Modulation of Stretch-Shortening-Cycle Behavior With Eccentric Loading of Triceps Surae: A Possible Therapeutic Mechanism.

CONTEXT: Eccentric exercises are increasingly being used to treat lower-limb musculoskeletal conditions such as Achilles tendinopathy. Despite widespread clinical application and documented efficacy, mechanisms underpinning clinical benefit remain unclear. Positive adaptations in motor performance are a potential mechanism. OBJECTIVE: To investigate how an eccentric loading intervention influences measures of stretch-shortening-cycle (SSC) behavior during a hopping task. DESIGN: Within-subjects repeated-measures observational study. SETTING: University motion-analysis laboratory. PARTICIPANTS: Healthy adults. INTERVENTIONS: A single intervention of 5 sets of 10 eccentric plantar-flexion contractions at 6 repetitions maximum using a commercial seated calf-raise machine. MAIN OUTCOME MEASURES: Lower-limb stiffness, sagittal-plane ankle kinematics, and temporal muscle activity of the agonist (soleus) and antagonist (tibialis anterior) muscles, measured during submaximal hopping on a custom-built sledge-jump system. RESULTS: Eccentric loading altered ankle kinematics during submaximal hopping; peak angle shifted to a less dorsiflexed position by 2.9° and ankle angle precontact shifted by 4.4° (P < .001). Lower-limb stiffness increased from 5.9 to 6.8 N/m (P < .001), while surface EMG measures of soleus occurred 14-44% earlier (P < .001) after the loading intervention. CONCLUSIONS: These findings suggest that eccentric loading alters SSC behavior in a manner reflective of improved motor performance. Decreased ankle excursion, increased lower-limb stiffness, and alterations in motor control may represent a positive adaptive response to eccentric loading. These findings support the theory that mechanisms underpinning eccentric loading for tendinopathy may in part be due to improved "buffering" of the tendon by the neuromuscular system.

Early mobilisation in intensive care units in Australia and Scotland: a prospective, observational cohort study examining mobilisation practises and barriers.

INTRODUCTION: Mobilisation of patients in the intensive care unit (ICU) is an area of growing research. Currently, there is little data on baseline mobilisation practises and the barriers to them for patients of all admission diagnoses. METHODS: The objectives of the study were to (1) quantify and benchmark baseline levels of mobilisation in Australian and Scottish ICUs, (2) compare mobilisation practises between Australian and Scottish ICUs and (3) identify barriers to mobilisation in Australian and Scottish ICUs. We conducted a prospective, observational, cohort study with a 4-week inception period. Patients were censored for follow-up upon ICU discharge or after 28 days, whichever occurred first. Patients were included if they were >18 years of age, admitted to an ICU and received mechanical ventilation in the ICU. RESULTS: Ten tertiary ICUs in Australia and nine in Scotland participated in the study. The Australian cohort had a large proportion of patients admitted for cardiothoracic surgery (43.3%), whereas the Scottish cohort had none. Therefore, comparison analysis was done after exclusion of patients admitted for cardiothoracic surgery. In total, 60.2% of the 347 patients across 10 Australian ICUs and 40.1% of the 167 patients across 9 Scottish ICUs mobilised during their ICU stay (p < 0.001). Patients in the Australian cohort were more likely to mobilise than patients in the Scottish cohort (hazard ratio 1.83, 95% confidence interval 1.38-2.42). However, the percentage of episodes of mobilisation where patients were receiving mechanical ventilation was higher in the Scottish cohort (41.1% vs 16.3%, p < 0.001). Sedation was the most commonly reported barrier to mobilisation in both the Australian and Scottish cohorts. Physiological instability and the presence of an endotracheal tube were also frequently reported barriers. CONCLUSIONS: This is the first study to benchmark baseline practise of early mobilisation internationally, and it demonstrates variation in early mobilisation practises between Australia and Scotland.

An AFM study of the nanostructural response of New Zealand white rabbit Achilles tendons to cyclic loading.

The nanostructural response of New Zealand white rabbit Achilles tendons to a fatigue damage model was assessed quantitatively and qualitatively using the endpoint of dose assessments of each tendon from our previous study. The change in mechanical properties was assessed concurrently with nanostructural change in the same non-viable intact tendon. Atomic force microscopy was used to study the elongation of D-periodicities, and the changes were compared both within the same fibril bundle and between fibril bundles. D-periodicities increased due to both increased strain and increasing numbers of fatigue cycles. Although no significant difference in D-periodicity lengthening was found between fibril bundles, the lengthening of D-periodicity correlated strongly with the overall tendon mechanical changes. The accurate quantification of fibril elongation in response to macroscopic applied strain assisted in assessing the complex structure-function relationship in Achilles tendons.

The influence of glycosaminoglycan proteoglycan side chains on tensile force transmission and the nanostructural properties of Achilles tendons.

This study investigates the nanostructural mechanisms that lie behind load transmission in tendons and the role of glycosaminoglycans (GAGs) in the transmission of force in the tendon extracellular matrix. The GAGs in white New Zealand rabbit Achilles tendons were enzymatically depleted, and the tendons subjected to cyclic loading at 6% strain for up to 2 hr. A nanoscale morphometric assessment of fibril deformation under strain was linked with the decline in the tendon macroscale mechanical properties. An atomic force microscope (AFM) was employed to characterize the D-periodicity within and between fibril bundles (WFB and BFB, respectively). By the end of the second hour of the applied strain, the WFB and BFB D-periodicities had significantly increased in the GAG-depleted group (29% increase compared with 15% for the control, p < .0001). No statistically significant differences were found between WFB and BFB D-periodicities in either the control or GAG-depleted groups, suggesting that mechanical load in Achilles tendons is uniformly distributed and fairly homogenous among the WFB and BFB networks. The results of this study have provided evidence of a cycle-dependent mechanism of damage accumulation. The accurate quantification of fibril elongation (measured as the WFB and BFB D-periodicity lengths) in response to macroscopic applied strain has assisted in assessing the complex structure-function relationship in Achilles tendon.

Changes in mechanical load and extensor muscle activity in the cervico-thoracic spine induced by sitting posture modification.

The influence of whole body sitting posture on cervico-thoracic posture, mechanical load and extensor muscle activity was examined in 23 asymptomatic adults. Cervical and upper thoracic extensor muscle activity measured in guided slouched and lumbo-pelvic neutral postures was normalised to that measured in a self-selected habitual posture. Head and neck posture and gravitational load moment measurements were obtained in each posture. Sagittal head translation, upper cervical extension and load moment were significantly greater in the slouched posture (p < 0.001). Contrasting patterns of cervical and thoracic extensor activity were observed in the slouched and neutral postures, with cervical extensor activity 40% higher in the slouched posture (p < 0.0001). Thoracic extensor activity was significantly higher in the lumbo-pelvic neutral posture than the habitual posture (p = 0.002). The significant changes in extensor muscle activity with postural modification appear to be induced by the associated change in mechanical load moment of the head. STATEMENT OF RELEVANCE: More neutral sitting postures reduce the demand on the cervical extensor muscles and modify the relative contribution of cervical and thoracic extensors to the control of head and neck posture. Postures that promote these patterns of muscular activity may reduce cervical spine loading and the development of posture-related neck pain.

A multiscale study of morphological changes in tendons following repeated cyclic loading.

The response of white New Zealand rabbit Achilles tendons to load was assessed using mechanical measures and confocal arthroscopy (CA). The progression of fatigue-loading-induced damage of the macro- (tenocyte morphology, fiber anisotropy and waviness), as well as the mechanical profile, were assessed within the same non-viable intact tendon in response to prolonged cyclic and static loading (up to four hours) at different strain levels (3%, 6% and 9%). Strain-mediated repeated loading induced a significant decline in mechanical function (p < 0.05) with increased strain and cycles. Mechanical and structural resilience was lost with repeated loading (p < 0.05) at macroscales. The lengthening of D-periodicity correlated strongly with the overall tendon mechanical changes and loss of spindle shape in tenocytes. This is the first study to provide a clear concurrent assessment of form (morphology) and function (mechanics) of tendons undergoing different strain-mediated repeated loading at multiple-scale assessments. This study identifies a variety of multiscale properties that may contribute to the understanding of mechanisms of tendon pathology.

Contribution of glycosaminoglycans to the structural and mechanical properties of tendons - A multiscale study.

Tendinopathy of the Achilles tendon contributes to a large range of disorders, including mechanical damage and degenerative diseases. Glycosaminoglycans (GAGs), are thought to play a role in the mechanical strength of tendons by forming cross-links between collagen molecules and allowing the transmission of forces between fibrils. This study assessed the response of GAG-depleted tendons to damage induced by fatigue loading, investigating the mechanical damage (stiffness, hysteresis and maximum load), macrostructural changes (tenocyte morphology, fiber anisotropy and waviness) assessed by confocal imaging and nanostructural changes (fibril D-periodicity length) within the same non-viable intact tendons. Changes in fiber waviness and tenocyte shape are strongly correlated to mechanical and nano-structural (D-periodicity elongation) properties in both Control and GAG-depleted tendons. This study supports firstly, the vital role GAGs play as mechanical connectors facilitating the load transfer between the fibrils and their hydrophilic role in facilitating fibril sliding. Secondly, that observed changes in tenocyte shape and fiber waviness correlate with tendon stiffness and other mechanical profiles.

Effect of Visual Information on Postural Control in Children with Autism Spectrum Disorder.

Visual information is crucial for postural control. Visual processing in children with autism spectrum disorder (ASD) was hypothesized to be less efficient and thus they would display a less stable standing posture than typically developing children. The present study compared the static standing responses and attentional demands of 15 children with ASD and 18 control participants in conditions of eyes open and eyes closed. The results showed that postural responses and attention invested in standing were similar between the participant groups in the two visual conditions. Both groups displayed a more stable posture when their eyes were open in comparison to eyes closed. The finding suggests that normal postural control development could occur in children with ASD.

Running in people with cerebral palsy: A systematic review.

BACKGROUND: Running is a fundamental motor skill which is important for participation in recreational activities throughout the lifespan. AIM: To identify, appraise, and synthesize the evidence related to running in people with cerebral palsy (CP). METHOD: A search of electronic databases was conducted in April 2016. Articles were reviewed by two assessors and had to meet the following criteria: 1) population included people with CP; and 2) included information about running. Articles were assessed for quality using the Checklist for Measuring Study Quality by Downs and Black. RESULTS: Of 2607 articles initially identified, 56 underwent full-text review and 17 were included. Quantitative analysis was not possible. The quality of descriptive studies was fair-good, while intervention studies scored poor-good. Four of the 12 descriptive studies reported kinematic and kinetic data. Five intervention studies included running as an outcome measure, although running was not the focus of intervention. A few studies showed that sprint speed, agility, and running efficiency are impaired in people with CP, but mechanisms underlying these impairments have yet to be reported. INTERPRETATION: Research on running in people with CP is limited, methodology and findings are inconsistent and studies are generally fair quality. Further investigation is warranted.

Effect of Visual Information on Postural Control in Adults with Autism Spectrum Disorder.

Sensory processing difficulties affect the development of sensorimotor skills in individuals with autism spectrum disorder (ASD). However, the effect of sensory information on postural control is unclear in the ASD adult population. The present study examined the effect of visual information on postural control as well as the attentional demands associated with postural control in fourteen adults with ASD and seventeen typically developed adults. The results showed that postural sway and attention demands of postural control were larger in adults with ASD than in typically developed adults. These findings indicate that visual processing used for postural control may be different in adults with ASD. Further research in visual field processing and visual motion processing may elucidate these sensorimotor differences.

Postural control adaptation to optic flow in children and adults with autism spectrum disorder.

BACKGROUND: Sensory reweighting is important for humans to flexibly up-weigh and down-weigh sensory information in dynamic environments. There is an element of time involved in the sensory reweighting process. A longer time spent on sensory reweighting may increase the destabilizing effect of postural control. Individuals with autism spectrum disorder (ASD) are reported to have poor postural control. It is uncertain if a different sensory reweighting process underlies the postural control deficit in children and adults with ASD. RESEARCH QUESTION: To explore the sensory reweighting capability in ASD, the present study examined whether the temporal domains of postural control differed in children and adults, with and without ASD under various optic flow conditions. METHODS: Thirty-three children (8-12 years old) and 33 adults (18-50 years old) with and without ASD underwent quiet standing in six radial optic flow conditions. Each condition lasted for 60 s and was shown twice to all participants. For each optic flow condition, changes in postural response within-trial and between-trials were measured. RESULTS: Under various optic flow illusions, both children with and without ASD took a longer time to restore their posture compared with adults with and without ASD. Nonetheless, all groups demonstrated comparable abilities to adjust their posture to one that is close to the baseline position after one exposure to the optic flow stimulation. SIGNIFICANCE: The present study showed that the temporal domains of postural control under different optic flow conditions were similar between individuals with and without ASD from the same age group. The ability to down-weigh visual information efficiently comes with the developmental progression of the sensory reweighting system. These findings suggest that the sensory reweighting process does not elucidate the postural control deficits in individuals with ASD and thus alternative explanations to determine the underlying mechanism for postural instability are needed.

Feedforward responses of transversus abdominis are directionally specific and act asymmetrically: implications for core stability theories.

STUDY DESIGN: Experimental laboratory study supplemented with a repeated case study. OBJECTIVE: To examine bilateral muscle activity of the deep abdominals in response to rapid arm raising, specifically to examine the laterality and directional specificity of feedforward responses of the transversus abdominis (TrA). BACKGROUND: Based on the feedforward responses of trunk muscles during rapid arm movements, authors have concluded that the deep trunk muscles have different control mechanisms compared to the more superficial muscles. It has been proposed that deep trunk muscles such as TrA contribute substantially to the stability of the lumbar spine and that this is achieved through simultaneous bilateral feedforward activation. These inferences are based on unilateral fine-wire electromyographic (EMG) data and there are limited investigations of bilateral responses of the TrA during unilateral arm raising. METHODS AND MEASURES: Bilateral fine-wire and surface EMG data from the anterior deltoid, TrA, obliquus internus (OI), obliquus externus, biceps femoris, erector spinae, and rectus abdominis during repeated arm raises were recorded at 2 kHz. EMG signal linear envelopes were synchronized to the onset of the anterior deltoid. A feedforward window was defined as the period up to 50 ms after the onset of the anterior deltoid, and paired onsets for bilateral muscles were plotted for both left and right arm movements. RESULTS: Trunk muscles from the group data demonstrated differences between sides (laterality), which were systematically altered when alternate arms were raised (directional specificity). This was clearly evident for the TrA but less obvious for the erector spinae. The ipsilateral biceps femoris and obliquus externus, and contralateral OI and TrA, were activated earlier than the alternate side for both right and left arm movements. This was a consistent pattern over a 7-year period for the case study. Data for the rectus abdominis derived from the case study demonstrated little laterality or directionally specific response. CONCLUSION: This is the first study to show that the feedforward activity of the TrA is specific to the direction of arm movement and not bilaterally symmetrical. The asymmetry of TrA activity during arm raising suggests that the interpretation of the role of TrA as a bilateral stabilizer during anticipatory postural adjustments needs to be revised. Future research needs to examine muscle synergies associated with the asymmetrical function of the TrA and the underlying mechanism associated with low-load stability training. LEVEL OF EVIDENCE: Therapy, level 5.

Multidimensional impact of low-Dye taping on low-load hopping in individuals with and without plantar fasciitis.

OBJECTIVES: Evaluate the acute effect of low-Dye, placebo and no tape on motor behaviour in individuals with plantar fasciitis (PF). DESIGN: Prospective, experimental. SETTING: Motion analysis laboratory. PARTICIPANTS: Ten participants with PF and ten matched controls. MAIN OUTCOME MEASURES: Hopping behaviour (lower-limb stiffness and ankle angle at peak loading) were evaluated during low-load sleigh hopping, during three taping conditions. Stiffness and ankle angle were determined using three-dimensional motion analysis. Pain during submaximal loading was assessed with a numeric pain rating scale. RESULTS: The lower-limb stiffness response to therapeutic taping was modulated by the presence of PF (interaction, F = 4.48, p = 0.018). Matched controls demonstrated a significant increase in stiffness post application of low-Dye taping (p = 0.001), stiffness was unchanged in the PF group. In the PF group, low-Dye taping decreased hopping pain in comparison to placebo (p = 0.037) and no-tape (p = 0.024). There was no difference in ankle angle at peak loading between the groups or across taping conditions. CONCLUSIONS: Low-Dye taping reduces nociceptive inputs more than placebo in the presence of PF pain. Low-Dye tape alters stiffness in the control group but not the PF group. The motor behavioural outputs such as stiffness, during low-load hopping is modulated by both pathology and therapeutic taping.

Effect of Optic Flow on Postural Control in Children and Adults with Autism Spectrum Disorder.

Individuals with autism spectrum disorder (ASD) have been associated with sensorimotor difficulties, commonly presented by poor postural control. Postural control is necessary for all motor behaviors. However, findings concerning the effect of visual motion on postural control and the age progression of postural control in individuals with ASD are inconsistent. The aims of the present study were to examine postural responses to optic flow in children and adults with and without ASD, postural responses to optic flow in the central and peripheral visual fields, and the changes in postural responses between the child and adult groups. Thirty-three children (8-12 years old) and 33 adults (18-50 years old) with and without ASD were assessed on quiet standing for 60 seconds under conditions of varying optic flow illusions, consisting of different combinations of optic flow directions and visual field display. The results showed that postural responses to most optic flow conditions were comparable between children with and without ASD and between adults with and without ASD. However, adults with ASD appeared more responsive to forward-moving optic flow in the peripheral visual field compared with typically developed adults. The findings suggest that children and adults with ASD may not display maladaptive postural responses all the time. In addition, adults in the ASD group may have difficulties prioritizing visual information in the central visual field over visual information in the peripheral visual field when in unfamiliar environments, which may have implications in understanding their motor behaviors in new surroundings.

Statistical and clinical interpretation of research results.

There is a well-known phenomenon of publication bias toward manuscripts that report statistically significant differences. The clinical implications of these statistically significant differences are not always clear because the magnitude of the changes may be clinically meaningless. This article relates the critical P value threshold to the magnitude of the actual observed change and provides a rationale for reporting confidence intervals in clinical studies. Strategies for improving statistical power and reducing the magnitude of the confidence interval range for clinical trials are also described.

Three dimensional microstructural network of elastin, collagen, and cells in Achilles tendons.

Similar to most biological tissues, the biomechanical, and functional characteristics of the Achilles tendon are closely related to its composition and microstructure. It is commonly reported that type I collagen is the predominant component of tendons and is mainly responsible for the tissue's function. Although elastin has been found in varying proportions in other connective tissues, previous studies report that tendons contain very small quantities of elastin. However, the morphology and the microstructural relationship among the elastic fibres, collagen, and cells in tendon tissue have not been well examined. We hypothesize the elastic fibres, as another fibrillar component in the extracellular matrix, have a unique role in mechanical function and microstructural arrangement in Achilles tendons. It has been shown that elastic fibres present a close connection with the tenocytes. The close relationship of the three components has been revealed as a distinct, integrated and complex microstructural network. Notably, a "spiral" structure within fibril bundles in Achilles tendons was observed in some samples in specialized regions. This study substantiates the hierarchical system of the spatial microstructure of tendon, including the mapping of collagen, elastin and tenocytes, with 3-dimensional confocal images. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1203-1214, 2017.

Reliability and validity of the Hindi version of the Neck Pain and Disability Scale in cervical radiculopathy patients.

PURPOSE: To assess the reliability and validity of the Neck Pain and Disability Scale (NPAD) translated into Hindi. METHOD: Following a pilot study to ascertain uncertainties with existing terminology in the NPAD scale, a cervical radiculopathy patient cohort (n = 63) was assessed with the translated NPAD. Reliability was assessed by regression analysis for test-retest and by item-factor and factor-total score correlations. Face validity was compared in a cross-sectional design study with an asymptomatic group (n = 38). Convergent and divergent validity were investigated by correlating the NPAD scores with the Numerical Pain Rating Scale (NPRS) for neck and arm pain, and 10 cm long VAS Activity and VAS Depression scales. RESULTS: ICC values for test-retest NPAD total and factor scores were >0.92 and R2 values >0.912. Pearson product moment correlation of item vs. factor scores varied from 0.17 - 0.91 and for factor vs. total scores 0.72 - 0.91. Differences in NPAD scores between the patient and the asymptomatic group were significant (t = 30.90, p < 0.05). Convergent validity was explained when Factor 2 (minus item 20) was correlated (r = 0.67) with NPRS maximum value scores. Divergent validity was illustrated by low correlation with VAS Activity (r = 0.15) and negative correlation with VAS Depression (r = -0.80) scores. CONCLUSION: Based on the results of this study, the Hindi version of the NPAD is a reliable and valid instrument for the assessment of pain and disability in cervical radiculopathy patients.

Physical therapy treatment dose for nontraumatic neck pain: a comparison between 2 patient groups.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To classify patients with nonacute, nontraumatic neck pain according to the dominant impairment of spinal function, and to determine whether there were differences in the amount of treatment sessions required (treatment dose) to achieve a significant change in the patients disorder. BACKGROUND: Classification of patients with mechanical neck pain may be an important process in optimizing treatment prescription and evaluating treatment response. However, patient classification has not been used to consider possible differences in the amount of treatment sessions (treatment dose) required to achieve a significant change in the neck pain disorder. METHODS AND MEASURES: Ninety-two patients with nonacute, nontraumatic neck pain were classified into 2 groups, according to the dominant impairment of spinal function. Of the 77 patients who completed treatment, 63 (82%) were classified as having a "movement disorder," while the remainder was classified into a "loading disorder" group. Physical therapists who were blinded to the patient classification provided multimodal physical therapy treatment as considered appropriate and the patients were discharged when the optimal treatment response had been achieved. RESULTS: There was no difference in pain intensity or global disability level between the groups at baseline. Both groups achieved a significant improvement in neck pain and disability following treatment, and there was no significant difference between groups in the magnitude of the treatment response. The number of treatment sessions received by the loading group (mean +/- SD, 7.3 +/- 4.5) was significantly lower than the number received by the movement group (mean +/- SD, 11.5 +/- 5.9; 95% CI: -7.6 to -0.8; P<.01). Patients in the loading group were 2.4 times as likely to be discharged at any particular treatment session (95% CI: 1.1 to 4.1, P<.005) compared to those in the movement group. CONCLUSION: For patients with nontraumatic neck pain, classification according to impairment of spinal function may be a useful indicator of the number of physical therapy treatment sessions required to achieve a significant treatment response.

Locomotor Performance During Rehabilitation of People With Lower Limb Amputation and Prosthetic Nonuse 12 Months After Discharge.

BACKGROUND: It is recognized that multifactorial assessments are needed to evaluate balance and locomotor function in people with lower limb amputation. There is no consensus on whether a single screening tool could be used to identify future issues with locomotion or prosthetic use. OBJECTIVE: The purpose of this study was to determine whether different tests of locomotor performance during rehabilitation were associated with significantly greater risk of prosthetic abandonment at 12 months postdischarge. DESIGN: This was a retrospective cohort study. METHOD: Data for descriptive variables and locomotor tests (ie, 10-Meter Walk Test [10MWT], Timed "Up & Go" Test [TUGT], Six-Minute Walk Test [6MWT], and Four Square Step Test [FSST]) were abstracted from the medical records of 201 consecutive participants with lower limb amputation. Participants were interviewed and classified as prosthetic users or nonusers at 12 months postdischarge. The Mann-Whitney U test was used to analyze whether there were differences in locomotor performance. Receiver operating characteristic curves were generated to determine performance thresholds, and relative risk (RR) was calculated for nonuse. RESULTS: At 12 months postdischarge, 18% (n=36) of the participants had become prosthetic nonusers. Performance thresholds, area under the curve (AUC), and RR of nonuse (95% confidence intervals [CI]) were: for the 10MWT, if walking speed was ≤0.44 ms(-1) (AUC=0.743), RR of nonuse=2.76 (95% CI=1.83, 3.79; P<.0001); for the TUGT, if time was ≥21.4 seconds (AUC=0.796), RR of nonuse=3.17 (95% CI=2.17, 4.14; P<.0001); for the 6MWT, if distance was ≤191 m (AUC=0.788), RR of nonuse=2.84, (95% CI=2.05, 3.48; P<.0001); and for the FSST, if time was ≥36.6 seconds (AUC=0.762), RR of nonuse=2.76 (95% CI=1.99, 3.39; P<.0001). LIMITATIONS: Missing data, potential recall bias, and assessment times that varied were limitations of the study. CONCLUSIONS: Locomotor performance during rehabilitation may predict future risk of prosthetic nonuse. It may be implied that the 10MWT has the greatest clinical utility as a single screening tool for prosthetic nonuse, given the highest proportion of participants were able to perform this test early in rehabilitation. However, as locomotor skills improve, other tests (in particular, the 6MWT) have specific clinical utility. To fully enable implementation of these locomotor criteria for prosthetic nonuse into clinical practice, validation is warranted.

Achilles tendinopathy alters stretch shortening cycle behaviour during a sub-maximal hopping task.

OBJECTIVES: To describe stretch shortening cycle behaviour of the ankle and lower limb in patients with Achilles tendinopathy (AT) and establish differences with healthy volunteers. DESIGN: Between-subjects case-controlled. METHODS: Fifteen patients with AT (mean age 41.2±12.7 years) and 11 healthy volunteers (CON) (mean age 23.2±6.7 years) performed sub-maximal single-limb hopping on a custom built sledge-jump system. Using 3D motion analysis and surface EMG, temporal kinematic (lower limb stiffness, ankle angle at 80ms pre-contact, ankle angle at contact, peak ankle angle, ankle stretch amplitude) and EMG measures (onset, offset and peak times relative to contact) were captured. Data between AT and CON were compared statistically using a linear mixed model. RESULTS: Patients with AT exhibited significantly increased lower limb stiffness when compared to healthy volunteers (p<0.001) and their hopping range was shifted towards a more dorsiflexed position (p<0.001). Furthermore, ankle stretch amplitude was greater in AT compared with healthy volunteers (p<0.001). A delay in muscle activity was also observed; soleus onset (p<0.001), tibialis anterior peak (p=0.026) and tibialis anterior offset (p<0.001) were all delayed in AT compared with CON. CONCLUSIONS: These findings indicate that patients with AT exhibit altered stretch-shortening cycle behaviour during sub-maximal hopping when compared with healthy volunteers. Patients with AT hop with greater lower limb stiffness, in a greater degree of ankle dorsiflexion and have a greater stretch amplitude. Likewise, delayed muscle activity is evident. These findings have implications in terms of informing the understanding of the pathoaetiology and management of AT.