Achilles tendon biomechanics in response to acute intense exercise

NewsBot · Feb 20, 2014

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Achilles tendon biomechanics in response to acute intense exercise
Joseph, Michael F PT, PhD; Lillie, Kurtis R DPT, CSCS; Bergeron, Daniel J DPT; Cota, Kevin DPT; Yoon, Joseph DPT; Kraemer, William J PhD, FACSM, FNSCA; Denegar, Craig R PhD, PT, ATC, FNATA
Journal of Strength & Conditioning Research: 18 February 2014

Achilles tendinopathy is a common disorder and is more prevalent in men. Although differences in tendon mechanics between men and women have been reported, understanding of tendon mechanics in young active people is limited. Moreover, there is limited understanding of changes in tendon mechanics in response to acute exercise. Our purpose was to compare Achilles tendon mechanics in active young adult men and women at rest and after light and strenuous activity in the form of repeated jumping with an added load. Participants consisted of 17 men and 14 women (18-30y) who were classified as being at least moderately physically active by the International Physical Activity Questionnaire completed the study. Tendon force / elongation measures were obtained during an isometric plantarflexion contraction on an isokinetic dynamometer with simultaneous ultrasound imaging of the Achilles tendon approximate to the soleus myotendinous junction. Data were collected at rest, after a 10 min treadmill walk, and after a fatigue protocol of 100 toe jumps performed in a Smith machine, with a load equaling . 20% of body mass. We found greater tendon elongation, decreased stiffness and Young's modulus only in women after the jumping exercise. Force and stress were not different between groups but decreased subsequent to the jumping exercise bout. In general women had greater elongation and strain, less stiffness and a lower Young's modulus during plantarflexor contraction. These data demonstrate differences in tendon mechanics between men and women and suggest a potential protective mechanism explaining the lower incidence of Achilles tendinopathy in women.
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NewsBot · Apr 16, 2014

Australian football players’ Achilles tendons respond to game loads within 2 days: an ultrasound tissue characterisation (UTC) study
Samuel D Rosengarten, Jill L Cook, Adam L Bryant, Justin T Cordy, John Daffy, Sean I Docking
Br J Sports Med doi:10.1136/bjsports-2013-092713

Background/aim The Achilles tendon is a tissue that responds to mechanical loads at a molecular and cellular level. In vitro and in vivo studies have shown that the expression of anabolic and/or catabolic proteins can change within hours of loading and return to baseline levels within 72 h. These biochemical changes have not been correlated with changes in whole tendon structure on imaging. We examined the nature and temporal sequence of changes in Achilles tendon structure in response to competitive game loads in elite Australian football players.

Methods Elite male Australian football players with no history of Achilles tendinopathy were recruited. Achilles tendon structure was quantified using ultrasound tissue characterisation (UTC) imaging, a valid and reliable measure of intratendinous structure, the day prior to the match (day 0), and then reimaged on days 1, 2 and 4 postgame.

Results Of the 18 participants eligible for this study, 12 had no history of tendinopathy (NORM) and 6 had a history of patellar or hamstring tendinopathy (TEN). Differences in baseline UTC echopattern were observed between the NORM and TEN groups, with the Achilles of the TEN group exhibiting altered UTC echopattern, consistent with a slightly disorganised tendon structure. In the NORM group, a significant reduction in echo-type I (normal tendon structure) was seen on day 2 (p=0.012) that returned to baseline on day 4.

Summary There was a transient change in UTC echopattern in the Achilles tendon as a result of an Australian football game in individuals without a history of lower limb tendinopathy.
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NewsBot · Sep 12, 2014

Achilles Tendons Hypertrophy in Response to High Loading Training
Yael Milgrom et al
Foot & Ankle International September 11, 2014

Background: Whether the human Achilles tendon undergoes hypertrophic changes as measured by an increase in cross-sectional area, in response to endurance training exercise remains in question. We investigated the hypothesis that transition from civilian life through 6 months of elite infantry training would induce adaptive Achilles tendon hypertrophy.
Methods: Seventy-two new elite infantry recruits had the cross-sectional area of their Achilles tendons measured at a point 2.5 cm proximal to the Achilles insertion by ultrasound before beginning elite infantry training. Measurements were repeated by the same ultrasonographer for those recruits who were still in the training program at 6 months. Prior to beginning the study the intraobserver reliability of the ultrasonographer’s Achilles tendon measurements was calculated (intraclass correlation coefficient = .96). Fifty-five recruits completed 6 months of training.
Results: The mean cross-sectional area of their right Achilles tendon increased from 47.0 ± 11.2 to 50.2 ± 9.6 mm2 (P = .037) and the left Achilles tendon from 47.2 ± 8.9 to 51.1 ± 8.3 mm2 (P = .013). The change in cross-sectional area did not correlate with subject height, weight, prior sport history, or jumping and running abilities.
Conclusions: An abrupt stimulus of 6 months of elite infantry training was adequate to induce hypertrophic changes in the Achilles tendon. This is the first human prospective study showing an increase in the Achilles tendon cross-sectional area in response to rigorous endurance type training. The finding supports the hypothesis that the Achilles tendon in response to sufficiently high and sustained loading can remodel its morphological properties and thereby strengthen itself.
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NewsBot · May 5, 2015

Achilles tendon structure improves on UTC imaging over a 5-month pre-season in elite Australian football players
S. I. Docking, S. D. Rosengarten and J. Cook
Scandinavian Journal of Medicine & Science in Sports; Early View

Pre-season injuries are common and may be due to a reintroduction of training loads. Tendons are sensitive to changes in load, making them vulnerable to injury in the pre-season. This study investigated changes in Achilles tendon structure on ultrasound tissue characterization (UTC) over the course of a 5-month pre-season in elite male Australian football players. Eighteen elite male Australian football players with no history of Achilles tendinopathy and normal Achilles tendons were recruited. The left Achilles tendon was scanned with UTC to quantify the stability of the echopattern. Participants were scanned at the start and completion of a 5-month pre-season. Fifteen players remained asymptomatic over the course of the pre-season. All four echo-types were significantly different at the end of the pre-season, with the overall echopattern suggesting an improvement in Achilles tendon structure. Three of the 18 participants developed Achilles tendon pain that coincided with a change in the UTC echopattern. This study demonstrates that the UTC echopattern of the Achilles tendon improves over a 5-month pre-season training period, representing increased fibrillar alignment. However, further investigation is needed to elucidate with this alteration in the UTC echopattern results in improved tendon resilience and load capacity.
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NewsBot · Mar 9, 2016

Implications of the calf musculature and Achilles tendon architectures for understanding the site of injury
H Toumi, G Larguech, M Cherief, A Batakis, R Hambli, R Jennane, TM Best, E Lespessailles
Journal of Biomechanics; Article in Press

Clinically the sites of Achilles Tendon (AT) overuse conditions can be divided into the tendon mid-portion and osteotendinous attachment.
PURPOSE: We propose an anatomical analysis of the triceps surae musculotendon unit that could provide a possible anatomic explanation for these 2 sites of injury.
METHOD: Twelve cadavers (age 74 ? 7 years) were studied. In both legs, calf muscles (lateral gastrocnemius (LG), medial gastrocnemius (MG) and soleus) were dissected and their volumes measured. Fine saw cuts were made in the sagittal plane, either side of the midline of the calcaneus. Each strip contained the distal part of the tendon and its insertion, together with the superior tuberosity of the calcaneus. Trabecular architecture was analysed from X-rays taken with Faxitron radiography. Histological sections of the enthesis and the thickness of the uncalcified fibrocartilage and the subchondral plate were evaluated. A finite element model of tendon coupled to a rupture index was developed to investigate the AT response to mechanical load.
RESULTS: Muscle volume was highest for the soleus, followed by the MG, and LG. Within the AT, the soleus fibers occupy the antero-medial parts, the MG fibers form the posterior lateral layer, yet the LG head fibers retain the antero-lateral part. The quantity of bone and the apparent trabecular thickness at the enthesis were greatest in the central part of the enthesis. Thickness of calcified fibrocartilage tissue was significantly greater in the central part than medially (P = 0.04) and laterally (P = 0.03). Uncalcified fibrocartilage was significantly thicker medially than laterally (P = 0.02). Finally, finite element analysis showed that AT mechanical stress increased with muscle load and converged at 4.6?7.9 cm of the enthesis.
CONCLUSION: Our data suggest that the triceps surae musculotendon unit is composed of anatomically distinct parts that undergo non-uniform mechanical loading. There are two sites where potentially tendon mechanical stress increases, the medial/central portions of the enthesis and the tendon midportion.
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NewsBot · Mar 11, 2016

Muscle-specific acute changes in passive stiffness of human triceps surae after stretching
Kosuke Hirata, Eri Miyamoto-Mikami, Hiroaki Kanehisa, Naokazu Miyamoto
European Journal of Applied Physiology; 05 March 2016

Purpose
It remains unclear whether the acute effect of stretching on passive muscle stiffness differs among the synergists. We examined the muscle stiffness responses of the medial (MG) and lateral gastrocnemii (LG), and soleus (Sol) during passive dorsiflexion before and after a static stretching by using ultrasound shear wave elastography.
Methods
Before and after a 5-min static stretching by passive dorsiflexion, shear modulus of the triceps surae and the Achilles tendon (AT) during passive dorsiflexion in the knee extended position were measured in 12 healthy subjects.
Results
Before the static stretching, shear modulus was the greatest in MG and smallest in Sol. The stretching induced significant reductions in shear modulus of MG, but not in shear modulus of LG and Sol. The slack angle was observed at more plantar flexed position in the following order: AT, MG, LG, and Sol. After the stretching, the slack angles of each muscle and AT were significantly shifted to more dorsiflexed positions with a similar extent. When considering the shift in slack angle, the change in MG shear modulus became smaller.
Conclusion
The present study indicates that passive muscle stiffness differs among the triceps surae, and that the acute effect of a static stretching is observed only in the stiff muscle. However, a large part of the reduction of passive muscle stiffness at a given joint angle could be due to an increase in the slack length.
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NewsBot · Mar 12, 2016

Sonographic Evaluation of the Effect of Long-Term Exercise on Achilles Tendon Stiffness using Shear Wave Elastography
Wai-lam Siu, Chi-ho Chan, Cheuk-hei Lam, Chu-man Lee, Michael Ying
Journal of Science and Medicine in Sport; Article in Press

Objectives
This study aimed to assess the feasibility of using quantitative Shear Wave Elastography (SWE) to assess the stiffness (Young's modulus) of Achilles tendon and to investigate the effect of long-term weight-bearing exercise on the stiffness of human Achilles tendon by comparing the frequent and infrequent exercise groups.

Design
Case-control study.

Methods
A total of 36 healthy subjects aged 19-25 were recruited. Subjects were categorized into frequent and infrequent exercise groups dependent on their level of lower limb weight bearing exercise. B-mode and shear-wave ultrasound examination of Achilles tendon were performed. Measurements of the Achilles tendon stiffness were conducted with the foot position standardized by an ankle fixer. To evaluate inter and intra-operator reliability of Young's modulus measurements, each subject was scanned by three operators and each operator scanned the subject three times.

Results
The intra-operator reliability of Young's modulus measurements ranged between 0.803 and 0.845. The inter-operator measurement reliability was 0.585. Result showed that Achilles tendon on non-dominant ankle in frequent-exercisers (median: 320.1 kPa) was significantly stiffer than that in infrequent-exercisers (median: 296 kPa) (p < 0.05), whereas there was no significant difference in Achilles tendon stiffness on dominant ankle between the two groups (p > 0.05).

Conclusions
Shear Wave Elastography is feasible for assessing the Achilles tendon's stiffness in vivo. The stiffness of Achilles tendon of frequent-exercisers was significantly higher than that of infrequent-exercisers on non-dominant ankle but not on dominant ankle. With the use of an ankle fixer, there was high repeatability and moderate reproducibility in SWE measurement of Achilles tendon stiffness.
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NewsBot · Jan 28, 2018

The Role of the Vascular and Structural Response to Activity in the Development of Achilles Tendinopathy: A Prospective Study.
Wezenbeek E et al
Am J Sports Med. 2018 Jan 1:363546517750854. doi: 10.1177/0363546517750854.

BACKGROUND:
Several risk factors have been suggested in the development of Achilles tendinopathy, but large-scale prospective studies are limited.

PURPOSE:
To investigate the role of the vascular response to activity of the Achilles tendon, tendon thickness, ultrasound tissue characterization (UTC) of tendon structure, and foot posture as possible risk factors in the development of Achilles tendinopathy.

STUDY DESIGN:
Cohort study; Level of evidence, 2.

METHODS:
The study began with 351 first-year students at Ghent University. After 51 students were excluded, 300 were tested in the academic years 2013-2014 and 2014-2015 and were followed prospectively for 2 consecutive years by use of a multilevel registration method. Of those, 250 students were included in the statistical analysis. At baseline, foot posture index and UTC were investigated bilaterally. Blood flow and tendon thickness were measured before and after a running activity. Cox regression analyses were performed to identify significant contributors to the development of Achilles tendinopathy.

RESULTS:
During the 2-year follow-up, 27 of the included 250 participants developed Achilles tendinopathy (11%). Significant predictive effects were found for female sex and blood flow response after running ( P = .022 and P = .019, respectively). The risk of developing Achilles tendinopathy increased if the blood flow increase after running was reduced, regardless of sex, foot pronation, and timing of flow measurements. The model had a predictive accuracy of 81.5% regarding the development of Achilles tendinopathy, with a specificity of 85.0% and a sensitivity of 50.0%.

CONCLUSION:
This prospective study identified both female sex and the diminished blood flow response after running as significant risk factors for the development of Achilles tendinopathy. UTC of tendon structure, Achilles tendon thickness, and foot posture did not significantly contribute to the prediction of Achilles tendinopathy. A general evaluation of tendon structure by UTC, measurement of tendon thickness, or determination of the foot posture index will not allow clinicians to identify patients at risk for developing Achilles tendinopathy. Furthermore, it may be possible to improve blood flow after activity by using noninvasive techniques (such as prostaglandins, compression stockings, heat, massage, and vibration techniques). These techniques may be useful in the prevention and management of Achilles tendinopathy, but further research is needed.
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NewsBot · May 23, 2018

Achilles tendon structure differs between competitive distance runners and non-runners despite no clinical signs or symptoms of mid-substance tendinopathy
Todd J. Hullfish, Kenton L. Hagan, Ellen Casey, and Josh R. Baxter*
Source 17 MAY 2018

Achilles tendinopathy affects many running athletes and often leads to chronic pain and functional deficits. While changes in tendon structure have been linked with tendinopathy, the effects of distance running on tendon structure is not well understood. Therefore, the purpose of this study was to characterize structural differences in the Achilles tendons in healthy young adults and competitive distance runners using quantitative ultrasound analyses. We hypothesized that competitive distance runners with no clinical signs or symptoms of tendinopathy would have quantitative signs of tendon damage, characterized by decreased collagen alignment and echogenicity, in addition to previous reports of thicker tendons. Longitudinal ultrasound images of the right Achilles tendon mid-substance were acquired in competitive distance runners and recreationally-active adults. Collagen organization, mean echogenicity, and tendon thickness were quantified using image processing techniques. Clinical assessments confirmed that runners had no signs or symptoms of tendinopathy and controls were only included if they had no history of Achilles tendon pain or injuries. Runner tendons were 40% less organized, 48% thicker, and 41% less echogenic compared to the control tendons (p < 0.001). Young adults engaged in competitive distance-running have structurally different tendons than recreationally-active young adults.
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NewsBot · Dec 7, 2019

Differences between long distance road runners and trail runners in Achilles tendon structure, jumping and balance performance
Gali Dar PhD Gordon Waddington PhD Myriam Stern MD Nadav Dotan B.Ed Nili Steinberg PhD
PM R: 24 November 2019

Background
Load and joint kinematics change with differences in running surface. Running regularly on trails compared to roads might influence the load on the Achilles tendon and its adaptations, along with other factors such as balance, strength and proprioception.

Objective
To investigate Achilles tendon structure and functional tests in road and trail runners.

Design
Cross‐sectional study.

Setting
Laboratory, sport sciences college.

Participants
The study included 26 road and 17 trail runners who run at least 3 times per week with a minimum of 20km per week and who participated in running competitions over the preceding 2 years.

Methods
Each participant was examined for Achilles tendon structure (via ultrasound tissue characterization (UTC) imaging) and underwent functional tests in addition to completing a demographical questionnaire.

Main Outcome Measures
The percentages of Echo types I, II, III and IV within the tendon, tendon length and width, tendon cross‐sectional area (via UTC imaging); ankle inversion movement discrimination ability (via AMEDA device); dynamic postural balance (via Y balance test); jumping performance (by triple hop distance test); and hip muscle abduction muscle strength (by hand‐held dynamometry).

Results
Percentage of echo‐types I was significantly lower while echo‐types II was higher in the road group compared with the trail group (67.3% type I and 28.9% type II in the road group compared with 74.15% type I and 22.1% type II in the trail group, p<0.001). No differences between genders were found and no significant differences between groups were found for the other tests.

Conclusion
Tendon integrity as examined with UTC is different between road and trail runners. This suggests an influence of running surface on Achilles tendon structure. This difference was not reflected in other tests thus the influence of tendon structure on function needs further examination.
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NewsBot · Mar 23, 2020

The Achilles Tendon Response to a Bout of Running is not affected by Triceps Surae Stretch Training in Runners
Coulter D. Neves, Joshua K. Sponbeck, Katy Andrews Neves, Ulrike H. Mitchell, Iain Hunter, Aaron Wayne Johnson
Journal of Sports Science and Medicine (2020) 19, 358 - 363

An acute bout of distance running decreases Achilles tendon CSA. The purpose of this study was to examine if three-week stretch training of the Achilles tendon alters the Achilles tendon thinning response to running. Thirty-three recreational runners were divided into a control group (n = 17) and an intervention group (n = 16). The intervention included a three-week soleus stretch (knee flexed) and gastrocnemius stretch (knee extended). Three gastrocnemius stretches and three soleus stretches were performed each day, six days per week. Stretches were held for 30 s per repetition for a total duration of 180 s per leg per day. Achilles tendon CSA and range of motion measures were completed pre and post-run before and after the three-week stretching intervention. The runs prior to and following the three-week stretch training intervention both resulted in a 6% decrease in Achilles tendon CSA (p < 0.0001). There was no interaction across time between control and intervention groups in CSA (p = 0.446). Only the intervention group experienced a significant increase in dorsiflexion range of motion following the stretch training (p = 0.009). We therefore conclude that even when an increased dorsiflexion range of motion occurs, three weeks of triceps surae stretching does not alter the response of the Achilles tendon CSA.
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Key Points
Achilles tendon cross-sectional area does not change following a three-week triceps surae stretching protocol in recreational runners.
Achilles tendon cross-sectional area significantly decreases following running.
A three-week triceps surae stretching protocol is effective for increasing dorsiflexion range of motion.
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NewsBot · May 31, 2020

The influence of a multidisciplinary intervention program on Achilles tendon structure in children with overweight and obesity
Nili Steinberg, Alon Eliakim, Liav Elbaz, Michal Pantanowitz, Aviva Zeev & Dan Nemet
European Journal of Pediatrics (2020)

The effects of childhood obesity on tendon structure and its relation to physical activity are barely known. We aimed to investigate the influence of a 6-month multidisciplinary childhood obesity management program (which included dietary intervention and an exercise program) on Achilles tendon structure in overweight/obese children. Twenty-five overweight/obese children (overweight group) who participated in a 6-month multidisciplinary childhood obesity program, and 27 normal-weight controls were examined for anthropometric measurements and for Achilles tendon structure (using ultrasound tissue characterization to capture a three-dimensional structure of four echo type fibers and the cross-sectional area) at baseline, 3, and 6 months. The BMI of the overweight group significantly decreased from the pre- to the post-intervention period, (p = .002, η2 = .229), yet among the control group, the BMI significantly increased (p = .002, η2 = .222). Interactions (pre-post × group) showed a significant decrease in the prevalence of echo type I and in echo type III fibers and a significant increase in the prevalence of echo type II fibers and in the cross-sectional area along the intervention. No significant changes in echo type fibers were found in the control group along the 6 months.
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NewsBot · Jun 11, 2020

Tendon morphological changes after a prolonged ski race can be detected by ultrasound echo intensity
Alessandro Schneebeli, Lorenzo Visconti, Corrado Cescon, Ron Clijsen, Guido Giardini, Maria Elisabetta Arizzio & Marco Barbero
Journal of Foot and Ankle Research volume 13, Article number: 34 (2020)

Background
Ultrasound imaging techniques have been used to assess the characteristics of skeletal muscles and tendons. Such techniques (gray scale analysis) allow qualitative evaluation and have been used recently to assess the internal structure of muscles and tendons by computer-aided gray scale analysis. We hypothesized that changes in the internal structure of the Achilles and patellar tendons after a ski mountaineering race competition could be detected with ultrasound.

Methods
Twenty athletes were recruited during the 19th Millet Tour du Rutor extreme, a three-day ski mountaineering competition. Ultrasound measurements of the Achilles and patellar tendons were carried out before the first race and immediately after each of the three competition days. Tendon thickness, cross-sectional area (CSA), and ultrasound gray scale analysis were calculated.

Results
Significant differences (p < 0.05) were observed between the pre- and post-race measurements for the Achilles tendon thickness and CSA, while no significant differences were noted for the patellar tendon thickness and CSA. However, gray scale analysis of both the Achilles and patellar tendons showed significantly higher post-race values, than the pre-race values (p < 0.05).

Conclusions
Achilles and patellar tendons of healthy athletes are highly responsive to an acute increase in mechanical load. Those changes can be detected from classical (thickness and CSA) and innovative (gray scale) ultrasound-based parameters.
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NewsBot · Mar 9, 2021

Morphological Characteristics of Passive and Active Structures of the Foot Across Populations With Different Levels of Physical Activity
Inmaculada Reina-Martin, Santiago Navarro-Ledesma, Ana Belen Ortega-Avila, Kevin Deschamps, Alfonso Martinez-Franco, Alejandro Luque-Suarez, Gabriel Gijon-Nogueron
J Sport Rehabil. 2021 Mar 3;1-7

Background: Imaging diagnosis plays a fundamental role in the evaluation and management of injuries suffered in sports activities.

Objective: To analyze the differences in the thickness of the Achilles tendon, patellar tendon, plantar fascia, and posterior tibial tendon in the following levels of physical activity: persons who run regularly, persons otherwise physically active, and persons with a sedentary lifestyle.

Design: Cross-sectional and observational.

Participants: The 91 volunteers recruited from students at the university and the Triathlon Club from December 2016 to June 2019. The data were obtained (age, body mass index, and visual analog scale for quality of life together with the ultrasound measurements).

Results: Tendon and ligament thickness was greater in the runners group than in the sedentary and active groups with the exception of the posterior tibial tendon. The thickness of the Achilles tendon was greater in the runners than in the other groups for both limbs (P = .007 and P = .005). This was also the case for the cross-sectional area (P < .01) and the plantar fascia at the heel insertion in both limbs (P = .034 and P = .026) and for patellar tendon thickness for the longitudinal measurement (P < .01). At the transversal level, however, the differences were only significant in the right limb (P = .040).

Conclusion: The thickness of the Achilles tendon, plantar fascia, and patellar tendon is greater in runners than in persons who are otherwise active or who are sedentary.
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