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Neuromuscular control in functional situations and possible impairments due to Achilles tendinopathy are not well understood.
Thirty controls (CO) and 30 runners with Achilles tendinopathy (AT) were tested on a treadmill at 3.33 m s(-1) (12 km h(-1)). Neuromuscular activity of the lower leg (tibialis anterior, peroneal, and gastrocnemius muscle) was measured by surface electromyography. Mean amplitude values (MAV) for the gait cycle phases preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle.
MAVs of the tibialis anterior did not differ between CO and AT in any gait cycle phase. The activation of the peroneal muscle was lower in AT in weight acceptance (p = 0.006), whereas no difference between CO and AT was found in preactivation (p = 0.71) and push-off (p = 0.83). Also, MAVs of the gastrocnemius muscle did not differ between AT and CO in preactivity (p = 0.71) but were reduced in AT during weight acceptance (p = 0.001) and push-off (p = 0.04).
Achilles tendinopathy does not seem to alter pre-programmed neural control but might induce mechanical deficits of the lower extremity during weight bearing (joint stability). This should be addressed in the therapy process of AT.
Achilles (AT) and patellar tendons (PT) are commonly affected by tendinopathy in adult athletes but prevalence of symptoms and morphological changes in adolescents is unclear. The study aimed to determine prevalence of tendinopathy and intratendinous changes in ATs and PTs of adolescent athletes. A total of 760 adolescent athletes (13.0 +/- 1.9 years; 160 +/- 13cm; 50 +/- 14kg) were examined. History, local clinical examination, and longitudinal Doppler ultrasound analysis for both ATs and PTs were performed including identification of intratendinous echoic changes and vascularization. Diagnosis of tendinopathy was complied clinically in case of positive history of tendon pain and tendon pain on palpation. Achilles tendinopathy was diagnosed in 1.8% and patellar tendinopathy in 5.8%. Vascularizations were visible in 3.0% of ATs and 11.4% of PTs, hypoechogenicities in 0.7% and 3.2% as well as hyperechogenicities in 0% and 0.3%, respectively. Vascularizations and hypoechogenicities were statistically significantly more often in males than in females (P0.02). Subjects with patellar tendinopathy had higher prevalence of structural intratendinous changes than those without PT symptoms (P0.001). In adolescent athletes, patellar tendinopathy is three times more frequent compared with Achilles tendinopathy. Longitudinal studies are necessary to investigate physiological or pathological origin of vascularizations and its predictive value in development of tendinopathy.
The aim of this study was to investigate the effect of a 6-week sensorimotor or resistance training on maximum trunk strength and response to sudden, high-intensity loading in athletes. Interventions showed no significant difference for maximum strength in concentric and eccentric testing (p>0.05). For perturbation compensation, higher peak torque response following SMT (Extension: +24Nm 95%CI +/- 19Nm; Rotation: + 19Nm 95%CI +/- 13Nm) and RT (Extension: +35Nm 95%CI +/- 16Nm; Rotation: +5Nm 95%CI +/- 4Nm) compared to CG (Extension: -4Nm 95%CI +/- 16Nm; Rotation: -2Nm 95%CI +/- 4Nm) was present (p<0.05).
Background: The anterior cruciate ligament (ACL) rupture is a severe knee injury. Altered kinematics and kinetics in ACL reconstructed (ACL-R) patients compared to healthy participants (ACL-I) are known and attributed to an altered sensorimotor control. However, studies on neuromuscular control often lack homogeneous patient cohorts. The objective was to examine neuromuscular activity during stair descent in patients one year after ACL reconstruction. Method: Neuromuscular activity of vastus medialis (VM) and lateralis (VL), biceps femoris (BF) and semitendinosus (ST) was recorded by electromyography in 10 ACL-R (age: 26 +/- 10 years; height: 175 +/- 6 cm; mass: 75 +/- 14 kg) and 10 healthy matched controls (age: 31 +/- 7 years; height: 175 +/- 7 cm; mass: 68 +/- 10 kg). A 10-minute walking treadmill warm-up was used for submaximal normalization. Afterwards participants descended 10 times a six-step stairway at a self-selected speed. The movement was separated into pre-activation (PRE), weight acceptance (WA) and push-off phase (PO). Normalized root mean squares for each muscle, limb and movement phase were calculated. Kruskal-Wallis ANOVA compared ACL-R injured and contralateral leg and the ACL-I leg (alpha = 0.05). Results: Significant increased normalised activity in ST during WA in ACL-R injured leg compared to ACL-I and during PO in VL in the ACL-R contralateral leg compared to ACL-I. Decreased activity was shown in VM in ACL-R injured compared to contralateral leg (p < 0.05). Conclusion: Altered neuromuscular activations are present one year after ACL reconstruction compared to the contralateral and healthy matched control limb. Current standard rehabilitation programs may not be able to fully restore sensorimotor control and demand further investigations. (C) 2018 Elsevier B.V. All rights reserved.
In dynamic H-reflex measurements, the standardisation of the nerve stimulation to the gait cycle is crucial to avoid misinterpretation due to altered pre-synaptic inhibition. In this pilot study, a plantar pressure sole was used to trigger the stimulation of the tibialis nerve with respect to the gait cycle. Consequently, the intersession reliability of the soleus muscle H-reflex during treadmill walking was investigated.
Seven young participants performed walking trials on a treadmill at 5 km/h. The stimulating electrode was placed on the tibial nerve in the popliteal fossa. An EMG was recorded from the soleus muscle. To synchronize the stimulus to the gait cycle, initial heel strike was detected with a plantar pressure sole. Maximum H-reflex amplitude and M-wave amplitude were obtained and the Hmax/Mmax ratio was calculated.
Data reveals excellent reliability, ICC = 0.89. Test-retest variability was 13.0% (+/- 11.8). The Bland-Altman analysis showed a systematic error of 2.4%.
The plantar pressure sole was capable of triggering the stimulation of the tibialis nerve in a reliable way and offers a simple technique for the evaluation of reflex activity during walking.
Introduction: Gait speed is one of the most commonly and frequently used parameters to evaluate gait development. It is characterized by high variability when comparing different steps in children. The objective of this study was to determine intra-individual gait speed variability in children.
Methods: Gait speed measurements (6-10 trials across a 3 m walkway) were performed and analyzed in 8263 children, aged 1-15 years. The coefficient of variation (CV) served as a measure for intra-individual gait speed variability measured in 6.6 +/- 1.0 trials per child. Multiple linear regression analysis was conducted to evaluate the influence of age and body height on changes in variability. Additionally, a subgroup analysis for height within the group of 6-year-old children was applied.
Results: A successive reduction in gait speed variability (CV) was observed for age groups (age: 1-15 years) and body height groups (height: 0.70-1.90 m). The CV in the oldest subjects was only one third of the CV (CV 6.25 +/- 3.52%) in the youngest subjects (CV 16.58 +/- 10.01%). Up to the age of 8 years (or 1.40 m height) there was a significant reduction in CV over time, compared to a leveling off for the older (taller) children.
Discussion: The straightforward approach measuring gait speed variability in repeated trials might serve as a fundamental indicator for gait development in children. Walking velocity seems to increase to age 8. Enhanced gait speed consistency of repeated trials develops up to age 15.
The aim of this study was to acquire static and dynamic foot geometry and loading in childhood, and to establish data for age groups of a population of 1-13 year old infants and children.
A total of 10,382 children were recruited and 7788 children (48% males and 52% females) were finally included into the data analysis. For static foot geometry foot length and foot width were quantified in a standing position. Dynamic foot geometry and loading were assessed during walking on a walkway with self selected speed (Novel Emed X, 100 Hz, 4 sensors/cm(2)). Contact area (CA), peak pressure (PP), force time integral (FTI) and the arch index were calculated for the total, fore-, mid- and hindfoot.
Results show that most static and dynamic foot characteristics change continuously during growth and maturation. Static foot length and width increased with age from 13.1 +/- 0.8 cm (length) and 5.7 +/- 0.4 cm (width) in the youngest to 24.4 +/- 1.5 cm (length) and 8.9 +/- 0.6 cm (width) in the oldest. A mean walking velocity of 0.94 +/- 0.25 m/s was observed. Arch-index ranged from 0.32 +/- 0.04 [a.u.] in the one-year old to 0.21 +/- 0.13 [a.u.] in the 5-year olds and remains constant afterwards.
This study provides data for static and dynamic foot characteristics in children based on a cohort of 7788 subjects. Static and dynamic foot measures change differently during growth and maturation. Dynamic foot measurements provide additional information about the children's foot compared to static measures.
BAUR, H., A. HIRSCHMULLER, S. MULLER, and F. MAYER. Neuromuscular Activity of the Peroneal Muscle after Foot Orthoses Therapy in Runners. Med. Sci. Sports Exerc., Vol. 43, No. 8, pp. 1500-1506, 2011. Purpose: Foot orthoses are a standard option to treat overuse injury. Biomechanical data providing mechanisms of foot orthoses' effectiveness are sparse. Stability of the ankle joint complex might be a key factor. The purpose was therefore to analyze neuromuscular activity of the musculus peroneus longus in runners with overuse injury symptoms treated with foot orthoses. Methods: A total of 99 male and female runners with overuse injury symptoms randomized in a control group (CO) and an orthoses group (OR) were analyzed on a treadmill at 3.3 m.s(-1) before and after an 8-wk foot orthoses intervention. Muscular activity of the musculus peroneus longus was measured and quantified in the time domain (initial onset of activation (T-ini), time of maximal activity (T-max), total time of activation (T-tot)) and amplitude domain (amplitude in preactivation (A(pre)), weight acceptance (A(wa)), push-off (A(po))). Results: Peroneal activity in the time domain did not differ initially between CO and OR, and no effect was observed after therapy (T-ini: CO = -0.88 +/- 0.09, OR = -0.88 +/- 0.08 / T-max: CO = 0.14 +/- 0.06, OR = 0.15 +/- 0.06 / T-tot: CO = 0.40 +/- 0.09, OR = 0.41 +/- 0.09; P > 0.05). In preactivation (Apre), muscle activity was higher in OR after intervention (CO = 0.97 +/- 0.32, 95% confidence interval = 0.90-1.05; OR = 1.18 +/- 0.43, 95% confidence interval = 1.08-1.28; P = 0.003). There was no group or intervention effect during stance (A(wa): CO = 2.33 +/- 0.66, OR = 2.33 +/- 0.74 / A(po): CO = 0.80 +/- 0.41, OR = 0.88 +/- 0.40; P > 0.05). Conclusions: Enhanced muscle activation of the musculus peroneus longus in preactivation suggests an altered preprogrammed activity, which might lead to better ankle stability providing a possible mode of action for foot orthoses therapy.
Background and objectives Treatment of chronic running-related overuse injuries by orthopaedic shoe orthoses is very common but not evidence-based to date.
Hypothesis Polyurethane foam orthoses adapted to a participant's barefoot plantar pressure distribution are an effective treatment option for chronic overuse injuries in runners.
Design Prospective, randomised, controlled clinical trial.
Intervention 51 patients with running injuries were treated with custom-made, semirigid running shoe orthoses for 8 weeks. 48 served as a randomised control group that continued regular training activity without any treatment.
Main outcome measures Evaluation was made by the validated pain questionnaire Subjective Pain Experience Scale, the pain disability index and a comfort index in the orthoses group (ICI).
Results There were statistically significant differences between the orthoses and control groups at 8 weeks for the pain disability index (mean difference 3.2; 95% CI 0.9 to 5.5) and the Subjective Pain Experience Scale (6.6; 2.6 to 10.6). The patients with orthoses reported a rising wearing comfort (pre-treatment ICI 69/100; post-treatment ICI 83/100) that was most pronounced in the first 4 weeks (ICI 80.4/100).
Conclusion Customised polyurethane running shoe orthoses are an effective conservative therapy strategy for chronic running injuries with high comfort and acceptance of injured runners.
HIRSCHMULLER, A., V. FREY, L. KONSTANTINIDIS, H. BAUR, H-H. DICKHUTH, N. P. SUDKAMP, and P. HELWIG. Prognostic Value of Achilles Tendon Doppler Sonography in Asymptomatic Runners. Med. Sci. Sports Exerc., Vol. 44, No. 2, pp. 199-205, 2012. Introduction: Midportion Achilles tendinopathy (MPT) is a common problem in running athletes. Nevertheless, its etiology is not fully understood, and no valid prognostic criterion to predict the development of MPT could be identified to date. The purpose of the present study, therefore, was to evaluate whether power Doppler ultrasonography (PDU) is a suitable method to identify a predisposition to MPT in yet asymptomatic runners. Methods: At 23 major running events, 634 asymptomatic long-distance runners were tested for Achilles tendon thickness, vascularization, and structural abnormalities using a high-resolution PDU device (Toshiba Aplio SSA-770A/80, 12 MHz). In addition, their medical history and anthropometric data were documented. All subjects were contacted 6 and 12 months later and asked about any new symptoms. The collected anamnestic, anthropometric, and ultrasonographic data were subjected to regression analysis to determine their predictive value concerning the manifestation of midportion Achilles tendon complaints (P < 0.05). Results: The highest odds ratio (OR) for manifestation of MPT within 1 yr was found for intratendinous blood flow ("neovascularization,'' OR = 6.9, P < 0.001). An increased risk was also identified for subjects with a positive history of Achilles tendon complaints (OR = 3.8, P < 0.001). A third relevant parameter, just above the level of significance, was a spindle-shaped thickening of the tendon on PDU (Wald chi(2) = 3.42). Conclusions: PDU detection of intratendinous microvessels in the Achilles tendons of healthy runners seems to be a prognostically relevant factor concerning the manifestation of symptomatic MPT. This finding lays the foundation for an early identification of a predisposition to MPT as well as prophylactic intervention in as yet asymptomatic runners.