Function, strength, and muscle activation of the shoulder complex in Crossfit practitioners with and without pain: a cross-sectional observational study

Background The shoulder joint is the most commonly injured joint in CrossFit practitioners, because of the high intensity and loads associated with this sport. Despite the large number of clinical cases, there is a shortage of studies that investigate influence of biomechanical aspects of upper limbs' injuries on CrossFit practitioners. This study hypothesized that there would be a difference in function, strength, and muscle activation between Crossfit practitioners with and without shoulder pain. Methods We divided 79 Crossfit practitioners into two groups according to whether they reported pain (n = 29) or no pain (n = 50) in the shoulder during Crossfit training. Muscle function, strength, and activation were assessed using the Disability Arm, Shoulder and Hand function questionnaire, Upper Quarter Y Balance Test and Closed Kinetic Chain Upper Extremity Stability Test shoulder tests, isometric muscle strength assessment by manual dynamometry and muscle activation by surface electromyography and pain report. Results The function based on questionnaire was associated with pain (p = 0.004). We observed a statistically significant difference between the two groups only in the surface electromyography activity of the lower trapezius, and in the variables of shoulder pain and function (p = 0.038). Conclusion Crossfit practitioners with shoulder pain occurring during training showed good function and stability of the shoulder joint, but there was a reduction in the activation of stabilizing muscles, especially the lower trapezius. Trial registration Registro Brasileiro de Ensaios Clinico (Brasilian National Registry) with the ID: RBR-2gycyv.

Startle Increases the Incidence of Anticipatory Muscle Activations but Does Not Change the Task-Specific Muscle Onset for Patients After Subacute Stroke

Objectives: To demonstrate the task-specificities of anticipatory muscle activations (AMAs) among different forward-reaching tasks and to explore the StartleReact Effect (SE) on AMAs in occurrence proportions, AMA onset latency or amplitude within these tasks in both healthy and stroke population.Methods: Ten healthy and ten stroke subjects were recruited. Participants were asked to complete the three forward-reaching tasks (reaching, reaching to grasp a ball or cup) on the left and right hand, respectively, with two different starting signals (warning-Go, 80 dB and warning-startle, 114 dB). The surface electromyography of anterior deltoid (AD), flexor carpi radialis (FCR), and extensor carpi radialis (ECR) on the moving side was recorded together with signals from bilateral sternocleidomastoid muscles (SCM), lower trapezius (LT), latissimus dorsi (LD), and tibialis anterior (TA). Proportions of valid trials, the incidence of SE, AMA incidence of each muscle, and their onset latency and amplitude were involved in analyses. The differences of these variables across different move sides (healthy, non-paretic, and paretic), normal or startle conditions, and the three tasks were explored. The ECR AMA onset was selected to further explore the SE on the incidence of AMAs.Results: Comparisons between move sides revealed a widespread AMA dysfunction in subacute stroke survivors, which was manifested as lower AMA onset incidence, changed onset latency, and smaller amplitude of AMAs in bilateral muscles. However, a significant effect of different tasks was only observed in AMA onset latency of muscle ECR (F = 3.56, p = 0.03, η2p = 0.011), but the significance disappeared in the subsequent analysis of the stroke subjects only (p > 0.05). Moreover, the following post-hoc comparison indicated significant early AMA onsets of ECR in task cup when comparing with reach (p < 0.01). For different stimuli conditions, a significance was only revealed on shortened premotor reaction time under startle for all participants (F = 60.68, p < 0.001, ηp2 = 0.056). Furthermore, stroke survivors had a significantly lower incidence of SE than healthy subjects under startle (p < 0.01). But all performed a higher incidence of ECR AMA onset (p < 0.05) than with normal signal. In addition, the incidence of ECR AMAs of both non-paretic and paretic sides could be increased significantly via startle (p ≤ 0.02).Conclusions: Healthy people have task-specific AMAs of muscle ECR when they perform forward-reaching tasks with different hand manipulations. However, this task-specific adjustment is lost in subacute stroke survivors. SE can improve the incidence of AMAs for all subjects in the forward-reaching tasks involving precision manipulations, but not change AMA onset latency and amplitude.

Early Efficacy Assessment of Arthroscopic Lower Trapezius Transfer With Tendon Autograft in the Management of Massive Irreparable Posterosuperior Rotator Cuff Tears

Objectives: To explore the indications and surgical techniques for arthroscopic lower trapezius transfer (LTT) with tendon autograft in managing massive irreparable posterosuperior rotator cuff tears (PSRCTs); to validate the feasibility, safety, and efficacy of this technique.Methods: This study retrospectively enrolled 23 patients with massive irreparable PSRCTs, admitted to and followed up by the Taizhou Hospital of Zhejiang province between July 2020 and April 2021, and treated with ipsilateral LTT and ipsilateral hamstring tendon autograft. The control group consisted of 23 patients with massive RCTs receiving conventional repair procedures within the same frame. Follow-up data at the preoperative visit, and postoperative month 3 were collected to assess the active range of motion, Constant–Murley Score (CMS),American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), University of California, Los Angeles (UCLA)shoulder score, visual analog scale (VAS)and the post-operative MRI results, all of which could provide a comprehensive postoperative early efficacy assessment.Results: Three months follow-up visits were completed for all patients, revealing improvements in all aspects compared to the preoperative state, with no complications, such as postoperative infection of surgical sites and nerve injuries of infection and nerve injury. The distribution of active shoulder range of motion of patients and function scores with two types of operation was as follow: angles of flexion and lifting (130.00° ± 31.55° vs. 90.78° ± 19.85°), abduction (123.26° ± 30.47°vs. 85.87° ± 18.74°), external rotation at side (101.74° ± 14.74° vs. 91.74° ± 11.92°), external rotation at 90° abduction (41.52° ± 21.97° vs. 24.57° ±12.60°), VAS (0.74± 0.81 vs. 1.87 ±0.87), CMS(56.3 ± 13.01 vs. 48.30 ± 8.38), UCLA shoulder score (24.04 ± 2.88 vs.20.96 ± 3.47), ASES (72.91 ± 9.99 vs.60.74 ± 8.84). Significantly better improvements were found in the study group on month 3.19 of 23 patients in the study group and 17 of 23 patients in the control group underwent MRI on the 3 months follow up. Retear was found in only one patient who had grade 4 subscapularis tendon injury, However, revision was not performed due to postoperative pain relief and functional improvement.Conclusion: Compared to conventional repair procedures, in the early postoperative period, LTT with tendon autograft could achieve better pain relief, more rapid motor functional recovery, and higher functional scores for massive irreparable PSRCTs.

Comparison of Activity in Scapular Stabilizing Muscles during Knee Push-Up Plus and Modified Vojta’s 3-Point Support Exercises

Selective serratus anterior (SA) strengthening without compensatory movement of the shoulder stabilizers is essential for shoulder stability and functional movement without causing shoulder injury and dysfunction. The purpose of this study was to compare electromyographic (EMG) activity between the SA, upper trapezius (UT), lower trapezius (LT), and pectoralis major (PM) during the knee push-up plus (KPUP) and modified Vojta’s 3-point support (MV3PS) exercises. Scapular stabilizer muscle activity (UT, LT, SA, and PM) was investigated during the KPUP and MV3PS exercises in 40 healthy adults (19 males, 21 females) using surface EMG. Muscle activity of the SA was significantly higher during the MV3PS exercise than during the KPUP (p < 0.05). However, muscle activity in the PM was significantly lower during the MV3PS exercise (p < 0.05). In addition, the LT and UT showed less muscle activity during the MV3PS exercise, although the difference was not statistically significant (p > 0.05). These findings suggest that the MV3PS exercise better activates the SA than KPUP.

EFFICACY OF THORACIC JOINT UNILATERAL VERTEBRAL PRESSURE AS ADJUNCT TO CENTRAL VERTEBRAL PRESSURE ON MIDDLE AND LOWER TRAPEZIUS MUSCLE STRENGTH. A RANDOMIZED CONTROLLED TRIAL

INTRODUCTION: A joint must have normal mobility in order for its corresponding muscles to work efciently. Weakness of lower trapezius is common clinical nding. Manual therapy has a potential to achieve reexogenic changes in muscle and enhance the motor activity and strength. PURPOSE OF THE STUDY: To nd out the efcacy of thoracic joint unilateral vertebral pressure on middle and lower trapezius muscle strength. STUDY DESIGN: A Randomized Controlled Trial. METHOD: Hundred normal male individuals were included in the sample. The subjects were randomly assigned into two groups. Experimental (EX) group n=50 received Postero-anterior unilateral vertebral pressure along with Postero-anterior central vertebral pressure. Control (CON) group n=50 received Postero-anterior central vertebral pressure. RESULTS: The mean difference of pre and post of middle and lower trapezius mobilization pressure biofeedback unit was signicant < 0.0001 and < 0.0001 in EX and CON group respectively. The mean value and standard deviation (SD) of middle trapezius mobilization PBU value between EX and CON group was non-signicant, post treatment value was 34.54+9.57 and 34.82+9.16 respectively. The mean value and standard deviation (SD) of lower trapezius mobilization PBU value between EX and CON group was non-signicant, posttreatment value was 37.04+10.47 and 36.60+9.91 respectively. CONCLUSION: The study concluded that both postero-anterior central vertebral pressure and Postero-anterior central vertebral pressure along with postero-anterior unilateral vertebral pressure were effective in increasing strength of middle and lower trapezius. But when compared between experimental (EX) group and control (CON) group there was no difference in strength of middle and lower trapezius muscle. Adding of postero-anterior unilateral vertebral pressure did not gave additional benet in increasing muscle strength.