Achilles Tendon Loading Research Articles

The Difference in Achilles Tendon Loading within Immobilizing Boots Based on Ankle Angle, Boot Type, and Walking Speed.

Achilles tendon rupture is an increasingly common injury treated with progressive rehabilitation in an immobilizing boot. However, it is poorly understood how ankle angle, boot type, and walking speed affect Achilles tendon loading. These different parameters would affect Achilles tendon loading in terms of (from greatest to least) ankle angle constraint, immobilization style, boot construction, and walking speed. Descriptive laboratory study. Ten healthy young adults (8 women and 2 men; age, 21 ± 2 years; body mass index, 21.5 ± 3.0 kg/m2) walked in 3 different immobilizing boots at self-selected slow, medium, and fast walking speeds. The authors estimated Achilles tendon loading using a 3-part instrumented insole within the immobilizing boot. The authors averaged tendon load across every stride for each condition and calculated 2-sided bootstrap confidence intervals. Peak tendon loading was compared across all boots, ankle angles, and walking speeds. All boots and immobilization styles decreased tendon loading with respect to shod walking. Immobilization angle had the largest effect on tendon loading, followed by boot construction, and finally walking speed. Ankle angle, boot type, and walking speed can be modified to change loading progression during rehabilitation. Understanding how immobilization affects tendon loading will enable clinicians to modify rehabilitation to improve functional outcomes.

Effect of the temporal coordination and volume of cyclic mechanical loading on human Achilles tendon adaptation in men

Human tendons adapt to mechanical loading, yet there is little information on the effect of the temporal coordination of loading and recovery or the dose–response relationship. For this reason, we assigned adult men to either a control or intervention group. In the intervention group, the two legs were randomly assigned to one of five high-intensity Achilles tendon (AT) loading protocols (i.e., 90% maximum voluntary contraction and approximately 4.5 to 6.5% tendon strain) that were systematically modified in terms of loading frequency (i.e., sessions per week) and overall loading volume (i.e., total time under loading). Before, at mid-term (8 weeks) and after completion of the 16 weeks intervention, AT mechanical properties were determined using a combination of inverse dynamics and ultrasonography. The cross-sectional area (CSA) and length of the free AT were measured using magnetic resonance imaging pre- and post-intervention. The data analysis with a linear mixed model showed significant increases in muscle strength, rest length-normalized AT stiffness, and CSA of the free AT in the intervention group (p < 0.05), yet with no marked differences between protocols. No systematic effects were found considering the temporal coordination of loading and overall loading volume. In all protocols, the major changes in normalized AT stiffness occurred within the first 8 weeks and were mostly due to material rather than morphological changes. Our findings suggest that—in the range of 2.5–5 sessions per week and 180–300 s total high strain loading—the temporal coordination of loading and recovery and overall loading volume is rather secondary for tendon adaptation.

Asymmetric running is associated with pain during outdoor running in individuals with Achilles tendinopathy in the return-to-sport phase

ObjectivesTo determine the relationships between (1) Achilles tendon pain and loading symmetry, and (2) number of running bouts and symptom severity, during two weeks of outdoor running in individuals with Achilles tendinopathy. DesignProspective, observational study. SettingBiomechanics laboratory and outdoors. ParticipantsSeventeen runners with Achilles tendinopathy in the return-to-sport phase of rehabilitation. Main outcome measuresSymptom severity was recorded with the Victorian Institute of Sports Assessment-Achilles (VISA-A) questionnaire. Running bouts and Achilles tendon pain during runs were recorded with daily training logs. Ground contact time was collected during runs with wearable sensors. Linear mixed modeling determined if the relationship between Achilles tendon pain and ground contact time symmetry during running was moderated by consecutive run days. Multiple regression determined the relationship between number of running bouts and change in VISA-A scores over two weeks, adjusted for run distance. ResultsGreater ground contact time on the contralateral leg corresponded to increased ipsilateral tendon pain for each consecutive run day (b = −0.028, p < 0.001). Number of running bouts was not associated with 2-week changes in VISA-A scores (p = 0.672). ConclusionsPain during running is associated with injured leg off-loading patterns, and this relationship strengthened with greater number of consecutive run days. Number of running bouts was not related to short-term symptom severity.

Achilles Tendon Loading during Running Estimated Via Shear Wave Tensiometry: A Step Toward Wearable Kinetic Analysis.

Understanding muscle-tendon forces (e.g., triceps surae and Achilles tendon) during locomotion may aid in the assessment of human performance, injury risk, and rehabilitation progress. Shear wave tensiometry is a noninvasive technique for assessing in vivo tendon forces that has been recently adapted to a wearable technology. However, previous laboratory-based and outdoor tensiometry studies have not evaluated running. This study was undertaken to assess the capacity for shear wave tensiometry to produce valid measures of Achilles tendon loading during running at a range of speeds. Participants walked (1.34 m·s -1 ) and ran (2.68, 3.35, and 4.47 m·s -1 ) on an instrumented treadmill while shear wave tensiometers recorded Achilles tendon wave speeds simultaneously with whole-body kinematic and ground reaction force data. A simple isometric task allowed for the participant-specific conversion of Achilles tendon wave speeds to forces. Achilles tendon forces were compared with ankle torque measures obtained independently via inverse dynamics analyses. Differences in Achilles tendon wave speed, Achilles tendon force, and ankle torque across walking and running speeds were analyzed with linear mixed-effects models. Achilles tendon wave speed, Achilles tendon force, and ankle torque exhibited similar temporal patterns across the stance phase of walking and running. Significant monotonic increases in peak Achilles tendon wave speed (56.0-83.8 m·s -1 ), Achilles tendon force (44.0-98.7 N·kg -1 ), and ankle torque (1.72-3.68 N·m·(kg -1 )) were observed with increasing locomotion speed (1.34-4.47 m·s -1 ). Tensiometry estimates of peak Achilles tendon force during running (8.2-10.1 body weights) were within the range of those estimated previously via indirect methods. These results set the stage for using tensiometry to evaluate Achilles tendon loading during unobstructed athletic movements, such as running, performed in the field.

Where is Your Pain? Achilles Tendinopathy Pain Location on Loading Is Different to Palpation, Imaging and Recall Location.

OBJECTIVE: To describe and compare pain maps reported during Achilles tendon loading exercises with recall pain location, in people with pain on palpation in their Achilles tendon and tendon pathology on imaging. DESIGN: Cross-sectional analysis of baseline RCT. METHOD: Participants were recruited from a larger Achilles tendinopathy clinical trial. Inclusion criteria were at least 2-month self-reported history of Achilles tendinopathy, midtendon palpation pain, and pathology on ultrasound tissue characterization. Participants were asked to identify their Achilles tendon pain location on a pain map with 8 prespecified locations while at rest prior to loading (recall pain), and subsequently during tendon loading exercises (loading pain). Participants could select multiple locations or select "other" if the locations did not represent their pain. RESULTS: Ninety-three participants were included (93% of participants from a clinical trial). The locations of pain on loading were diverse; all 8 pain locations (and an "other" option) were represented within this sample. Twenty-five percent of participants did not report pain with loading (n = 23 of 93). Of the 70 participants with loading pain, recall pain location differed to loading pain location in 40% (n = 28 of 70) of the participants. CONCLUSION: Palpation pain location, recall pain location, or location of pathology on imaging were not valid proxies for load-related pain in the Achilles tendon. How different pain locations respond to treatment is unknown. Some pathologies (eg, plantaris) have clear pain locations (eg, medial tendon), and assessing pain location may assist differential diagnosis. J Orthop Sports Phys Ther 2024;54(1):1-9. Epub 7 December 2023. doi:10.2519/jospt.2023.12131.

Wearable sensor and machine learning estimate tendon load and walking speed during immobilizing boot ambulation

The purpose of this study is to develop a wearable paradigm to accurately monitor Achilles tendon loading and walking speed using wearable sensors that reduce subject burden. Ten healthy adults walked in an immobilizing boot under various heel wedge conditions (30°, 5°, 0°) and walking speeds. Three-dimensional motion capture, ground reaction force, and 6-axis inertial measurement unit (IMU) signals were collected. We used a Least Absolute Shrinkage and Selection Operator (LASSO) regression to predict peak Achilles tendon load and walking speed. The effects of altering sensor parameters were also explored. Walking speed models (mean absolute percentage error (MAPE): 8.81 ± 4.29%) outperformed tendon load models (MAPE: 34.93 ± 26.3%). Models trained with subject-specific data performed better than models trained without subject-specific data. Removing the gyroscope, decreasing the sampling frequency, and using combinations of sensors did not change the usability of the models, having inconsequential effects on model performance. We developed a simple monitoring paradigm that uses LASSO regression and wearable sensors to accurately predict (MAPE ≤ 12.6%) Achilles tendon loading and walking speed while ambulating in an immobilizing boot. This paradigm provides a clinically implementable strategy to longitudinally monitor patient loading and activity while recovering from Achilles tendon injuries.

Residual Asymmetries In Functional Achilles Tendon Loading Following Rupture And Repair: A Preliminary Analysis

Residual Asymmetries In Functional Achilles Tendon Loading Following Rupture And Repair: A Preliminary Analysis

Effects of Body Weight Support in Running on Achilles Tendon Loading.

Achilles tendon (AT) tendinopathy is common in runners. Repetitive AT loading may play a role in etiology. Interventions such as body weight support (BWS) may reduce loading on the AT in running. Examine how ground reaction force, AT loading, foot strike and cadence variables change in running with BWS. Twenty-four healthy female runners free from injury were examined. Participants ran on an instrumented treadmill with and without BWS using a harness-based system at a standardized speed. The system has 4 elastic cords affixed to a harness that is attached to a frame-like structure. Kinematic data and kinetic data were used in a musculoskeletal model (18 segments and 16 degrees of freedom) to determine AT loading variables, foot strike angle and cadence. Paired t-tests were used to compare each variable between conditions. Ground reaction force was 9.0% lower with BWS (p<.05). Peak AT stress, force, and impulse were 9.4%, 11.7% and 14.8% lower when using BWS in running compared to no support (p<.05). Foot strike angle was similar (p<.05) despite cadence being reduced (p<.05). BWS may reduce AT loading and impulse variables during running. This may be important in the rehabilitation efforts.

Do the fasciae of the soleus have a role in plantar fasciitis?

Plantar fasciitis is a chronic, self-limiting, and painful disabling condition affecting the inferomedial aspect of the heel, usually extending toward the metatarsophalangeal joints. There is compelling evidence for a strong correlation between Achilles tendon (AT) loading and plantar aponeurosis (PA) tension. In line with this, tightness of the AT is found in almost 80% of patients affected by plantar fasciitis. A positive correlation has also been reported between gastrocnemius-soleus tightness and heel pain severity in this condition. Despite its high prevalence, the exact etiology and pathological mechanisms underlying plantar heel pain remain unclear. Therefore, the aim of the present paper is to discuss the anatomical and biomechanical substrates of plantar fasciitis with special emphasis on the emerging, though largely neglected, fascial system. In particular, the relationship between the fascia, triceps surae muscle, AT, and PA will be analyzed. We then proceed to discuss how structural and biomechanical alterations of the muscle-tendon-fascia complex due to muscle overuse or injury can create the conditions for the onset of PA pathology. A deeper knowledge of the possible molecular mechanisms underpinning changes in the mechanical properties of the fascial system in response to altered loading and/or muscle contraction could help healthcare professionals and clinicians refine nonoperative treatment strategies and rehabilitation protocols for plantar fasciitis.

Is the energy loss of footwear related to Achilles tendon loading during treadmill walking?

Is the energy loss of footwear related to Achilles tendon loading during treadmill walking?

Combined Midportion Achilles and Plantaris Tendinopathy: A 1-Year Follow-Up Study after Ultrasound and Color-Doppler-Guided WALANT Surgery in a Private Setting in Southern Sweden.

Background and Objectives: Chronic painful midportion Achilles combined with plantaris tendinopathy can be a troublesome condition to treat. The objective was to prospectively follow patients subjected to ultrasound (US)- and color doppler (CD)-guided wide awake, local anesthetic, no-tourniquet (WALANT) surgery in a private setting. Material and Methods: Twenty-six Swedish patients (17 men and 9 women, mean age 50 years (range 29-62)) and eight international male patients (mean age of 38 years (range 25-71)) with combined midportion Achilles and plantaris tendinopathy in 45 tendons altogether were included. All patients had had >6 months of pain and had tried non-surgical treatment with eccentric training, without effect. US + CD-guided surgical scraping of the ventral Achilles tendon and plantaris removal under local anesthesia was performed on all patients. A 4-6-week rehabilitation protocol with an immediate full-weight-bearing tendon loading regime was used. The VISA-A score and a study-specific questionnaire evaluating physical activity level and subjective satisfaction with the treatment were used for evaluation. Results: At the 1-year follow-up, 32/34 patients (43 tendons) were satisfied with the treatment result and had returned to their pre-injury Achilles tendon loading activity. There were two dropouts (two tendons). For the Swedish patients, the mean VISA-A score increased from 34 (0-64) before surgery to 93 (61-100) after surgery (p < 0.001). There were two complications, one wound rupture and one superficial skin infection. Conclusions: For patients suffering from painful midportion Achilles tendinopathy and plantaris tendinopathy, US + CD-guided surgical Achilles tendon scraping and plantaris tendon removal showed a high satisfaction rate and good functional results 1 year after surgery.

American Society of Biomechanics Clinical Biomechanics Award 2021: Redistribution of muscle-tendon work in children with cerebral palsy who walk in crouch

BackgroundPrevious study showed the triceps surae exhibits spring-like behavior about the ankle during walking in children with cerebral palsy. Thus, the work generated by the triceps surae is diminished relative to typically developing children. This study investigated whether the quadriceps offset the lack of triceps surae work production in children with cerebral palsy who walk in crouch. MethodsSeven children with cerebral palsy (8-16 yrs) and 14 typically developing controls (8-17 yrs) walked overground at their preferred speed in a motion analysis laboratory. Shear wave tensiometers were used to track patellar and Achilles tendon loading throughout the gait cycle. Tendon force measures were coupled with muscle-tendon kinematic estimates to characterize the net work generated by the quadriceps and triceps surae about the knee and ankle, respectively. FindingsChildren with cerebral palsy generated significantly less triceps surae work when compared to controls (P < 0.001). The reverse was true at the knee. Children with cerebral palsy generated positive net work from the quadriceps about the knee, which exceeded the net quadriceps work generated by controls (P = 0.028). InterpretationThere was a marked difference in functional behavior of the triceps surae and quadriceps in children with cerebral palsy who walk in crouch. In particular, the triceps surae of children with cerebral palsy exhibited spring-like behavior about the ankle while the quadriceps exhibited more motor-like behavior about the knee. This redistribution in work could partly be associated with the elevated energetic cost of walking in children with cerebral palsy and is relevant to consider when planning treatments to correct crouch gait.

Percutaneous Bioelectric Current Stimulation in the Treatment of Chronic Achilles Tendinopathy: Protocol for a Double-Blind, Placebo-Controlled Randomized Multicenter Trial.

The consensus for the optimal treatment strategy for chronic Achilles tendinopathy (AT) is still debated and treatment options are limited. This results in a significant medical need for more effective treatment options. The aim of this study is to investigate the therapeutic effects of percutaneous bioelectric current stimulation (PBCS) on AT. A multicenter, randomized, double-blind, placebo-controlled clinical trial will be conducted. A total of 72 participants with chronic (ie, >3 months) midpoint AT will be randomized and receive four PBCS sessions-either verum or placebo-over 3 weeks. Both groups will complete daily Achilles tendon loading exercises in addition to the intervention. Evaluation sessions will be completed at baseline and during the intervention (weeks 0-3). Self-reported outcome measures will be completed at follow-up at weeks 4, 12, 26, and 52. The primary outcomes are the Victorian Institute of Sports Assessment-Achilles questionnaire scores and statistical evaluation of intraindividual differences between baseline and 12-week evaluations after initial treatment of verum therapy compared to control. Secondary outcomes will assess Pain Disability Index scores; average pain, using the 11-point Numeric Rating Scale; return to sports; and use of emergency medication. The study began in May 2021. As of October 2022, we randomized 66 out of 72 participants. We anticipate completing recruitment by the end of 2022 and completing primary data analysis by March 2023. The study will evaluate the effects of PBCS on pain, physical function, and clinical outcomes. German Clinical Trials Register DRKS00017293; https://tinyurl.com/mvz7s98k. DERR1-10.2196/40894.

Effect of Fibular Malrotation on Tibiotalar Joint Contact Mechanics in a Weber B Ankle Fracture Model.

In minimally displaced Weber B ankle fractures, the distal fibular fracture fragment can be externally rotated. This malrotation is difficult to detect on radiographs and, when left malreduced through nonoperative treatment, may contribute to altered joint mechanics, predisposing to posttraumatic osteoarthritis. This study evaluates the effects of fibular malrotation on tibiotalar joint contact mechanics. Six cadaveric ankles were tested using a materials testing system (MTS) machine. A tibiotalar joint sensor recorded contact area and pressure. Samples were tested in the intact, neutrally rotated, and malrotated state. Each trial applied a 686N axial load and a 147N Achilles tendon load in neutral position, 15° dorsiflexion, and 15° plantarflexion. In the comparison of malrotated to intact ankles, peak contact pressure was found to be significantly greater at neutral flexion (intact 5.56 MPa ± 1.39, malrotated 7.21 MPa ± 1.07, P = .03), not significantly different in dorsiflexion, and significantly decreased in plantarflexion (intact 11.2 MPa ± 3.04, malrotated 9.01 MPa ± 1.84, P = .01). Significant differences in contact area were not found between conditions. The findings suggest that fibular malrotation contributes to significant alterations in tibiotalar joint contact pressures, which may contribute to the development of posttraumatic osteoarthritis. When malrotation of the fibula is suspected on plain radiographs, a computer tomography (CT) scan should be obtained to evaluate its extent and further consideration should be given to surgical treatment. Level V: Bench testing.

Tracking Day-To-Day Achilles Tendon Loading Progression During Rupture Recovery: A Case Study

Category: Sports; Basic Sciences/Biologics Introduction/Purpose: Achilles tendon rupture patients often suffer long-term functional deficits. Although progressive tendon loading improves healing, it is difficult to reliably measure in the real world and thus be precisely prescribed in rehabilitation. Modern wearable sensors, including instrumented shoe insoles, provide powerful platforms to measure real-world biomechanics. Using simple algorithms, we showed that these instrumented insoles can accurately quantify Achilles tendon loads. Yet, the feasibility of using wearables to enhance targeted Achilles tendon therapeutics remain unknown, partly due to the challenges of obtaining data on many patients over the long recovery process. Therefore, we leveraged a case study to verify whether instrumented insoles are able to track the longitudinal progression of Achilles tendon loading in daily life, and relate to clinically relevant events of tendon health. Methods: A patient (F, 30y/o) who underwent a right Achilles tendon repair was enrolled after consent in this IRB-approved study. During a standard rehabilitation protocol, an immobilizing boot fit with a 3-sensor instrumented insole (Loadsol) was worn starting from week 4 post-surgery. The insole remained in footwear after switching from boot to shoe, and data collection continued until week 22. The patient recorded &gt;10 seconds of insole data during gait each day, logged daily step count, and documented any event that may be related to tendon health, including pain and notable daily living activities. For each step identified by insole, we estimated Achilles tendon loads using our established algorithm, including load peak, impulse over a step, and load rates. We compared the daily average of these variables to self-reported events to explore their inter-relationships. We also correlated the load variables to determine whether they each provide unique insights into tendon loading. Results: The insole recorded up to 70 steps each day on a total of 116 days. Peak Achilles tendon load increased gradually yet non-linearly along the recovery process, with large variations between week 12-19 (Figure). 'Sharp' loading changes often corresponded to tendon health-related events, such as days of pain and swelling following rapid load increases in late week 12. A day of high step count (20k+) in week 18 was followed by a large decrease of the peak tendon load at the end of the same day. The insole also identified tendon load changes according to patient instructions, including a 65% increase in peak load by intentionally 'trying to push off' during gait. Finally, tendon load rates and impulse strongly correlated with peak load (R2 &gt;0.85). Conclusion: Longitudinally monitoring Achilles tendon loading is challenging because 1) it is limited by the scarce frequency of clinical visits, and 2) lab-based gait measurements do not faithfully reflect real-world biomechanics. Our first-of-kind case study shows the feasibility of using instrumented insoles to track day-to-day Achilles tendon loading in the real world. The results suggest Achilles tendon loading can be sufficiently tracked using peak load, and modified instantly and interactively via instructions or biofeedback. Our innovative paradigm empowers future studies to leverage accessible tools and deliver personalized rehabilitation according to quantitative guidance, thereby optimizing long-term Achilles tendon healing and functional recovery.

Achilles Tendon Loading During Walking Differs Between Commonly Used Immobilizing Boots

Category: Sports; Basic Sciences/Biologics Introduction/Purpose: Achilles tendon ruptures have increased 10-fold in the past three decades, leading to long-term functional deficits in nearly two-thirds of patients. To counter this, rehabilitation protocols have been developed to strike a balance between protecting the healing tendon from re-rupture while allowing patients to return to activities of daily living as early as possible. However, Achilles tendon loading is neither prescribed nor quantified during immobilization and there is no standardized method of immobilization. Therefore, the purpose of this study was to quantify the amount of tendon loading experienced while walking in 3 different kinds immobilizing boot with respect to prescribed ankle angle and walking speed. Methods: Two healthy-young adults (2M; Age: 29.6 +- 2.3 y/o; BMI: 30 +- 7) walked over flat ground while wearing 3 different immobilizing boots and athletic shoes after providing written informed consent in this IRB approved study. We calculated Achilles tendon loading while subjects walked in 3 boots that positioned the ankle in 30 degrees of plantar flexion (Figure A, Air Cam Walker, United Ortho; AirSelect Walker, Aircast, VACOped, OPED). In all three boots, an instrumented insole (Loadsol, Novel) was placed under the foot to quantify load experienced by the tendon. We calculated the Achilles tendon loading profiles during gait for each immobilizing boot and compared them against the normal shod condition. We also provided the surgical repair threshold of 0.5 bodyweights to visualize the potential efficacy of each immobilizing boot for early rehabilitation when the tendon is early in the healing phase. Results: As expected, tendon loading was highest in the shod condition with no ankle bracing and lowest in the fully plantarflexed adjustable boot (Figure B). On average, the immobilizing boots reduced tendon loading decreased by 68% compared to unsupported walking in shoes but there were differences among the boots. The 3 different immobilizing boots provided differing levels of support. The 2 walking boots that use heel wedges to support the ankle in plantar flexion provided the least support, reducing loading by an average of 60-68%. The more rigid boot that constrained ankle angle using a posterior strut reduced tendon loading by 77% compared to gait in a normal walking shoe. Based on biomechanical studies of Achilles tendon repair strength in cadaveric experiments, only the rigid boot with the posterior strut reduced tendon loading biomechanics to levels that could be resisted by the surgical repair (Figure B). Conclusion: In this study, we used an instrumented insole to quantify Achilles tendon loading in a variety of immobilizing boots used by rupture patients. Our initial findings show that tendon loading is varies greatly between boot types and patients, highlighting the importance of understanding how these loads change in patients. Our future work centers around identifying the tendon loading profiles that promote tendon healing and optimize patient outcomes. These loading profiles will then provide the quantitative data needed to personalize loading for patients and guide rehabilitation to improve outcomes.

Measurement of Achilles tendon loading using shear wave tensiometry: A reliability study

BackgroundShear wave tensiometry is a recent promising technology which can be used to evaluate tendon loading. Knowing the clinimetric features (e.g., reliability) of this technology is important for use in clinical and research settings. ObjectivesTo evaluate the inter-session reliability of a novel shear wave tensiometer for the assessment of Achilles tendon loading. A further aim was to test the construct validity of this device by evaluating its precision in detecting Achilles tendon loading changes induced by a plantar flexor isometric contraction of increasing intensity. MethodTen healthy participants were recruited. Five measurements were performed at different time points to evaluate inter-session reliability. Shear wave speed along the Achilles tendon was evaluated during different isometric contractions using a shear wave tensiometer composed of an array of four accelerometers fixed on the tendon, ranging from 4 to 8.5 cm from the calcaneal insertion of the tendon. Test-retest, intra- and inter-session reliability were determined using intraclass correlation coefficient (ICC3.1). Absolute reliability was calculated using the standard error of measurement and minimal detectable change. ResultsTest-retest reliability was good to excellent (ICC3.1 0.87–0.99) for each of the contraction levels examined. Intra-session reliability was good to excellent (ICC3.1 0.85–0.96) and inter-session reliability was also good to excellent (ICC3.1 0.75–0.93) for each of the contraction levels. ConclusionsThis study confirms the reliability of this novel device. Future studies analyzing participants with Achilles tendinopathy are needed to evaluate the capability of shear wave tensiometry to detect transient changes in loading due to pathology.

Determining the feasibility of exercise therapy and activity modification for treating adolescents with heel pain: a study protocol

Calcaneal apophysitis and Achilles tendinopathy are common overuse injuries characterised by insidious posterior heel pain with activity. Calcaneal apophysitis is commonly diagnosed in adolescents, although Achilles tendinopathy is understudied in...

Foundational Principles and Adaptation of the Healthy and Pathological Achilles Tendon in Response to Resistance Exercise: A Narrative Review and Clinical Implications.

Therapeutic exercise is widely considered a first line fundamental treatment option for managing tendinopathies. As the Achilles tendon is critical for locomotion, chronic Achilles tendinopathy can have a substantial impact on an individual’s ability to work and on their participation in physical activity or sport and overall quality of life. The recalcitrant nature of Achilles tendinopathy coupled with substantial variation in clinician-prescribed therapeutic exercises may contribute to suboptimal outcomes. Further, loading the Achilles tendon with sufficiently high loads to elicit positive tendon adaptation (and therefore promote symptom alleviation) is challenging, and few works have explored tissue loading optimization for individuals with tendinopathy. The mechanism of therapeutic benefit that exercise therapy exerts on Achilles tendinopathy is also a subject of ongoing debate. Resultingly, many factors that may contribute to an optimal therapeutic exercise protocol for Achilles tendinopathy are not well described. The aim of this narrative review is to explore the principles of tendon remodeling under resistance-based exercise in both healthy and pathologic tissues, and to review the biomechanical principles of Achilles tendon loading mechanics which may impact an optimized therapeutic exercise prescription for Achilles tendinopathy.

Tendon loading in runners with Achilles tendinopathy: Relations to pain, structure, and function during return-to-sport.

We aimed to (1) compare pain, tendon structure, lower limb function, and Achilles tendon loads while running between limbs in runners with Achilles tendinopathy, and (2) explore the relations of pain, tendon structure, and lower limb function to Achilles tendon loads while running. Twenty runners with Achilles tendinopathy participated in this pilot study. Pain was assessed with questionnaires, quantitative sensory testing, and functional testing. Tendon morphology and mechanical properties were evaluated with ultrasound imaging, continuous shear wave elastography, and ultrasound imaging combined with dynamometry. Lower limb function was assessed with an established test battery. Achilles tendon loads were estimated from biomechanical data acquired during running. Compared to the least symptomatic limb, the most symptomatic limb had lower scores on the Victorian Institute of Sports Assessment - Achilles questionnaire and worse pain during drop countermovement jumping, hopping, and running. Tendon thickness and cross-sectional area were greater, and Young's modulus, drop countermovement jump height, and plyometric quotient during hopping were lower on the most symptomatic limb. Side-to-side differences in drop countermovement jump height were significantly associated with side-to-side differences in Achilles tendon peak forces and average loading rates during running. Various measures of pain, structure, and function differ between limbs in runners with Achilles tendinopathy during return-to-sport. Tendon forces, however, do not differ between limbs during comfortable running. In addition to measures that differ between limbs, measures of performance during drop countermovement jumping may aid in clinical decision-making during return-to-sport because they are associated with tendon forces while running.