Properties Of Achilles Tendon Research Articles

Effects of Moderate and Heavy Slow Resistance Training on Achilles and Patellar Tendons and Muscles Aponeuroses in Elderly Men.

To investigate the effect of moderate or heavy slow resistance training on structural and mechanical properties of patellar and Achilles tendons in older men, invivo. Healthy older men (n = 27) undertook a 12-week resistance training program (3 times/week) of triceps surae and quadriceps muscle-tendon complexes. Participants were randomly assigned to either a moderate load of 55% 1RM (O55, n = 13, age: 70.0 ± 4.6 years) or a progressively heavier load from 55% up to 80% 1RM (O80, n = 14, age: 69.8 ± 4.4 years). Tendon morphology was investigated using a 1.5 T MRI scanner. Mechanical properties of the free Achilles tendon (AT) and medial gastrocnemius (MG) aponeurosis, patellar tendon (PT), and deep aponeurosis of the vastus lateralis (VL) muscle were assessed using ultrasound imaging. Both training programs led to an increase in mean CSA of the PT (O55; +2.7%, O80; +1.7%, p = 0.002) and AT (O55; +2.8%, O80; +2.5%, p < 0.001). Force and stress were increased for all the four regions investigated, while stiffness and Young's modulus assessed at a common force level were only increased for the AT and VL aponeurosis. No interaction between group and time was demonstrated for any of the outcomes. No interaction between time and the four tendon sites was observed for any of the outcomes at common force. A supervised short-term heavy or moderate slow resistance training of equal volume yielded an increase in tendon size and altered mechanical properties of tendinous tissue.

Minimum effective plyometric training volume in sedentary individuals: Impact on lower limb viscoelastic properties and functional performance in a randomised controlled trial

ABSTRACT Sedentary lifestyles reduce muscle mass, strength, power, and alter viscoelastic properties. Plyometric jump training (PJT) shows promise in countering these effects, but the optimal training volume for individuals with low athletic performance remains unclear. This study aimed to determine the minimal PJT volume required to improve muscle and tendon viscoelastic properties, strength, and power in sedentary individuals. A double-blind randomised controlled trial included 44 participants divided into three groups: Control Group (CG) (n = 16), Reduced Volume Training Group (RVTG) (n = 16), and Training Group (TG) (n = 12). The four-week PJT programme involved three weekly sessions with gradual volume increments; RVTG performed 50% less volume than TG. Baseline and follow-up assessments included the isokinetic standing up (SU) and sitting down (SD) phases at 15 cm/s and 5 cm/s, and myotonometer measurements. In the SU phase at 15 cm/s, significant differences were found (p = 0.01) with higher values in TG (10.0 ± 3.3 N/kg) compared to CG and RVTG. At 5 cm/s, differences in SD were observed (p = 0.002). For Achilles tendon properties in RVTG: stiffness (p = 0.04), decrement (p = 0.01), and relaxation (p = 0.02). A PJT volume of 2,414 jumps improved muscle strength, while 1,207 jumps altered tendon properties.

Panda Rope Bridge Technique promoted Achilles tendon regeneration in a novel rat tendon defect model.

This study aimed to determine whether the Achilles tendon tissue can undergo the pathological process of Achilles tendon regeneration after the Panda Rope Bridge Technique (PRBT). Rats (n = 120) that operated with Achilles tendon rupture were divided into three treatment groups: Defect group (D group), PRBT group and Defect + Fix group (DF group). The D group represented natural healing with no treatment, the PRBT group represented healing receiving PRBT treatment and the DF group represented healing through conservative treatment by ankle fixation. The morphological, histological and biomechanical properties of the defective Achilles tendon were assessed at 7, 10, 12, 14, 28 and 56 days postoperatively. Compared to that observed in the other two groups, defected rat Achilles tendons that underwent PRBT recruited more cells earlier, eventually forming mature tendons, as revealed by histological analysis. PRBT also enabled defected tendons to regain stronger mechanical properties, thereby improving the prognosis. This improvement may be related to the earlier polarization of macrophages. By establishing and using a novel surgical model of Achilles tendon rupture in rats, most injured Achilles tendons can regenerate and regain normal histological properties, whereas tendons with other interventions formed fibrotic scar tissue. The strong regenerative capacity of tendon tissue enabled us to describe the pathological process of tendon regeneration after PRBT surgery in detail, which would aid in the treatment of tendon injuries. PRBT promotes Achilles tendon regeneration and has the potential to become a standard treatment. Not applicable.

The Effect of Biomechanical and Viscoelastic Properties of Gastrocnemius (Lateral-Medial) Muscle and Achilles Tendon on Jumping Performance in Professional Soccer Players

Anaerobic performance (vertical jumps) is an important indicator in determining athletic performance in soccer. The aim of this study was to investigate the effects of biomechanical and viscoelastic properties of lateral and medial gastrocnemius (LG&amp;amp;MG) muscle and achilles tendon (AT) on jumping performance of professional soccer players. A total of 21 male professional soccer players with a mean age of 18.19±0.40 years, a mean height of 180.48±6.25 cm, a mean body weight of 70.71±7.82 kg, and a mean BMI of 21.66±1.65 kg/m₂ were included in this study. LG and MG muscle, as well as AT biomechanical and viscoelastic properties were evaluated with Myoton Pro device. Measurements were performed in the prone position of the soccer players, LG and MG at 50° plantar flexion, and AT at 0° (neutral position) at an angle of 4 cm above the calcaneal tubercle. Counter movement jump (CMJ) were recorded with the high-speed camera in the validated My Jump 2 application. A significant correlation was observed between the LG (F) tension value and CMJ (P) value and between the MG (R&amp;amp;C) values and the CMJ (F&amp;amp;P) value of professional soccer players (p&amp;lt;0.05). There was no significant relationship between AT values and CMJ values (p&amp;gt;0.05). It should not be forgotten that training coaches on this subject and applying this information to soccer players by conscious coaches will bring about increases in the athletic performance of soccer players, and all these performance characteristics can be achieved with planned and programmed training.

Determinants of Achilles tendon thickness and their influence on knee function and foot alignment in knee osteoarthritis

Knee osteoarthritis (OA) significantly impacts the quality of life of individuals globally. However, the interconnections between Achilles tendon thickness, knee symptoms/functions, and foot alignment remain understudied in knee OA patients. This study determines the relationships between Achilles tendon thickness (ATT), knee symptoms/functions, and foot alignment in knee OA patients, considering their interconnected biomechanical nature. In a cross-sectional analysis involving 122 knee OA patients, Knee injury and Osteoarthritis Outcome Score (KOOS) assessed knee function and symptoms. Forefoot, midfoot, and rearfoot alignment were measured using hallux valgus angle, navicular/foot ratio, and rearfoot angle. The navicular/foot ratio represented the ratio of navicular height to total foot length. ATT was measured using a digital calliper. Pearson correlations and stepwise multiple linear regression models were employed to explore relationships and determinants. Out of 122 participants, 88 (72.1%) were females. ATT correlated significantly with ankle range of motion, forefoot alignment, and midfoot alignment. In stepwise multivariable regression, ankle range of motion, navicular/foot ratio, and age were significantly associated with ATT (adjusted R2 = 0.44). Similarly, KOOS-Symptoms scores were linked to the OA severity, navicular/foot ratio, ankle range of motion, gastrocnemius strength, and age (adjusted R2 = 0.22). KOOS-Function scores were significantly associated with knee OA severity, gastrocnemius strength, ankle range of motion, and age (adjusted R2 = 0.19). Midfoot alignment was significantly associated with ATT and knee symptoms in patients with Knee OA. This suggests potential benefits of interventions targeting both Achilles tendon properties and foot alignment for improved knee OA outcomes.

Investigation of Biomechanical and Viscoelastic Properties of Achilles Tendon in Professional Soccer Players According to Position

Investigation of Biomechanical and Viscoelastic Properties of Achilles Tendon in Professional Soccer Players According to Position

Crocin elicits potent anti-inflammatory and fibrinolytic properties post tendon injury, A new molecule for adhesion therapy

BackgroundPost-surgical tendon adhesion formation is a frequent clinical complication with limited treatment options. The aim of this study is to investigate safety and efficacy of orally administration of crocin in attenuating post-operative tendon-sheath adhesion bands in an Achilles tendon rat model. MethodsStructural, mechanical, histological, and biochemical properties of Achilles tendons were analyzed in the presence and absence of crocin. Inflammation and total fibrosis of tendon tissues were graded between groups using macroscopic and histological scoring methods. ResultsCrocin significantly alleviated the severity, length, and density of Achilles tendon adhesions. Moreover, the recruitment of inflammatory cells and inflammation were significantly decreased in post-operative tissue samples of the crocin-treated group, as quantified with Moran scoring system. Histological results showed that crocin elicited a potent anti-fibrotic effect on tendon tissue samples as visualized by decreasing quantity, quality, grading of fibers, and collagen deposition at the site of surgery when scored either by Tang or Ishiyama grading systems. The H&E staining showed no histo-pathological changes or damage to heart, kidney, and liver tissues of treated rats. ConclusionOur results showed that crocin is a safe effective therapeutic candidate with potent anti-inflammatory and anti-fibrotic properties for adhesion band therapy post tendon surgery.

Probing nanoscale structural response of collagen fibril in human Achilles tendon during loading using in situ SAXS

The specific viscoelastic mechanical properties of the human Achilles tendon are strongly dependent on the structural characteristics of collagen. Although research on the deformation mechanisms of the Achilles tendon in various animals is extensive, understanding of these mechanisms in the human Achilles tendon remains largely empirical and macroscopic. In this work, the evolution of D-space, orientation, and average length of voids between fibers are investigated during the stretching using SAXS techniques. Initially, the void length increases marginally, while the misorientation breadth decreased rapidly as the D-space steadily increased. In the second region, D-space and the void length increase sharply under rising stress, even though misorientation width decreased. During the third region, the increases in void length and D-space decelerate, but the misorientation width widens, suggesting the onset of irreversible microscopic fibril failure in the Achilles tendon. In the final region, the fibers undergo macroscopic failure, with D-space and void length returning to their initial states. The macroscopic alterations are elucidated by the nanoscale structural responses, providing a fundamental understanding of the mechanisms driving the complex biomechanics, tissue structural organization, and Achilles tendon regeneration.

Gastrocnemius medialis and Achilles tendon properties do not differ between children with unilateral or bilateral spastic cerebral palsy

Spastic cerebral palsy (SCP) is a common neurodevelopmental disorder in children, which can be categorized into unilateral and bilateral subtypes. Most studies examining the muscle-tendon properties of the lower extremities in individuals with SCP do not distinguish between subtypes. However, spastic muscle morphology is an important determinant for its function. Therefore, differences in muscle-tendon pathology might lead to different treatment strategies. The aim of this retrospective study was to investigate the muscle–tendon properties between children with unilateral SCP and those with bilateral SCP.Overall, 33 ambulatory children (15 with unilateral SCP and 18 with bilateral SCP, Gross Motor Function Classification System Level I–III) were included. Ankle joint range of motion, isometric muscle strength, and muscle–tendon properties of the gastrocnemius medialis (GM) muscle–tendon unit (MTU) (e.g., muscle volume, tissue lengthening behavior) were assessed with isokinetic dynamometry, 3D motion capture, and ultrasound, respectively. Independent t-tests or Mann-Whitney tests were used to test for group differences (α = 0.05). Effect sizes (Cohen’s d) were also calculated.No significant differences in any assessed parameter were found between children with unilateral SCP and children with bilateral SCP (p > 0.05, d < 0.57).Our findings suggest that the functional and morphological properties of the GM MTU are similarly developed in children with unilateral SCP and children with bilateral SCP. We assume that activity levels might be the decisive factor. Nonetheless, our investigations need be extended by including gait parameters and associated tissue dynamics.

Hyperlipidemia Induced Pathological Changes with no Effect in Biomechanical Properties in the Achilles Tendon of Young Swine.

Hyperlipidemia is linked to atherosclerosis and various diseases. Its strong association with Achilles tendinopathies and xanthomas affects tendon properties through lipid deposition in tendon tissue. We examined the impact of hyperlipidemia on the biomechanical properties of the swine Achilles tendons. Swines were fed a high-cholesterol-high-fat diet to induce hyperlipidemia, and their Achilles tendons were collected and examined for biomechanical properties. The ultimate tensile strength, modulus of elasticity and viscoelastic properties did not exhibit significant differences between hyperlipidemic and control swines. H&E and pentachrome staining revealed extracellular matrix (ECM) disorganization and cellular infiltration in the hyperlipidemic swines, highlighting a marked difference between the control and hyperlipidemic groups. These results suggest hyperlipidemia in young swines alters the tendon composition and may contribute to weak biomechanical properties with time.

A Comparison of Achilles Tendon Morphological Characteristics Based Upon VISA-A Score in Active Adults Over Age 50

Morphologic Achilles tendon properties obtained via diagnostic ultrasound imaging are valuable in understanding Achilles tendon health and injury. Currently, limited information exists regarding Achilles tendon morphological properties amongst active aging adults based upon Victorian Institute of Sport Assessment (VISA-A) scores. Achilles tendon morphologic properties defined by VISA-A score groupings allow clinicians and researchers to compare data values amongst current patients. Purpose: Comparison of physically active aging adults Achilles tendon morphological properties with various VISA-A scores or a previous Achilles tendon rupture. A convenience sample of 121 participants (71 females, 50 males) at least moderately active and 50 years old, were recruited. Participants completed a VISA-A survey, and assigned groups by scores (Group 1: 90-100, Group 2: 70-89, Group 3: 45-69, Group 4: Previous Achilles tendon tear). Achilles tendon ultrasound imaging occurred at the malleolar line (The apex of the medial and lateral malleolus). Following imaging Achilles tendon cross-sectional area (CSA), thickness, and elastography were measured and analyzed. Participants with a previous Achilles tendon rupture displayed significantly larger tendon CSA and thickness compared with other groups (p&lt;0.05). Individuals with VISA-A scores from 45-69 displayed significantly larger tendon CSA and thickness than participants with scores greater than 90 (p&lt;0.03). No significant differences were noted for elastography between groups (p&gt;0.05). Achilles tendon morphological differences exist based upon pain level in physically active aging adults. Diagnostic ultrasound may be used during assessment and rehabilitation of injured tendon tissue to inform about current tendon tissue properties.

Achilles tendon and triceps surae muscle properties in athletes

PurposeThe aim of this study was to investigate internal Achilles tendon (AT) displacement, AT shear wave velocity (SWV), and triceps surae (TS) muscle shear modulus in athletes.MethodsInternal AT displacement was assessed using ultrasound during isometric contraction. Shear wave elastography was used to assess AT SWV (m × s–1) at rest and TS muscle shear modulus (kPa) during passive ankle dorsiflexion.ResultsA total of 131 athletes participated in this study. Athletes who had not exercised within two days had greater AT non-uniformity and mean anterior tendon displacement, and lower SWV at the proximal AT measurement site (mean difference [95% CI]: 1.8 mm [0.6–2.9], p = 0.003; 1.6 mm [0.2–2.9], p = 0.021; – 0.9 m × s–1 [– 1.6 to – 0.2], p = 0.014, respectively). Male basketball players had a lower mean AT displacement compared to gymnasts (– 3.7 mm [– 6.9 to – 0.5], p = 0.042), with the difference localised in the anterior half of the tendon (– 5.1 mm [– 9.0 to – 1.1], p = 0.022). Male gymnasts had a smaller absolute difference in medial gastrocnemius-minus-soleus shear modulus than basketball players (59.6 kPa [29.0–90.2], p < 0.001) and track and field athletes (52.7 kPa [19.2–86.3], p = 0.004). Intraclass correlation coefficients of measurements ranged from 0.720 to 0.937 for internal AT displacement, from 0.696 to 0.936 for AT SWE, and from 0.570 to 0.890 for TS muscles.ConclusionThis study provides a reliability assessment of muscle and tendon SWV. The relative differences in passive TS muscle shear modulus suggest sport-specific adaptation. Importantly, in healthy individuals, lower AT displacement after exercise may reflect the time required for tendon recovery.

Effects of Collagen and Exercise on Tendon Properties and Pain: A Critically Appraised Topic.

Achilles tendon ruptures are prevalent and devastating injuries that require the need for extensive rehabilitation. The methods for preventing these injuries vary between different exercise methods and nutritional supplementation. Although proven effective for decreasing pain and increasing tendon properties, the influence of these 2 methods in combination has not yet been evaluated. Does exercise combined with collagen supplementation improve Achilles tendon structural and mechanical properties and diminish subsequent patient-reported pain compared with exercise alone in adults? Exercise training, including eccentric training protocols and concentric resistance training protocols, combined with collagen supplementation influence Achilles tendon properties and subsequent patient-reported pain compared with exercise alone. Evidence supports that collagen along with exercise training has a significant influence on pain mitigation, augmented cross-sectional area, and tendon thickness, but may have little to no influence on tendon stiffness and microvascularity compared with exercise alone. Further research is needed to determine the effects of combined methods on various populations. Collectively, the body of evidence included to answer the clinical question aligns with the strength of recommendation of A.

Correlations between elastic modulus and ultrashort echo time (UTE) adiabatic T1ρ relaxation time (UTE-Adiab-T1ρ) in Achilles tendons and entheses

Patients with psoriatic arthritis commonly have abnormalities of their entheses, which are the connections between tendons and bone. There are shortcomings with the use of conventional magnetic resonance imaging (MRI) sequences for the evaluation of entheses and tendons, whereas ultrashort echo time (UTE) sequences are superior for the detection of high signals, and can also be used for non-invasive quantitative assessments of these structures. The combination of UTE-MRI with an adiabatic-T1ρ preparation (UTE-Adiab-T1ρ) allows for reliable assessment of entheses and tendons with decreased susceptibility to detrimental magic angle effects. This study aimed to investigate the relationship between quantitative UTE-MRI measures and the biomechanical properties of Achilles tendons and entheses. In total, 28 tendon-enthesis sections were harvested from 11 fresh-frozen human cadaveric foot–ankle specimens (52 ± years old). Tendon-enthesis sections were scanned using the UTE-Adiab-T1ρ and UTE-T1 sequences on a clinical 3 T scanner. MRI-based measures and indentation tests were performed on the enthesis, transitional, and tensile tendon zones of the specimens. Hayes’ elastic modulus showed significant inverse correlations (Spearman’s) with UTE-Adiab-T1ρ in all zones (R= − 0.46, − 0.54, and − 0.61 in enthesis, transition, and tensile tendon zones, respectively). Oliver-Pharr’s elastic modulus showed significant inverse correlations with UTE-Adiab-T1ρ in transition (R= − 0.52) and tensile tendon zone (R=- 0.60). UTE-T1 did not show significant correlations with the elastic modulus. UTE-MRI and elastic modulus were significantly lower in the tensile tendon compared with the enthesis regions This study highlights the potential of the UTE-Adiab-T1ρ technique for the non-invasive evaluation of tendons and enthuses.

Effects of passive static stretching on the Achilles tendon properties of adults: a randomized controlled trial

Effects of passive static stretching on the Achilles tendon properties of adults: a randomized controlled trial

Multimodal and multiscale characterization reveals how tendon structure and mechanical response are altered by reduced loading.

Tendons are collagen-based connective tissues where the composition, structure and mechanics respond and adapt to the local mechanical environment. Adaptation to prolonged inactivity can result in stiffer tendons that are more prone to injury. However, the complex relation between reduced loading, structure, and mechanical performance is still not fully understood. This study combines mechanical testing with high-resolution synchrotron X-ray imaging, scattering techniques and histology to elucidate how reduced loading affects the structural properties and mechanical response of rat Achilles tendons on multiple length scales. The results show that reduced in vivo loading leads to more crimped and less organized fibers and this structural inhomogeneity could be the reason for the altered mechanical response. Unloading also seems to change the fibril response, possibly by altering the strain partitioning between hierarchical levels, and to reduce cell density. This study elucidates the relation between in vivo loading, the Achilles tendon nano-, meso‑structure and mechanical response. The results provide fundamental insights into the mechanoregulatory mechanisms guiding the intricate biomechanics, tissue structural organization, and performance of complex collagen-based tissues. STATEMENT OF SIGNIFICANCE: Achilles tendon properties allow a dynamic interaction between muscles and tendon and influence force transmission during locomotion. Lack of physiological loading can have dramatic effects on tendon structure and mechanical properties. We have combined the use of cutting-edge high-resolution synchrotron techniques with mechanical testing to show how reduced loading affects the tendon on multiple hierarchical levels (from nanoscale up to whole organ) clarifying the relation between structural changes and mechanical performance. Our findings set the first step to address a significant healthcare challenge, such as the design of tailored rehabilitations that take into consideration structural changes after tendon immobilization.

How do Achilles tendon properties correlate with gait performance in cerebral palsy?

How do Achilles tendon properties correlate with gait performance in cerebral palsy?

518-P: Prior to Development of Neuropathy, People with Diabetes Have Altered Morphological and Mechanical Properties of the Ankle Joint, Tendons, and Muscles

Diabetes-related anatomical changes to the foot that foment ulcer formation are attributed to diabetic neuropathy. We hypothesized that prior to development of neuropathy, diabetes is associated with biomechanical changes in the ankle joint. To test this hypothesis, morphological properties of Achilles tendon, soleus, medial and lateral gastrocnemius muscles were evaluated by a LOGIQ ultrasound device at preset ankle (−30, −15,0,10) and knee (90,180) positions in both subjects with diabetes without neuropathy (DM; n=11, age 53±11, 3M, 8F, 87±16 kg, HbA1c 7.37±1.80, disease duration 75±79 months) and nondiabetic controls (CON; n=12, age 45±17, 5M, 7F, 75±14 kg). Monofilament (5.07/10 g) testing confirmed absence of neuropathy. As compared to CON, DM demonstrated significantly shorter Achilles length (p=0.002), smaller cross section area (p=0.018), higher Achilles stiffness (p=0.006), shorter muscle fascicles across the soleus muscle (p=0.03), higher stiffness in the soleus (p=0.001) and lateral gastrocnemius (p=0.002), and higher pennation angles for all three muscles (p&amp;lt;0.05). The current study demonstrates altered muscle-tendon unit mechanical properties in subjects with diabetes without neuropathy. These changes indicate a pathological process that may contribute to plantar ulcer formation even in absence of diabetic neuropathy. Disclosure R. Hoveizavi: None. F. Gao: None. S. Fisher: None.

Pro-inflammatory activity of long noncoding RNA FOXD2-AS1 in Achilles tendinopathy

Achilles tendinopathy is a prevalent clinical problem that plagues athletes and general populations. Achilles tendon healing is a complex process, and so far, there is no successful long-term solution to Achilles tendinopathy in the field of microsurgery due to its poor natural regeneration ability. Limitations in understanding the pathogenesis of Achilles tendon development and Achilles tendon injury hinder clinical treatment developments. There is an increasing demand for innovative conservative treatments that can improve Achilles tendon injury. In this study, a Sprague–Dawley rat model of Achilles tendinopathy was established. Lentiviral vectors that interfere with the expression of FOXD2-AS1, miR-21-3p, or PTEN were injected every 3 days. Rats were euthanized after 3 weeks, and the effect of FOXD2-AS1, miR-21-3p, or PTEN on Achilles tendon healing was analyzed by histological observation, biomechanical test, and examinations of inflammatory factors and tendon markers. As measured, downregulating FOXD2-AS1 or upregulating miR-21-3p improved histological structure, suppressed inflammation, promoted the expression of tendon markers, and optimized the biomechanical properties of Achilles tendon. Upregulating PTEN was capable of reversing the promoting effect of inhibition of FOXD2-AS1 on Achilles tendon healing. As concluded, deficiency of FOXD2-AS1 accelerates the healing of Achilles tendon injury and improves tendon degeneration by regulating the miR-21-3p/PTEN axis and promoting the activation of the PI3K/AKT signaling pathway.

Adolescent boys who participate in sports exhibit similar ramp torque control with young men despite differences in strength and tendon characteristics.

The goal of this paper was to determine if sports participation influences torque control differently for adolescent boys and young men during a slow ramp task. Twenty-one adolescent boys (11 athletes) and 31 young men (16 athletes) performed a slow ramp increase in plantar flexion torque from 0 to maximum. We quantified torque control as the coefficient of variation (CV) of torque during the ramp and quantified the Achilles tendon mechanical properties using ultrasonography. Relative to adolescent boys, young men were taller, heavier, stronger, and had a longer and stiffer Achilles tendon. However, these characteristics were not different between athletes and non-athletes in adolescent boys. For the CV of torque, there was a significant interaction with sports participation, indicating that only adolescent boys who were non-athletes had greater variability than young men. The CV of torque of all participants was predicted from the maximum torque and torque oscillations from 1 to 2Hz, whereas the CV of torque for adolescent boys was predicted only from torque oscillations from 1 to 2Hz. These findings suggested that adolescent boys who participate in sports exhibited lower torque variability during a slow ramp task, which was not explained by differences in Achilles tendon properties or strength.