Now showing 1 - 10 of 22
  • Publication
    Technology in Rehabilitation: Evaluating the Single Leg Squat Exercise with Wearable Inertial Measurement Units
    Background: The single leg squat (SLS) is a common lower limb rehabilitation exercise. It is also frequently used as an evaluative exercise to screen for an increased risk of lower limb injury. To date athlete / patient SLS technique has been assessed using expensive laboratory equipment or subjective clinical judgement; both of which are not without shortcomings. Inertial measurement units (IMUs) may offer a low cost solution for the objective evaluation of athlete / patient SLS technique. Objectives: The aims of this study were to determine if in combination or in isolation IMUs positioned on the lumbar spine, thigh and shank are capable of: (a) distinguishing between acceptable and aberrant SLS technique; (b) identifying specific deviations from acceptable SLS technique. Methods: Eighty-three healthy volunteers participated (60 males, 23 females, age: 24.68 + / − 4.91 years, height: 1.75 + / − 0.09 m, body mass: 76.01 + / − 13.29 kg). All participants performed 10 SLSs on their left leg. IMUs were positioned on participants’ lumbar spine, left shank and left thigh. These were utilized to record tri-axial accelerometer, gyroscope and magnetometer data during all repetitions of the SLS. SLS technique was labelled by a Chartered Physiotherapist using an evaluation framework. Features were extracted from the labelled sensor data. These features were used to train and evaluate a variety of random-forests classifiers that assessed SLS technique. Results: A three IMU system was moderately successful in detecting the overall quality of SLS performance (77 % accuracy, 77 % sensitivity and 78 % specificity). A single IMU worn on the shank can complete the same analysis with 76 % accuracy, 75 % sensitivity and 76 % specificity. Single sensors also produce competitive classification scores relative to multi-sensor systems in identifying specific deviations from acceptable SLS technique. Conclusions: A single IMU positioned on the shank can differentiate between acceptable and aberrant SLS technique with moderate levels of accuracy. It can also capably identify specific deviations from optimal SLS performance. IMUs may offer a low cost solution for the objective evaluation of SLS performance. Additionally, the classifiers described may provide useful input to an exercise biofeedback application.
      855Scopus© Citations 33
  • Publication
    Balance failure in single limb stance due to ankle sprain injury: An analysis of center of pressure using the fractal dimension method
    Instrumented postural control analysis plays an important role in evaluating the effects of injury on dynamic stability during balance tasks, and is often conveyed with measures based on the displacement of the center-of-pressure (COP) assessed with a force platform. However, the desired outcome of the task is frequently characterized by a loss of dynamic stability, secondary to injury. Typically, these failed trials are discarded during research investigations, with the potential loss of informative data pertaining to task success. The novelty of the present study is that COP characteristics of failed trials in injured participants are compared to successful trial data in another injured group, and a control group of participants, using the fractal dimension (FD) method. Three groups of participants attempted a task of eyes closed single limb stance (SLS): twenty-nine participants with acute ankle sprain successfully completed the task on their non-injured limb (successful injury group); twenty eight participants with acute ankle sprain failed their attempt on their injured limb (failed injury group); sixteen participants with no current injury successfully completed the task on their non-dominant limb (successful non-injured group). Between trial analyses of these groups revealed significant differences in COP trajectory FD (successful injury group: 1.58 ± 0.06; failed injury group: 1.54 ± 0.07; successful non-injured group: 1.64 ± 0.06) with a large effect size (0.27). These findings demonstrate that successful eyes-closed SLS is characterized by a larger FD of the COP path when compared to failed trials, and that injury causes a decrease in COP path FD.
      680Scopus© Citations 26
  • Publication
    Laboratory Measures of Postural Control During the Star Excursion Balance Test After Acute First-Time Lateral Ankle Sprain
    Context: No researchers, to our knowledge, have investigated the immediate postinjury-movement strategies associated with acute first-time lateral ankle sprain (LAS) as quantified by center of pressure (COP) and kinematic analyses during performance of the Star Excursion Balance Test (SEBT). Objective: To analyze the kinematic and COP patterns of a group with acute first-time LAS and a noninjured control group during performance of the SEBT. Design: Case-control study. Setting: University biomechanics laboratory. PATIENTS OR Other particpants: A total of 81 participants with acute first-time LAS (53 men, 28 women; age = 23.22 ± 4.93 years, height = 1.73 ± 0.09 m, mass = 75.72 ± 13.86 kg) and 19 noninjured controls (15 men, 4 women; age = 22.53 ± 1.68 years, height = 1.74 ± 0.08 m, mass = 71.55 ± 11.31 kg). Intervention: Participants performed the anterior (ANT), posterolateral (PL), and posteromedial (PM) reach directions of the SEBT. Main outcome Measure(s): We assessed 3-dimensional kinematics of the lower extremity joints and associated fractal dimension (FD) of the COP path during performance of the SEBT. Results: The LAS group had decreased normalized reach distances in the ANT, PL, and PM directions when compared with the control group on their injured (ANT: 58.16% ± 6.86% versus 64.86% ± 5.99%; PL: 85.64% ± 10.62% versus 101.14% ± 8.39%; PM: 94.89% ± 9.26% versus 107.29 ± 6.02%) and noninjured (ANT: 60.98% ± 6.74% versus 64.76% ± 5.02%; PL: 88.95% ± 11.45% versus 102.36% ± 8.53%; PM: 97.13% ± 8.76% versus 106.62% ± 5.78%) limbs (P < .01). This observation was associated with altered temporal sagittal-plane kinematic profiles throughout each reach attempt and at the point of maximum reach (P < .05). This result was associated with a reduced FD of the COP path for each reach direction on the injured limb only (P < .05). Conclusions: Acute first-time LAS was associated with bilateral deficits in postural control, as evidenced by the bilateral reduction in angular displacement of the lower extremity joints and reduced reach distances and FD of the COP path on the injured limb during performance of the SEBT.
      402Scopus© Citations 52
  • Publication
    Evaluating Performance of the Lunge Exercise with Multiple and Individual Inertial Measurement Units
    The lunge is an important component of lower limb rehabilitation, strengthening and injury risk screening. Completing the movement incorrectly alters muscle activation and increases stress on knee, hip and ankle joints. This study sought to investigate whether IMUs are capable of discriminating between correct and incorrect performance of the lunge. Eighty volunteers (57 males, 23 females, age: 24.68± 4.91 years, height: 1.75± 0.094m, body mass: 76.01±13.29kg) were fitted with five IMUs positioned on the lumbar spine, thighs and shanks. They then performed the lunge exercise with correct form and 11 specific deviations from acceptable form. Features were extracted from the labelled sensor data and used to train and evaluate random-forests classifiers. The system achieved 83% accuracy, 62% sensitivity and 90% specificity in binary classification with a single sensor placed on the right thigh and 90% accuracy, 80% sensitivity and 92% specificity using five IMUs. This multi-sensor set up can detect specific deviations with 70% accuracy. These results indicate that a single IMU has the potential to differentiate between correct and incorrect lunge form and using multiple IMUs adds the possibility of identifying specific deviations a user is making when completing the lunge.
      1715
  • Publication
    Star Excursion Balance Test performance and application in elite junior rugby union players
    Objectives: To evaluate performance on selected reach directions of the Start Excursion Balance Test (SEBT) in an elite underage rugby union population, and determine if differences exist between the forward and back position units. This information may have implications for the application of this test in player injury prevention and management. Design: Descriptive study. Setting: Gymnasium at an elite junior rugby union screening camp. Participants: 102 healthy male elite rugby union players (age = 17.9 ± 1.1 years, height = 1.83 ± 0.07 m, body mass = 90.5 ± 11.3 kg). Main outcome measures: Participants were assessed on the Anterior (A), Posterior-medial (PM), and Posterior-lateral (PL) reach directions of the SEBT. Results: Normative data for SEBT performance in the A, PM and PL reach directions were established for an elite junior rugby union population. No significant differences in dynamic postural stability were observed between the forward and back position units. Conclusions: This study provides normative SEBT data on an elite junior rugby union population, which enables clinicians to compare player dynamic postural stability and has implications for use in the prevention and management of player injuries.
    Scopus© Citations 11  3138
  • Publication
    Single-leg drop landing movement strategies 6 months following first-time acute lateral ankle sprain injury
    No research exists predicating a link between acute ankle sprain injury-affiliated movement patterns and those of chronic ankle instability (CAI) populations. The aim of the current study was to perform a biomechanical analysis of participants, 6 months after they sustained a first-time acute lateral ankle sprain (LAS) injury to establish this link. Fifty-seven participants with a 6-month history of first-time LAS and 20 noninjured participants completed a single-leg drop landing task on both limbs. Three-dimensional kinematic (angular displacement) and sagittal plane kinetic (moment of force) data were acquired for the joints of the lower extremity, from 200 ms pre-initial contact (IC) to 200 ms post-IC. Individual joint stiffnesses and the peak magnitude of the vertical component of the ground reaction force (GRF) were also computed. LAS participants displayed increases in hip flexion and ankle inversion on their injured limb (P < 0.05); this coincided with a reduction in the net flexion-extension moment at the hip joint, with an increase in its stiffness (P < 0.05). There was no difference in the magnitude of the peak vertical GRF for either limb compared with controls. These results demonstrate that altered movement strategies persist in participants, 6 months following acute LAS, which may precipitate the onset of CAI.
      961Scopus© Citations 37
  • Publication
    Evaluating Performance of the Single Leg Squat Exercise with a Single Inertial Measurement Unit
    The single leg squat (SLS) is an important component of lower limb rehabilitation and injury risk screening tools. This study sought to investigate whether a single lumbar-worn IMU is capable of discriminating between correct and incorrect performance of the SLS. Nineteen healthy volunteers (15 males, 4 females, age: 26.09± 3.98 years, height: 1.75± 0.14m, body mass: 75.2±14.2kg) were fitted with a single IMU on the lumbar spine and asked to perform 10 left leg SLS. These repetitions were recorded and labelled by a chartered physiotherapist. Features were extracted from the labelled sensor data. These features were used to train and evaluate a random-forests classifier. The system achieved an average of 92% accuracy, 78% sensitivity and 97% specificity. These results indicate that a single IMU has the potential to differentiate between a correctly and incorrectly completed SLS. This may allow such devices to be used by clinicians to help track rehabilitation of patients and screen for potential injury risks. Furthermore, the classifier described may be a useful input to an exercise biofeedback application.
      567Scopus© Citations 21
  • Publication
    Use of body worn sensors to predict ankle injuries using screening tools
    Background The Single Leg Squat (SLS) is an important screening tool in predicting those at an increased risk of ankle injuries as it relates to landing, running and cutting tasks. However, clinical analysis of this exercise is often completed visually with relatively poor intra-rater reliability. More detailed analysis of SLS completed in biomechanics laboratories is time-consuming and costly. Recent developments in body worn sensors may allow for quick assessments that produce valid and reliable data.Objective To explore a model for leveraging data obtained from wearable sensors to aid in ankle injury risk factor screening.Design A single case study design, with qualitative analysis of quantitative data.Setting University research laboratory.Participants A single participant (female, age = 24 years; height = 158 cm, body mass = 47 kg) was chosen. The participant was familiar with the SLS exercise and had completed it as part of their exercise routine for the past year.Interventions The participant completed 10 left SLS repetitions. These were recorded using the sensors and repetitions where the participant lost balance were noted. Loss of balance was defined as when the subject was unable to maintain single leg stance during the downward or upward phase of the movement and placed their other foot on the ground for support.Main outcome measurements Visual analysis showed signals from the wearable sensors (accelerometer Y and gyroscope Z) were altered when the participant lost their balance compared to signals obtained when the participant maintained balance.Conclusions These preliminary results indicate that body worn sensors may be able to automatize screening tools such as the SLS. An automated system for characterising and quantifying deviations from good form could be developed to aid clinicians and researchers. Such a system would provide objective and reliable data to clinicians and allow researchers to analyse movements quicker and in a more naturalistic setting.
      330
  • Publication
    Lower extremity coordination and symmetry patterns during a drop vertical jump task following acute ankle sprain
    Purpose: Evaluate the potentially adaptive movement patterns associated with acute lateral ankle sprain (LAS) using biomechanical analyzes. Methods: Thirty participants with acute LAS and nineteen controls performed a drop vertical jump (DVJ) task. 3D kinematic and sagittal plane kinetic profiles were plotted for the hip, knee and ankle joints of both limbs for the drop jump (phase 1) and drop landing (phase 2) phases of the DVJ. Inter-limb symmetry and the rate of force development (RFD) relative to bodyweight (BW) during both phases of the DVJ were also determined. Results: The LAS group displayed reduced ankle plantar-flexion on their injured limb during phase 2 of the DVJ, with greater associated inter-limb asymmetry for this movement (p < .05). The LAS group also displayed altered kinetic profiles, with increased inter-limb hip asymmetry for both phases of the DVJ (p < .05). This was associated with a decrease in the LAS participants’ injured limb RFD during phase 2 of the DVJ when compared with that of controls (11.76 ± 3.43 BW/s vs 14.60 ± 3.20 BW/s; p = .01, η2 = 0.14). Conclusion: Participants with LAS display potentially aberrant coordination strategies during a DVJ as evidenced by an increased dependence on the non-injured limb.
    Scopus© Citations 26  901
  • Publication
    An Ambulatory Method of Identifying Anterior Cruciate Ligament Reconstructed Gait Patterns
    The use of inertial sensors to characterize pathological gait has traditionally been based on the calculation of temporal and spatial gait variables from inertial sensor data. This approach has proved successful in the identification of gait deviations in populations where substantial differences from normal gait patterns exist; such as in Parkinsonian gait. However, it is not currently clear if this approach could identify more subtle gait deviations, such as those associated with musculoskeletal injury. This study investigates whether additional analysis of inertial sensor data, based on quantification of gyroscope features of interest, would provide further discriminant capability in this regard. The tested cohort consisted of a group of anterior cruciate ligament reconstructed (ACL-R) females and a group of non-injured female controls, each performed ten walking trials. Gait performance was measured simultaneously using inertial sensors and an optoelectronic marker based system. The ACL-R group displayed kinematic and kinetic deviations from the control group, but no temporal or spatial deviations. This study demonstrates that quantification of gyroscope features can successfully identify changes associated with ACL-R gait, which was not possible using spatial or temporal variables. This finding may also have a role in other clinical applications where small gait deviations exist.
    Scopus© Citations 39  394