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Research question: The purpose of this study was to evaluate the test-retest reliability of lower extremity kinematics during squat, hip abduction and lunge exercises captured by the Kinect and to evaluate the agreement to a reference 3D camera-based motion system. Methods: Twenty-one healthy individuals performed five repetitions of each lower limb exercise on two different days. Movements were simultaneously assessed by the Kinect and the reference 3D motion system. Joint angles and positions of the lower limb were calculated for sagittal and frontal plane. For the inter-session reliability and the agreement between the two systems standard error of measurement (SEM), bias with limits of agreement (LoA) and Pearson Correlation Coefficient (r) were calculated. Results: Parameters indicated varying reliability for the assessed joint angles and positions and decreasing reliability with increasing task complexity. Across all exercises, measurement deviations were shown especially for small movement amplitudes. Variability was acceptable for joint angles and positions during the squat, partially acceptable during the hip abduction and predominately inacceptable during the lunge. The agreement between systems was characterized by systematic errors. Overestimations by the Kinect were apparent for hip flexion during the squat and hip abduction/adduction during the hip abduction exercise as well as for the knee positions during the lunge. Knee and hip flexion during hip abduction and lunge were underestimated by the Kinect. Significance: The Kinect system can reliably assess lower limb joint angles and positions during simple exercises. The validity of the system is however restricted. An application in the field of early orthopedic rehabilitation without further development of post-processing techniques seems so far limited.
Repetitive overhead movements have been identified as a main risk factor to develop shoulder complaints with scapular muscle activity being altered. Reliable assessment of muscle activity is essential to differentiate between symptomatic and asymptomatic individuals. Therefore, the present study aimed to investigate the intra-and inter-session reliability of scapular muscle activity during maximal isokinetic shoulder flexion and extension. Eleven asymptomatic adults performed maximum effort isokinetic shoulder flexion and extension (concentric and eccentric at 60 degrees/s) in a test-retest design. Muscle activity of the upper and lower trapezius and serratus anterior was assessed by sEMG. Root Mean Square was calculated for whole ROM and single movement phases of absolute and normalized muscle activity. Absolute (Bland-Altman analysis (Bias, LoA), Minimal detectable change (MDC)) and relative reliability parameters (Intraclass correlation coefficient (ICC), coefficient of variation (CV)/test-retest variability (TRV)) were utilized for the evaluation of reproducibility. Intra-session reliability revealed ICCs between 0.56 and 0.98, averaged CVs of 18% and average MDCs of 81 mV. Inter-session reliability resulted in ICCs between 0.13 and 0.93, averaged TRVs of 21%, average MDCs of 15% and systematic and random error between -8 +/- 60% and 12 +/- 36%. Scapular muscle activity assessed in overhead movements can be measured reliably under maximum load conditions, though variability is dependent on the movement phase. Measurement variability does not exceed magnitudes of altered scapular muscle activities as reported in previous studies. Therefore, maximum load application is a promising approach for the evaluation of changes in scapular control related to pathologies. (C) 2017 Elsevier Ltd. All rights reserved.
Altered scapular muscle activity is mostly described under unloaded and submaximal loaded conditions in impingement patients. However, there is no clear evidence on muscle activity with respect to movement phases under maximum load in healthy subjects. Therefore, this study aimed to investigate scapular muscle activity under unloaded and maximum loaded isokinetic shoulder flexion and extension in regard to the movement phase. Fourteen adults performed unloaded (continuous passive motion [CPM]) as well as maximum loaded (concentric [CON], eccentric [ECC]) isokinetic shoulder flexion (Flex) and extension (Ext). Simultaneously, scapular muscle activity was measured by EMG. Root mean square was calculated for the whole ROM and four movement phases. Data were analyzed descriptively and by two-way repeated measures ANOVA. CPMFlex resulted in a linear increase of muscle activity for all muscles. Muscle activity during CONFlex and ECCFlex resulted in either constant activity levels or in an initial increase followed by a plateau in the second half of movement. CPMExt decreased with the progression of movement, whereas CONExt and ECCExt initially decreased and either levelled off or increased in the second half of movement. Scapular muscle activity of unloaded shoulder flexion and extension changed under maximum load showing increased activity levels and an altered pattern over the course of movement.
Characterization of scapular kinematics under demanding load conditions might aid to distinguish between physiological and clinically relevant alterations. Previous investigations focused only on submaximal external load situations. How scapular movement changes with maximal load remains unclear. Therefore, the present study aimed to evaluate 3D scapular kinematics during unloaded and maximal loaded shoulder flexion and extension. Twelve asymptomatic individuals performed shoulder flexion and extension movements under unloaded and maximal concentric and eccentric loaded isokinetic conditions. 3D scapular kinematics assessed with a motion capture system was analyzed for 20° intervals of humeral positions from 20° to 120° flexion. Repeated measures ANOVAs were used to evaluate kinematic differences between load conditions for scapular position angles, scapulohumeral rhythm and scapular motion extent. Increased scapular upward rotation was seen during shoulder flexion and extension as well as decreased posterior tilt and external rotation during eccentric and concentric arm descents of maximal loaded compared to unloaded conditions. Load effects were further seen for the scapulohumeral rhythm with greater scapular involvement at lower humeral positions and increased scapular motion extent under maximal loaded shoulder movements. With maximal load applied to the arm physiological scapular movement pattern are induced that may imply both impingement sparing and causing mechanisms.
Flexion-extension ratio of trunk peak torque measures and antagonistic activity in males and females
(2014)
Repetitive overhead motions in combination with heavy loading were identified as risk factors for the development of shoulder pain. However, the underlying mechanism is not fully understood. Altered scapular kinematics as a result of muscle fatigue is suspected to be a contributor. PURPOSE: To determine scapular kinematics and scapular muscle activity at the beginning and end of constant shoulder flexion and extension loading in asymptomatic individuals. METHODS: Eleven asymptomatic adults (28±4yrs; 1.74±0.13m; 74±16kg) underwent maximum isokinetic loading of shoulder flexion (FLX) and extension (EXT) in the sagittal plane (ROM: 20- 180°; concentric mode; 180°/s) until individual peak torque was reduced by 50%. Simultaneously 3D scapular kinematics were assessed with a motion capture system and scapular muscle activity with a 3-lead sEMG of upper and lower trapezius (UT, LT) and serratus anterior (SA). Scapular position angles were calculated for every 20° increment between 20-120° humerothoracic positions. Muscle activity was quantified by amplitudes (RMS) of the total ROM. Descriptive analyses (mean±SD) of kinematics and muscle activity at begin (taskB) and end (taskE) of the loading task was followed by ANOVA and paired t-tests. RESULTS: At taskB activity ranged from 589±343mV to 605±250mV during FLX and from 105±41mV to 164±73mV during EXT across muscles. At taskE activity ranged from 594±304mV to 875±276mV during FLX and from 97±33mV to 147±57mV during EXT. Differences with increased muscle activity were seen for LT and UT during FLX (meandiff= 141±113mV for LT, p<0.01; 191±153mV for UT, p<0.01). Scapula position angles continuously increased in upward rotation, posterior tilt and external rotation during FLX and reversed during EXT both at taskB and taskE. At taskE scapula showed greater external rotation (meandiff= 3.6±3.7°, p<0.05) during FLX and decreased upward rotation (meandiff= 1.9±2.3°, p<0.05) and posterior tilt (meandiff= 1.0±2.1°, p<0.05) during EXT across humeral positions. CONCLUSIONS: Force reduction in consequence of fatiguing shoulder loading results in increased scapular muscle activity and minor alterations in scapula motion. Whether even small changes have a clinical impact by creating unfavorable subacromial conditions potentially initiating pain remains unclear.
Background Low back pain (LBP) is a common pain syndrome in athletes, responsible for 28% of missed training days/year. Psychosocial factors contribute to chronic pain development. This study aims to investigate the transferability of psychosocial screening tools developed in the general population to athletes and to define athlete-specific thresholds.
Methods Data from a prospective multicentre study on LBP were collected at baseline and 1-year follow-up (n=52 athletes, n=289 recreational athletes and n=246 non-athletes). Pain was assessed using the Chronic Pain Grade questionnaire. The psychosocial Risk Stratification Index (RSI) was used to obtain prognostic information regarding the risk of chronic LBP (CLBP). Individual psychosocial risk profile was gained with the Risk Prevention Index – Social (RPI-S). Differences between groups were calculated using general linear models and planned contrasts. Discrimination thresholds for athletes were defined with receiver operating characteristics (ROC) curves.
Results Athletes and recreational athletes showed significantly lower psychosocial risk profiles and prognostic risk for CLBP than non-athletes. ROC curves suggested discrimination thresholds for athletes were different compared with non-athletes. Both screenings demonstrated very good sensitivity (RSI=100%; RPI-S: 75%–100%) and specificity (RSI: 76%–93%; RPI-S: 71%–93%). RSI revealed two risk classes for pain intensity (area under the curve (AUC) 0.92(95% CI 0.85 to 1.0)) and pain disability (AUC 0.88(95% CI 0.71 to 1.0)).
Conclusions Both screening tools can be used for athletes. Athlete-specific thresholds will improve physicians’ decision making and allow stratified treatment and prevention.
Back pain is a complex phenomenon that goes beyond a simple medical diagnosis. The aetiology and chronification of back pain can be best described as an interaction between biological, psychological, and social processes. However, to date, multimodal prevention and intervention programs for back pain that target all three aetiological factors have demonstrated limited effectiveness. This lack of supportive evidence for multimodal programmes in the treatment of back pain could be due to the fact that few programs are suitable for long-term and unsupervised use in everyday life. Moreover, in combining the elements from various therapies, little attention has been paid to the mechanisms underlying the synergistic effects of the separate components. In this contribution, we will describe the development of a new multimodal intervention for back pain that set out to address these limitations. To this end, the biological elements of neuromuscular adaptation is supplemented with cognitive behavioral and psychophysiological techniques in an intervention that can be followed at home as well as in clinics, and that is suitable for all grades of pain. The efficacy of this intervention will be tested in a multicentric randomized controlled longitudinal trial (n = 714) at five time points over a period of 6 months. Here we will describe the development and the content of this new intervention.