Real-time kinematic biofeedback improves scapulothoracic control and performance during scapular-focused exercises: A single-blind randomized controlled laboratory study

Emerging evidence suggests that scapular-focused therapeutic exercises hold promise for shoulder dynamic stability retraining. While recent findings show that therapeutic exercises can alter scapular neuromuscular function measured with muscle electromyography, no study has yet addressed the effects of kinematic biofeedback for improving scapulothoracic control and performance. The aim of this study was to assess the effectiveness of kinematic biofeedback on motor relearning transfer during shoulder flexion and a daily activity, on the quality of scapular-focused exercise performance, and on execution time. Thirty healthy young adults were randomly distributed into two groups. Skin mounted electromagnetic sensors were used to collect kinematic data of the thorax, scapula and humerus while subjects performed a shoulder flexion and a daily activity, prior to and after scapular-focused exercises. For both groups, the exercise execution error and the execution time determined the scapulothoracic control and performance. Significant statistical differences were found in the exercise execution error results within the experimental group (z = 5.313; p = 0.037) and between groups (u = 37.00; p = 0.001; u = 64.00; p = 0.024). This study’s results demonstrate that real-time kinematic biofeedback improves scapulothoracic control and performance during scapular-focused exercise execution.     

Effects of scapular retraction/protraction position and scapular elevation on shoulder girdle muscle activity during glenohumeral abduction

According to scapulohumeral rhythm, shoulder abduction is followed through scapular upward rotation to ensure joint mobility and stability. Of interest, the shoulder abduction can be performed holding the scapula in different positions and in association with scapular elevation, with possible effects on shoulder muscle activity. Therefore, the aim of the study was to analyze the activity of relevant shoulder muscles and the activity ratios between the scapulothoracic muscles, during shoulder abduction performed in different combinations of scapular position (neutral, retracted, protracted) and scapular elevation.The electromyographic activity of middle deltoid, serratus anterior, upper, middle and lower fibers of trapezius was recorded during shoulder abduction movements executed holding the scapula in neutral, retracted and protracted position, and subsequently a shoulder elevation movement. The activation of each muscle and the scapulothoracic muscles activity ratios were determined every 15 degrees, from 15° to 120° of abduction.Scapular retraction led to higher activation of the entire trapezius muscle, whereas protraction induced higher upper trapezius, middle deltoid and serratus anterior activity, along with lower activity of middle and lower trapezius. Shoulder elevation led to higher activity of the upper trapezius and middle deltoid. Moreover, it induced lower activation of the serratus anterior and middle and lower trapezius, thus leading to high ratios between the upper trapezius and the other scapulothoracic muscles, especially between 15 and 75 degrees of abduction.This study highlights that shoulder abduction performed with scapular protraction and in combination with scapular elevation leads to increased activity of the middle deltoid and upper trapezius, resulting in imbalances between the scapulothoracic muscles that could hamper the optimal scapulohumeral rhythm. The abduction performed in the aforementioned scapular conditions also induce potential reciprocal inhibition effects between the movers and stabilizers muscles of scapula, suggesting different motor control strategies of integrating a common shoulder movement with various modification of the scapular position.     

The Shoulder and Elbow Joints and Right and Left Sides Demonstrate Similar Joint Position Sense

Proper orientation of the shoulder and elbow is necessary for accurate and precise positioning of the hand. The authors’ goal was to compare these joints with an active joint position sense task, while also taking into account the effects of joint flexion angle and arm dominance. Fifteen healthy subjects were asked to replicate presented joint angles with a single degree of freedom active positioning protocol. There were no significant differences in angular joint position sense errors with respect to joint (shoulder vs. elbow) and side (left vs. right). However, when considering linear positioning, errors were lower for the elbow, due to a shorter lever arm. Also, as flexion angles increased toward 90°, there was a consistent pattern of lower errors for both joints.     

Comparison of range of motion and function of subjects with reverse anatomy Bayley-Walker shoulder replacement with those of normal subjects

Patients with rotator cuff tear and degenerative shoulder joint disease commonly experience severe pain and reduced performance during activities of daily living. A popular way to treat these patients is by means of reverse anatomy shoulder prosthesis. Studying the kinematics of subjects with reverse anatomy implant would be useful in order to gain knowledge about functionality of different designs. It is hypothesized that the kinematics of these subjects, in the absence of rotator cuff muscles, differs from that of normal subjects. In this study the upper limb kinematics of 12 subjects with a Bayley-Walker reverse anatomy shoulder prosthesis while performing tasks common in everyday activities and those that represent the range of motion was analyzed and compared to that of 12 normal subjects. Each patient also completed an Oxford Shoulder Score. Substantial reduction in the Bayley-Walker subjects' ranges of motion was observed compared to normal subjects. The mean abduction angle decreased from 109° (±20) for normal subjects to 64° (±25). A similar trend was observed during flexion and axial rotation tasks. Furthermore, the normal group showed less variable ranges of motion performing the standard tasks, whereas for the prosthetic group this varied greatly, which is likely to be dependent on muscle strength. Although the decreased range of motion was prominent, subjects were able to complete most of the tasks by compensating with their elbow and trunk. The most challenging task for Bayley-Walker subjects was lifting an object to head height.     

Quantifying the three-dimensional joint position sense of the shoulder

Joint position sense is important for performing activities of daily living and recreational activities. The objective of this study was to develop new insights into the proprioceptive capabilities of the shoulder using a novel virtual reality paradigm where participants actively recreated shoulder positions in all three dimensions. This allows for better identification of changes in joint position sense across different shoulder postures. Ten males and ten female healthy adults matched a cursor controlled by shoulder rotations calculated from motion capture tracking, to a target shoulder position presented in a virtual environment with the use of a virtual reality headset. Four elevation angles, three plane of elevation angles, and three rotation angles were investigated, totaling thirty-six angles that encompassed the range of motion of the shoulder. Joint position sense was enhanced as the elevation angle was increased, and further enhanced when the arm was more externally rotated and elevated. As elevation angle increased to 90°, joint position sense significantly increased. There was also a significant interaction of external rotation on elevation angle. As elevation angle increased, participants were more accurate when the arm was externally, but exhibited greater variability. These improvements in joint position sense are likely produced by increased tension in muscles and capsuloligamentous mechanoreceptors within the shoulder. As many sports and activities of daily living require joint position sense to complete a task, the ability to elevate and externally rotate is important for adequate shoulder proprioception and control.     

Quadrupedal movement training improves markers of cognition and joint repositioning

IntroductionExercise, and in particular balance and coordination related activities such as dance, appear to have positive effects on cognitive function, as well as neurodegenerative conditions such as dementia and Parkinson’s disease. Quadrupedal gait training is a movement system requiring coordination of all four limbs that has previously been associated with cognitive development in children. There is currently little research into the effect of complex QDP movements on cognitive function in adults.PurposeTo determine the effects of a novel four-week quadrupedal gait training programme on markers of cognitive function and joint reposition sense in healthy adults.MethodsTwenty-two physically active sports science students (15 male and 7 female) were divided into two groups: a training group (TG) and a control group (CG). All participants completed the Wisconsin Card Sorting Task (WCST) and were tested for joint reposition sense before and after a four-week intervention, during which time the TG completed a series of progressive and challenging quadrupedal movement training sessions.ResultsParticipants in the TG showed significant improvements in the WCST, with improvements in perseverative errors, non-perseverative errors, and conceptual level response. This improvement was not found in the CG. Joint reposition sense also improved for the TG, but only at 20 degrees of shoulder flexion.ConclusionsPerformance of a novel, progressive, and challenging task, requiring the coordination of all 4 limbs, has a beneficial impact on cognitive flexibility, and in joint reposition sense, although only at the specific joint angle directly targeted by the training. The findings are consistent with other studies showing improvements in executive function and joint reposition sense following physical activity.     

The Impact of Deep Muscle Training on the Quality of Posture and Breathing

Postural control and breathing are mechanically and neuromuscularly interdependent. Both systems– of spinal stability and respiration– involve the diaphragm, transversus abdominis, intercostal muscles, internal oblique muscles and pelvic floor muscles. The aim of the study was to evaluate the effect of exercises activating deep stabilizer muscles on postural control and quality of breathing movements. Eighteen volunteers (25,7 ± 3,5) were recruited from the general population. All the subjects implemented an exercise program activating deep muscles. Head, pelvic and trunk positions in the sagittal and frontal planes were assessed with the photogrammetric method. Breathing movements were estimated with the respiratory inductive plethysmography. The results indicate that the use of deep muscle training contributed to a significant change in the position of the body in the sagittal plane (p = 0.008) and the increase in the amplitude of breathing (p = 0.001).     

Shoulder joint position sense is not enhanced at end range in an unconstrained task

Shoulder joint position sense (JPS) is important for maintaining stability and contributing to coordinated movements. It is provided by afferent and centrally-derived signals interpreted and integrated by the central nervous system (CNS) for subsequent use. Shoulder JPS is enhanced as the joint approaches end range of motion (ROM) in studies involving internal and external rotation with the arm supported, but this finding has not been confirmed in unconstrained movements. To address this issue, the present study examined the effect of shoulder position in the horizontal plane on JPS at a constant elevation. Twenty-three healthy individuals were recruited from a university campus. Subjects attempted to actively replicate various target positions in both plane and elevation. Target positions consisted of five positions in the horizontal plane, normalized to individual horizontal abduction ROM, at 90° of arm elevation. All target positions were tested three times, and average absolute and variable errors were analyzed for each position. No differences in either absolute (p = .312) or variable (p = .185) errors were observed between positions. These results further support the contention that the muscle spindles are a dominant source of afferent feedback regarding shoulder JPS in unconstrained movements, even approaching end ROM, when the capsuloligamentous receptors are active.     

Three-dimensional kinematics of the scapula and trunk,and associated scapular muscle timing in individuals with stroke

Poor scapulothoracic control is a risk for developing shoulder pathology, but has received little attention so far in individuals with stroke (IwS). Trunk and scapular kinematics and surface muscle activity were measured in 15 healthy controls and 18 IwS during a low and high forward flexion (FF). Group-differences in trunk and scapular kinematics were assessed during low and high FF using a t-test (independent samples). Differences in muscle onset and offset time relative to movement start (both FF tasks) were determined using a mixed model taking into account the different groups and muscles. Recruitment patterns per group and task were described based on significant differences between muscles. In IwS, earlier lower trapezius and late infraspinatus offset were found during low FF, as well as a later onset and earlier offset of serratus anterior. For low FF, significantly more trunk axial rotation was found in IwS during both elevation and lowering. During high FF, IwS showed significantly less scapular posterior tilt during elevation and more scapular lateral rotation during lowering. IwS demonstrated adaptive muscle timing with earlier initiation and late inactivation of lower trapezius and infraspinatus, possibly to compensate for a late activation and early deactivation of the serratus anterior and to establish as such the correct pattern of scapulothoracic movement.     

Force matching errors following eccentric exercise

During eccentric exercise contracting muscles are forcibly lengthened, to act as a brake to control motion of the body. A consequence of eccentric exercise is damage to muscle fibres. It has been reported that following the damage there is disturbance to proprioception, in particular, the senses of force and limb position. Force sense was tested in an isometric force-matching task using the elbow flexor muscles of both arms before and after the muscles in one arm had performed 50 eccentric contractions at a strength of 30% of a maximum voluntary contraction (MVC). The exercise led to an immediate reduction of about 40%, in the force generated during an MVC followed by a slow recovery over the next four days, and to the development of delayed onset muscle soreness (DOMS) lasting about the same time. After the exercise, even though participants believed they were making an accurate match, they made large matching errors, in a direction where the exercised arm developed less force than the unexercised arm. This was true whichever arm was used to generate the reference forces, which were in a range of 5-30% of the reference arm's MVC, with visual feedback of the reference arm's force levels provided to the participant. The errors were correlated with the fall in MVC following the exercise, suggesting that participants were not matching force, but the subjective effort needed to generate the force: the same effort producing less force in a muscle weakened by eccentric exercise. The errors were, however, larger than predicted from the measured reduction in MVC, suggesting that factors other than effort might also be contributing. One factor may be DOMS. To test this idea, force matches were done in the presence of pain, induced in unexercised muscles by injection of hypertonic (5%) saline or by the application of noxious heat to the skin over the muscle. Both procedures led to errors in the same direction as those seen after eccentric exercise.     

Various shrug exercises can change scapular kinematics and scapular rotator muscle activities in subjects with scapular downward rotation syndrome

Scapular dyskinesis, characterized by scapular downward rotation syndrome (SDRS) affects scapula-humeral rhythm and results in shoulder dysfunction. Previous study has led to the recommendation of standard shrug exercise to contend with SDRS and strengthen the upper trapezius (UT) muscle. However, few researchers have examined which shrug exercise is most effective. The aim of this research was to compare scapular kinematic changes and scapular rotator muscles activity across three different shrug exercises in SDRS. The amounts of scapular downward rotation were measured by a caliper and the scapular upward rotation angle was measured using two digital inclinometers. Surface electromyography was used to measure EMG amplitude from the UT, lower trapezius (LT), serratus anterior (SA), and levator scapula (LS). Seventeen subjects with SDRS were recruited for this study. The subjects performed three shrug exercises with 30° shoulder abduction (preferred shrug, frontal shrug, and stabilization shrug). The stabilization shrug showed a significantly greater scapular upward rotation angle compared with the preferred shrug (P = 0.004) and frontal shrug (P = 0.006). The UT activity was significantly greater in the frontal shrug than in the preferred shrug (P = 0.002). The UT/LS muscle activity ratio was also significantly greater in the frontal shrug than in the preferred shrug (P = 0.004). The stabilization shrug should be preferred to enhance the upward rotation angle. In addition, the frontal shrug can be used as an effective method to increase UT activity and to decrease LS activity in SDRS.     

品管圈对卒中偏瘫患者肢体功能锻炼的效果观察

探讨品管圈活动在卒中偏瘫患者肢体功能锻炼中的应用效果。将66例患者随机分为对照组（常规锻炼组）和试验组（品管圈组）,分别行不同模式的功能锻炼。采用康复护理日常生活活动（RNADL）量表分别对其日常生活活动能力（ADL）进行评定。试验组自理能力高于对照组,差异有统计学意义（P〈0．01）,且其依从性与对照组比较,差异有统计学意义（P〈O．05）。品管圈有助于提高卒中偏瘫患者功能锻炼的依从性。     

Comparison of muscle functions during three contrasting abdominal exercises

That different amplitudes of muscle activities during various abdominal exercises not only reflect the inherent differences in motor control but movement speed as well was hypothesized. 20 healthy adults (M age = 23 yr.) performed three exercises that involved varying amounts of trunk control: the partial sit-up, full sit-up, and AbSlide roll. Covariate analyses indicated that the amplitude of muscle activities could be partitioned into three categories: motor control and scaling (speed and amplitude), scaling only, and motor control only. Overall, the AbSlide exercise activated the most amount of muscular activity, followed by the full and partial sit-up exercises. Results are discussed in terms of how the various muscles contribute to motor control and velocity scaling.     

Effect of relaxation or exercise on undergraduates' test anxiety

The purpose of this study was to determine whether test anxiety could be significantly reduced through regular practice of relaxation exercises or physical exercise. Test anxiety was assessed at pretest and posttest using the 37-item true-false Test Anxiety Questionnaire developed by Sarason. 47 undergraduate students self-selected to participate. The 9 subjects in the group who engaged in a nonmeditative relaxation exercise 3 times per week for 7 weeks showed a significant decline in test anxiety. The 16 subjects in a supervised aerobic dance class 3 times per week for 7 weeks improved their fitness and their test anxiety significantly declined. The 20 control subjects did not meet over the 7-week study ahd showed no significant change in test anxiety, fitness, or relaxation.     

Cross-association analysis of EEG and EMG signals according to movement intention state

Rehabilitation within three months plays a significant role in the recovery of damaged motor functions following the onset of a stroke. To increase the effectiveness of rehabilitation, it is important to perform rehabilitative exercises with movement intention. This study analyzed the association between electroencephalogram (EEG) and electromyogram (EMG) signals in healthy individuals in an attempt to verify the differences between the two signals in corticomuscular connectivity as well as the time delay in the flow of information in accordance with the presence of movement intention. To examine the relationship between the brain and muscles, coherence and mutual information analyses were performed on the EEG signals in the motor cortex and EMG signals in the flexor digitorum superficialis muscle during grasping training. Coherence and mutual information between EEG and EMG signals were significantly higher and the time delay of information flow was shorter when subjects performed active exercise with movement intention than when they performed passive exercise without movement intention. These findings could be applied to the rehabilitation of stroke patients to develop a rehabilitative training system with heightened effectiveness through verification of the presence of movement intention in the patients.     

Effects of Warm-Up and Fatigue on Knee Joint Position Sense and Jump Performance

The purpose of this study was to evaluate the effects of a warm-up and fatigue protocol on the vertical jump and knee joint position sense of sprinters. Thirty-two sprinters were randomly allocated to either a control group (CONT) or a plyometric group (PLYO) that performed a warm-up, followed by a high-intensity plyometric protocol. Absolute (AAE), relative (RAE), and variable (VAE) angular errors and vertical jump were evaluated before and after the warm-up, as well as after the plyometric protocol and again 5 min later. After the warm-up, athletes improved RAE and jump performance. After the plyometric protocol, scores on the RAE, VAE, and the vertical jump performance worsened compared to the control group and to the values obtained after the warm-up. Five minutes later, RAE and vertical jump continued to be impaired. AAE did not show significant differences. The vertical jump is improved after the warm-up, although it is deteriorated after high-intensity plyometry. Regarding knee proprioception, the lack of impairments in the AAE make unclear the effects of the plyometric exercises on knee proprioception.     

Longitudinal improvement of self-regulation through practice: building self-control strength through repeated exercise.

This study examined the results of repeated exercises of self-control in relation to self-regulatory strength over time. A sample of 69 U.S. college students spent 2 weeks doing 1 of 3 self-control exercises: monitoring and improving posture, regulating mood, or monitoring and recording eating. Compared with a no-exercise control group, the participants who performed the self-control exercises showed significant improvement in self-regulatory capacity as measured by quitting faster on a hand-grip exercise task following a thought-suppression exercise.     

Anxiety and heart rate under psychological stress: The effects of exercise-training

Abstract The effects of a 12-week exercise-training program on cognitive, somatic, and behavioral anxiety and on heart rate responses to evaluative stress were scrutinized in 89 subjects randomly assigned to an experimental (exercise) or a control group. The training program consisted of exercises that were aimed to the improvement of the general physical fitness (i.e., strength, flexibility, and endurance). Following the 12-week training period, exercising subjects showed improved motor skill capacity as well as higher VO(2) max. In an anxiety inciting test situation, that consisted of the video-taped delivery of a 5-min speech, a mental arithmetic and a fine motor task, exercising subjects showed more favourable responses than control subjects in three ways: (a) they exhibited lower behavioral anxiety during the anticipation phase of the three stressors, (b) they reported lower cognitive and somatic anxiety during the anxiety provoking situation, and (c) their heart rate recovered faster, in contrast to both their baseline heart rate and the control subjects' heart rate, from the stress episode. These results demonstrate that a fitness-oriented exercise program has anxiolytic properties. They also provide a primary evidence that overt behavioral anxiety, as opposed to the usually measured self-reported anxiety, may be affected by exercise.     

Exercise training can improve spatial characteristics of time-critical obstacle avoidance in elderly people

Fall prevention programs have rarely been evaluated by quantitative movement analysis methods. Quantitative movement analyses could provide insight into the mechanisms underlying the effects of training. A treadmill obstacle avoidance task under time pressure has recently been used to evaluate a fall prevention exercise program for community-dwelling elderly people and it showed that participants improved their obstacle avoidance success rates. The mechanism, by which the increased success rates were achieved, however, remained to be determined. Participants were elderly who had fallen at least once in the year prior to participation. They were assigned to either the exercise or the control group. The control group did not receive any specific treatment. The exercise group was administered a five week exercise program, which consisted of exercises on a functionally oriented obstacle course, walking exercises, and practice of fall techniques. Pre- and post-intervention laboratory obstacle avoidance tests were conducted. Three possible determinants of success were investigated, namely avoidance reaction times, the distribution of avoidance strategies, and three spatial parameters (toe distance, foot clearance and heel distance). Analysis yielded significant TimexGroup interactions in heel distances. The exercise group increased heel distance, while the control group did not. Increased heel distance may result in reduced risk of heel contact with the obstacle and, consequently, larger success rates. The remaining parameters showed no effect of training. In conclusion, the training program was effective in improving time-critical obstacle avoidance skills. In every day life, these effects of training may contribute to less obstacle-related fall incidents in elderly. In addition, these findings could indicate that the execution of other time-critical events, like an actual fall, could also be improved by training.     

Abdominal exercise intensities on firm and compliant surfaces

Muscle activities at 15 sites were compared within a group of healthy young adults to evaluate their relative intensities during six abdominal exercises: partial and full sit-ups on a firm surface (floor) and on an exercise ball that was either stabilized or unstabilized. The most strenuous abdominal exercise overall (i.e., whole body workout) was the full sit-up on a firm surface which included significant muscle activities in the lower extremities. Exercise intensity was also high in the full and partial sit-ups when performed on a ball. The partial sit-up on the floor was the least strenuous of the six exercises. The greatest effect on the abdominal muscles was observed in the partial sit-up on a ball (stabilized and unstabilized). Results suggest that, although abdominal exercises on a ball may be gentler on the hip and lower back, overall exercise intensity is not necessarily lower than that on the floor. Moreover, partial sit-ups, both on the floor and on a ball, also required greater neck muscle activities than full sit-ups. In deciding what type of sit-up to do, exercise surface and different muscular activities between the partial and full sit-ups should be considered.