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: 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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
33
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.
Training sessions will be performed at university gym, twice a week, with a minimum interval of 72 hours between sessions.
Exercise Research Laboratory, School of Physical Education, Physical Therapy and Dance, Federal University of Rio Grande do Sul
Porto Alegre, Rio Grande do Sul, Brazil
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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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
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.
Time frame: 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).
Time frame: 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.
Time frame: 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).
Time frame: 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.
Time frame: 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)
Time frame: 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
Time frame: 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).
Time frame: 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
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