Shoulder Isokinetic Strength Balance Ratio in Overhead Athletes: A Cross-Sectional Study

An Assessment of the Ratio between Upper Body Push and Pull Strength in Female and Male Elite Swedish Track and Field Throwers

Data on the strength ratio between agonist and antagonist muscles are frequently examined in sports testing, given its correlation with athletic performance. The purpose of this study was to determine the agonist-to-antagonist ratio of upper body strength in female and male elite Swedish track and field throwers using a new push (bench press) and pull (supine bench row) test device, and to determine its reliability. The study involved eight female and nine male athletes, aged 19-29 years, engaging, respectively, in discus, hammer, and shot put competitions at both national and international levels. The athletes' maximum isometric force was assessed during the bench press (push) and supine bench row (pull) exercises, respectively, using a custom-built test device. The test-retest reliability of the device was also examined. The total push-to-pull strength ratio for the female throwers was 1.15, whereas male throwers demonstrated a ratio of 1.22. Total push and pull force for the female throwers was significantly less than for the male throwers (5511 N vs. 8970 N, p < 0.001). Intraclass correlation coefficients ranged from 0.93 to 0.96 for the bench press and supine bench row exercise, indicating that the push and pull test device was highly reliable. The main findings of this study were that elite female and male discus, hammer, and shot put throwers exhibited 15% and 22% more pushing (bench press) than pulling (supine bench row) strength. Push and pull strength in the female throwers ranged from 47% to 71% of that of the male throwers. The push and pull test device is a reliable tool in establishing the agonist-to-antagonist ratio of upper body strength of athletes. Coaches and athletes may benefit from examining upper body push and pull strength ratios for training planning and prescription.

Rehabilitation of the painful shoulder

Managing the painful shoulder in overhead athletes can be difficult because of a lack of time-loss injuries in overhead sports and focusing primarily on either pathoanatomic causes or movement impairments. Although managing the painful shoulder can be challenging, the combination of identifying pathoanatomic causes with movement impairments can provide a more focused rehabilitation approach directed at the causes of shoulder pain. Understanding the potential influence of scapular positioning as well as mobility and/or strength impairments on shoulder pain can help clinicians develop more directed rehabilitation programs. Furthermore, sports-specific methods such as long toss or the use of weighted balls for achieving physiological or performance-based gains have limited empirical evidence regarding their clinical and performance-based benefits, which may impede the rehabilitation process. Applying a comprehensive evaluation approach prior to and throughout the treatment process can assist clinicians with selecting the most appropriate treatment based on patient need. Reconsidering traditional treatments based on existing evidence may help refine the treatment process for overhead athletes with shoulder pain.

Benefits and limitations of isokinetic force assessments in swimmer's shoulders: A systematic review

OBJECTIVE

To indicate the benefits and limitations of the isokinetic test results for the performance of the main shoulder joint movements in swimmers, considering the different competitive levels, swimming techniques, race distances, and sex.

METHODS

Search on the PubMed, CENTRAL, Medline, LILACS, and SCOPUS databases for the oldest records up to October 2022. Risk of bias, methodological quality, and level of evidence were evaluated based on the NHLBI checklist.

RESULTS

29 articles met the criteria and were included in this study. The quality analysis classified three as "good" and 26 as "regular", with a KAPPA index of 0.87. The main benefits found involved assessments of the clinical condition of the shoulder joint complex, relationships with performance, and reliability studies. The limitations found point to the participant's positioning in the instrument, use of angular velocity above 180°/s, and sample size.

CONCLUSION

The use of the isokinetic dynamometer allows verifying the levels of strength, endurance, balance, and asymmetries among swimmers of different techniques, distances, competitive levels, and sex. Thus, it helps in the analysis and monitoring of the clinical conditions of swimmers' shoulder joints, contributing to the decision-making process of physiotherapists and coaches.

Musculoskeletal, Functional and Performance Impairment in Female Overhead Athletes with a Previous Shoulder Injury

BACKGROUND

Shoulder injuries are substantial problems in overhead athletes, and more studies are necessary to deepen the knowledge on this type of injury. The objective of this study was to compare the overall function and performance of female overhead athletes with and without a previous history of shoulder injuries.

METHODS

In this cross-sectional study, female overhead athletes with and without a previous shoulder injury were included. Muscular impairment, the stability of the shoulder, strength, scapular dyskinesia, functionality and sports performance were evaluated. A total of 50 females were included.

RESULTS

There were significant differences in strength (p = 0.046) and stability (p = 0.039) between groups, with a poorer score in the group with a history of shoulder injury. Regarding scapular dyskinesia, significant differences were also observed between groups (p = 0.048), with higher levels of dyskinesia in the group with previous shoulder injury. Also, muscular impairment showed significant differences between groups for the three muscles evaluated (p < 0.005). Additionally, the group without a previous shoulder injury presented with a significantly greater score in functionality (p = 0.046) and sports performance (p = 0.004).

CONCLUSION

In conclusion, previous shoulder injuries are an important factor to take into account in female overhead athletes. Players with a history of shoulder injury present clinical impairments during the game, leading to poorer functional status and performance in sport.

Reliability and validity of new isokinetic strength assessment for rotator cuff muscles in a muscle architecture-based position

Background/aim

Isokinetic strength assessment of the rotator cuff muscle is frequently applied in a variety of shoulder postures, but none of these consider muscular architecture, which is one of the most important aspects of improving strength development. This study aimed to examine the test and retest reliability and validity of the muscle architecture-based position (MABP), which is 25° abduction and 20° external rotation, in healthy subjects to be able to select a better isokinetic assessment position for shoulder rotator cuff muscles.

Materials and methods

A total of 54 healthy males with a mean age of 21.0 ± 1.2 years and mean body mass index of 22.8 ± 1.7 kg/m2 completed an isokinetic measurement session. All of the tests were performed on an IsoMed 2000 isokinetic dynamometer concentrically and eccentrically for both upper limbs at 60°/s angular velocity. All of the participants completed 3 measurement sessions: the first represented the isokinetic testing and was performed in the scapular neutral position (SNP) (45° shoulder flexion and abduction), the second represented the MABP (25° abduction and 20° ER) for shoulder rotator cuff muscles, and the third represented the test and retest of the MABP.

Results

The correlations between the 2 techniques for assessing concurrent validity ranged from 0.908 to 0.994. The values obtained from the MABP were higher than those obtained in the SNP. There was no systematic bias for any measurements between the MABP and the retest of the MABP (p > 0.05). The intraclass correlation coefficients representing the test and retest reliability results for each variable measured with the MABP was higher than 0.98 and this value was considered as excellent reliability.

Conclusion

In conclusion, the MABP can be used to assess the isokinetic strength of the rotator cuff muscles safely and confidently, with increased quantities of force being released and measurement at optimal muscle tension.

Criterion-Based Rehabilitation and Return to Play in Fast Bowlers Following Arthroscopic Bankart Repair: Recommendations Based on a Detailed Clinical Review

Background

Anterior shoulder instability due to labral tears in the dominant arm of cricket fast bowlers can be particularly disabling and results in significant match time loss. This often follows injuries sustained during fielding and training, although micro-instability following repetitive throwing progressing to overt anterior shoulder instability is also known. To ensure ball release speeds of over 140 km/h with different ball variations, these athletes require not only physical fitness and technical skill, but also a completely stable shoulder.

Methods

A literature search of "MEDLINE", "SPORT DISCUSS", and "GOOGLE SCHOLAR" was done to identify relevant articles published till the year 2023.

Results

A treatment approach that involves anatomic restoration of the shoulder via an arthroscopic Bankart capsulo-labral repair, followed by functional and biomechanical restoration via rehabilitation is the most predictable method to ensure a successful return to pre-injury fast-bowling status. A post-operative rehabilitation program that ensures a quick return to fast bowling without disrupting the surgical repair is crucial. Timely integration of exercises to recruit and strengthen the kinetic chain used for bowling and throwing plays a key role in this faster recovery. This current review provides a phase-wise, evidence-based rehabilitation guideline for return to competitive cricket after arthroscopic Bankart repair in a fast bowler. This review also highlights a structured return to bowling, throwing, and fielding program with a clinical decision-making process.

Conclusion

Exercise selection at an early stage that does not compromise the healing tissue, and timely integration of workouts to recruit and strengthen the kinetic chain used for bowling and throwing is the key strategy to allow faster recovery.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-023-00931-5.

Shoulder muscle imbalance as a risk factor for shoulder injury in elite badminton players: A prospective study

OBJECTIVES

To assess the impact of preseason shoulder testing on the risk of significant shoulder injury (SSI) in elite badminton players.

DESIGN

Prospective cohort study.

SETTING

Secondary care, academic medical center.

PARTICIPANTS

Nineteen elite badminton players (19.37 ± 4.79 years, n = 13 males).

MAIN OUTCOME MEASURES

At preseason, they had shoulder examination tests including the table-to-acromion distance and the glenohumeral rotation range of motion. The glenohumeral internal rotation deficit (GIRD) was calculated. Isokinetic internal and external rotator shoulder muscle strength was tested at 60°/s (concentric and eccentric modes) and 240°/s (concentric mode). Bilateral strength ratio (non-dominant:dominant) and unilateral agonist:antagonist conventional and functional ratios (FR: eccentric-to-concentric) were calculated.

RESULTS

During the follow-up time of 38 weeks, SSIs were assessed by an experienced sport physician and 42% of the participants sustained at least one SSI at their dominant side. The preseason GIRD and FR at 240°/s (FR₂₄₀) were independently associated with SSIs (G² = 6.28, p = .012 and G² = 6.23, p = .013, respectively). FR₂₄₀ < 0.69 (odds ratio = 28.0) and GIRD> 14° (odds ratio = 36.14) were predictors for SSIs.

CONCLUSIONS

Lower functional deceleration ratio and greater GIRD are associated with a higher risk of SSI at the dominant side in elite badminton players.

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.

Shoulder Rotational Strength and Range of Motion in Unilateral and Bilateral Overhead Elite Athletes

CONTEXT

Overhead athletes place tremendous demands on the shoulder complex, which result in adaptive kinematics but potential susceptibility to injury. This study aimed to compare shoulder glenohumeral range of motion (ROM) and rotator muscles strength in bilateral and unilateral overhead sports.

DESIGN

Cross-sectional study; secondary care.

METHODS

Forty-two elite athletes (17.7 [4.5] y; 42.9% female), including 18 swimmers and 24 badminton players, were included. Preseason glenohumeral rotation ROM and isokinetic shoulder internal and external rotator muscles strength was tested (60°·s-1). Bilateral (nondominant:dominant) and agonist:antagonist (external rotator:internal rotator) conventional and functional deceleration ratios (eccentric to concentric) were calculated. The impact of sport and number of competitive years on shoulder ROM and strength was tested.

RESULTS

Badminton players had greater glenohumeral internal rotation deficit, total ROM deficit, and lower bilateral strength ratio than swimmers (P < .050). Rotational strength was positively associated with the competitive years, but greater in swimmers (P < .050) and on the internal rotator (P < .001). The functional deceleration ratio was negatively associated with the competitive years on the dominant side in swimmers and for both sides in badminton.

CONCLUSIONS

Unilateral overhead athletes had greater ROM and rotational strength asymmetries than bilateral athletes. Interestingly, the functional deceleration ratio was lower over time on the dominant shoulder for both sports, but, surprisingly, also on the nondominant shoulder in badminton, potentially creating a greater risk for shoulder injuries.

Reliability and Validity of the Athletic Shoulder (ASH) Test Performed Using Portable Isometric-Based Strength Training Device

Simple Summary

The Athletic Shoulder (ASH) test was developed to quantify force across the shoulder girdle in athletes for diagnosis and monitoring. Initially, this test was performed using force plates. The question remains whether force plates may be replaced with a more feasible tool for field testing, such as an isometric-based strength training device. Hence, the present study determined whether Active5™ may be an alternative to force plates for ASH test purposes. Consequently, the ASH test was performed on different days by the same rater and different raters using Active5™ and K-Force plates. It was also checked whether the test results obtained using various tools correlated with each other. The study indicated that both devices were reliable tools, and the ASH test results obtained with the use of the two devices were largely correlated with each other.

Abstract

The Athletic Shoulder (ASH) test was introduced as a tool for quantifying the ability to produce and transfer force across the shoulder girdle. Whether using the portable isometric-based strength training device Active5™ is a reliable alternative to a gold standard force plate for ASH testing purposes remains unknown; therefore, the present study determined the reliability and validity of Active5™ usage in the ASH test compared to force plates. Fifty-one healthy participants performed the ASH test using Active5™ and K-Force plates in three separate sessions. The maximal force was measured bilaterally in a prone position at three shoulder abduction angles, precisely at 180°, 135°, and 90°. The first rater carried out the first and third sessions, spaced at a one-week interval. A second rater performed the second session. The reliability was assessed using the intraclass correlation coefficient (ICC). The linear Pearson’s correlation coefficient (r) calculation was used to determine the relationship between ASH test results using the two devices. The ICC = 0.77–0.99 result indicated good to excellent reliability for Active5™ usage. A high to a very high correlation between the two devices at 180° and 90° was noted (r = 0.75–0.95). This data supports the isometric-based strength training device Active5™ as a reliable and valid tool for ASH test performance.

The Concept of Acceleration and Deceleration in Isokinetics and Its Relation to 3 Hop Tests

CONTEXT

Both isokinetic testing and functional tests are often used during patient rehabilitation programs. Most researchers have assessed the relationship of isokinetic testing and functional tests in parameters such as peak moment, work, or power. However, little information exists regarding the acceleration and deceleration parameters and their relationship to function.

DESIGN

The purpose of the study was to investigate the concept of acceleration and deceleration of the knee flexor and extensor muscle groups during isokinetic testing and its relationship to function.

METHODS

Twenty-six healthy individuals (14 men and 12 women) participated in the study. Isokinetic bilateral concentric knee flexion and extension muscular performance was assessed isokinetically at the angular velocities of 60°/s, 180°/s, and 300°/s. Functional performance was also assessed using (1) single hop for distance, (2) triple hop for distance, and (3) single timed hop. Functional data were normalized to body weight. A P value <.05 was considered to be significant.

RESULTS

Fair and moderate to good correlations (r = .396, P = .045 to r = .705, P = .001) were discovered between flexors' and extensors' acceleration/deceleration variables and the normalized to body weight functional tests.

CONCLUSIONS

Appropriate understanding of isokinetic parameters as described in this study, including acceleration/deceleration values, may provide useful information about the functional ability of the lower limb muscular system.