Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass

Favorable Clinical Outcomes After Humeral Head Depressor Muscle Coactivation Training With EMG for Patients With Arthroscopic Rotator Cuff Repair: A Randomized Controlled Trial

BACKGROUND

The coactivation (Co-A) of shoulder muscles that contribute to humeral head depression can lead to mechanical unloading of the subacromial structures during abduction and thus can be beneficial for patients with arthroscopic rotator cuff repair (ARCR). The present study aims to examine the effectiveness of humeral head depressor muscle Co-A (DM-Co-A) training on clinical outcomes in a sample of patients with ARCR.

HYPOTHESIS

We hypothesized that DM-Co-A training with medioinferior vector during glenohumeral exercises can improve clinical results in the rehabilitation of ARCR.

STUDY DESIGN

Randomized controlled single-blind study.

LEVEL OF EVIDENCE

Level 1B.

METHODS

A total of 27 patients who underwent ARCR after a medium-sized rotator cuff tear and completed their Phase 1 training with ≥80% compliance were included. Together with 14 weeks of conservative treatment (6 weeks of Phase 2 training and 8 weeks of Phase 3 training), synchronized "DM-Co-A Training" was applied to the treatment group with an electromyography (EMG) biofeedback (EMG-BF) device. Patients in the treatment group were asked to voluntarily activate the humeral head depressor muscles guided by visual and auditory feedback of the EMG-BF device during the Phase 2 and Phase 3 conservative treatment exercises performed by the control group. Demographic characteristics of the participants were recorded. Visual analog scale and universal goniometer were used to assess pre- and posttreatment pain severity and joint range of motion, respectively. The Disabilities of Arm, Shoulder and Hand Questionnaire, Revised Oxford Shoulder Score, Modified Constant-Murley Shoulder Score, and the Western-Ontario Rotator Cuff Index were used to assess functionality.

RESULTS

There was a clinically meaningful improvement in pain severity, active ROM excluding internal rotation, and functionality in the treatment group compared with the control group (P < 0.05).

CONCLUSION

A 14-week duration DM-Co-A with EMG may be beneficial in the postoperative rehabilitation of patients after ARCR.

Quadriceps and gluteus medius activity during stable and unstable loading exercises in athletes. A cross-sectional study

The aim of this study was to evaluate the muscle activation of the vastus medialis, vastus lateralis, and gluteus medius during different strength and stability exercises with a water tank compared with a sandbag. A cross-sectional study was conducted in the Functional Anatomy Laboratory, and the sample consisted of 28 athletes. The main outcome measures were surface electromyography (dependent variable), water tank and sandbag, and exercise type (independent variables): Isometric Single Leg Stance (ISLS), One Leg Deadlift (OLDL), Front Rack Forward Lunge (FRFL), and Lateral Lunge (LL). Repeated measures analysis of variance (ANOVA) revealed a significant Group × Time interaction in gluteus medius root mean square (RMS) (F = 14.198, p < 0.001, ŋ2 = 0.35), vastus lateralis RMS (F = 24.374, p < 0.001, ŋ2 = 0.47), and vastus medialis RMS (F = 27.261, p < 0.001, ŋ2 = 0.50). In the between-group analysis, statistically significant differences were observed in gluteus medius RMS in the ISLS: 28.5 ± 15.8 water tank and 20.8 ± 12.6 sandbag (p < 0.001, ŋ2 = 0.08) and OLDL: 29.7 ± 13.3 water tank and 26.5 ± 13.1 sandbag (p < 0.001, ŋ2 = 0.01). In vastus lateralis in ISLS: 30.4 ± 37.6 water tank and 19.0 ± 26.7 sandbag (p < 0.001, ŋ2 = 0.03). In vastus medialis in ISLS: 14.2 ± 13.0 water tank and 7.0 ± 5.6 sandbag (p < 0.001, ŋ2 = 0.12), OLDL: 21.5 ± 16.9 water tank and 15.5 ± 10.7 sandbag (p = 0.002, ŋ2 = 0.04), and LL: 51.8 ± 29.6 water tank and 54.3 ± 29.3 sandbag (p = 0.017, ŋ2 = 0.00). These results confirm significantly greater activation of the gluteus medius and vastus medialis in the ISLS and OLDL exercises, and of the vastus lateralis in the water tank ISLS exercise. However, the vastus medialis shows greater activation in the LL exercise.

Peroneal muscle activity during stable and unstable load exercises. A cross-sectional study

OBJECTIVE

To evaluate the muscle activity of the peroneus longus during the execution of different unstable load exercises compared to stable load exercises.

DESIGN

Cross-sectional study.

SETTING

Functional Anatomy Laboratory.

PARTICIPANTS

28 healthy athletes.

MAIN OUTCOME MEASURES

Surface electromyography (sEMG), unstable load (water tank), Stable Load (Sandbag), type of exercise (Isometric single leg stance, single-leg Romanian deadlift, front rack forward lunge and lateral lunge).

RESULTS

The repeated measures ANOVA revealed significant Group ∗ Time interaction in Root Mean Square (RMS) (F = 51.307, P < 0.001, ŋ² = 0.70). In the between-group analysis there were statistically significant differences in RMS isometric single leg stance in favor to unstable load (P < 0.001, ŋ² = 0.07). In the within-group analysis of RMS statistically significant differences were found in the stable load group between isometric single leg stance and single-leg Romanian deadlift (P < 0.001, ŋ² = 0.05).

CONCLUSIONS

Single leg stance exercise with unstable load showed higher peroneus muscle activity than stable load. However, no peroneus muscle activity differences were found between unstable and stable loads for single-leg Romanian deadlift, frontal rack forward lunge and lateral lunge. Single-leg Romanian deadlift with stable load showed higher peroneus muscle activity than isometric single leg stance with stable load.

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.