Eccentric Training Effects on Functionality and Neuromechanical Properties After Achilles Tendon Surgical Repair

Study Overview
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Brief Summary
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Early rehabilitation protocols have been studied in Achilles tendon (AT) rupture patients, but deficits in tendon biomechanical properties have been observed several years after the injury. AT rupture patients are unable to return to their previous levels of physical activity. They present deleterious adaptations in the plantar flexor muscles that lead to functional deficits, and deficits in the tendon's structural and mechanical properties. Eccentric contractions have been suggested to recover these muscle properties. This contraction is known to produce higher force compared to isometric and concentric contractions, and increases tendon stiffness. However, there is a lack of studies showing the effects of the eccentric training in AT rupture rehabilitation. We want to know if an isokinetic eccentric training program will determine the desired adaptations on triceps surae muscle-tendon unit's properties in patients subjected to the AT surgical repair. More specifically, the aim of this study is verifying the effects of a 12-week eccentric training program on triceps surae muscle-tendon unit's properties in subjects that were subjected to the AT surgical repair. 30 subjects will be randomized in two groups: (1) isokinetic eccentric training; and (2) traditional eccentric training control group. All participants will be submitted to a four-week control period, followed by a 12-week period of training for the plantar flexor muscles. Neuromuscular system properties, AT biomechanical properties and functional tests will be evaluated. Participants will be evaluated in four moments: at baseline; after 4, 8 and 12 weeks of rehabilitation. Tendon mechanical (stiffness, stress, strain), material (Young's modulus) and morphological (cross-sectional area and tendon length) properties; muscle architecture (thickness, pennation angle and fascicle length); and functional tests (heel rise resistance and height) will be analyzed between groups and periods. Effects and interactions will be analyzed with ANOVA two-way. Clinical effects will be analyzed using effect size and magnitude-based inferences.

Detailed Description
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Detailed Description: Early rehabilitation protocols have been studied in Achilles tendon (AT) rupture patients, but deficits in tendon biomechanical properties have been observed several years after the injury. AT rupture patients are unable to return to their previous levels of physical activity. They present deleterious adaptations in the plantar flexor muscles that lead to functional deficits and deficits in the tendon structural and mechanical properties. Deficits in calf muscle endurance and strength remained 7 years after the injury. In this regards, eccentric contractions are recommended to recover muscle morphology and mechanical properties. This contraction type produces higher force compared to isometric and concentric contractions, and increases tendon stiffness. However, there is a lack of studies showing the effect of the eccentric training in AT rupture rehabilitation. We want to know if an isokinetic eccentric training program will determine the desired adaptations on triceps surae muscle-tendon unit's properties in patients subjected to the AT surgical repair. More specifically, the aim of this study is verifying the effects of a 12-week eccentric training program on triceps surae muscle-tendon unit's properties in subjects that were subjected to the AT surgical repair. Our hypothesis is that the eccentric training program will (1) increase the ability to produce muscular strength; (2) will produce an increase in gastrocnemius and soleus muscles thickness, fascicle length, and pennation angle; (3) will increase AT stiffness and Young's modulus; (4) will increase ankle functionality; (5) will improve the patient's quality of life. Finally, we expect that the abovementioned changes from isokinetic eccentric training will be greater than those from the traditional eccentric control group that will be subjected to 12 weeks of plantar flexor training with weights. 30 subjects will be randomized in two groups: (1) isokinetic eccentric training; and (2) traditional eccentric training control group. All participants will be submitted to a four-week control period, followed by a 12- week period of training for the plantar flexor muscles. Neuromuscular system properties, AT biomechanical properties and functional tests will be evaluated. Participants will be evaluated in four moments: at baseline; after 4, 8 and 12 weeks of rehabilitation. Tendon mechanical (stiffness, stress, strain), material (Young's modulus) and morphological (cross sectional area and tendon length) properties; muscle architecture (thickness, pennation angle and fascicle length); and functional tests (heel rise resistance and height) will be analyzed between groups and periods. Effects and interactions will be analyzed with ANOVA two- way (group x period). Clinical effects will be analyzed using effect size (Cohen's d) and magnitude-based inferences.

Official Title
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Eccentric Training Effects on Functionality and on Triceps Surae Neuromechanical Properties After Achilles Tendon Surgical Repair

Conditions
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Achilles Tendon Rupture

Intervention / Treatment
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* Other: Isokinetic eccentric training
* Other: Traditional eccentric training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants will be male and female subjects who suffered total acute Achilles tendon rupture, and which underwent surgical repair. In addition, to participate in this study all volunteers will need to present medical and/or physiotherapeutic release for physical/sports activities practice. Exclusion Criteria: Volunteers that did not have Achilles tendon surgical reconstruction, that did not present medical and/or physiotherapeutic release for physical/sports activities, who have participated in strength training program for the plantar flexors in the last 6 months, patients with diabetic diseases, as well as those with difficulty for understanding and/or executing the test and training protocols in the isokinetic dynamometer will be excluded.

Ages Eligible for Study
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Minimum Age: 25 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Isokinetic eccentric group<br>The isokinetic eccentric training will be carried out with the volunteers positioned seated on the dynamometer with the apparent axis of the ankle joint rotation aligned with the dynamometer's axis of rotation. Movement will be executed in the angular velocity of 30°·s-1. Ankle range of motion (ROM) will be standardized for all participants in 50º, which shall respect each individual's maximal dorsiflexion amplitude. The 50° eccentric training ROM will start from each subject's 80% of the maximal dorsiflexion. This procedure will be used to ensure that all subjects perform training on the same plantar flexor muscular length, which should promote the same level of muscular requirement among the participants. This methodology was recently used by GEREMIA and VAZ (2016) study. | Other: Isokinetic eccentric training<br>* Training sessions will be performed in the same isokinetic dynamometer used in previous evaluations, twice a week, with a minimum interval of 72 hours between sessions.<br>|
| Active Comparator: Traditional eccentric training<br>Participants will be engaged in an intervention program consisting of 12 weeks of traditional eccentric training. The training will be carried out with the volunteers at gym in stand position. Concentric phase will be realized with both legs and the eccentric one only with one of them. Training progression will be the same from de isokinetic eccentric group. The same periodization from eccentric group will be used to permit us a posteriori comparison between groups. Training sessions will be performed at university gym, twice a week, with a minimum interval of 72 hours between sessions. Each training session will comprise the same specific warming protocol for the ankle joint from the eccentric training. | Other: Traditional eccentric training<br>* Training sessions will be performed at university gym, twice a week, with a minimum interval of 72 hours between sessions.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Tendon Young's modulus | Tendon elastic modulus (Young's modulus) will be obtained by calculating the slope in the last 40% of the linear region of the stress-strain curve. | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Tendon stiffness | Tendon stiffness will be obtained by calculating the slope in the last 40% of the linear region of the force-deformation curve. | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Resistance to plantar flexion test | The number of times, as well as the elevation height, will be used for data analysis. Height will be recorded and will be analyzed with Kinovea software. | First baseline evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Vertical countermovement jump | Vertical jump will be recorded using cameras and maximal vertical height will be measured using Kinovea software. | First baseline evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Triple hop test | Maximal distance of a triple unilateral jump will be measure with a metric tape. | First baseline evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Achilles tendon cross-sectional area | To obtain the Achilles tendon cross-sectional area (CSA), the US probe (GE Healthcare, Waukesha, Washington, USA) will be placed perpendicular to the tendon (in the transverse plane), and 3 images will be obtained with reference to the distances of 2, 4, 6, 8 and 10 cm of the muscle insertion in the calcaneus bone (ARYA and KULIG, 2010). Area values will be obtained for each image, and the final value of the area will be calculated by the average of these five values. | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Achilles tendon length | To obtain Achilles tendon length, the US (LOGIQ P6, GE Healthcare, Waukesha, Washington, USA) and a linear matrix array transducer (GE Healthcare, Waukesha, Washington, USA) will be placed longitudinally to the tendon (in the sagittal plane). The most distal portion of the Achilles tendon, inserted into the calcaneus bone, will be determined by US, and the respective point will be marked on the skin. After this, the probe will be moved to a proximal position until the visualization of the medial gastrocnemius myotendinous junction (MTJ), which is also marked on the skin. The distance between the two marked points on the skin will be measured with a measuring tape, this distance being considered representative of the tendon length (ARYA and KULIG, 2010; GEREMIA et al., 2015; GEREMIA and VAZ, 2016). | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Muscle strength | The plantar flexor capacity of force production will be obtained during isometric and isokinetic tests using an isokinetic dynamometer (Biodex System 3 Pro, Biodex Medical Systems, USA). Firstly, the isometric tests will be performed, followed by the concentric and eccentric tests. | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Muscle Architecture | Muscular architecture will be evaluated with an US system and a linear matrix array probe (GE Healthcare, Waukesha, Washington, USA). Muscle architecture parameters will involve fascicle length, pennation angle and muscle thickness (NARICI, 1999). Echo-intensity of the medial gastrocnemius will also be evaluated. The images will be obtained with the subjects in the ventral decubitus position on a stretcher, with the knees extended and the ankle in neutral position (heel line at a 90° angle with respect to the longitudinal axis of the leg, 0° of plantarflexion). A custom system will be used to secure the ankle in the neutral position. The probe will be positioned longitudinally to the muscle fibers at 30% proximal for medial and lateral gastrocnemius, and 50% for soleus, of the distance between the popliteal fold and the lateral malleolus center (KAWAKAMI et al., 1998). | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Resistance to plantar flexion test | The number of times, as well as the elevation height, will be used for data analysis. | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Calf muscle perimetry | To calculate the calf muscles perimetry, the leg length will be determined from the distance between the center of the lateral malleolus and the popliteal fossa at the knee. From the determination of this distance, the value corresponding to 30% of the distance from the articular line of the knee will be calculated for the measurement of the leg perimetry (MIYATANI et al., 2004) | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Muscle echo-intensity | For the echo-intensity evaluation, the probe will be positioned transversally at the proximal 30% of the lower leg length (AKAGI et al., 2018). Three images will be recorded in the same position of the muscle architecture. Echo-intensity has been associated with force production (CADORE et al., 2012; RECH et al., 2014; AKAGI et al., 2018), an aspect that we want to analyze is if there is some correlation among structural and functional variables | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 
| Muscle Activation | Gastrocnemius and sóleo muscles electromyography (EMG) signals will be measured through pairs of passive surface electrodes (Ag/AgCl, Meditrace, Kendall, Canada) in bipolar configuration. A reference electrode will be placed on the skin covering the anterior surface of the tibia, according to the procedures proposed by the Surface Electromyography for the Non-Invasive Assessment of Muscles (SENIAM, 2018). The electrodes will be fixed on the skin and a slight pressure will be applied on them to increase the contact between the electrode gel and the skin. The electrodes placement will respect the recommendations proposed by (SENIAM, 2018). | First evaluation, change from baseline to 4 weeks of training, change from baseline to 8 weeks of training and change from baseline to 12 weeks of training | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Achilles tendon, physical therapy, eccentric training, Achilles tendon rupture, rehabilitation