protocol

Delayed peroneal reaction time and impaired single-legged dynamic stability were risk factors of lateral ankle sprain (LAS), yet no study explored the change of them during a football match. The aim is to explore the change of peroneal reaction time and single-legged dynamic stability during a football simulation protocol. Twelve collegiate football players voluntarily completed a 105-min football match simulation protocol in which peroneal reaction time, root-mean-square of mediolateral ground reaction force in first 0.4 s (RMS ML 0.4), and the mean mediolateral ground reaction force in the late stage (late dynamic MLGRF), were measured for both legs at 15-min intervals during the protocol. Peroneal reaction time was tested using an electromyography (EMG) system. The ground reaction force variables were measured from GRF data after a single-legged drop-jump landing. Repeated measures one-way MANOVA was conducted to evaluate variables over time and leg dominance. Statistical significance was set at p < 0.05 level. Peroneal reaction time significantly increased for both legs at 45 minutes and after 60 minutes. RMS ML 0.4 of both legs and late dynamic MLGRF for dominant leg remained unchanged throughout the protocol and late dynamic MLGRF for non-dominant leg significantly reduced at the 90th minute.

The influence of fatigue in evertor muscles during lateral ankle sprain

Ankle sprain in plantarflexion and inversion is one of the most common injuries occurring in daily activities and sports. Although acute symptoms may resolve quickly, many individuals have reported persistent pain and instability. Thus, understanding the factors that contribute to the occurrence of this type of injury is extremely important. Although sprains are multifactorial, a relationship can be established between sprain and fatigue. Therefore, the present study examined the latency and intensity of activation of the peroneus longus and brevis muscles under conditions of fatigue. Twenty-three women participated in the study, including 12 with functional instability of the ankle and 11 without a history of sprain. To induce fatigue, the volunteers maintained the force of eversion and plantarflexion at 70% of the maximum voluntary isometric contraction for as long as possible until a 10% decline in the rated force occurred. Ten simulations of ankle sprains were performed before and after fatigue at random for each side, with simultaneous recordings of the electromyographic signals, using a simulator platform for inversion sprain and plantarflexion. As a result, after fatigue, no change in latency was observed. However, a reduction in the intensity of contraction of the muscles analyzed in both groups was observed. Neuromuscular control was concluded to be compromised in situations of fatigue, while differences in muscle behavior were not observed between stable and unstable ankles.

Effects of sudden unexpected mechanical perturbation training aimed at the primary prevention of inversion ankle sprain on reactiveness of ankle movement and cortical activity in normal young adults

[Purpose] To determine the effects of sudden unexpected mechanical perturbation training aimed at the primary prevention of inversion ankle sprain on the reactiveness of ankle eversion movement and cortical activity. [Participants and Methods] Sixty healthy participants were randomly allocated equally into 1) the sudden unexpected mechanical perturbation training group, 2) self-paced training group, or 3) control group. The first two groups performed each course of training 3 days per week for 4 weeks. During pre-training and post-training, the latency to peak amplitude on the surface electromyography of the peroneus longus and the time to reposition the plate back to its initial position under the right foot after sudden unexpected mechanical perturbation were measured. Functional near-infrared spectroscopy was used to measure the changes in the concentration of oxygenated hemoglobin. [Results] The latency to peak amplitude was significantly shorter in group 1 than in group 2; time to reposition the plate was the shortest among the 3 groups during post-training. The changes in the concentration of oxygenated hemoglobin were significantly increased in the supplementary motor and pre-motor areas during post-training than during pre-training in group 1. [Conclusion] Sudden unexpected mechanical perturbation training may facilitate the primary prevention of inversion ankle sprain via the positive effects on the reactiveness of ankle eversion movement and cortical activity.

Reliability of two methods for identifying the timing of medium latency responses in subjects with and without chronic ankle instability

This study aims to: (1) to compare 2 methods of assessing the timing of medium latency responses (MLR), in regard to intrasession reliability and mean values, in subjects with and without chronic ankle instability (CAI), and (2) to analyze the influence of CAI in timing of MLR and in its reliability. Thirty six athletes with (16) and without (20) CAI participated. Bilateral electromyography of peroneus longus (PL), peroneus brevis (PB), tibialis anterior (TA) and soleus (SOL) muscles was collected during a unilateral sudden inversion perturbation to assess the timing of MLR onset, in both standing and perturbed positions, through a baseline-based method and a peak-response-based method. The group without CAI presented higher relative reliability of SOL and peroneal muscles MLR with the peak response-based method than with the baseline-based method. Compared with the group without CAI and in both methods, the group with CAI presented a delayed and less reliable TA MLR, as well decreased coefficient variation of PL MLR in the uninjured limb. In conclusion, regardless of the method subjects with CAI present delayed and less reliable TA MLR while in subjects without CAI the peak response-based method provides higher reliability.

Muscle stretching changes neuromuscular function involved in ankle stability

It has been postulated that the mechanical and neurophysiological effects induced by stretching decrease maximal muscle strength and power. Additionally, the reduction in neural input and muscle stiffness can affect the joint stabilization process. However, there is no evidence available to support this hypothesis. Thus, the aim of this study is to analyze the influence of static stretching on dynamic joint stability. Twenty physically active female university students (22.8 ± 5.3 years; 58 ± 8.8 kg; 1.62 ± 0.07 m) performed a series of static-passive stretching exercises for the peroneus longus and brevis muscles (four repetitions of 30 s). Before and after the stretches, electromyography was performed on both muscles during simulated ankle sprain. Mathematical algorithms calculate the latency and the electromyography activity (RMS). After stretching, the latency increased from 66ms to 73 ms (p = 0.003) for the peroneus brevis muscle and from 70 ms to 79 ms (p = 0.001) for the peroneus longus muscle. The RMS, calculated 100 ms after the simulation, decreased in the peroneus brevis muscle, from 25.05 to 18.16 (p = 0.001), and in the peroneus longus muscle, from 22.84 to 15.61 (p = 0.001). Muscle stretching changed the motor responses of both muscles. The increase in latency and the decrease in RMS indicate that static stretching influences the neuromuscular function involved in the joint stabilization process.

Bilateral Proprioceptive Evaluation in Individuals With Unilateral Chronic Ankle Instability

CONTEXT

  Despite extensive research on chronic ankle instability, the findings regarding proprioception have been conflicting and focused only on the injured limb. Also, the different components of proprioception have been evaluated in isolation.

OBJECTIVE

  To evaluate bilateral ankle proprioception in individuals with unilateral ankle instability.

DESIGN

  Cohort study.

SETTING

  Research laboratory center in a university.

PATIENTS OR OTHER PARTICIPANTS

  Twenty-four individuals with a history of unilateral ankle sprain and chronic ankle instability (mechanical ankle instability group, n = 10; functional ankle instability [FAI] group, n = 14) and 20 controls.

MAIN OUTCOME MEASURE(S)

  Ankle active and passive joint position sense, kinesthesia, and force sense.

RESULTS

  We observed a significant interaction between the effects of limb and group for kinesthesia (F = 3.27, P = .049). Increased error values were observed in the injured limb of the FAI group compared with the control group (P = .031, Cohen d = 0.47). Differences were also evident for force sense (F = 9.31, P < .001): the FAI group demonstrated increased error versus the control group (injured limb: P < .001, Cohen d = 1.28; uninjured limb: P = .009, Cohen d = 0.89) and the mechanical ankle instability group (uninjured limb: P = .023, Cohen d = 0.76).

CONCLUSIONS

  Individuals with unilateral FAI had increased error ipsilaterally (injured limb) for inversion movement detection (kinesthesia) and evertor force sense and increased error contralaterally (uninjured limb) for evertor force sense.

Muscle timing in injured and non-injured leg of athletes with chronic ankle instability in response to a visual stimulus during forward jumping

OBJECTIVE

The aim of this study was to investigate premotor time, motor time and reaction time of the injured and non-injured leg muscles of athletes with chronic ankle instability in response to a visual stimulus during forward jumping.

METHODS

Surface electromyography was performed on injured and non-injured leg of eight athletes with chronic ankle instability during forward jumping.

RESULTS

Results showed that premotor time of the peroneus longus was significantly longer in non-injured leg compared with injured leg (489.37 ± 220.22 ms vs. 306.46 ± 142.92 ms, P = 0.031); on the contrary, motor time of the peroneus longus was significantly shorter in non-injured leg compared with injured leg (569.04 ± 318.62 ms vs. 715.12 ± 328.72 ms, P = 0.022). No significant difference was noted in the timing of other calf muscles (P > 0.05).

CONCLUSION

According to the results of this study, rehabilitation protocols, regarding ankle instability, need to put greater emphasis on tasks that require proper timing of muscles and muscle re-education so that protocols could reduce residual symptoms after sprain and prevent recurrent sprains.

The ergogenic effect of elastic therapeutic tape on stride and step length in fatigued runners

OBJECTIVE

The purpose of this study was to determine if elastic therapeutic tape placed on anterior lower limbs would affect stride and step length in fatigued runners' gait.

METHODS

Forty-two healthy participants were equally divided into a kinesiology tape group (Rocktape) and a no-tape control group. Participants in both groups underwent a baseline running gait test at 6 mph without tape. After this, participants engaged in an exhaustive lower body fatigue protocol until they reached maximal volitional exhaustion. Participants were then randomized to 1 of 2 interventions: (1) Experimental group, which had kinesiology tape placed under tension on the anterior aspect of their lower limbs bilaterally from the upper thigh to just below the patella, or (2) Control group, which did not receive taping. All participants then engaged in a similar 6-mph running gait postanalysis. Participant's gait was analyzed for 90 seconds during each test iteration. Researchers used a 2-way repeated-measures analysis of variance considering fatigue (prefatigue, postfatigue) and group (tape, no-tape) as subject factors.

RESULTS

After the fatigue protocol, the no-tape group demonstrated a significant decrease in step length of 14.2 mm (P = .041) and stride length of 29.4 mm (P = .043). The kinesiology tape group did not demonstrate a significant decline in these gait parameters.

CONCLUSIONS

In this preliminary study, placing elastic therapeutic tape over the anterior lower limbs demonstrated short-term preservation of runner step length and stride length in a fatigued state.

Biomechanical comparison of 3 ankle braces with and without free rotation in the sagittal plane

CONTEXT

Various designs of braces including hinged and nonhinged models are used to provide external support of the ankle. Hinged ankle braces supposedly allow almost free dorsiflexion and plantar flexion of the foot in the sagittal plane. It is unclear, however, whether this additional degree of freedom affects the stabilizing effect of the brace in the other planes of motion.

OBJECTIVE

To investigate the dynamic and passive stabilizing effects of 3 ankle braces, 2 hinged models that provide free plantar flexion-dorsiflexion in the sagittal plane and 1 ankle brace without a hinge.

DESIGN

Crossover study.

SETTING

University Movement Analysis Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Seventeen healthy volunteers (5 women, 12 men; age = 25.4 ± 4.8 years; height = 180.3 ± 6.5 cm; body mass = 75.5 ± 10.4 kg).

INTERVENTION(S)

We dynamically induced foot inversion on a tilting platform and passively induced foot movements in 6 directions via a custom-built apparatus in 3 brace conditions and a control condition (no brace).

MAIN OUTCOME MEASURE(S)

Maximum inversion was determined dynamically using an in-shoe electrogoniometer. Passively induced maximal joint angles were measured using a torque and angle sensor. We analyzed differences among the 4 ankle-brace conditions (3 braces, 1 control) for each of the dependent variables with Friedman and post hoc tests (P < .05).

RESULTS

Each ankle brace restricted dynamic foot-inversion movements on the tilting platform as compared with the control condition, whereas only the 2 hinged ankle braces differed from each other, with greater movement restriction caused by the Ankle X model. Passive foot inversion was reduced with all ankle braces. Passive plantar flexion was greater in the hinged models as compared with the nonhinged brace.

CONCLUSIONS

All ankle braces showed stabilizing effects against dynamic and passive foot inversion. Differences between the hinged braces and the nonhinged brace did not appear to be clinically relevant.

Effects of fatiguing treadmill running on sensorimotor control in athletes with and without functional ankle instability

BACKGROUND

Sensorimotor control is permanently impaired following functional ankle instability and temporarily decreased following fatigue. Little is known on potential interactions between both conditions. The purpose was to investigate the effect of fatiguing exercise on sensorimotor control in athletes with and without (coper, controls) functional ankle instability.

METHODS

19 individuals with functional ankle instability, 19 ankle sprain copers, and 19 non-injured controls participated in this cohort study. Maximum reach distance in the star excursion balance test, unilateral jump landing stabilization time, center of pressure sway velocity in single-leg-stance, and passive ankle joint position sense were assessed before and immediately after fatiguing treadmill running. A three factorial linear mixed model was specified for each outcome to evaluate the effects of group, exhausting exercise (fatigue) and their interactions (group by fatigue). Effect sizes were calculated as Cohen's d.

FINDINGS

Maximum reach distance in the star excursion balance test, jump stabilization time and sway velocity, but not joint position sense, were negatively affected by fatigue in all groups. Effect sizes were moderate, ranging from 0.27 to 0.68. No significant group by fatigue interactions were found except for one measure. Copers showed significantly larger prefatigue to postfatigue reductions in anterior reach direction (P≤0.001; d=-0.55) compared to the ankle instability (P=0.007) and control group (P=0.052).

INTERPRETATION

Fatiguing exercise negatively affected postural control but not proprioception. Ankle status did not appear to have an effect on fatigue-induced sensorimotor control impairments.

Local anaesthetics use does not suppress muscle activity following an ankle injection

PURPOSE

To determine if peroneus longus (PL), peroneus brevis (PB), medial gastrocnemius (MG) and tibialis anterior (TA) muscle activation patterns during inversion perturbation and running tasks are suppressed following lidocaine injection to the anterior talofibular (ATF) and calcaneofibular (CF) ligament regions.

METHODS

Fourteen recreationally active male subjects (age, 24.8 ± 2.9 years; height, 177.0 ± 6.0 cm; mass, 77.7 ± 6.7 kg) participated. Testing was performed under five injection conditions to the ATF and CF regions: 1 ml saline, 1 ml lidocaine, 3 ml saline, 3 ml lidocaine or no injection. Following injection condition, traditional ankle taping was applied. Electromyography patterns of the PL, PB, MG and TA were collected while subjects performed continuous lateral jumps on a custom-built device which elicited an ankle inversion perturbation and treadmill running (3.35 m s(-1), 0.5 % incline).

RESULTS

No significant differences were demonstrated in muscle activation patterns of the PL (n.s.), PB (n.s.), MG (n.s.) or TA (n.s.) for any variable across injected conditions during both tasks. Statistical power was 0.214-0.526 for the PL, 0.087-0.638 for the PB, 0.115-0.560 for the MG and 0.118-0.410 for the TA.

CONCLUSIONS

Injection of lidocaine up to 3 ml to the ATF and CF regions did not suppress muscle activity of the PL, PB, MG or TA during the inversion perturbation or running tasks. Injection up to 3 ml of 1 % lidocaine to the ATF and CF regions may be used without sacrificing the muscle activation patterns about the ankle. This finding is clinically relevant since the use of the injection does not put the patient at any higher risk of reinjury to the site.

[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.

Stability of measurement outcomes for voluntary task performance in participants with chronic ankle instability and healthy participants

CONTEXT

Acceptable measurement stability during data collection is critically important to research. To interpret differences in measurement outcomes among participants or changes within participants after an intervention program, we need to know whether the measurement is stable and consistent.

OBJECTIVE

To determine the within-session stability of muscle activation patterns for a voluntary postural-control task in a group of noninjured participants and a group of participants with chronic ankle instability (CAI).

DESIGN

Descriptive laboratory study.

SETTING

Musculoskeletal laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty control participants (8 men, 12 women; age = 21.8 ± 2.4 years, height = 164.3 ± 13.4 cm, mass = 68.4 ± 17.9 kg) and 20 participants with CAI (12 men, 8 women; age = 21.2 ± 2.1 years, height = 176 ± 10.2 cm, mass = 71.7 ± 11.3 kg).

INTERVENTION(S)

Participants performed 4 barefoot standing trials, each of which included a 30-second double-legged stance followed by a 30-second single-legged stance in 3 conditions: with vision, without vision, and with vision on a balance pad.

MAIN OUTCOME MEASURE(S)

The activity of 7 muscles of the lower limb was measured for the stance task in the 3 different conditions for each trial. The onset of muscle activity and muscle recruitment order were determined and compared between the first and the fourth trials for both groups and for each condition.

RESULTS

We found no differences in the onset of muscle activity among trials for both groups or for each condition. The measurement error was 0.9 seconds at maximum for the control group and 0.12 seconds for the CAI group. In the control group, 70% to 80% of the participants used the same muscle recruitment order in both trials. In the CAI group, 75% to 90% used the same recruitment order.

CONCLUSIONS

Within 1 session, measurement stability for this task was acceptable for use in further research. Furthermore, no differences were found in measurement stability across conditions in the control or CAI groups.

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.

Peroneal reaction time measurement in unipodal stance for two different destabilization axes

BACKGROUND

The variability of peroneal reaction time measurements is a major problem when using this parameter to control rehabilitation or proprioceptive training processes. In order to control peroneal reaction time values, some extrinsic factors should be considered. The purpose of this study was to measure peroneal reaction time in unipodal stance for two different destabilization axes.

METHODS

The peroneal reaction time of 10 healthy subjects was measured from kinematic and electromyograhic data in an experimental study using an ankle destabilization device.

FINDINGS

In a preliminary analysis, results showed that the destabilization axis orientation did not affect peroneal reaction time values (68.5 ms, standard deviation=9.5 ms and 71.5 ms, standard deviation=8 ms for destabilizations in the frontal plane and around the Henke's axis, respectively). However, the inter-trial variance of inversion velocity peaks explained between 40% and 49% of the peroneal reaction time variance. When trials were selected on the basis of homogeneous inversion velocity peaks, results showed that peroneal reaction time values for the peroneus brevis were shorter during inversion movements performed around the physiological Henke's tilting axis (63 ms, standard deviation=9 ms vs. 71 ms, standard deviation=8 ms).

INTERPRETATION

Our findings evidenced that tilting axis orientation must be considered as an extrinsic factor that may influence peroneal reaction time. Moreover it also seems necessary to consider inversion speed values to adequately compare peroneal reaction time values.

The influence of a balance training program on the electromyographic latency of the ankle musculature in subjects with no history of ankle injury

BACKGROUND

Balance training is often employed for the prevention of ankle injuries. However, until now, most of the studies have focused on the prevention of a recurrent injury. The objective of this study was to look into the effects of balance training on the onset of peroneal muscle activity in healthy subjects.

METHODS

34 participants (mean age = 19.5 years ± 1.5; height = 1.70 m ± 0.12; weight = 62.06 kg ± 11.24), physically active, with no history of injuries took part in this study. The participants underwent a 4-week balance training program using an ankle disk. Onset of peroneal muscles activation was measured using surface electromyography and a trap-door.

FINDINGS

Parametric and non-parametric tests showed no significant differences between the control group and the experimental group (P > 0.05).

INTERPRETATION

The results indicate that the use of balance training, for a 4-week period with two training sessions per week, on physically active subjects with no history of injuries in the ankle joint, does not cause noteworthy changes on the onset of peroneal muscles activity.

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

BACKGROUND

The aim of this study was to examine the influence of age, body mass index (BMI) and leg dominance on the PRT, balance control and foot position sense.

MATERIALS AND METHODS

The proprioception of the ankle was investigated in 210 participants. All participants completed a questionnaire. The PRT was measured on a tilting platform. The position sense test was performed. Balance control was assessed with the Biodex Stability System (BSS), measuring the overall stability index (OSI) at the stable level 8 and the unstable level 2. Correlation analyses were performed between these data and age, BMI and leg dominance, using the Spearman-Rho coefficient with a two-sided significance level of p < 0.05.

RESULTS

Significant increases of the PRT and OSI in correlation to increased age and BMI were noted for both legs (p < 0.05). No positive correlation to age, BMI or leg dominance could be demonstrated for the foot position sense test. The PRT of the right leg was always significantly faster than that of the left leg, irrespective of leg dominance (p < 0.05). Surprisingly, individuals with a dominant right leg achieved better OSI scores in left single leg stance at the unstable level 2 (p < 0.05).

CONCLUSION

The PRT and the postural stability correlate with age and BMI, whereas the position sense test of the ankle does not. Furthermore, the PRT in right legs is always faster. This should be noted when functional ankle stability is evaluated in patients.

Prevention of physical training-related injuries recommendations for the military and other active populations based on expedited systematic reviews

BACKGROUND

The Military Training Task Force of the Defense Safety Oversight Council chartered a Joint Services Physical Training Injury Prevention Working Group to: (1) establish the evidence base for making recommendations to prevent injuries; (2) prioritize the recommendations for prevention programs and policies; and (3) substantiate the need for further research and evaluation on interventions and programs likely to reduce physical training-related injuries.

EVIDENCE ACQUISITION

A work group was formed to identify, evaluate, and assess the level of scientific evidence for various physical training-related injury prevention strategies through an expedited systematic review process. Of 40 physical training-related injury prevention strategies identified, education, leader support, and surveillance were determined to be essential elements of a successful injury prevention program and not independent interventions. As a result of the expedited systematic reviews, one more essential element (research) was added for a total of four. Six strategies were not reviewed. The remaining 31 interventions were categorized into three levels representing the strength of recommendation: (1) recommended; (2) not recommended; and (3) insufficient evidence to recommend or not recommend.

EVIDENCE SYNTHESIS

Education, leadership support, injury surveillance, and research were determined to be critical components of any successful injury prevention program. Six interventions (i.e., prevent overtraining, agility-like training, mouthguards, semirigid ankle braces, nutrient replacement, and synthetic socks) had strong enough evidence to become working group recommendations for implementation in the military services. Two interventions (i.e., back braces and pre-exercise administration of anti-inflammatory medication) were not recommended due to evidence of ineffectiveness or harm, 23 lacked sufficient scientific evidence to support recommendations for all military services at this time, and six were not evaluated.

CONCLUSIONS

Six interventions should be implemented in all four military services immediately to reduce physical training-related injuries. Two strategies should be discouraged by all leaders at all levels. Of particular note, 23 popular physical training-related injury prevention strategies need further scientific investigation, review, and group consensus before they can be recommended to the military services or similar civilian populations. The expedited systematic process of evaluating interventions enabled the working group to build consensus around those injury prevention strategies that had enough scientific evidence to support a recommendation.

Novel approach for a precise determination of short-time intervals in ankle sprain experiments

The etiology of ankle sprain injury is still under debate. Therefore, diagnoses of ankle inversion experiments play an important role. Recent studies stress the importance of exact time measurements due to the short inversion period of around 70ms. This paper presents a novel approach using the vertical ground reaction force (vGRF) to determine the short-time intervals in ankle sprain experiments, which are present in the form of short periods from the beginning of the movement to its end and short latencies to following signals, e.g. EMG onset of peroneal muscles. We compare our method to electrogoniometry at the ankle which is considered as the gold standard. During the inversion movement the kinematic action at the ankle can be measured with electrogoniometry, whereas the vGRF quantifies the vertical dynamic reaction of the tested subject entirely. We observe a difference of DeltaT(f,0-->g,0)=10+/-0.5ms between the first observable vGRF response and the first observable electrogoniometer response following platform release. The end of the ankle inversion measured with electrogoniometry is DeltaT(f,1-->g,1)=3+/-0.5ms later than the maximal vGRF peak. The potential supplementary (mechanical) information of this novel approach compared to electrogoniometry and its ease of use, may be not only interesting for researchers when studying ankle sprain simulations but also for clinicians when testing functional ankle stability.

Neuromuscular control and ankle instability

Lateral ankle sprains (LAS) are common injuries in athletics and daily activity. Although most are resolved with conservative treatment, others develop chronic ankle instability (AI)-a condition associated with persistent pain, weakness, and instability-both mechanical (such as ligamentous laxity) and functional (neuromuscular impairment with or without mechanical laxity). The predominant theory in AI is one of articular deafferentation from the injury, affecting closed-loop (feedback/reflexive) neuromuscular control, but recent research has called that theory into question. A considerable amount of attention has been directed toward understanding the underlying causes of this pathology; however, little is known concerning the neuromuscular mechanisms behind the development of AI. The purpose of this review is to summarize the available literature on neuromuscular control in uninjured individuals and individuals with AI. Based on available research and reasonable speculation, it seems that open-loop (feedforward/anticipatory) neuromuscular control may be more important for the maintenance of dynamic joint stability than closed-loop control systems that rely primarily on proprioception. Therefore, incorporating perturbation activities into patient rehabilitation schemes may be of some benefit in enhancing these open-loop control mechanisms. Despite the amount of research conducted in this area, analysis of individuals with AI during dynamic conditions is limited. Future work should aim to evaluate dynamic perturbations in individuals with AI, as well as subjects who have a history of at least one LAS and never experienced recurrent symptoms. These potential findings may help elucidate some compensatory mechanisms, or more appropriate neuromuscular control strategies after an LAS event, thus laying the groundwork for future intervention studies that can attempt to reduce the incidence and severity of acute and chronic lateral ankle injury.

EVALUATION OF THE PROPRIOCEPTIVE INFLUENCE OF THE CUTANEOUS AFFERENTS TO THE ANKLE IN PATIENTS AFTER SURAL NERVE HARVESTING

OBJECTIVE

Cutaneous afferent nerves contribute to joint proprioception. The aim of this study was to retrospectively analyze the proprioceptive influence of the cutaneous afferents to the ankle in patients after sural nerve harvesting in comparison to controls.

METHODS

The proprioception of the ankle in 24 patients after sural nerve harvesting was investigated. The sural nerve was harvested bilaterally in Group 1 (n = 10), in the right leg in Group 2 (n = 6), and in the left leg in Group 3 (n = 8). The proprioception of the ankle was also tested in controls (Group 4, n = 24). The peroneal reaction time (PRT) was measured on a tilting platform. The position sense test was performed. Balance control was investigated with the Biodex Stability System (Biodex Medical Systems, Shirley, NY) at the stable Level 8 and unstable Level 2.

RESULTS

No significant differences among the groups were seen in the position sense test, the PRT, and all scores of the Biodex Stability System. The PRT showed significant differences in comparison to the contralateral leg for the peroneus brevis muscle in Group 1 (P = 0.005) and Group 4 (P = 0.001) as well as for the peroneus longus muscle in Group 3 (P = 0.036) and Group 4 (P = 0.001).

CONCLUSION

The proprioception of the ankle in patients after sural nerve harvesting is not reduced in comparison to controls. Significant differences of the PRT between the left and right legs are attributable to leg dominance in most cases and not to a loss of innervation. Harvesting of the sural nerve does not result in ankle instability.

Ankle bracing, plantar-flexion angle, and ankle muscle latencies during inversion stress in healthy participants

CONTEXT

Ankle braces may enhance ankle joint proprioception, which in turn may affect reflexive ankle muscle activity during a perturbation. Despite the common occurrence of plantar-flexion inversion ankle injuries, authors of previous studies of ankle muscle latencies have focused on inversion stresses only.

OBJECTIVE

To examine the latency of the peroneus longus (PL), peroneus brevis (PB), and tibialis anterior (TA) muscles in response to various degrees of combined plantar-flexion and inversion stresses in braced and unbraced asymptomatic ankles.

DESIGN

Repeated measures.

SETTING

University biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-eight healthy females and 12 healthy males (n = 40: mean age = 23.63 years, range = 19 to 30 years; height = 172.75 +/- 7.96 cm; mass = 65.53 +/- 12.0 kg).

INTERVENTION(S)

Participants were tested under 2 conditions: wearing and not wearing an Active Ankle T1 brace while dropping from a custom-made platform into 10 degrees , 20 degrees , and 30 degrees of plantar flexion and 30 degrees of inversion.

MAIN OUTCOME MEASURE(S)

The time between platform drop and the onset of PL, PB, and TA electromyographic activity was measured to determine latencies. We calculated a series of 2-way analyses of variance to determine if latencies were different between the conditions (braced and unbraced) and among the plantar-flexion angles (alpha = .05).

RESULTS

No interaction was found between condition and plantar-flexion angle. No significant main effects were found for condition or plantar-flexion angle. Overall means for braced and unbraced conditions were not significantly different for each muscle tested. Overall means for angle for the PL, PB, and TA were not significantly different.

CONCLUSIONS

Reflexive activity of the PL, PB, or TA was unaffected by the amount of plantar flexion or by wearing an Active Ankle T1 brace during an unanticipated plantar-flexion inversion perturbation.

The effect of fatigue and habituation on the stretch reflex of the ankle musculature

Many ankle injuries are said to occur when athletes are in a fatigued state; therefore, studies investigating the role that fatigue plays in ankle injuries are warranted. Furthermore, the contributions of the stretch reflex in countering the injury mechanism are still unclear. We hypothesized that (1) fatigue would impair the reflex response, (2) there would be no differences between genders, (3) habituation would be present, and (4) fatigue would exacerbate the effect of habituation. Forty healthy subjects participated and were divided into treatment and control groups. Stretch reflex measurements were taken for the tibialis anterior (TA), peroneus longus (PL), and peroneus brevis (PB) muscles in response to a rapid inversion perturbation. A fatigue intervention was administered to the treatment group, while the control group sat quietly. Post-test measurements were recorded within 5min and reflex latency (RL) and amplitude (RA) were calculated. RA decreased significantly, however a significant improvement was noted in RL in the PL and PB muscles. The effect that peripheral fatigue has on RL should not be considered a cause of ankle injuries. However, the diminished RA may suggest reduced dynamic stability after fatigue. Habituation was present and was exacerbated by fatigue, indicating that reflex testing is affected by fatigue and habituation, which must be taken into consideration in future studies.

Effects of neuromuscular training on the reaction time and electromechanical delay of the peroneus longus muscle

OBJECTIVE

To examine the influence of a 6-week neuromuscular training program on the electromechanical delay and reaction time of the peroneus longus muscle.

DESIGN

A 2 x 2 pre-post factorial design.

SETTING

Human performance research center biomechanics laboratory.

PARTICIPANTS

Thirty-six healthy, physically active, college-age subjects were recruited for this study and 26 completed it. There were 5 men and 8 women in the treatment group (mean age +/- standard deviation, 21.9+/-2.1 y; height, 173.7+/-11.1cm; weight, 67.4+/-17.8 kg) and 6 men and 7 women in the control group (age, 21.8+/-2.3 y; height, 173.7+/-11.9 cm; weight, 70.8+/-19.4 kg). Subjects were not currently experiencing any lower-extremity pathology and had no history of injuries requiring treatment to either lower extremity.

INTERVENTIONS

Subjects in the treatment group completed a 6-week neuromuscular training program involving various therapeutic exercises. Subjects in the control group were asked to continue their normal physical activity during the 6-week period.

MAIN OUTCOME MEASURES

The electromechanical delay of the peroneus longus was determined by the onset of force contribution after artificial activation, as measured by electromyographic and forceplate data. Reaction time was measured after a perturbation during walking. Data were analyzed using two 2 x 2 analyses of covariance (covariate pretest score). Group (treatment, control) and sex (male, female) were between-subject factors.

RESULTS

Neuromuscular training caused a decrease in reaction time to perturbation during walking compared with controls (F=4.030, P=.029), while there was a trend toward an increase in electromechanical delay (F=4.227, P=.052). There was no significant difference between sexes or the interaction of sex and treatment in either reaction time or electromechanical delay.

CONCLUSIONS

The 6-week training program significantly reduced reaction time of the peroneus longus muscle in healthy subjects. Neuromuscular training may have a beneficial effect on improving dynamic restraint during activity.

Efeitos da fadiga muscular induzida por exercícios no tempo de reação muscular dos fibulares em indivíduos sadios

A fadiga muscular (FM) é um fenômeno comum nas atividades esportivas e diárias, resultando numa piora da performance motora. Ela é considerada um dos fatores causadores de lesões músculo-esqueléticas. A entorse de tornozelo é um exemplo: a FM afetaria tanto o sistema aferente quanto o eferente. Vários estudos têm analisado a influência da FM no controle neuromuscular (CNM); entretanto, existe pouca pesquisa sobre essa influência na velocidade de reação dos músculos. O objetivo deste estudo foi verificar os efeitos da FM no tempo de reação muscular (TRM) dos músculos fibulares, que são os primeiros a responder a um estresse em inversão do tornozelo. Foram estudados 14 indivíduos saudáveis masculinos (idade: 20-35 anos), que tiveram seus TRM avaliados por meio de eletromiografia (EMG) de superfície. O início da atividade muscular foi definido como a média de repouso + 3x o desvio-padrão (DP). O TRM dos fibulares foi mensurado após uma inversão súbita de 20º realizada numa plataforma. A inversão súbita foi realizada antes e depois da fadiga muscular, que foi induzida por exercícios localizados dos fibulares até a exaustão. Os resultados mostraram que houve um aumento significativo do tempo de reação muscular após a fadiga (p < 0,01). Durante atividades esportivas prolongadas e durante o processo de reabilitação, deve-se ter cautela na realização de tarefas que requeiram respostas musculares extremamente rápidas sob condições de fadiga muscular.

Joint stabilizing response to expected and unexpected tilts

BACKGROUND

The results found in the literature regarding functional ankle joint stabilization are controversial possibly because of the testing methods used.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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 peroneal reaction time (PRT)--reference data in a healthy sample population

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Anatomical repair of lateral ligaments in patients with chronic ankle instability

In a prospective study, 19 patients with chronic ankle instability underwent clinical and radiographic reexaminations 36 months after anatomical reconstruction. In addition, dynamic pedography was conducted and peroneal reaction time measured on a tilting platform for an evaluation of functional aspects. Prior to this examination, 32 patients had been asked to fill in a questionnaire and make a detailed subjective evaluation of current discomfort, stability, flexibility and sporting abilities. Eighty-eight percent of the patients reported satisfactory results; only 3% complained of persistent instability. In 71% the ability to take part in sports had improved after surgery, and 85% of the patients reported unrestricted walking abilities. Supination ability was impaired in 5% of the patients at the follow-up. The radiographic examination showed restored ankle stability with a significant reduction of talar tilt and talar translation; a postoperative increase in signs and symptoms of arthrosis was not observed. Dynamic pedography showed a large degree of symmetry of plantar pressure distribution after surgery. There were no significant differences in peroneal reaction time in the repaired and intact ankles. The results of the study show that it is possible to restore ankle stability with anatomical reconstruction without impairing the range of movement in the ankle joint complex. Progressive osteoarthrosis can be prevented.

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.

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.

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 of possible neuromuscular adaptations resulting in diminished dynamic support offered by the peroneus longus.

OBJECTIVE

To investigate the immediate and chronic effects of ankle brace application on the amplitude of peroneus longus stretch reflex.

METHODS

Twenty physically active college students (mean (SD) age 23.6 (1.7) years, height 168.7 (8.4) cm, and mass 69.9 (12.0) kg) who had been free from lower extremity pathology for the 12 months preceding the study served as subjects. None had been involved in a strength training or conditioning programme in the six months preceding the study. A 3 x 3 x 2 (test condition x treatment condition x time) design with repeated measures on the first and third factor was used. The peroneus longus stretch reflex (% of maximum amplitude) during sudden foot inversion was evaluated under three ankle brace conditions (control, lace up, and semi-rigid) before and after eight weeks of ankle brace use.

RESULTS

A 3 x 3 x 2 repeated measures analysis of variance showed that peroneus longus stretch reflex amplitude increased immediately after application of a lace up brace (67.1 (4.4)) compared with the semi-rigid (57.9 (4.3)) and control (59.0 (5.2)) conditions (p<0.05). Peroneus longus stretch reflex also increased after eight weeks of use of the semi-rigid brace compared with the lace up and control conditions (p<0.05).

CONCLUSIONS

Initial application of a lace up style ankle brace and chronic use of a semi-rigid brace facilitates the amplitude of the peroneus longus stretch reflex. It appears that initial and long term ankle brace use does not diminish the magnitude of this stretch reflex in the healthy ankle.

The main function of ankle braces is to control the joint position before landing

The aim of the present investigation was to evaluate the stabilizing effect of 10 different ankle braces during simulated inversion on a tilting platform. Twenty-five subjects participated in the study (23 +/- 3 yrs, 71 +/- 12 kg, 177 +/- 9 cm). Ten commercially available ankle braces and a trapdoor in combination with a goniometer system that measured hindfoot inversion inside the shoe were used. Inversion was subdivided into a free fall and a maximum inversion phase. Results showed that all braces restricted inversion significantly between 51% and 15% compared to the no-brace condition but distinct differences between models were found. Maximum inversion angle and inversion velocity were lower for those braces that restricted inversion most effectively during the free fall phase. Reaction times of the peroneus longus did not appear to influence the degree of inversion. Relatively constant differences between free fall and maximum inversion angles for all models (between 6 degrees and 10 degrees) and a high correlation between these two parameters suggests that the main function of ankle braces is to restrict inversion during the free fall phase and not at the extremes of motion.

Scapular muscle recruitment pattern: electromyographic response of the trapezius muscle to sudden shoulder movement before and after a fatiguing exercise

STUDY DESIGN

Test-retest reliability study and single-group repeated measures design.

OBJECTIVES

To evaluate the muscle latency times of the 3 portions of the trapezius muscle to a sudden arm movement in normal shoulders and to determine if this recruitment pattern is altered as a result of fatigue.

BACKGROUND

It has been suggested that shoulder impingement may be related to altered muscle activity and muscle fatigue in the scapular stabilizers. Fatigue-induced changes in latency times of the trapezius might influence scapular stability.

METHODS AND MEASURES

Muscle latency times were investigated in 30 healthy shoulders with surface electromyography. Muscle activity was measured in all 3 sections of the trapezius and the middle deltoid muscle during a sudden downward falling movement of the arm. Subsequently the shoulder was fatigued on an isokinetic dynamometer, after which muscle latency time measurement was repeated.

RESULTS

ANOVA for repeated measures revealed significant differences in latency times (P < 0.05) among the 4 muscles of interest. Although there were no significant differences among the 3 sections of the trapezius muscle, they all were recruited after the initialization of the deltoid muscle. The recruitment order of the shoulder muscles did not change with muscle fatigue. However, after fatigue, muscle responses were significantly slower in all muscles except for the lower trapezius (P < 0.05).

CONCLUSIONS

There is a specific recruitment sequence in the shoulder muscles in response to a sudden arm movement characterized by initial activation of the middle deltoid muscle and followed by simultaneous contraction of all 3 sections of the trapezius. This muscle activation pattern is delayed but not altered with fatigue.

A multi-station proprioceptive exercise program in patients with ankle instability

PURPOSE

The aim of the present study was to investigate the effects of a 6-wk multi-station proprioceptive exercise program that is easy to integrate in normal training programs.

METHODS

Patients with chronic ankle instability were used, and results of three testing procedures before and afterward were compared: joint position sense, postural sway, and muscle reaction times to sudden inversion events on a tilting platform. A total of 30 subjects with 48 unstable feet were evaluated (exercise group: N = 31; control group: N = 17).

RESULTS

In the exercise group, the results showed a significant improvement in joint position sense and postural sway as well as significant changes in muscle reaction times.

CONCLUSION

Based on the present results, a multi-station proprioceptive exercise program can be recommended for prevention and rehabilitation of recurrent ankle inversion injuries.