Changes in clinical measures and tissue adaptations in collegiate swimmers across a competitive season

Identifying evidence-practice gaps for shoulder injury risk factors in competitive swimmers: uniting literature and expert opinion

OBJECTIVES

To identify evidence-practice gaps regarding shoulder injury risk factors in competitive swimmers.

METHODS

We gathered insights from 27 swimming experts including elite swimmers, coaches, high-performance staff and applied researchers using Concept Mapping. Participants brainstormed, sorted and rated (from 1 (least) to 10 (most) important and modifiable) their ideas of shoulder injury risk factors in competitive swimmers. Proposed risk factors rated above the grand mean for importance (6.2±0.4) or modifiability (6.5±0.5) ratings were considered highly important/modifiable. Expert opinions were then juxtaposed with systematic review findings to identify overlaps or convergences.

RESULTS

Brainstorming generated 126 proposed shoulder injury risk factors for competitive swimmers, subsequently refined to 61 unique proposed risk factors by removing duplicates and combining similar responses. The participants sorted the 61 risk factors into seven distinct clusters. Experts perceived 36/61 proposed risk factors as highly important, of which 6 were supported by literature, 6 showed no association with injury, 2 had conflicting evidence and the remaining 22 have not yet been investigated, suggesting an evidence-practice gap. Three proposed risk factors 'inconsistent training load', 'poor stroke technique' and 'low posterior shoulder strength-endurance' exhibited high perceived importance, high perceived modifiability and supporting evidence.

CONCLUSION

An evidence-practice gap was identified for 28 proposed risk factors perceived as highly important by swimming experts despite either (1) no relevant empirical research (n=22), or (2) no association with injury (n=6) from synthesised evidence. Greater collaboration between researchers and practitioners is needed to effectively address shoulder injury risk factors in competitive swimmers.

Chronic Adaptation of the Coracohumeral Space and Subscapularis Tendon in Professional Baseball Pitchers

BACKGROUND

Pitchers frequently experience anterior shoulder pain, possibly associated with coracohumeral impingement; however, whether the coracohumeral distance (CHD) and/or subscapularis tendon adapt chronically (bilateral difference) due to pitching, and whether clinical measures are associated with CHD and subscapularis tendon organization have not been evaluated in professional pitchers.

HYPOTHESIS

The authors hypothesized that dominant arm CHD would be smaller than the nondominant arm, dominant subscapularis tendon would have increased spatial frequency (ie, be more disorganized), and humeral retroversion (HR) would predict CHD and subscapularis tendon organization.

LEVEL OF EVIDENCE

Level 4.

METHODS

Healthy professional baseball pitchers were recruited during their preseason physical examination. Bilateral diagnostic ultrasound measured CHD, HR, and posterior capsule thickness (PCT), and quantified subscapularis tendon organization. External rotation, neutral, and crossbody CHD was measured.

RESULTS

Overall, 52 healthy professional baseball pitchers participated. The dominant arm of pitchers demonstrated a significantly narrower CHD in all 3 positions (P < 0.01), increased scapular protraction (163 vs 156 mm; P < 0.01), and increased spatial frequency of the subscapularis tendon (1.8 vs 1.6 peaks/mm; P < 0.01). HR was associated with CHD in 30° of external rotation (R2 = 0.12; P < 0.01), neutral rotation (R2 = 0.11; P < 0.01), and the crossbody position (R2 = 0.28; P < 0.01). PCT was associated with CHD in 30° of external rotation (R2 = 0.16; P = 0.05). HR and CHD in 30° of external rotation was associated most strongly with subscapularis tendon organization (R2 = 0.11; P = 0.03).

CONCLUSION

The dominant shoulder of professional pitchers presents with a smaller CHD, more scapular protraction, and more subscapularis tendon disorganization than the nondominant shoulder.

CLINICAL RELEVANCE

Professional pitchers demonstrate chronic CHD and subscapularis tendon adaptations, which may increase their risk for anterior shoulder pain and subscapularis tendon injury.

Glenohumeral Internal Rotation Deficit in Young Asymptomatic Elite Swimmers

CONTEXT

Glenohumeral internal rotation deficit (GIRD) may affect overhead athletes and contribute to shoulder injury.

OBJECTIVES

To assess data on passive shoulder range of motion (ROM) in young elite swimmers and to determine the prevalence of anatomical and pure GIRD (aGIRD and pGIRD, respectively) in a large sample size of asymptomatic elite swimmers with a new classification method.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 752 asymptomatic elite swimmers were recruited by voluntary participation (391 males and 361 females; mean age, 15.88 ± 2.31 years). Passive glenohumeral rotational ROM was measured bilaterally to investigate the prevalence of aGIRD and pGIRD. Evaluations were performed with athletes at rest before any training or competition.

MAIN OUTCOME MEASURE(S)

Glenohumeral internal rotation deficit and associated aGIRD and pGIRD in elite youth swimmers by identifying a standard classification procedure.

RESULTS

Glenohumeral internal rotation deficits were found in 136 participants (18.1%). Anatomical GIRD was present in 28 cases (3.7%), whereas pGIRD was observed in 108 cases (14.4%). No significant differences were found regarding GIRD between sex, age, age group, years of training, breathing side, and distance. Swimmers with pGIRD showed significantly less dominant internal rotation, total ROM, and external rotation gain (P < .01) than swimmers with aGIRD; conversely, swimmers with aGIRD showed significantly less nondominant internal rotation, external rotation, and total ROM than swimmers with pGIRD (P < .01).

CONCLUSION

Glenohumeral internal rotation deficit is a relatively common condition in asymptomatic elite youth swimmers; as to not overestimate this condition, aGIRD and pGIRD have to be distinguished. Although they play a role, the respiratory side, dominant limb, and crawl did not have a significant impact on an elite swimmer with GIRD.

Sink or Swim? Clinical Objective Tests and Measures Associated with Shoulder Pain in Swimmers of Varied Age Levels of Competition: A Systematic Review

BACKGROUND

Swimming is enjoyed by athletes of all ages, and shoulder pain is a common problem. Clinicians identify impairments which impact shoulder pain and these impairments may differ depending on the swimmer's age competition level.

PURPOSE

The purpose of this study was to investigate objective measures utilized to assess swimmers and assess the relationship of test values to shoulder pain in distinct age groups/competition levels. A secondary aim was to report normative/expected values for these tests.

DESIGN

Systematic review.

METHODS

PRISMA methodology was employed to assess studies evaluating clinical tests and measures associated with shoulder pain for swimmers in varied age competition levels. The Methodological Index for Non-Randomized Studies instrument was used to evaluate the quality of the included studies, and a qualitative synthesis of findings was conducted to determine the strength of the evidence in four age competition levels for nine objective measures. Distinct cut points for proposed measures were identified.

RESULTS

Twenty-seven studies were included in the analysis and the majority were of moderate quality in adolescent/adult swimmers. Youth swimmers had limited evidence for the development of shoulder pain associated with scapular position/dyskinesia, weakness of periscapular muscles, low endurance of core muscles, and moderate evidence for shoulder pain associated with laxity and altered range of motion (ROM). Adolescent/adult swimmers demonstrated limited evidence for a positive association between developing shoulder pain if there is a low eccentric ER:concentric IR ratio, and moderate evidence for pectoralis minor tightness and glenohumeral laxity. There were limited studies regarding masters swimmers to derive conclusive evidence. Cut points were identified from the included studies but these have not been validated in other studies.

CONCLUSION

Swimmers of various ages may have different objective clinical tests and measures associated with the risk for developing shoulder pain. More studies are needed to fully understand risk factors for shoulder pain in the masters swim competition level, and to validate recommended cut points for various tests and measures.

Key level of evidence

3, Systematic review of mostly Level 3 studies.

Shoulder structures and strength in competitive preadolescent swimmers: A longitudinal ultrasonographic study

BACKGROUND

Repetitive shoulder movements during competitive training may cause changes in the strength of periarticular shoulder structures in preadolescent swimmers.

OBJECTIVE

To prospectively determine the effects of training on shoulder periarticular structures and muscle strength in preadolescent swimmers.

DESIGN

Prospective cohort study.

SETTING

Community-based natatorium.

PARTICIPANTS

Twenty-four preadolescent swimmers aged 10-12 years.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Measurements were repeated in three periods as preseason, midseason, and postseason. Ultrasonographic measurements (supraspinatus tendon thickness, humeral head cartilage thickness, deltoid muscle thickness, and acromiohumeral distance) were performed using a portable device and a linear probe. Shoulder (flexion, extension, abduction, internal and external rotation) and back (serratus anterior, lower, and middle trapezius) isometric muscle strength were measured with a handheld dynamometer.

RESULTS

Supraspinatus tendon thickness and acromiohumeral distance were similar in all periods (all p > .05); however, deltoid muscle and humeral head cartilage thicknesses increased throughout the season (p = .002, p = .008, respectively). Likewise, whereas shoulder muscle strength increased (all p < .05), back muscle strength was similar in all periods (all p > .05).

CONCLUSIONS

In preadolescent swimmers, acromiohumeral distance and supraspinatus tendon thickness seem to not change; but humeral head cartilage and deltoid muscle thicknesses as well as shoulder muscle strength increase throughout the season.

Shoulder pain and injury risk factors in competitive swimmers: A systematic review

AIM

To synthesize and assess the literature for shoulder pain and injury risk factors in competitive swimmers.

DESIGN

Systematic review with best-evidence synthesis.

DATA SOURCES

CINHAL, SportDiscus, Scorpus, PubMed, and Embase databases from 1966 to April 30 2022.

SEARCH AND INCLUSION

Cohort, cross-sectional, and case-control studies investigating shoulder pain or injury risk factors in competitive swimmers were included. Quality of eligible studies were assessed using a modified Newcastle-Ottawa scale. Risk factors were divided into four categories: modifiable-intrinsic, modifiable-extrinsic, non-modifiable, and other/secondary.

RESULTS

Of 1356 studies identified, 24 full texts were evaluated for methodological quality, 22 met the criteria and were included in best evidence synthesis. There was no strong evidence supporting or refuting the association between 80 assessed variables and shoulder injury or pain. The swimmers' competitive level (nondirectional), and shoulder muscle recruitment profiles (e.g., increased activity of serratus anterior) exhibited moderate evidence supporting an association. Conversely, internal and external range of motion, middle finger back scratch test, training frequency, specialty stroke, height/weight, sex, and age all had moderate evidence opposing an association. Limited evidence was found for 58 variables, and conflicting for 8. The highest quality study (n = 201) suggested high acute-to-chronic workload ratio and reduced posterior shoulder strength endurance are associated with injury.

CONCLUSIONS

Due to the paucity of high-quality studies, future prospective studies are needed to reevaluate known risk factor associations over exploring additional potential risk factors. Swimming practitioners should be aware of the nondirectional association of a swimmer's competitive level and pain, as squad changes could impact injury incidence. Moreover, swimmers experiencing shoulder pain may show increased activity in shoulder stabilizers during specific movements. Importantly, shoulder strength-endurance may be the most clinically relevant modifiable intrinsic risk factor.

Shoulder Pain and Trunk Muscles Endurance in Young Male and Female Swimmers

Shoulder pain is a common syndrome in swimming and affects a large number of competitive swimmers. The purpose of the study was to investigate the relationship between pain in the shoulder girdle and the endurance of the trunk muscles in young swimmers. A total of 24 boys and 22 girls, aged 13 to 18 years, participated in the study. The measurements included the completion of a questionnaire (Shoulder Pain and Disability Index, SPADI) and a field test (McGill's Torso Muscular Endurance Test). The total SPADI score correlated weakly and negatively with the endurance time of back muscles in both sexes (r2 = 0.10, p = 0.035), and moderately and negatively in girls (r2 = 0.23, p = 0.023). A weak negative correlation was found between the disability index and the back muscles' endurance time in both sexes (r2 = 0.15, p = 0.007), which was moderate in girls only (r2 = 0.25, p = 0.019). The disability index displayed moderate negative correlations with the right oblique's (r2 = 0.18, p = 0.049) and left oblique's endurance time (r2 = 0.23, p = 0.024) in girls. Weight, body mass index, the total out-of-water training time per week and age significantly affected the endurance times of the trunk muscles in boys and girls (p < 0.05). In conclusion, strengthening the dorsal and the oblique muscles could reduce shoulder pain and disability in young swimmers and especially girls.

The Effects Of Differing Density Of Swim-Training Sessions On Shoulder Range Of Motion and Isometric Force Production In National and University Level Swimmers

Background

Well-developed physical qualities (i.e., greater load capacity) in athletes can provide protection against injuries. Although higher competitive level swimmers have more developed physical qualities, no studies have investigated how physical qualities of the shoulder respond to a swim-training session in different competitive levels.

Purpose

To compare baseline shoulder external rotation range of motion (ER ROM) and isometric peak torque of the shoulder internal rotators (IR) and external rotators (ER) between national and university level swimmers with differing training volumes. To compare the post-swim changes of these physical qualities between groups.

Study design

Cross-sectional.

Methods

Ten male swimmers (age= 18.7 ± 1.2 years) were divided into high-load (N= 5 national-level, weekly swim-volume= 37.0 ± 2.7 km) and low-load groups (N= 5 university-level, weekly swim-volume= 6.8 ± 1.8 km). For each group, shoulder active ER ROM and isometric peak torque of the shoulder IR and ER were measured before and immediately after a high-intensity swim-training session (for each group, the hardest swim-session of the week was analyzed). The results were evaluated by the level of significance (p-value), effect size, and whether changes exceeded the measurement error.

Results

University-level swimmers had lower baseline ER torque (p= 0.006; d= 2.55) and IR torque (p= 0.011; d= 2.42) than national-level swimmers. For post-swim analysis, ER ROM decreased more in university swimmers (change= -6.3° to -8.4°; d= 0.75-1.05) than national counterparts (change= -1.9° to -5.7°; d= 0.43-0.95). Greater drops in rotation torque were found in university swimmers (IR change= -15% to -21.0%; d= 0.83-1.66; ER change= -9.0% to -17.0%; d= 1.14-1.28) compared to national swimmers (IR change= -10.0% to -13.0%; d= 0.61-0.91; ER change= -3.7% to -9.1%; d= 0.50-0.96). The average change of all tests in university swimmers exceeded the minimal detectable change (MDC), whereas in national level swimmers some tests exceeded the MDC. Despite this, only post-swim ER torque in the dominant side (p= 0.003; d= 1.18) was significantly lower in university swimmers (possibly due to the small sample size).

Conclusions

University swimmers have less baseline shoulder external and internal rotator torque and had greater drops of all shoulder physical qualities after a swim-training session, which may have implications for injury risk. However, due to the sample size, the results have to be interpreted with caution.

Level of evidence

3.

National Collegiate Athletic Association Swimmers With Glenohumeral Multidirectional Laxity Have an Increased Glenohumeral Joint Range of Motion Profile

CONTEXT

Adaptations in glenohumeral joint laxity and range of motion (ROM) are prevalent in competitive swimmers. Increased glenohumeral laxity in swimmers has been found to exist in multiple directions. However, it is unclear if swimmers with multidirectional laxity (MDL) possess altered glenohumeral ROM compared with swimmers without MDL. The purpose of this study was to compare the glenohumeral ROM characteristics of external rotation (ER), internal rotation (IR), total arc of motion (ER + IR), and total arc of motion ratio (ER/IR) between swimmers with MDL and without MDL. Our secondary objective was to investigate the effect of MDL on self-reported pain and function.

DESIGN

Observational study.

METHODS

Twenty-nine NCAA Division I swimmers (females: 15 and males: 14; age 19.5 [1.2] y; body mass index 23.9 [2.0] km/m2) participated in a preseason physical assessment including measures of glenohumeral ROM and joint laxity. These measures were used to determine the presence or absence of MDL for both shoulders of each participant. Glenohumeral ROM characteristics were compared between shoulders with MDL and shoulders without MDL with independent t tests. Self-reported pain and function scores were recorded biweekly across the season with a modified Kerlan-Jobe Orthopedic Clinic questionnaire. The seasonal average Kerlan-Jobe Orthopedic Clinic questionnaire scores were compared between swimmers with MDL and swimmers without MDL with analysis of variance, with factors of sex and MDL status.

RESULTS

Shoulders with MDL possessed increased glenohumeral IR (P < .001; effect size: 0.65) and total arc of motion (P < .004; effect size: 0.45) compared with shoulders without MDL. There were no differences in ER. There was no difference in self-reported pain and function between groups.

CONCLUSIONS

Shoulders with MDL possess increased glenohumeral IR and total arc of motion compared with shoulders without MDL. The presence of MDL may not affect self-reported pain and function in competitive swimmers.

The Effect of Exercise Therapy Interventions on Shoulder Pain and Musculoskeletal Risk Factors for Shoulder Pain in Competitive Swimmers: A Scoping Review

CONTEXT

Shoulder pain is the main cause of missed or modified training in competitive swimmers. Exercise therapy can improve the outcomes, yet uncertainty exists regarding the characteristics of these interventions.

OBJECTIVES

The primary aim was to describe the evidence base relating to the effectiveness of exercise therapy interventions on shoulder pain and shoulder musculoskeletal risk factors for shoulder pain in swimmers. The secondary aim was to identify gaps in the literature and provide recommendations for future research and practice.

EVIDENCE ACQUISITION

A scoping review methodology was applied through the search of MEDLINE, PubMed, Scopus, Web of Science, and CINAHL databases. The authors included any research studies (except clinical commentaries and conference papers) that assess the effect of exercise therapy on shoulder pain and musculoskeletal risk factors for shoulder pain in swimmers. The literature was critically appraised using the Modified Down and Black checklist.

EVIDENCE SYNTHESIS

From 452 papers identified, 14 studies were included in this review. An exercise program of 6 to 8 weeks, including strengthening exercises (shoulder external rotator and scapula retractor muscles) and stretches (pectoral muscles), can decrease the incidence of shoulder pain in swimmers. Furthermore, a combination of exercises and stretches with manual therapy techniques can help to decrease shoulder pain in injured swimmers. Regarding risk factors, a strengthening program of more than 12 weeks increased shoulder external rotation peak force, endurance, and external rotation/internal rotation ratio; however, this was not associated to decreases in pain. Finally, open kinetic chain exercises and a dry-land program are superior to close kinetic exercises and water training for improving shoulder external rotation strength and endurance.

CONCLUSIONS

Exercise therapy has positive effects on reducing the incidence of shoulder pain, the management of shoulder pain, and improving shoulder musculoskeletal risk factors in competitive swimmers. However, due to methodological limitations of the studies, caution must be used when applying these results in practice. Future research should focus on high-quality randomized controlled trials for prevention and management of shoulder pain in swimmers.

Cumulative Effects of a Week's Training Loads on Shoulder Physical Qualities and Wellness in Competitive Swimmers

BACKGROUND

Competitive swimmers are exposed to high training loads, which can contribute to the development of shoulder pain. There is a lack of research investigating the interactions between the accumulation of training loads and factors associated to shoulder pain in swimmers.

PURPOSE

The primary objective was to analyze the changes in shoulder physical qualities and wellness factors over a week of training in competitive swimmers. A secondary objective was to compare the changes in these variables between different swim-training volumes performed during the week.

DESIGN

Cross-sectional.

METHODS

Thirty-one national and regional-level swimmers were included (18 females, 13 males; age= 15.5 ± 2.2 years). Active shoulder external rotation (ER) range of motion (ROM), shoulder-rotation isometric torque, and wellness factors using the Hooper questionnaire were measured twice over the week: a baseline measurement (before Monday´s training session) and a follow-up during the week. Participants were divided into a high-volume group (HVG) and low-volume group (LVG) based on the day follow-up was performed. HVL (n= 15) was tested at the end of the training week (after Saturday´s session) and LVG (n= 16) during the week (after Thursday or Friday´s session). Rating of perceived exertion (RPE) of the whole week was recorded after the follow-up session.

RESULTS

At follow-up, the LVG averaged a volume of 26.2 ± 2.2 km, whereas the HVG averaged a volume of 37.5 ± 3.7 km. LVG and HVG participants decreased active shoulder ER ROM on dominant (p= 0.002; p= 0.006) and nondominant sides (p= 0.001; p= 0.004), displayed increased muscular soreness (p= 0.001; p= 0.007) and worsened overall wellness (p< 0.001; p= 0.010). Fatigue (p= 0.008) and poor sleep quality were increased (p= 0.023) in HVG, but not in LVG. There were no changes in shoulder-rotation torque and stress in any group. Regarding between-groups differences, only weekly RPE was higher (p= 0.004) in HVG.

CONCLUSIONS

The accumulation of training loads over the week negatively affect physical and wellness factors. Greater swim-volumes were associated with an increase perception of training loads. The regular monitoring of multiple factors to assess swimmers' response to training might be necessary.

LEVEL OF EVIDENCE

3.

Master swimmers with shoulder pain and disability have altered functional and structural measures

CONTEXT

Supraspinatus tendinopathy and shoulder pain are common in competitive youth swimmers; however, no studies have investigated clinical and structural factors contributing to shoulder pain and disability in master level swimmers.

OBJECTIVE

The objectives of this study were: 1) to determine the prevalence of shoulder pain and disability in master level swimmers, 2) to identify the most provocative special tests for shoulder pain, and 3) to determine if shoulder clinical and tissue specific measures, training variables and volume vary between those with and without shoulder pain, dissatisfaction and disability.

DESIGN

Cross-sectional.

SETTING

Collegiate swimming facilities.

PATIENTS OR OTHER PARTICIPANTS

Thirty-nine adult masters level swimmers were evaluated and included in the data analysis.

MAIN OUTCOME MEASURES

A survey of demographics, training, and pain and disability ratings using the Penn Shoulder Score and Disability of Arm Shoulder Hand sports module. Swimmers underwent a clinical exam including shoulder passive range of motion (PROM), posterior shoulder endurance test (PSET), supraspinatus tendon structure and posterior capsule thickness. One-way ANOVAs were used to compare demographics, clinical and structural findings between those with significant pain, dissatisfaction and disability (+PDD) and those without (-PDD).

RESULTS

Fifteen percent of subjects reported pain at rest, 28% with normal activities (eating, dressing), and 69% with strenuous activities (sports) and 50% reported disability. The +PDD group had less shoulder internal rotation (10°), less ER (8°), and completed less yardage per day and per year. There were significant differences in the supraspinatus tendon structure between the +PDD and -PDD groups.

CONCLUSION

Masters swimmers with pain and disability are able to self-limit yardage and likely why they recorded less yardage. The reduced shoulder motion (IR and ER) without posterior capsule differences may be due to rotator cuff muscle/tendon restrictions and the supraspinatus tendon structure may indicate degeneration caused by previous overuse resulting in pain.