Glenohumeral joint rotation range of motion in competitive swimmers

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1 This article was downloaded by: [Bryan Riemann] On: 31 July 11, At: 9:9 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Journal of Sports Sciences Publication details, including instructions for authors and subscription information: Glenohumeral joint rotation range of motion in competitive swimmers Bryan L. Riemann a, Joe Witt a & George J. Davies b a Health Sciences, Armstrong Atlantic State University, Savannah, Georgia, USA b Physical Therapy, Armstrong Atlantic State University, Savannah, Georgia, USA Available online: Jul 11 To cite this article: Bryan L. Riemann, Joe Witt & George J. Davies (11): Glenohumeral joint rotation range of motion in competitive swimmers, Journal of Sports Sciences, DOI:1.18/ To link to this article: PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan, sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

2 Journal of Sports Sciences, 11; 1 9, ifirst article Glenohumeral joint rotation range of motion in competitive swimmers BRYAN L. RIEMANN 1, JOE WITT 1, & GEORGE J. DAVIES 1 Health Sciences, Armstrong Atlantic State University, Savannah, Georgia, USA and Physical Therapy, Armstrong Atlantic State University, Savannah, Georgia, USA (Accepted 9 May 11) Downloaded by [Bryan Riemann] at 9:9 31 July 11 Abstract Much research has examined shoulder range of motion adaptations in overhead-unilateral athletes. Based on the void examining overhead-bilateral athletes, especially competitive swimmers, we examined shoulder external rotation, isolated internal rotation, composite internal rotation, and total arc of motion range of motion of competitive swimmers. The range of motion of registered competitive swimmers (n ¼ 144, age ¼ 1 61 years) was compared by limb (dominant, nondominant), sex, and age group (youth, high school, college, masters). Significantly (P 5.5) greater dominant external rotation was observed for both men and women high school and college swimmers, youth women swimmers, and men masters swimmers compared with the non-dominant limb. The isolated internal rotation (glenohumeral rotation), composite internal rotation (glenohumeral rotation plus scapulothoracic protraction), and total arc of motion (external rotation plus composite internal rotation) of the non-dominant limb was significantly greater than that of the dominant limb by sex and age group. Youth and high school swimmers demonstrated significantly greater composite internal rotation than college and masters swimmers. Youth swimmers displayed significantly greater total arc of motion than all other age groups. These data will aid in the interpretation of shoulder range of motion values in competitive swimmers during preseason screenings, injury evaluations and post-rehabilitation programmes, with the results suggesting that differences exist in bilateral external rotation, isolated internal rotation, composite internal rotation, and total arc of motion range of motion. Keywords: Shoulder, internal rotation, external rotation, total arc of motion Introduction The biomechanical stress placed upon the shoulder joint during a swimmer s career can contribute to repetitive microtrauma and/or overuse injuries (Bak, 1996; Ciullo & Stevens, 1989). Competitive swimming is a very time-demanding sport for which elite swimmers practise 3 h per week (Bak, 1996). In one year, an elite swimmer performs more than 5, stroke revolutions per arm (Richardson, Jobe, & Collins, 198). Therefore, it is no surprise that shoulder pain is the most frequent musculoskeletal problem among competitive swimmers (Bak, 1996). The prevalence of shoulder pain has been reported to be as high as 8% in competitive swimmers (Rupp, 1995). The term swimmer s shoulder is commonly used to refer to the constellation of shoulder complaints in competitive swimmers without reference to aetiology (McMaster, Roberts, & Stoddard, 1998). Although this term is usually synonymous with impingement syndrome/ instability and rotator cuff tendonitis, it is becoming increasingly more evident that swimmer s shoulder consists of a variety of conditions that affect swimmers and other overhead athletes (McMaster, 1999). Recognizing range of motion and muscular imbalances in the upper extremities of competitive swimmers may aid in reducing and preventing injuries to the shoulder joint. The propulsive phase of the front-crawl swim stroke involves muscles such as the pectoralis major and latissimus dorsi to propel the body, which produce internal shoulder rotation concurrently with shoulder extension (Pink, Perry, Browne, Scovazzo, & Kerrigan, 1991). During the recovery phase of the swim stroke, external rotation occurs along with activation of the external shoulder rotators such as the infraspinatus (Pink et al., 1991). Thus, similar to other overhead sports such as throwing events, internal and external shoulder rotation is an important component of swimming. Given the relationship between altered internal and external shoulder range of motion and shoulder pathology, studying active internal and external range of motion in Correspondence: B. L. Riemann, Health Sciences, Armstrong Atlantic State University, Savannah, GA 31419, USA. bryan.riemann@armstrong.edu ISSN print/issn X online Ó 11 Taylor & Francis DOI: 1.18/

3 Downloaded by [Bryan Riemann] at 9:9 31 July 11 B. L. Riemann et al. swimmers is warranted. Because the swim stroke is a voluntary movement, including the range of motion utilized, and under the control of the swimmer, active range of motion assessments may be most appropriate. Previous research (Bigliani et al., 1997; Ellenbecker, Roetert, Bailie, Davies, & Brown, ; Kibler, Chandler, Livingstong, & Roetert, 1996) has shown that overhead throwing athletes demonstrate adaptive glenohumeral internal and external rotation range of motion of the dominant shoulder compared with the non-dominant shoulder. Specifically. these studies have shown that throwers demonstrate significantly increased glenohumeral external rotation and significantly decreased glenohumeral internal rotation in the throwing arm without compromising total arc of motion. Although it is reasonable to assume that bilateral athletes, such as swimmers, may demonstrate equal adaptations and ranges of motion in both the dominant and non-dominant limbs, very few studies have investigated this premise. Studies considering shoulder range of motion of swimmers are limited in scope because of limited sample size (Bak & Magnusson, 1997) and participant age (only youth swimmers) (Ozcaldiran, ). Compared with age- and gender-matched controls, competitive youth swimmers demonstrated significantly greater shoulder range of motion (Ozcaldiran, ). Furthermore, a direct relationship between range of motion and shoulder pain was revealed in both the dominant and non-dominant shoulders of the youth swimmers (Ozcaldiran, ). Bak and Magnusson (1997) documented no bilateral (injured versus healthy) differences in their sample of swimmers, suggesting that either no range of motion adaptations accompany swimming or that equal adaptations in both shoulders occur. In contrast, a bilateral arm swim bench power test in competitive swimmers revealed external power output to markedly favour one arm (Potts, Charlton, & Smith, ). The left arm displayed significantly greater power output (8% greater) than the right arm. Potts and colleagues (Potts, Charlton, & Smith, ) attributed this disparity to preferred breathing side of the athlete. In addition, Whiteley and colleagues (Whiteley, Ginn, Nicholson, & Adams, 9) reported significantly greater humeral torsion of the dominant versus the non-dominant arm in adolescent swimmers. The results of these two latter studies suggest that despite equal repetitive movements in both limbs, swimmers may not adapt bilaterally in terms of power output or humeral torsion. Therefore, it is not unreasonable to speculate that competitive swimmers may show similar side imbalances for shoulder range of motion. In addition to the validity of making bilateral shoulder range of motion comparisons, the increased range of motion that the youth swimmers exhibited compared with controls (Bak & Magnusson, 1997; Ozcaldiran, ) also challenges the utility of using normative data based on controls to interpret a swimmer s shoulder range of motion measurements. Furthermore, it is unknown whether total arc of motion is dependent upon sex and age, and whether smaller bilateral differences exist than could not be detected in the previous studies because of the small sample sizes used (Bak & Magnusson, 1997; Ozcaldiran, ). Therefore, the purpose of this study was to examine shoulder external rotation, isolated internal rotation, composite internal rotation, and total arc of motion range of motion in competitive swimmers by dominance, sex, and age group. It was hypothesized there would be no significant differences between men and women, the dominant shoulder would have significantly greater range of motion (all motions) than the nondominant shoulder, and younger swimmers would demonstrate significantly greater range of motion (all motions) than older swimmers. Methods Participants Swimmers from registered National Association of Intercollegiate Athletes, high school, US Masters, and USA Swimming teams were invited to participate in the study. Swimmers who expressed interest were informed about the protocol of the study and they (and their parents where applicable) signed an informed consent document to participate. The sponsoring University s Institutional Review Board reviewed and approved the study. Inclusion criteria for the study were years of experience (41 year) and practice frequency ( 3 times per week). Exclusion criteria included recent history (56 months) of shoulder pain or injury. Altogether, 144 swimmers aged 1 61 years met the inclusion criteria and participated in the study. Before the range of motion assessments, participants completed a demographics questionnaire that included years of experience, dominant limb (throwing arm), age, and preferred breathing side in freestyle (Table I). Preferring to breathe on the right side means that during breathing the head turns to the right, and the left arm is pulling while the right arm is recovering. Procedure and data collection The protocol for the current study replicated a technique used in previous research (Ellenbecker, Roetert, Bailie, Davies, & Brown, ). Only active range of motion was considered, partly because of previous research (Ozcaldiran, ) and to be

4 Competitive swimmers glenohumeral range of motion 3 Table I. Descriptive statistics for men and women within each age group (mean + s). Youth (N ¼ 36) High school (N ¼ 47) College (N ¼ 3) Masters (N ¼ 31) Men (n ¼ 17) Women (n ¼ 19) Men (n ¼ 5) Women (n ¼ ) Men (n ¼ 15) Women (n ¼ 15) Men (n ¼ 15) Women (n ¼ 16) Age (years) Height (m) Mass (kg) Experience (years) Dominant Right Left Breathing side Right Left Both Downloaded by [Bryan Riemann] at 9:9 31 July 11 consistent with the range of motion used during a swim stroke, which is under the volitional control of the swimmer. One of two researchers measured each participant with the order of limb (dominant, nondominant) randomized. The researchers performed the tests before the beginning of swim practice or other exercise. Data collection lasted for 4 months, and each swim team was allotted two concurrent weeks for testing. Data collection lasted approximately 15 min per participant. Once height and body mass were recorded, one of two researchers used standard, 368 hand-held universal goniometers (Baseline 1 plastic 368 ISOM, White Plains, NY, USA) to assess isolated internal, composite internal, and external rotation of the glenohumeral joint. Goniometric measurements were selected because of their widespread clinical utilization, as well as being portable for remote data collection. For all range of motion measurements, participants assumed a supine position, with the arm being tested in 98 of elbow flexion and 98 abduction of the glenohumeral joint. The start position involved the forearm being pronated and positioned perpendicular to the supporting surface. The axis of the goniometer was aligned with the long axis of the humerus, with the olecranon process being the superficial landmark for alignment. The stationary arm of the goniometer was aligned perpendicular to the supporting surface. The moving arm of the goniometer was aligned with the lateral aspect of the ulna (Ellenbecker, Roetert, Bailie, Davies, & Brown, ; Norkin & White, 1995). External rotation To measure external rotation, participants were given a cue ( move the back of your hand toward the floor ) to maximally externally rotate the shoulder. Stabilization was provided at the distal end of the humerus to keep the shoulder in 98 of abduction achieved by the tester using a free hand to support the humerus. Scapulothoracic stabilization was provided by the table and the examiner. The tester palpated the coracoid process and anterior aspect of the shoulder to detect scapular motion. Scapular retraction or elevation was not permitted. Once the participant reached an active end range of motion position, the angle was recorded from the goniometer (Figure 1). This was repeated for a total of three trials and the average value was used in the data analysis. Isolated internal rotation Isolated internal rotation was assessed using landmarks as above for goniometer alignment and stabilization (Ellenbecker, Roetert, Bailie, Davies, & Brown, ; Norkin & White, 1995). Participants were given a cue ( move the palm of your hand toward the floor until instructed to stop ) to actively internally rotate the humerus while the tester palpated the anterior acromion for scapular motion. The humerus was rotated until scapular motion was initiated, at which time the tester instructed the participant to stop actively rotating the humerus, and hold the position (Figure ). At this point, the measurement was recorded using the standard goniometer. This was repeated for a total of three trials and the average value was used in the data analysis. Composite internal rotation From the maximum internal-isolated position, composite internal rotation was assessed by instructing the participants to further actively internally rotate the humerus. The end of range of motion was recorded during the point at which the participant

5 Downloaded by [Bryan Riemann] at 9:9 31 July 11 4 B. L. Riemann et al. could no longer internally rotate the glenohumeral joint without lifting the scapula from the supporting surface (Figure 3). This was repeated for a total of three trials and the average value was used in the data analysis. Total arc of motion rotation Total arc of motion for the glenohumeral joint was calculated as the sum of the external rotation and composite internal rotation measurements together for each extremity (Ellenbecker, Roetert, Bailie, Davies, & Brown, ). Reliability study Before data collection for the current study, a reliability study using the two examiners was conducted to assess the intra- and inter-rater reliabilities of the data collection procedures. In the reliability study, the same two examiners from the parent study duplicated the procedures using 13 non-sedentary (active days per week minimum) persons (1 women, 3 men, age 1 7 years). To determine whether the examiners were reliable in assessing both left and right extremities, the data were analysed according to limb (left, right) rather than dominance (dominant, non-dominant). Intraclass correlation coefficients (ICC, model ¼ (3, k)) and standard errors of measurement were calculated as estimates of intra-tester and inter-tester reliabilities (Table II). Data analysis Determining minimal subgroup sample sizes was based on the assumption that 1% differences between the sexes and age groups and 5% differences between sides would be clinically relevant. The rationale for using a smaller difference for the dominance effect was based on within-participants versus between-participants comparisons and an expectation that the side difference in bilateral Figure 3. Measurement of composite internal rotation. Figure 1. Recording active external shoulder range of motion. Table II. Intra-tester and inter-tester reliabilities. Intra-tester (Examiner 1) Intra-tester (Examiner ) Inter-tester ICC SEM (8) ICC SEM (8) ICC SEM (8) Isolated internal rotation Right Left Composite internal rotation Right Left External rotation Right Left Total Right Left Figure. Palpation of scapula to determine limit of isolated glenohumeral internal rotation. Note: ICC ¼ intraclass correlation coefficient; SEM ¼ standard error of measurement.

6 Competitive swimmers glenohumeral range of motion 5 Downloaded by [Bryan Riemann] at 9:9 31 July 11 athletes would be less than previously reported (Ellenbecker, Roetert, Bailie, Davies, & Brown, ) side differences in unilateral athletes (baseball and tennis athletes). Using the internal rotation, external rotation, and total range of motion data reported for pain-free swimmers by Bak and Magnusson (1997) with the adoption of an alpha of.5 revealed that 15 participants in each subgroup would provide a minimum power of.89 for all main effects and interactions. Following an exploratory analysis of normality using Shapiro-Wilk tests and visual inspection of the box plots, four separate three-factor repeatedmeasures analyses of variance (ANOVA) were used for each of the dependent variables (external rotation, isolated internal rotation, composite internal rotation, and total arc of motion). The withinparticipant factor dominance had two levels (dominant, non-dominant), the between-participants factor sex had two levels (men and women), and the between-participants factor age group had four levels (youth, high school, college, masters). For all tests, statistical significance was set at P 5.5. When appropriate, simple main effect and simple, simple main effect post hoc tests with Bonferroni adjustments were used to identify significant omnibus tests. Results Descriptive statistics for the isolated internal, composite internal, external rotation, and total arc of motion for the dominant and non-dominant arm in both men and women in all age groups appear in Tables III VI. External rotation A significant dominance 6 sex 6 age group interaction (F 3,136 ¼ 3.76, P ¼.1, Z p ¼.77) was Table III. Shoulder external rotation range of motion (degrees) (mean + s and associated 95% confidence intervals for mean values). Dominant side Non-dominant side Men Women Men Women mean + s 95% CI mean + s 95% CI mean + s 95% CI mean + s 95% CI Youth High school College Masters Table IV. Shoulder isolated internal rotation range of motion (degrees) (mean + s and associated 95% confidence intervals for mean values). Dominant side Non-dominant side Men Women Men Women mean + s 95% CI mean + s 95% CI mean + s 95% CI mean + s 95% CI Youth High school College Masters Table V. Shoulder composite internal rotation range of motion (degrees) (mean + s and associated 95% confidence intervals for mean values). Dominant side Non-dominant side Men Women Men Women mean + s 95% CI mean + s 95% CI mean + s 95% CI mean + s 95% CI Youth High school College Masters

7 6 B. L. Riemann et al. Table VI. Shoulder total arc of motion (degrees) (mean + s and associated 95% confidence intervals for mean values). Dominant side Non-dominant side Men Women Men Women mean + s 95% CI mean + s 95% CI mean + s 95% CI mean + s 95% CI Youth High school College Masters Downloaded by [Bryan Riemann] at 9:9 31 July 11 revealed (Figure 4). Post hoc comparisons for the simple, simple dominance main effect yielded significantly greater (P 5.63) dominant external rotation for both men and women high school and college swimmers, youth women swimmers, and masters men swimmers. There were no significant differences between the limbs for the youth men and masters women swimmers. Post hoc comparisons for the simple, simple age group effect revealed significantly greater non-dominant external rotation for the youth men swimmers than the high school men swimmers. In addition, the masters women demonstrated significantly greater non-dominant external rotation than the high school women. There were no significant differences between the men and women for the simple, simple sex main effect. Isolated internal rotation For isolated internal rotation, only a significant main effect for dominance existed (F 1,136 ¼ 49.56, P 5.1, Z p ¼.67). Regardless of sex or age group, isolated internal rotation was significantly greater in the non-dominant arm ( , 95% CI ¼ ) than in the dominant arm ( , 95% CI ¼ ). Composite internal rotation Significant main effects for dominance (F 1,136 ¼ 78.41, P 5.1, Z p ¼.366), sex (F 1,136 ¼ 5.48, P ¼.1, Z p ¼.39), and age group (F 1,136 ¼ 14.45, P 5.1, Z p ¼.4) were observed for composite internal rotation. The nondominant shoulder ( , 95% CI ¼ ) had greater composite internal rotation than the dominant shoulder ( , 95% CI ¼ ), and men ( , 95% CI ¼ ) displayed less composite internal rotation than women ( , 95% CI ¼ ). Post hoc testing indicated that youth ( , 95% CI ¼ ) and high school ( , 95% CI ¼ ) swimmers had significantly (P ¼.8) more composite internal rotation than college ( , 95% CI ¼ 5. Figure 4. Graphical display of external rotation for men (A) and women (B) swimmers. Black solid lines indicate youth swimmers, grey solid lines indicate high school swimmers, black dashed lines indicate college swimmers, and grey dashed lines indicate masters swimmers. External rotation was significantly greater for the dominant limb than for the non-dominant limb for all age groups except youth men and women masters swimmers. Error bars represent standard deviations ) and masters ( , 95% CI ¼ ) swimmers. Total arc of motion For total arc of motion, a significant main effect was observed for dominance (F 1,136 ¼ 4.6, P ¼.3, Z p ¼.33) and age group (F 1,136 ¼ 7., P 5.1, Z p ¼.138). The dominant shoulder ( , 95% CI ¼ ) had less total arc of motion than the non-dominant shoulder ( ,

8 Downloaded by [Bryan Riemann] at 9:9 31 July 11 95% CI ¼ ). Post hoc testing identified that youth swimmers ( , 95% CI ¼ ) had significantly (P ¼.8) greater total arc of motion than high school ( , 95% CI ¼ ), college ( , 95% CI ¼ ), and masters ( , 95% CI ¼ ) swimmers. Discussion Based on the current lack of evidence concerning shoulder range of motion in competitive swimmers, the purpose of this study was to determine if significant differences existed between external rotation, isolated internal rotation, composite internal rotation, and total arc of motion by sex, age group (youth, high school, college, masters), and dominance (dominant vs. non-dominant shoulder) in competitive swimmers. The identification of significant age group and sex differences for external rotation, composite internal rotation, and total arc of motion suggest that both demographic characteristics need to be considered when comparing normative shoulder range of motion values. Despite the attractiveness of the notion that range of motion adaptations in swimmers should be equal bilaterally secondary to the demands of the activity, our data suggest otherwise. For external rotation, it appears that greater range of motion for the dominant arm may be expected for both men and women high school and college swimmers, youth women swimmers, and men masters swimmers, whereas based on the lack of statistical differences no bilateral differences may be expected in youth men swimmers and women masters swimmers. In addition, greater isolated internal rotation, composite internal rotation, and total arc of motion may be expected for the non-dominant shoulder across age groups and sexes. These data will help interpretation of shoulder range of motion values in competitive swimmers during preseason screenings, injury evaluations, and postrehabilitation programmes. Our first hypothesis was that no range of motion differences would be observed between men and women swimmers. This hypothesis was based upon men and women swimmers performing the same repetitive, overhead movements on a daily basis. This hypothesis was refuted by our data for both external rotation and composite internal rotation. This result is similar to that of Barnes et al. (1), who revealed non-athletic women to have significantly greater range of motion for internal and external rotation of the glenohumeral joint than men. The sex-related differences in external rotation and composite internal rotation may help explain the finding that collegiate women swimmers reported Competitive swimmers glenohumeral range of motion 7 more shoulder injuries than their male counterparts (Sallis, Jones, Sunshine, Smith, & Simon, 1). The second hypothesis was that significantly greater external rotation, isolated internal rotation, composite internal rotation, and total arc of motion would be revealed for the dominant versus the nondominant side. This hypothesis was based on adaptations that occur with greater use of the dominant shoulder during activities of daily living (Conte, Marquies, Casarollo, & Amado-Joao, 9; Roy et al., 9) and other forms of physical activity (Bigliani, Codd, Connor, Levine, Littlefield, & Hershon, 1997; Ellenbecker, Roetert, Bailie, Davies, & Brown, ; Kibler, Chandler, Livingstong, & Roetert, 1996), especially unilateral activities. Parts of our hypothesis were supported by our data, specifically external rotation range of motion for men and women college and high school swimmers, youth women swimmers, and masters men swimmers. Unexpected results included a lack of significant side external rotation range of motion differences for youth men and masters women swimmers and significantly greater isolated internal rotation, composite internal rotation, and total arc of motion for the non-dominant arm. As total arc of motion was calculated as the sum of external rotation and composite internal rotation range of motion, the significantly greater non-dominant total arc of motion may be explained by the fact that the dominant/non-dominant difference was slightly greater for composite internal rotation than external rotation. It is important to note that the dominant/ non-dominant total arc of motion difference, while statistically significant, has questionable clinical significance because the difference is so small and not beyond measurement error. Our results are consistent with previous research (Baltaci, Johnson, & Kohl, 1; Brown, Niehues, Harrah, Yovorsky, & Hirshman, 1988; Ellenbecker, Roetert, Bailie, Davies, & Brown, ) that has revealed greater external rotation in the dominant shoulder accompanied by greater internal rotation in the nondominant shoulder in unilateral overhead athletes. This was an unexpected finding because swimming is usually considered to be a symmetrical bilateral overhead sport. Perhaps one possible explanation for the asymmetrical findings is the use of the dominant arm for activities of daily living and other recreational activities. Although we did not inquire about other physical activity participation, our sample of competitive swimmers may indulge in overhead unilateral physical activities to such an extent that characteristic unilateral adaptation occurred. Furthermore, because the front-crawl stroke is the most frequently used stroke for training (Richardson, Jobe, & Collins, 198), the preferred breathing side used during freestyle may also contribute to the

9 Downloaded by [Bryan Riemann] at 9:9 31 July 11 8 B. L. Riemann et al. bilateral range of motion imbalances. Although we queried preferred breathing side, it was not included in our original data analysis. One explanation for the differences revealed could have been the larger number of right dominant swimmers (134/ 144 ¼ 93%) who declared a preferred breathing side to the right (53/134 ¼ 4%). For these swimmers, they may have an asymmetric stroke whereby the left (non-dominant) arm pulls harder than the right (dominant) arm secondary to the body roll, thereby allowing right-sided breathing. Over time, it is plausible that these swimmers would develop greater left (non-dominant) limb isolated internal rotation/ composite internal rotation and less external rotation than the right (dominant) limb. Additional bilateral composite internal rotation, isolated internal rotation, and external rotation range of motion comparisons were made using only those swimmers who identified themselves as bilateral breathers. Identical to the original analyses, and in contrast with the above hypothesis, significantly greater external rotation and less internal rotation of the dominant limb than the non-dominant limb were revealed. Although the swimmers may have identified themselves as bilateral breathers, they still may have had a preferred breathing side, which in turn produced an asymmetrical stroke and the resulting range of motion differences. It is important to note that other studies considering upper extremity function and adaptations in swimmers have also documented bilateral differences (Potts, Charlton, & Smith, ; Tourny-Chollet, Seifert, & Chollet, 9; Whiteley, Ginn, Nicholson, & Adams, 9), although these findings are not without controversy (Beach, Whitney, & Dickoff-Hoffman, 199). With respect to differences between the age groups, we hypothesized that all range of motion values would decline as age increased. Our hypothesis was partially supported by the composite internal rotation and total arc of motion results. The significantly higher composite internal rotation range of motion in the youth and high school swimmers compared with the college and masters swimmers, and the significantly higher total arc of motion in the youth swimmers compared with all other age groups may in part reflect the fewer years of swim training and greater range of motion values in younger populations. Although formal statistical comparisons of experience were not conducted, with the exception of the masters women, the youth and high school swimmers had fewer years of experience, making it less likely that osseous and soft tissue adaptive changes may have developed due to the repeated overhead swimming motion. Although the length of time and intensity of training needed for adaptive range of motion changes to occur are unknown in swimmers, it may be assumed that both factors would be directly related. In a similar manner, Kibler and colleagues (Kibler, Chandler, Livingstone, & Roetert, 1996) demonstrated an inverse relationship between years of experience and internal rotation in a sample of elite tennis players. Another possibility for the differences between the youth (composite internal rotation and total arc of motion) and high school swimmers (composite internal rotation) compared with the college and masters swimmers could be related to developmental changes. Generally, youth have greater joint range of motion and flexibility of the muscles than older individuals. Meister et al. (5) reported that significant reductions in internal rotation for the dominant and non-dominant arms of baseball athletes occurred between ages 1 and 13 years and 14 and 15 years, respectively. While the dominant arm reduction could be attributed to baseball participation, the non-dominant arm reduction suggests a period of developmental change and therefore provides a partial explanation for our youth swimmer composite internal rotation result. However, it is important to note that Meister et al. (5) did not reveal any significant changes in external rotation or total range of motion across the ages they considered (8 16 years). Finally, our data only revealed two age-related differences for external rotation. Both differences involved the significantly less non-dominant limb external rotation in high school swimmers compared with the male youth and women masters swimmers. Neither of these differences supported our age reduction hypothesis. From a clinical perspective, our data might prove useful to clinicians when making range of motion assessments in swimmers during preseason screenings, injury evaluations, and post-rehabilitation programmes. In addition to providing clinicians with normative data for competitive youth, high school, college, and masters swimmers, the results provide an indication about what may be expected when making bilateral comparisons. It is important to note that all shoulders included in the current study were pain free at the time of assessment and therefore whether previous injury and/or pain influenced the measurements is unknown. Although a direct relationship between shoulder pathology/pain and range of motion in swimmers has not been supported by some reports (Bak & Magnusson, 1997; Beach, Whitney, & Dickoff- Hoffman, 199), others have revealed significant relationships with range of motion (Ozcaldiran, ) and laxity (Meister et al., 5; Rupp, 1995). Thus, the utility of comparing range of motion measurements from a swimmer with shoulder pain to the present range of motion values is unknown. Further research is recommended to consider shoulder range of motion in swimmers with shoulder pain.

10 Downloaded by [Bryan Riemann] at 9:9 31 July 11 Conclusions The present data establish glenohumeral rotational range of motion values in swimmers across age groups and sex. Despite swimming being a bilateraloverhead sport, differences in range of motion were revealed between the dominant and non-dominant shoulders. For external rotation, the dominant shoulder demonstrated significantly more range of motion than the non-dominant shoulder, whereas the non-dominant shoulder displayed significantly greater isolated internal rotation, composite internal rotation, and total arc of motion range of motion. These data will help the interpretation of shoulder range of motion values in competitive swimmers during preseason screenings, injury evaluations, and post-rehabilitation programmes. Further research is needed to examine the relationship between altered shoulder range of motion and injury risk and recovery. Research is also needed to determine the extent to which the differences detected may be attributed to swimming, as well as the effect of unilateral breathing on dominant and non-dominant glenohumeral range of motion and additive effects of prior unilateral sports experience. References Bak, K. (1996). Nontraumatic glenohumeral instability and coracoacromial impingement in swimmers. Scandinavian Journal of Medicine & Science in Sports, 6, Bak, K., & Magnusson, S. (1997). Shoulder strength and range of motion in symptomatic and pain-free elite swimmers. American Journal of Sports Medicine, 5, Baltaci, G., Johnson, R., & Kohl, H. (1). Shoulder range of motion characteristics in collegiate baseball players. Journal of Sports Medicine and Physical Fitness, 41, Beach, M., Whitney, S., & Dickoff- Hoffman, S. (199). Relationship of shoulder flexibility, external/internal rotation, abduction/adduction strength and endurance ratios to shoulder pain in competitive swimmers. 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