Peroneus Longus Activity Research Articles

Fatigue of the hip abductors results in increased medial–lateral center of pressure excursion and altered peroneus longus activation during a unipedal landing task

BackgroundPrevious studies have reported that diminished hip abductor muscle strength is associated with a loss of frontal plane postural stability and increased risk for ankle sprain. The purpose of this study was to determine whether hip abductor fatigue results in compensatory changes in neuromuscular activation of the peroneus longus (an important lateral stabilizer of the ankle) during a unipedal landing task. MethodsThirty healthy females performed a unipedal landing task before and after completing a hip abductor fatigue protocol. Paired t-tests were used to assess changes in medial–lateral center of pressure displacement, and EMG (electromyographic) amplitude of the peroneus longus following hip abductor fatigue. Changes in peroneus longus onset timing also were assessed. FindingsFollowing the hip abductor fatigue protocol, participants exhibited increased mean center of pressure displacement (7.7 (1.5) vs. 9.2 (2.0) cm, P<0.01), and increased EMG amplitude of peroneus longus (0.75 (0.18) vs. 0.86 (0.21), P<0.01) during the deceleration phase of landing. Post-fatigue, significantly earlier peroneus longus onset timing prior to landing was observed (88.9 (24.9) vs. 121.9 (25.7) ms, P<0.01). InterpretationThe increased EMG amplitude and earlier onset of the peroneus longus appears to be a protective compensatory adaptation to stabilize the ankle in response to frontal plane postural instability induced by hip abductor fatigue.

The effect of different Masai Barefoot Technology (MBT) shoe models on postural balance, lower limb muscle activity and instability assessment

Unstable shoe constructions may counteract balance deficits and underutilization of lower limb muscles. The Masai Barefoot Technology (MBT) concept has been widely analysed in terms of footwear-induced instability. However, previous experiments investigated predominately one specific MBT shoe model. Therefore, the purpose of this experiment was to evaluate the effects of differently shaped MBT soles on stance biomechanics. Mean velocity of centre of pressure (CoP) displacement, root mean square (RMS) tibialis anterior (TA), peroneus longus (PL), gastrocnemius medialis (GM), vastus lateralis (VL) and biceps femoris (BF) activity, as well as subjective perception of instability were recorded in 31 young asymptomatic adults during standing with three different MBT models and a standard control shoe. Statistical analysis included repeated-measures ANOVAs with Bonferroni–Holm adjusted post-hoc tests. MBT footwear, regardless of shape and structure, significantly increased postural sway compared to the control condition. Additionally, there were significant differences between the MBT shoe types. These results coincided with those obtained from instability assessment testing. No significant effects of MBT footwear were detected for the GM and BF muscles. A consistent increase in TA, PL and VL RMS activity was only found for one MBT model. On a muscular level, within-MBT differences were statistically less pronounced than for CoP and for instability rating measures. These findings suggest that specific variations in MBT sole construction criteria differently challenged the postural control system without forfeiting the principal feature of simulating a less firm surface for the user. Further investigations are warranted to examine the framework of instability within the MBT concept, as well as associated intrinsic and extrinsic influences related to rehabilitation and prevention programmes.

Dynamic equinus with hindfoot valgus in children with hemiplegia

In children with hemiplegia, it is important to distinguish between equinus with hindfoot varus (equinovarus) or valgus (equinovalgus). Premature onset of medial gastrocnemius (GM) EMG in individuals with equinus is well documented. Premature onset of Peroneus longus (PL) EMG has been described in neurologically impaired adults with equinovalgus, but not in children. Our aim was to record the onset of PL and GM activity on the hemiplegic side of children with equinovalgus deformity.Fifteen children GMFCS 1 (3.8yrs±2) with hemiplegia had a goniometric assessment of passive ankle range of motion and assessment of ankle function from video and surface EMG recording during gait. The clinical and video observations were used to determine the equinovalgus, as defined by Wren, at initial contact (IC). The premature onset of muscle activity was normalised as a swing (SW) percentage prior to IC of the following stance (ST). A paired T-test compared the onset of muscle activity between PL and GM.The ankle passive dorsiflexion was 13°±12° (hemiplegic side) versus 18°±10° (non-involved side) (p<0.05). For the non-involved limb, the onset of GM activity was at 14% of the gait cycle (midstance), the onset of PL activity was at 19% (p<0.05). For the hemiplegic limb with equinovalgus, there was a premature onset activity of PL (−24%) and GM(−8%) (p<0.001).On the non involved side, the onset of PL activity occurred, as in adults, after the onset of GM activity, during ST. On the hemiplegic side, there was no triceps surae contracture and the onset of PL activity occurred prior to the onset of GM activity, during terminal SW. This study confirmed the overactivity of PL in hemiplegic children with equinovalgus.

Alterations in evertor/invertor muscle activation and center of pressure trajectory in participants with functional ankle instability

Participants with ankle instability demonstrate more foot inversion during the stance phase of gait than able-bodied subjects. Invertor excitation, coupled with evertor inhibition may contribute to this potentially injurious position. The purpose of this experiment was to examine evertor/invertor muscle activation and foot COP trajectory during walking in participants with functional ankle instability (FI). Twelve subjects were identified with FI and matched to healthy controls. Tibialis anterior (TA) and peroneus longus (PL) electromyography (EMG), as well as COP, were recorded during walking. Functional analyses were used to detect differences between FI and control subjects with respect to normalized EMG and COP trajectory during walking. Relative to matched controls, COP trajectory was more laterally deviated in the FI group from 20% to 90% of the stance phase. TA activation was greater in the FI group from 15% to 30% and 45% to 70% of stance. PL activation was greater in the FI group at initial heel contact and toe off and trended lower from 20% to 40% of stance in the FI group. Altered motor strategies appear to contribute to COP deviations in FI participants and may increase the susceptibility to repeated ankle inversion injury.

Altered leg muscle activity in volleyball players with functional ankle instability during a sideward lateral cutting movement

Objectives To study the activation patterns of tibialis anterior, peroneus longus and gastrocnemius lateralis muscles during a lateral shuffle maneuver in volleyball players with functional instability of the ankle joint. Design Observational case-control study. Setting Research laboratory. Participants Sixteen players with functional instability and 18 matched controls. Main outcome measures RMS values of tibialis anterior, peroneus longus and gastrocnemius lateralis muscles for the 50 ms before initial ground contact, timing of onset of muscle activity and linear envelopes for the period of ground contact were calculated. Results Onset values showed similar patterns of activation for both groups. In healthy subjects, gastrocnemius lateralis activated earlier, followed by peroneus longus and tibialis anterior. In the unstable subjects, gastrocnemius lateralis and peroneus longus activated at the same time, followed by tibialis anterior. Unstable subjects also presented lower peroneus longus activity during the 50 ms before initial ground impact, a lower peroneus longus peak magnitude and a higher gastrocnemius lateralis peak magnitude. Conclusions Volleyball players with ankle functional instability showed decreased peroneus longus activity before ground impact that may predispose them to repetitive sprains and explain their “giving way” sensation, since peroneus longus is the main ankle evertor and an important stabilizer against sudden and excessive inversion.

Combined sensorimotor and resistance training for young short track speed skaters: A case study

The purpose of the study was to investigate the effects of a combined sensorimotor - resistance training on muscle strength and neuromuscular activation of selective muscles of the right ankle joint. Both treatments were performed successively in each training session. Seven short track speed skaters participated in the study. The training was performed twice a week for 12 weeks. Maximum peak torque during inversion/eversion, the associated neuromuscular activation of soleus and peroneus longus as well as eversion/inversion ratio were measured in a pre- and post-test, respectively. After the training the athletes revealed a significantly increased maximum peak torque during inversion (17.47 ± 4.37N · m vs. 23.57 ± 3.58N · m; p = 0.006) associated with a significantly increased root mean square of the EMG signal in the soleus (12.42 ± 6.09mV vs. 24.00 ± 9.37mV; p = 0.009). The eversion/inversion ratio was significantly decreased after training (0.96 ± 0.12 vs. 0.77 ± 0.11; p = 0.034). Eversion training adaptations were lower than inversion training adaptations probably due to the fact that resistance training did not contain an exercise for peroneus longus. Based on these the combined sensorimotor-resistance training is an attractive option for athletes where maximum strength, active joint stabilization and postural control plays a decisive role.

Facilitating Activation of the Peroneus Longus: Electromyographic Analysis of Exercises Consistent With Biomechanical Function

Exercises for the ankle are often used to improve sport performance through balance and stability or to prevent or recover from ankle injury. Ankle training programs often include exercises for the primary muscle of the lateral ankle, the peroneus longus (PL). However, many exercises for the PL are non-weight bearing and unidirectional. However, data from biomechanical studies show that peak activity of the PL occurs neither in non-weight-bearing nor during uniplanar movements. This lack of congruency may limit the effectiveness of PL training. Exercises more consistent with the biomechanical function of the PL may increase the efficacy of ankle training. This study examined and compared the electromyographic (EMG) activity of the PL during 2 exercises that specifically address the known biomechanical function of the PL and a traditional non-weight-bearing unidirectional PL exercise. Twenty healthy college-aged men and women (age 24.8 +/- 2.7 years) without history of ankle injury were examined in a single-session repeated measures design. The average root means square (RMS) values of the PL during each of the 3 exercises were measured and compared to assess for differences in magnitude of muscular activity. The RMS activity of the PL was significantly greater (p < 0.05) in each of the biomechanically correct exercises when compared with the conventional exercise. However, no significant difference was noted in EMG activity between the 2 biomechanical exercises. This study provides evidence for increased activity from the PL during 2 exercises that more accurately reflect its biomechanical function. Use of these exercises when training the PL for sports performance or rehabilitation may increase the effectiveness of ankle training programs that include PL activity.

Hallucal grasping in Nycticebus coucang: further implications for the functional significance of a large peroneal process

Euprimate grasping feet are characterized by a suite of morphological traits, including an enlarged peroneal process on the base of the first metatarsal, which serves as the insertion site of the peroneus longus muscle. In prosimians, a large process has typically been associated with a powerful hallucal grasp via the contraction of the peroneus longus to adduct the hallux. Recent electromyography (EMG) studies have documented that peroneus longus does not contribute substantially to hallucal grasping in lemurids ( Boyer et al., 2007). However, non-lemurid prosimians have a I-V opposable grasp complex that is morphologically different and phylogenetically more primitive than the I-II adductor grasp complex of the lemurids previously studied. Therefore, it is possible that peroneus longus did function during grasping in early euprimates, but lost this function in large-bodied lemurids. The present study tests the hypothesis that a large peroneal process is related to powerful grasping ability in primates displaying the more primitive I-V grasp complex. We use EMG to evaluate the recruitment of peroneus longus, other crural muscles, and adductor hallucis in static and locomotor grasping activities of the slow loris ( Nycticebus coucang). Results show that peroneus longus is active during grasping behaviors that require the subject to actively resist inversion of the foot, and likely contributes to a hallucal grasp in these activities. Peroneus longus activity level does not differ between grasping and power grasping activities, nor does it differ between grasping and non-grasping locomotor modes. Conversely, the digital flexors and hallucal adductor are recruited at higher levels during power grasping and grasping locomotor modes. Consequently, we reject the hypothesis that an enlarged peroneal process represents an adaptation specifically to enhance the power of the I-V grasp, but accept that the muscle likely plays a role in adducting the hallux during grasping behaviors that require stabilization of the ankle, and suggest that further work is necessary to determine if this role is sufficient to drive selection for a large peroneal process.

Effect of foot posture, foot orthoses and footwear on lower limb muscle activity during walking and running: A systematic review

The aim of this systematic review was to evaluate the literature pertaining to the effect of foot posture, foot orthoses and footwear on lower limb muscle activity during walking and running. A database search of Medline, CINAHL, Embase and SPORTDiscus without language restrictions revealed 504 citations for title and abstract review. Three articles were translated to English and a final 46 articles underwent a two-tiered quality assessment. First, all articles were scored for their reporting of electromyographic methodology using a set of standards adopted by the International Society of Electrophysiology and Kinesiology. Thirty-eight articles displayed adequate reporting of electromyographic methodology and qualified for detailed review including a second quality assessment using a modified version of the Quality Index. These included six studies investigating the effect of foot posture, 12 the effect of foot orthoses and 20 the effect of footwear on lower limb muscle activity during walking or running. Meta-analysis was not conducted due to heterogeneity between studies. Some evidence exists that: (i) pronated feet demonstrate greater electromyographic activation of invertor musculature and decreased activation of evertor musculature; (ii) foot orthoses increase activation of tibialis anterior and peroneus longus, and may alter low back muscle activity; and (iii) shoes with elevated heels alter lower limb and back muscle activation. Most studies reported statistically significant changes in electromyographic activation, although these findings were often not well supported when confidence intervals were calculated. Most important, however, is that there is a need for further research of more rigorous methodological quality, including greater consensus regarding standards for reporting of electromyographic parameters.

Foot posture influences the electromyographic activity of selected lower limb muscles during gait

BackgroundSome studies have found that flat-arched foot posture is related to altered lower limb muscle function compared to normal- or high-arched feet. However, the results from these studies were based on highly selected populations such as those with rheumatoid arthritis. Therefore, the objective of this study was to compare lower limb muscle function of normal and flat-arched feet in people without pain or disease.MethodsSixty adults aged 18 to 47 years were recruited to this study. Of these, 30 had normal-arched feet (15 male and 15 female) and 30 had flat-arched feet (15 male and 15 female). Foot posture was classified using two clinical measurements (the arch index and navicular height) and four skeletal alignment measurements from weightbearing foot x-rays. Intramuscular fine-wire electrodes were inserted into tibialis posterior and peroneus longus under ultrasound guidance, and surface EMG activity was recorded from tibialis anterior and medial gastrocnemius while participants walked barefoot at their self-selected comfortable walking speed. Time of peak amplitude, peak and root mean square (RMS) amplitude were assessed from stance phase EMG data. Independent samples t-tests were performed to assess for significant differences between the normal- and flat-arched foot posture groups.ResultsDuring contact phase, the flat-arched group exhibited increased activity of tibialis anterior (peak amplitude; 65 versus 46% of maximum voluntary isometric contraction) and decreased activity of peroneus longus (peak amplitude; 24 versus 37% of maximum voluntary isometric contraction). During midstance/propulsion, the flat-arched group exhibited increased activity of tibialis posterior (peak amplitude; 86 versus 60% of maximum voluntary isometric contraction) and decreased activity of peroneus longus (RMS amplitude; 25 versus 39% of maximum voluntary isometric contraction). Effect sizes for these significant findings ranged from 0.48 to 1.3, representing moderate to large differences in muscle activity between normal-arched and flat-arched feet.ConclusionDifferences in muscle activity in people with flat-arched feet may reflect neuromuscular compensation to reduce overload of the medial longitudinal arch. Further research is required to determine whether these differences in muscle function are associated with injury.

The effect of different skin–ankle brace application pressures with and without shoes on single-limb balance, electromyographic activation onset and peroneal reaction time of lower limb muscles

Background Several studies have been carried out in order to investigate the effect of ankle bracing on ankle joint function and performance. However, no study so far has examined the role of skin–brace interface pressure in neuromuscular control. The aim of this study was to investigate the effect of different skin–ankle brace interface pressures, with and without shoes, on quiet single-limb balance and the electromyographic (EMG) activation sequence of four lower limb muscles. Methods Twelve male physical education students who volunteered to take part in the study were measured with and without shoes under three ankle brace conditions: (i) without brace, (ii) with brace and 30 kilopascals (kPa) application pressure and (iii) with brace and 60 kPa application pressure. Single-limb balance (anteroposterior and mediolateral parameter) was assessed on the dominant lower limb, with open and closed eyes, on a force platform, simultaneously with the EMG recording of four lower lower limb muscles’ (gastrocnemius, peroneus longus, rectus femoris and biceps femoris) activation onset. Peroneus longus reaction time was also measured by provoking a sudden subtalar inversion stress test using a trap-door. Results The results showed that the application of athletic footwear resulted in a significant difference between the condition with shoes and without shoes, with a significantly increased anteroposterior sway and sway velocity, in all three ankle brace application conditions with shoes ( F = 50.9, d.f. = 1, p < 0.001 and F = 58.4, d.f. = 1, p < 0.001), but had no effect in the mediolateral stability, or the total stability parameter. Shoes had no significant effect on the EMG activation sequence of the four lower limb muscles. Lastly, ankle brace application with 30 and 60 kPa application pressures, with and without athletic footwear, led to a significant delay in the peroneus longus reaction time ( F = 9.71, d.f. = 2, p < 0.001). Conclusions These findings suggest that different ankle brace application pressures may have an effect on single-limb balance, and peroneal reaction time. The application of athletic footwear, further adversely affects these parameters significantly. Further research is needed in this area with more dynamic and functional measurements, before the safe use of ankle bracing can be widely recommended.

Tape That Increases Medial Longitudinal Arch Height Also Reduces Leg Muscle Activity

: To evaluate the initial effects of antipronation taping (APT) on foot posture and electromyographic (EMG) activity of tibialis anterior (TA), tibialis posterior (TP), and peroneus longus (PL) muscles during walking. : Five asymptomatic individuals who exhibited lower medial longitudinal arch height on a clinical assessment of gait walked on a treadmill for 10 min before and after the application of an APT technique-specifically, the augmented low-Dye. Arch height (AH) in standing as well as peak and average amplitude, duration, time of onset, and time of offset of recorded EMG activity during walking were analyzed for each condition. : APT produced a mean (95% confidence interval (CI)) increase in AH of 12.9% (6.5-19.3; P = 0.005). Mean (95% CI) reductions in peak and average EMG activation of TA (peak: -23.9% (-34.0 to -13.9); average: -7.8% (-13.6 to -2.0)) and TP (peak: -45.5% (-77.3 to -13.7); average: -21.1% (-41.6 to -0.6)) were observed when walking with APT (P < 0.05). The APT also produced a small increase in duration of TA EMG activity of 3.7% (0.9-6.5) of the stride cycle duration, largely because of an earlier onset of EMG activity (4.4%; -8.1 to -0.8 of a stride cycle; P < 0.05). : APT reduces activity of the TA and TP muscles during walking while increasing AH, which provides preliminary evidence of its role in reducing the load of these key extrinsic muscles of the ankle and the foot. Follow-up study is required to evaluate these findings.

Ankle Bracing, Plantar-Flexion Angle, and Ankle Muscle Latencies During Inversion Stress in Healthy Participants

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. 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. Repeated measures. University biomechanics laboratory. 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). 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. 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). 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. 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.

Whole Body Vibration and Dynamic Restraint

The purpose of this study was to identify changes due to whole body vibration in peroneus longus (PL) activation following ankle inversion perturbation. Participants were 22 (age 22.1 +/- 1.8 yrs, ht 168.8 +/- 8.2 cm, mass 65.5 +/- 11.2 kg) physically active male and female students with no recent history of lower extremity injury. Measurements of PL electromechanical delay (EMD), reaction time, and muscle activation were collected from two groups (WBV and control) over 3 time intervals (pretreatment, posttreatment, and 30 min posttreatment). Two-way ANOVAs were used to compare groups over time for all dependent variables. No group x time interactions were detected (p < 0.05) for any of the dependent variables. Whole body vibration did not alter PL EMD, reaction time, peak EMG, or average EMG. The use of WBV for enhancing ankle dynamic stability was not supported by this study. However, more data are needed to determine if WBV is an effective intervention in other areas of injury prevention or rehabilitation. These data were not consistent with the hypothesis that WBV enhances muscle spindle sensitivity.

The effect of different skin-ankle brace application pressures on quiet single-limb balance and electromyographic activation onset of lower limb muscles

BackgroundSeveral studies have been carried out in order to investigate the effect of ankle bracing on ankle joint function and performance. However, no study so far has examined the role of skin-brace interface pressure in neuromuscular control. The aim of this study was to investigate the effect of different skin-ankle brace interface pressures on quiet single limb balance and the electromyographic (EMG) activation sequence of four lower limb muscles.MethodsThirty three male physical education students who volunteered to take part in the study were measured under three ankle brace conditions: i) without brace, ii) with brace and 30 kPa application pressure and iii) with brace and 60 kPa application pressure. Single limb balance (anteroposterior and mediolateral parameter) was assessed on the dominant lower limb, with open and closed eyes, on a force platform, simultaneously with the EMG recording of four lower lower limb muscles' (gastrocnemius, peroneus longus, rectus femoris and biceps femoris) activation onset.ResultsThe results showed that overall balance (total stability parameter) was not significantly affected in any of the three ankle brace conditions. However, the anteroposterior centre of pressure excursion and centre of pressure excursion velocity were significantly increased with the application of ankle brace, both with 30 and 60 kPa application pressures. Furthermore, it was found that single limb balance was significantly worse with closed eyes compared to open eyes. EMG measurements showed that the sequence of lower limb activation onset was not affected in any of the three ankle brace application conditions. The results of this study showed that the application of an ankle brace with two different skin-brace interface pressures had no effect on overall single limb balance and the sequence of lower limb muscle activation.ConclusionThese findings suggest that peripheral joint receptors are either not adequately stimulated by the brace application and therefore are not able to alter the balance control strategy of the CNS, or that they play a less important role in the control of single limb balance. Further research is needed in this area with more dynamic and functional measurements, before the safe use of ankle bracing can be widely recommended.

Muscular activity in treadmill and overground running

It still remains unclear whether muscular activity on the treadmill (T) differs compared to overground (0) running. The purpose of this study was therefore to examine possible differences in muscular activation between T and 0. 14 healthy runners were analyzed in a neutral running shoe at 12 km·h -1 on a treadmill and in a field test. Muscular activity (EMG) of the tibialis anterior, peroneus longus, and soleus were measured. Time and amplitude quantities were assessed during the gait cycle. The EMG of the peroneus longus exhibited a later onset, a later maximum and shorter total time of activation (p < 0.05) in 0. The soleus showed a higher amplitudes in 0 during the push-off phase (p < 0.05). Altered peroneus longus activity may indicate its role as an ankle stabilizer and demonstrates a compensatory response due to changing mechanical conditions. Weaker amplitudes of the soleus in the push-off during T suggest adaptation to the movement of the treadmill belt, and/or changes in load receptor input. Differences in muscle activity between T and 0 running must thus be taken into consideration in studies of neuromuscular control of movement.

Patterns of leg muscle recruitment vary between novice and highly trained cyclists

This study compared patterns of leg muscle recruitment and coactivation, and the relationship between muscle recruitment, coactivation and cadence, in novice and highly trained cyclists. Electromyographic (EMG) activity of tibialis anterior (TA), tibialis posterior (TP), peroneus longus (PL), gastrocnemius lateralis (GL) and soleus (SOL) was recorded using intramuscular fine-wire electrodes. Four experimental conditions of varying cadence were investigated. Differences were evident between novice and highly trained cyclists in the recruitment of all muscles. Novice cyclists were characterized by greater individual variance, greater population variance, more extensive and more variable muscle coactivation, and greater EMG amplitude in periods between primary EMG bursts. Peak EMG amplitude increased linearly with cadence and was not different at individual preferred cadence in either novice or highly trained cyclists. However, EMG amplitude in periods between primary EMG bursts, as well as the duration of primary EMG bursts, increased with increasing cadence in novice cyclists but were not influenced by cadence in highly trained cyclists. Our findings suggest that muscle recruitment is highly skilled in highly trained cyclists and less refined in novice cyclists. More skilled muscle recruitment in highly trained cyclists is likely a result of neuromuscular adaptations due to repeated performance of the cycling movement in training and competition.

Altered Neuromuscular Control and Ankle Joint Kinematics during Walking in Subjects with Functional Instability of the Ankle Joint

Background The ankle joint requires very precise neuromuscular control during the transition from terminal swing to the early stance phase of the gait cycle. Altered ankle joint arthrokinematics and muscular activity have been cited as potential factors that may lead to an inversion sprain during the aforementioned time periods. However, to date, no study has investigated patterns of muscle activity and 3D joint kinematics simultaneously in a group of subjects with functional instability compared with a noninjured control group during these phases of the gait cycle. Purpose To compare the patterns of lower limb 3D joint kinematics and electromyographic activity during treadmill walking in a group of subjects with functional instability with those observed in a control group. Study Design Controlled laboratory study. Methods Three-dimensional angular velocities and displacements of the hip, knee, and ankle joints, as well as surface electromyography of the rectus femoris, peroneus longus, tibialis anterior, and soleus muscles, were recorded simultaneously while subjects walked on a treadmill at a velocity of 4 km/h. Results Before heel strike, subjects with functional instability exhibited a decrease in vertical foot-floor clearance (12.62 vs 22.84 mm; P <. 05), as well as exhibiting a more inverted position of the ankle joint before, at, and immediately after heel strike (1.69°, 2.10°, and -0.09° vs -1.43°, -1.43°, and -2.78°, respectively [minus value = eversion]; P <. 05) compared with controls. Subjects with functional instability were also observed to have an increase in peroneus longus integral electromyography during the post–heel strike time period (107.91%[.dotmath]millisecond vs 64.53%[.dotmath]millisecond; P <. 01). Conclusion The altered kinematics observed in this study could explain the reason subjects with functional instability experience repeated episodes of ankle inversion injury in situations with only slight or no external provocation. It is hypothesized that the observed increase in peroneus longus activity may be the result of a change in preprogrammed feed-forward motor control.

A pilot study of the initial effects of anti-pronation taping on electromyographic activity of lower leg muscles during walking

Clinicians frequently use anti-pronation (AP) taping to relieve symptoms and improve function in the management of musculoskeletal pain and injury, yet the mechanisms behind this effect have not been fully explored. To date, the majority of the literature has focused on the mechanical effects of AP taping and little has been done to explore its possible neurophysiological effects. This pilot study set out to investigate the effect of the Augmented LowDye taping technique on the electromyographic (EMG) activity of muscles of the lower leg during walking. Five asymptomatic subjects, who exhibited clinically abnormal pronation during a visual assessment of gait, walked on a treadmill for ten minutes before and after the application of the taping technique. Bipolar intra-muscular electrodes were used to record the EMG of the tibialis anterior (TA), tibialis posterior (TP), gastrocnemius (GN) and peroneus longus (PL) during walking. A two-way repeated measures analysis of variance was used to compare the EMG activity (peak amplitudes, duration of activity) for each muscle. The co-efficient of multiple correlations was calculated to evaluate the variability of muscle recruitment patterns within each subject. Visual comparisons of EMG activity during individual walking strides before and after the application of tape were also performed. Peak EMG activity decreased by 25% in TA and by 45% in TP following the application of tape. There were no significant differences in peak EMG activity of GN or PL, or in duration of EMG activity for any muscle. Results from this study suggest that neurophysiological changes could contribute to the mechanism behind AP taping.

The effects of ankle bracing on the activation of the peroneal muscles during a lateral shuffling movement

The effects of ankle bracing on the levels and patterns of ankle muscle activation are not well understood. Objectives The purpose of this study was to examine this issue during a dynamic functional activity that involved marked ankle inversion. Design Within subjects repeated measures. Setting University Research Laboratory. Participants Fifteen female collegiate athletes completed multiple trials of a lateral shuffling movement, both with and without an ankle brace. Main outcome measures Frontal plane kinematics of the ankle and EMG data of the peroneus longus (PL) were recorded during lateral shuffling test trials at four time points: prior to brace application, after brace application, following 2 weeks of continued use of the brace, and 2 weeks after discontinued use of the brace. Results The results demonstrated no significant changes in PL activity across the four time points. Conclusions In contrast to previous reports, the use of an ankle brace does not produce immediate changes in muscle activation or changes in activation following short-term use.