Isokinetic Dynamometry as a Tool to Predict Shoulder Injury in an Overhead Athlete Population: A Systematic Review

Isokinetic Shoulder Strength and its Associations to Injury in Tactical Populations: A Critical Review

The aim of this review is to evaluate existing isokinetic testing protocols for the shoulder in tactical occupations, document their shoulder strength profiles, and determine any associations to shoulder injury. Four electronic databases were searched (Medline/Pubmed, Ovid/Emcare, CINAHL/Ebsco and Embase) using the keywords police OR law enforcement, firefighter, military, AND isokinetic. Articles were eligible if they had at least one cohort of a tactical population and included isokinetic testing of the glenohumeral joint. The search yielded 275 articles. After screening for duplicates and inclusion criteria, 19 articles remained for review, six of which assessed injury correlation. 17 articles evaluated military personnel and two examined firefighters. Articles were categorized by study design, population, isokinetic protocols, strength outcome measures and statistical measures. Concentric internal rotation (IR) and external rotation (ER) strength at 60 degrees/second were reported most frequently (84% of cases). There was a paucity of testing speeds, repetition ranges and contraction types evaluated when compared to existing literature in other populations with high shoulder injury occurrence such as overhead and collision athletes. Outside of military cohorts, there is limited data available to characterise the isokinetic strength profile of the shoulder in tactical occupations. Meta-analysis for injury association was unable to be performed due to independent variable and statistical heterogeneity. However, a best evidence synthesis suggested conflicting evidence to support the association of injury with isokinetic strength testing in tactical populations. Future studies should prioritise prospective designs utilising variable speeds, repetition schemes and contraction types to better capture the dynamic occupational demands in tactical groups.

Assessment of proprioception, muscle strength and endurance during dynamic isokinetic test in patients with breast cancer-related lymphedema

BACKGROUND

Breast cancer-related lymphedema is a common complication after breast cancer treatment.This study examined isokinetic proprioception, muscular strength, and endurance by comparing extremity with lymphedema and the extremity without lymphedema in women with breast cancer-related lymphedema.

METHODS

A total of 15 individuals aged between 35 and 70 years participated in this study. Cybex Humac NORM Isokinetic dynamometer (CSMi, Stoughton, MA) were used to assess upper extremity passive proprioception, active proprioception, kinesthesia, muscle strength, and muscle endurance. The upper extremity lymphedema was measured with the water displacement arm volumetry test using a volumeter.

FINDINGS

All isokinetic measurements demonstrated a statistically significant difference between the extremity with lymphedema and the extremity without lymphedema, suggesting lower scores in the extremity with lymphedema (p < .05). There was a positive correlation between passive internal rotation in the extremity with lymphedema and the time after mastectomy (r= 0.628, p = .012) and a moderate positive relationship was found between the time after lymphedema and passive internal rotation (r = 0.577; p = .024), and active external rotation position sense (r = 0.540; p = .038) in the extremity with lymphedema. Also, a unidirectional positive moderate (r = 0.594; p = .020) relationship was found between the lymphedema stage and passive external rotation in the extremity with lymphedema.

INTERPRETATION

The difference in proprioception, muscle strength, and endurance between the extremity with lymphedema and the extremity without lymphedema in women with breast cancer-related lymphedema will provide valuable information in terms of prioritizing these parameters in treatment.

Inter-limb kinetic asymmetries during sit-to-stand performance persist following unilateral total knee arthroplasty: A systematic review and meta-analysis

BACKGROUND

Kinetic asymmetries during sit-to-stand have been consistently observed early after total knee arthroplasty; however, the longer-term outcomes are less clear. The purpose of this systematic review and meta-analysis was to analyze the results of studies examining inter-limb kinetic symmetry during sit-to-stand performance among individuals who were at least one-year post unilateral total knee arthroplasty.

METHODS

PubMed, SPORTDiscus, CINAHL, and Health Source databases were searched. Studies were included if they were published in a peer-reviewed journal, included subjects who had undergone unilateral total knee arthroplasty at least one-year prior, and examined vertical ground reaction forces and/or knee extension moments for the involved and uninvolved limbs during sit-to-stand performance. Data were transformed into a limb symmetry index, which expressed the ratio of the peak forces/moments for the involved limb, relative to the uninvolved limb (1.0 reflects perfect symmetry). These ratios were meta-analyzed using the ratio of means method.

FINDINGS

Seven studies were deemed eligible for inclusion. Ground reaction force data was pooled from seven studies and knee extension moment data was pooled from two studies. For the peak vertical ground reaction forces, the pooled limb symmetry index was 0.96 (CI95% = [0.93, 0.99]). For the peak knee extension moments, the pooled limb symmetry index was 0.91 (CI95% = [0.84, 0.98]). In both cases this reflects greater limb/knee loading for the uninvolved limb, relative to the involved limb.

INTERPRETATION

Asymmetries in limb/knee loading persist beyond the one-year post-operative period following total knee arthroplasty, potentially contributing to degenerative changes for the uninvolved limb.

Injury, Training, Biomechanical, and Physiological Profiles of Professional Breakdancers

Background

Breakdancing or breaking will enter the Olympics in 2024, however, there is a paucity of literature exploring the epidemiology, demands, and performance.

Purpose

The purpose of this study was to describe injury and training profiles, along with the results of a short performance test battery, in a group of elite breakers.

Study Design

Cross-sectional study (retrospective).

Methods

Fourteen breakdancers (breakers) (4 Bgirls, 10 Bboys) participated in an interview regarding their injury and training history, endurance test (cycle VO2max testing), counter movement jump, squat jump, drop jump, isometric hip abduction, adduction, shoulder external and internal rotation strength testing on a fixed-frame dynamometer. Breakers were divided into elite (n=10) and developing (n=4) based on their qualification for a world finals competition; Wilcoxen rank sums were used to compare the two groups, or in the case of strength testing between those with and without an injury history.

Results

The breakers had a median 11.0 [10.0 - 14.0] years breaking experience and trained 24.4 [20.5 - 30.0] hours per week. The knee was the most commonly injured body part and most frequently injured joint, with the thigh being the most common site for muscle injuries. There were no differences in endurance testing or jump height testing results between elite and developing breakers. There was no difference in shoulder external or internal rotation strength between athletes with a history of shoulder injury and those without. Similarly, there was no difference in hip abduction or adduction strength in those with a history of hip injury and those without.

Conclusion

The results of this study should be viewed with caution due to the small sample size. However, this study is the first to publish functional and physiological descriptives on breakers. The authors hope these results support clinicians treating breakers as well as encourages future research related to breaking.

Level of Evidence

2b.

Effects of an 11-Week Detraining, Imposed by the COVID-19 Confinement, on Handball Players' Shoulder Rotator Isokinetic Profile, Shoulder Range of Motion, and Ball Release Velocity

Background and Objectives: The COVID-19 confinement significantly impacted the physical condition of athletes. However, the detraining impacts of this period on the shoulder rotator and range of motion in handball players have not been studied. Thus, the main aim of this study was to investigate the effect of this 11-week detraining period, imposed by the COVID-19 pandemic confinement, on the shoulder rotator isokinetic profile (peak torque, ratio, fatigue index), shoulder rotator and flexion range of motion, and ball release velocity in handball players. Materials and Methods: A total of 16 handball players, with a mean age of 22.38 (5.28) years, participated in this study. The isokinetic strength was assessed using two protocols (three repetitions at an angular velocity of 60°/s and 20 repetitions at an angular velocity of 180°/s). In addition, the range of motion and ball release (at jump and standing shots) were measured. All these measurements were assessed before and after the COVID-19 confinement. Results: The results showed a significant reduction in the peak torque of the external rotation of their dominant and non-dominant shoulders. In addition, confinement significantly increased the fatigue index of external rotation and internal rotation and reduced the range of motion of internal rotation. Additionally, the ball release velocity during standing and jump shots was significantly reduced. Conclusions: These results suggested that strengthening external and internal rotation as well as recovering the internal rotation range of motion may be necessary after a detraining period in order to prevent shoulder injuries.

The dynamic control ratio and its equilibrium point: A preliminary study of isokinetic fatiguing internal-external rotational effort of the shoulder joint in healthy subjects

The shoulder joint-related dynamic control ratio (DCR) is derived by dividing the peak eccentric moment of the external rotators (ER) by the peak concentric moment of the internal rotators (IR). However, given the inherent limitation associated with a single value DCR, an alternative approach is to calculate it at fixed angular intervals. This preliminary study aimed at exploring the variation in the DCR at a resolution of 1° and under fatiguing external and internal rotation exertions. Eighteen young men, 10 experienced and 8 without experience in overhead sporting activities completed two separate series of 45 ER eccentric and 45 IR concentric isokinetic repetitions at 120°/s. The analysis focused on repetitions 1-3 (TR1), 21-23 (TR2) and 41-43 (TR3). The relative fatigue values for both muscle groups and for both E and NE participants were 25-40% with significantly higher fatigue resistance in eccentric compared with concentric exertions. The DCR traces varied substantially linearly for most of the internal rotation range of motion while significant differences (p < 0.001) were found in their values within group between TR1, TR2 and TR3 and between experienced and non-experienced participants. An antagonistic moment equilibrium (DCR = 1) was reached in all instances and for both groups only during TR3 with a significant progressive reduction in this moment as fatigue increased. Thus, considering the DCR as an angle-based variable rather than a single value isokinetic parameter, may add new insight regarding the interplay between the rotatory muscles of the shoulder joint.

Assessment of return to play after an acute shoulder injury: protocol for an explorative prospective observational German multicentre study

INTRODUCTION

To date, there is no valid single test or battery of tests for informing return-to-play (RTP) decisions following an acute shoulder injury. The purpose of this exploratory study is to evaluate a diagnostic test battery based on a Delphi consensus at the time of unrestricted return to team training after acute shoulder injury.

METHODS AND ANALYSIS

Data for this prospective multicentre cohort study are collected at two measurement time points: when the respective physician clears the patient for RTP (t1) and 12 months after RTP (t2). The study participants are 18-35 years old athletes participating at a professional level in the following team sports: handball, basketball, ice hockey, soccer, volleyball and American football. Maximum comparability will be ensured via uninjured matched pair teammates. To assess the subjective assessment of shoulder functioning and the athlete's readiness to RTP, patient-reported outcome measures (Western Ontario Shoulder Instability Index, Quick-Disabilities of the Arm, Shoulder and Hand, Psychological Readiness of Injured Athlete to Return to Sport and Shoulder Instability-Return to Sport after Injury) will be completed. After a medical check-up with a range of motion and anthropometric measurements as well as clinical tests, the participants will perform a structured warm-up protocol. The functional tests comprise handgrip strength, upper quarter Y-balance test, isometric strength, closed kinetic chain upper extremity stability test, wall hop test, functional throwing performance index and the unilateral seated shot put test and isokinetic tests.

ETHICS AND DISSEMINATION

The results of this study will be disseminated through peer-reviewed publications and scientific presentations at national and international conferences. Ethical approval was obtained through the Institutional Review Board of Martin-Luther-University Halle-Wittenberg (reference number: 2022-016).

TRIAL REGISTRATION NUMBER

DRKS00028265.

Preseason Prognostic Factors for Injuries and Match Loss in Collision Sports: A Systematic Review

This study aimed to identify which preseason factors had strong evidence of risks for physical injury during the season of collision sports including rugby, American football, and Australian rules football using qualitative synthesis. Pubmed, EMBASE, MEDLINE, SPORTDiscus, Scopus, and the Cochrane Library were reviewed. Eligibility criteria for selecting studies were: studies involving the collision sports; prospective cohort studies; and studies with outcomes of relative risks, odds ratios, and correlations between players' preseason conditions and injury during the season. The risk of bias based on the Scottish Intercollegiate Guidelines Network quality checklists for cohort studies was assessed in 57 studies. The current study identified strong evidence that 1) anthropometric characteristics (body mass index and estimated mass moment of inertia of the body around a horizontal axis through the ankle), which are calculated with weight and height; 2) physical function, in particular for the trunk and lower limb (trunk-flexion hold and wall-sit hold); and 3) Oswestry Disability Index disability, which is a patient-reported outcome measure for disability due to low back pain, were positive prognostic factors for injury during the collision sports season, regardless of playing experience.

The Relationship between Scapular Upward Rotation and Shoulder Internal and External Rotation Isokinetic Strength in Professional Baseball Pitchers

This study aims to assess the relationship between scapular upward rotation (SUR) across varying humeral-elevation angles (HEAs) and shoulder isokinetic strength and ratio in professional baseball pitchers. The subjects were professional baseball pitchers (n = 16) without a history of shoulder injury in the last six months. The subject’s SUR angles were measured with the humerus elevated at HEAs of 0° (at rest), 60°, 90°, and 120° to the scapular plane. Shoulder isokinetic strength was evaluated for shoulder internal rotation (IR) and external rotation (ER) strength (PT%BW and TW%BW), and the ER/IR strength ratios were determined at 60, 120 and 180°/s using an isokinetic dynamometer. The SUR angle at an HEA of 0° was positively correlated with IR strength at 120°/s (r = 0.535) and 180°/s (r = 0.522). The SUR angle at an HEA of 60° was negatively correlated with the ER/IR strength ratios at 60°/s (r = −0.505) and 120°/s (r = −0.500). The SUR angle at an HEA of 90° was negatively correlated with the ER/IR strength ratios at 60°/s (r = −0.574; r = −0.554) and 120°/s (r = −0.521; r = −0.589) as well as with ER strength at 180°/s (r = −0.591, r = −0.556). The SUR angle at an HEA of 120° was negatively correlated with ER strength at 60°/s (r = −0.558), 120°/s (r = −0.504; r = −0.524), and 180°/s (r = −0.543) and the ER/IR strength ratio at 60°/s (r = −0.517). In this study, we found that the ratio of isokinetic strength between ER and IR became closer to the normal range on increasing the SUR angle. In particular, an HEA of 90°, which resembles the pitching motion, showed a clear relationship between SUR, shoulder ER, and the ratio of ER/IR isokinetic strength in professional baseball pitchers.