Acromiohumeral Distance and 3-Dimensional Scapular Position Change After Overhead Muscle Fatigue (original) (raw)
Related papers
Journal of athletic training
Glenohumeral external rotation (GH ER) muscle fatigue might contribute to shoulder injuries in overhead athletes. Few researchers have examined the effect of such fatigue on scapular kinematics and muscle activation during a functional movement pattern. To examine the effects of GH ER muscle fatigue on upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscle activation and to examine scapular kinematics during a diagonal movement task in overhead athletes. Human performance research laboratory. Descriptive laboratory study. Our study included 25 overhead athletes (15 men, 10 women; age = 20 ± 2 years, height = 180 ± 11 cm, mass = 80 ± 11 kg) without a history of shoulder pain on the dominant side. We tested the healthy, dominant shoulder through a diagonal movement task before and after a fatiguing exercise involving low-resistance, high-repetition, prone GH ER from 0° to 75° with the shoulder in 90° of abduction. Surface electromyography was used to measure mus...
Upper body kinematic and muscular variability in response to targeted rotator cuff fatigue
Human Movement Science, 2018
The rotator cuff muscles are prominent stabilizers of the shoulder and are vulnerable to muscle fatigue. Rotator cuff fatigue may result in subacromial impingement (SAI) through the superior translation of the humeral head. Scapular changes have been reported inconsistently, but may prevent SAI. The purpose of this study was to quantify changes in scapular kinematics, as well as muscle activity during glenohumeral motions following targeted rotator cuff fatigue. Ten healthy men completed four planar glenohumeral motions (cross-flexion, frontal, scapular, and sagittal plane elevation) prior to and immediately following a rotator cuff fatigue protocol on two separate days. Scapular kinematics and muscle activity of thirteen muscles were recorded. Scapular protraction decreased significantly with fatigue during scapular plane elevation (p < 0.001; η p 2 = 0.74). Although not significant, large effect sizes were found with decreased scapular protraction during elevation in the frontal (p = 0.012; η p 2 = 0.52) and sagittal planes (p = 0.007; η p 2 = 0.58), as well as decreased scapular medial rotation during cross-flexion (p = 0.008; η p 2 = 0.56). Between-subject variability (standard deviations from 2.3°to 14.5°) and withinsubject day-today differences (upwards of 10°deviation in the opposite direction) were high among all kinematic changes following fatigue. Considerable day-today differences in scapular stabilizer muscle activity in response to fatigue were present. Due to the degrees of freedom at the upper extremity, individuals can employ a variety of compensatory strategies to fatigue. The variable compensatory strategies across the scapular stabilizers resulted in individual-specific scapular kinematic changes that could act as either impingement-sparing or impingement-promoting. The high variance in day-today differences within-subjects indicates that kinematic and muscular responses to fatigue may be adaptive within individuals over time.
Archives of Physical Medicine and Rehabilitation, 2010
Scapular muscle activity in overhead athletes with symptoms of secondary shoulder impingement during closed chain exercises. Arch Phys Med Rehabil 2010;91: 550-6. Objective: To determine the amount of muscle activation in 4 scapular muscles in overhead athletes with and without a history of secondary shoulder impingement, during 3 upper extremity closed chain exercises. Design: One-between (group), one-within (exercise) repeated measures. Setting: Controlled laboratory study. Participants: Overhead athletes (nϭ15; mean age Ϯ SD, 21.0Ϯ2.5y; mean height Ϯ SD, 176.0Ϯ7.8cm; mean weight Ϯ SD, 76.1Ϯ13.4kg) demonstrating with symptoms of shoulder impingement and overhead athletes (nϭ15; mean age Ϯ SD, 20.4Ϯ3.8y; mean height Ϯ SD, 174.1Ϯ9.7cm; mean weight Ϯ SD, 73.3Ϯ11.7kg) with no shoulder pathologies. Interventions: Subjects completed 5 individual trials of a standard push-up, a push-up on an unstable surface, and a revolution on a shoulder rehabilitation device while electromyography (EMG) recorded muscle activity of the serratus anterior, upper trapezius, middle trapezius, and lower trapezius. Main Outcome Measures: The mean EMG data for the 4 muscles from the standard push-up, push-up on an unstable surface, and shoulder rehabilitation device trials were normalized as a percentage of a maximum voluntary isometric contraction for each muscle. Results: There was a statistically significant interaction for the middle trapezius (F 2,56 ϭ3.856; Pϭ.027). The shoulder impingement push-up on an unstable surface (33.76%Ϯ26.45%) had significantly greater activation compared with the shoulder impingement standard push-up (25.88%Ϯ13.76%), the shoulder impingement shoulder rehabilitation device (9.40%Ϯ5.86%), and the nonpathology push-up on an unstable surface (19.49%Ϯ 7.73%). The shoulder impingement standard push-up had significantly greater activation compared with the shoulder impingement shoulder rehabilitation device and nonpathology standard push-up (17.99%Ϯ7.31%). The nonpathology standard push-up and nonpathology push-up on an unstable surface had significantly greater activation compared with the nonpathology shoulder rehabilitation device (7.95%Ϯ4.30%). Conclusions: These results suggest that the muscle activation of the middle trapezius differs in overhead athletes with a history of secondary shoulder impingement compared with those who lack this history during closed chain exercise, as well as within the 3 closed chain exercises. The levels of muscle activation of the serratus anterior and upper trapezius during these closed chain exercises were similar between the 2 groups. These results support the use of closed chain exercises in the rehabilitation process of overhead athletes with secondary shoulder impingement. However, clinicians should consider the muscle(s) of interest when selecting an exercise.
Muscle fatigue response of rotator cuff muscles in different postures
Archives of Orthopaedic and Trauma Surgery
Introduction Muscle fatigue is a leading cause of rotator cuff (RC) pathologies. Scapular orientation affected by changes in the thoracic spine account for differences in body postures leading to altered RC muscle activation. This posture-related alteration in RC muscle activation and its fatigue response needs to be analyzed. Materials and methods This study included 50 healthy shoulders with no coexisting spine pathologies. Raw data were recorded using electromyography sensors for RC muscles during two isometric maneuvers of abduction and external rotation, performed at 30% maximum voluntary contraction at 30°, 45°, and 90° arm elevation in sitting and standing. The raw data were analyzed in DataLITE® software, and the mean power frequency (MPF) was extracted to analyze the fatigue response of RC muscles. The Wilcoxon signed-rank test and Kruskal–Wallis test with Bonferroni corrections analyzed fatigue differences between postures and various activities. P < 0.05 was considered...
Journal of Rehabilitation Sciences & Research, 2023
Background: Throwing movements are repetitive motions in overhead athletes that cause soft tissue adaptations and ultimately lead to shoulder joint damage. The current study purposed to determine the torque of internal and external rotation of joint shoulder in overhead athletes with and without impingement syndrome in the ball throwing position. Methods: This cross-sectional study was conducted on 63 male overhead athletes (33 with and 30 without shoulder impingement syndrome). Simulated maximum functional torque was evaluated while the athlete threw a ball into a net from a sitting position. A 6-camera Vicon Motion Capture system incorporated markers on the upper limb and trunk. A kinematic model of the upper limb was used in OpenSim software with inverse dynamics to obtain maximum torque. Results: The internal and external rotation and elevation torques differed significantly in athletes with shoulder impingement syndrome compared to those without impingement syndrome (P<0.001, P=0.012, and P<0.001, respectively), while no significant difference was seen in shoulder depression (P=0.283) between the two groups. Conclusion: The current findings suggest that there may be adaptations to shoulder strength and torque in response to throwing a ball that ultimately cause injury to the shoulder.
Scapulothoracic and Glenohumeral Kinematics Following an External Rotation Fatigue Protocol
2006
Objective: To determine the effects of shoulder external rotator muscle fatigue on 3-dimensional scapulothoracic and glenohumeral kinematics. Background: The external rotator muscles of the shoulder are important for normal shoulder function. Impaired performance of these muscles has been observed in subjects with impingement syndrome and it is possible that external rotator muscle fatigue leads to altered kinematics of the shoulder girdle. Methods and Measures: Twenty subjects without a history of shoulder pathology participated in this study. Three-dimensional scapulothoracic and glenohumeral kinematics were determined from electromagnetic sensors attached to the scapula, humerus, and thorax. Surface electromyographic (EMG) data were collected from the upper and lower trapezius, serratus anterior, anterior and posterior deltoid, and infraspinatus muscles. Median power frequency (MPF) values were derived from the raw EMG data and were used to indicate the degree of local muscle fatigue. Kinematic and EMG measures were collected prior to and immediately following the performance of a shoulder external rotation fatigue protocol. Results: After completing the fatigue protocol subjects demonstrated less external rotation of the humerus. Additionally, they had less posterior tilt of the scapula in the beginning phase of arm elevation, and more scapular upward rotation and clavicular retraction in the mid ranges of arm elevation. Conclusions: Performance of an external rotation fatigue protocol results in altered scapulothoracic and glenohumeral kinematics. Further studies are needed to investigate the effects of external rotator muscle fatigue on scapulothoracic and glenohumeral kinematics in subjects with shoulder pathology.
The effects of repetitive overhead throwing on shoulder rotator isokinetic work-fatigue
North American journal of sports physical therapy : NAJSPT, 2007
Muscle strength and endurance of the shoulder rotators is important for overhead throwing performance and dynamic glenohumeral stability. Baseball pitching is distinguished as an intermittent activity with explosive, high intensity muscle contractions separated by periods of rest. Rotator cuff muscle performance could acutely decrease due to fatigue associated with bouts of throwing. This study examined the effects of repeated overhead throwing upon isokinetic muscle performance of the shoulder rotators. Repeated-measures analyses of vari-ance were used to compare peak torque, total work, and work-fatigue by muscle group, time, and contraction type. Ten collegiate baseball pitchers underwent isokinetic testing of the internal (IR) and external shoulder (ER) rotators one week before and immediately after a throwing protocol of 60 maximal-effort pitches arranged into four innings of 15 pitches per inning. Isokinetic testing consisted of 12 concentric and eccentric repetitions at 300 d...