FACTORS PREDISPOSING TO SHOULDER INJURIES IN ELITE SWIMMERS A LITERATURE REVIEW ■ / A Hall, MSc (Physio) Wits J Milligan, BSc (Physio) Wits, BSc Hons (Sports Medicine) UCT A Stewart, BSc (Physio), DPE, MSc (Medicine) Wits INTRODUCTION Swimming is a popular recreational and competitive sport in many countries, including South Africa. Competitive swimmers in training are likely to swim between 12 000 metres per day (sprinters) to 18 000 - 20 000 metres per day (distance swimmers)1̂ . As these distances are covered daily for ten to eleven months of the year, five to seven days per week, swimmers are susceptible to microtraumatic overuse injuries of the shoulder*’. Acute, macrotraumatic injuries may also occur. This review aims to describe normal stroke mechanics, shoul­ der injuries common to swimmers and also to identify risk factors predisposing to injuries of the shoulder in the child and adoles­ cent elite swimmer. This becomes particularly important when it is realised that elite swimmers begin swimming competitively by the age of eight and are thus at risk of injuries to the cartilage of epiphyseal plates, joint surfaces and apophysial insertions of tendons. NORMAL ARM ACTION TABLE I: N O R M AL A R M ACTION SA J o u r n a l P h y s io th e ra p y , V o l 51 N o 4 and butterfly. Breaststroke is excluded because the greater part of the propulsion is derived from the leg action5. "Dropping" the elbows causes increased external rotation and thus impedes propulsion. This is a clear sign of fatigue in a young swimmer with untrained adductors and internal rotators, because they cannot generate the force required during the recovery phase. 14Nuber et al (1986) found that supraspinatus, infraspinatus, middle deltoid and serratus anterior were predominantly recov­ ery phase muscles, being active throughout the phase. Serratus Anterior demonstrated a peak activity which occurred at hand entry and early pull- through phase. This highlights the impor­ tance of scapula rotation when the arm is fully abducted. Latis- simus Dorsi and the clavicular head of pectoralis major were the major pull- through muscles. Latissimus dorsi was most active at 90 degrees of abduction as the shoulder progressed from external rotation to internal rotation. There was a constant low level of activity in the Biceps in both phases. The elbow was flexed during both recovery and pull- through phases which would initiate biceps activity. COMMON SHOULDER COMPLAINTS IN SWIMMERS IMPINGEMENT SYNDROME Richardson et al (1980) found that the pain was located about the acromion and always involved the coracoacromial arch in 17some way . The coracoacromial arch consists of the coracoid process, the coracoacromial ligament and the acromion. The su- praspinatus and biceps tendons lie beneath the arch. Impinge­ ment generally occurs against the anterior edge of the acromion 13and the coracoacromial ligament as described by Neer (1972) . The greater tuberosity impinges against the lateral acromion and underneath the acromioclavicular joint with progressive ab­ duction as, for example, occurs in the freestyle stroke. In addition, Rathbun and MacNab (1970) demonstrated areas of avascularity in the supraspinatus and biceps tendons when held in the dependent position in which position both tendons are used1*’. It is felt that the irritation caused by the mechanical impingement of the avascular region of the supraspinatus leads to a tendinitis, which may progress to secondary involvement of 5 8the biceps tendon and rotator cuff tears ' ANTERIOR GLENOID LABRUM DAMAGE This lesion may result from anterior subluxation which may damage the labrum. This can occur as a result of the swimmer's arm motions and increased capsular laxity which may cause subclinical anterior subluxation which damages the anterior glenoid labrum. The patient presents with pain and a click on adduction and internal rotation as the lesion produces compres- 9 sion of the articular surfaces N o v e m b e r 1995 P a g e 59 PHASE STAGE SH O U LD ER ACTION BODY ACTION FREESTYLE Pulkhrough Recovery Hand entry M id p u lkh rou gh End of pull-through Elbow lift M id recovery Hand entry Abd & ext rotation 9 0 ° obd, neutral rotation Add & internal rotation Abd and external rotation 9 0 ° abd & ext rotation Abd & external rotation Roll begins Roll at m axim um Neutral Roll in opposite direction M a xim u m roll Neutrol BACKSTROKE Pull-through Recovery Hand entry M id pulkh rou gh End of pull-through Hand lift M id recovery Hand entiy Abd & ext rotation 9 0 ° abd, neutral rotation Add & internal rotation Abd & ext rotation 9 0 ° abduction M a x im u m abduction Roll begins M a xim u m roll Neutral Roll M a xim u m roll neutral BUTTERFLY Pulkhrough Recovery As for freestyle han ds spread apart at mid pulkh rou gh As for freestyle No roll - No roll - body lifts to allow arms to dea r water Table I describes the normal arm action in freestyle, backstroke R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) TABLE II: S W IM M E R W ITH A HISTORY OF SHOULDER PAIN STROKE RELATIONSHIP AUTHO RS COUNTRY N U M B E R OF S W IM M E R S % OF HISTORY WITH SH O U LD ER PAIN M A LE FEMALE Kennedy & H aw kins7 Canada 2 , 4 9 6 Not provided 1 9 7 4 (Competitive) Richardson, Jobe % U S A 6 3 (nonelite) 3 8 2 3 C o llin s'7 1 9 8 0 3 8 (elite) 4 7 5 7 6 3 (world cham pionship team) 5 0 6 8 TOTAL 4 6 4 0 M c M a ster & T r o u p '1 U S A 9 9 3 N A G * 5 5 3 8 1 9 9 3 1 9 8 S E D * * 6 7 6 4 71 National Team (elite) 71 7 5 * NAG: National Age Group 1 3 - 1 4 years old * * SED: Senior Developm ent 1 5 - 1 6 years old INCIDENCE The incidence of shoulder pain in competitive swimmers in North America has been established by surveys. The study by McMaster and Troup (1993) differentiated be­ tween swimmers currently experiencing shoulder pain and those who had suffered from shoulder pain at any time during their 11swimming careers . Whereas 38% to 75% had a "history of pain at some tim e", only 9% to 35% experienced "current pain". The findings of McMaster and Troup11 and Richardson, Jobe 17 7and Collins are in sharp contrast to those of Kennedy et al . It is possible that the swimmers surveyed in the cross-Canada analy­ sis, although swimming competitively, were not of the same calibre as those assessed in the United States studies. It is reason­ able to expect the percentage of shoulder injuries to be higher in the elite swimmers as the distances swum in training will be greater and the length of time for which they have been training greater. PREDISPOSING FACTORS AGE OF O NSET OF SHOULDER PAIN The average age at commencement of competitive swimming ranges from 7,3 to 8,5 years11. Neither the 1980 or the 1993 USA studies specify the age at which the swimmers first presented with shoulder pain. The survey by McMaster and Troup (1993) indicates that 55% of boys and 38% of girls in the NAG group (13-14 years old) already had a history of shoulder pain. 11McMaster.and Troup stated that the average age of referral for initial complaints of the shoulder is 18 years. SEX OF SW IMMERS A greater percentage of men experienced shoulder problems than women ' . The higher incidence of shoulder pain in men may be explained by a number of factors. Reduced buoyancy, coupled with the more rapid and ballistic arm motions of the male swimmer result in a greater torque applied through the shoulder joint and greater body drag during propulsion through the water. These differences necessitate the generation of a greater pull-through strength (lift) by the male 10,11swimmer Ninety-two percent of swimmers presenting with shoulder pain swam freestyle, butterfly or backstroke in competition and 90% also identified one of these three strokes as their second best 17 stroke as well . This concurs with the findings of the Cross-Can- ada survey , in which the shoulder complaints were caused pri­ marily by the freestyle and butterfly strokes and occasionally by the backstroke, although an exact breakdown of percentages was unavailable. Swimmers surveyed in McMaster and Troup's study indicated that the butterfly stroke was the most painful to perform because 11of the force required to lift the body out of the water . UNILATERAL VS BILATERAL PAIN 17The swimmers surveyed by Richardson et al ranged in age from 14 to 23 years. The numbers complaining of bilateral pain in McMaster and Troup's11 study are significantly higher in the NAG and SED groups which have swimmers who have presum­ ably been swimming competitively for only 5-8 years. TABLE III: UNILATERAL VS BILATERAL PAIN STUDY BILATERAL PAIN Richardson etaF 1 9 8 0 1 5 % (sex unspecified) M cM a ster & T r o u p " 1 9 9 3 Female M ale NAG 3 0 % 6 0 % SE D 5 5 % 4 5 . 5 % U S Team 6 2 % 5 7 % SIDE OF PAIN 17Richardson et al demonstrated that 53% of swimmers com­ plained of pain in their right shoulder and 32% suffered from left sided pain. Ciullo and Stevens (1989) found that 60% of swimmers per­ forming freestyle developed pain on the side on which they breathe, which is the dominant side of 81% of swimmers sur­ veyed2. None of the other studies included in this review provided details of the side of pain. W EIGHT TRAINING TABLE IV: FACTORS AGGRAVATING SHOULDER PAIN TRAINING ACTIVITY S W IM M E R S W ITH IN CR EA SED SH O U LD E R PAIN % NAG SED ELITE Weights Poddies Surgical tubing Stretching Kickboards MALE 7 13 0 7 9 FEMALE 11 21 0 11 11 M A LE 21 5 6 2 3 21 3 8 FEM ALE 41 6 8 3 2 41 14 M A LE 3 8 91 4 3 3 8 6 7 FEM ALE 2 9 1 0 0 17 2 9 1 4 Weight training has become an integral part of preparation for 12competition, but may contribute to shoulder pain . The pattern of movement used in weight training was not described. Some swimmers felt that the use of weights decreased shoulder pain. This is in contrast to the findings of McMaster and Troup11, where the respondents to their survey indicated that weight training increased the pain (Table IV). B la d s y 6 0 N o v e m b e r 1995 SA Tydskrif F is io te ra p ie , D e e l 51 n o 4 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) Brady et al cautioned that weight training needs to be closely monitored and designed for the needs of the swimmer1. The patterns of movement during weight training need to be carefully taught. Caution needs to be exercised in the commencement of weight training in pre-adolescent swimmers. A number of swim­ mers begin weight training before the age of 10 which may be a 12cause of growth plate injuries . RESISTANCE TRAINING Resistance training is necessary to improve power and strength after stroke techniques have been perfected. Hand paddles are a popular method of resistance training. The use of the hand paddle increases the load on muscles of the upper extremity and increases the length of time spent in the pull- 18through phase . This phase, together with the recovery phase, produced pain in 75% of the swimmers surveyed by Richard- 17son . The remaining 25% experienced pain in either the pull- through or recovery phase alone. Of the groups surveyed by McMaster and Troup11 the use of hand paddles ranged from 70% of the female SED group to 91% of the elite male swimmers and was seen to aggravate shoulder pain. The percentage of swimmers in which this occurred is seen in Table IV. In Richardson's study, 81% of the swimmers found 17that the use of hand paddles aggravated their pain . Resistance training using surgical tubing appears to be less widely used, but again is reported to exacerbate shoulder pain15 (Table IV). FLEXIBILITY Greipp (1985) studied shoulder flexibility in a group of 168 swimmers before the start of the swimming season in order to predict the incidence of shoulder pain. Results indicated that the poorer the shoulder flexibility the higher the incidence of shoul­ der pairA He suggested that posterior shoulder looseness could be associated with his findings. The postural forward shoulder 4slump often seen in swimmers, tends to support this . MUSCLE STRENGTH The stroke mechanism emphasises internal rotation and ad­ duction of the shoulder and it is not surprising that swimmers show significantly greater torque values of these movements. Warner et al (1990) indicated an increase in the internal/exter­ nal rotation ratios in patients suffering from impingement syn- 18drome, due to an increased internal rotation strength . It is the rotator cuff muscles which provide dynamic humeral stability and prevent vertical displacement of the humeral head during elevation. A significant muscle imbalance may therefore result in upward displacement of the humeral head resulting in impingement. KICKBOARDS The flexion and adduction of the shoulder which is required to hold the board may cause symptoms of impingement. (Table IV)17. EVENT The findings of Richardson et al indicate that shoulder pain is 17more common in sprinters and middle distance swimmers . Long distance swimmers swim further during practice , but the more forceful arm movements of the sprinter may cause impinge- ment of the supraspinatus tendon in the subacromial space . CONCLUSION South Africa's re-entrance to international sport competitions is likely to cause an increase in young participants with their sights set on the 1996 or 2000 Olympic Games. Similar surveys to those performed by McMaster and Troup and Richardson et al would need to be carried out in South Africa to determine which of the risk factors detailed in the review are problematic in South African swimmers. The coaches, parents and swimmers would then need to be educated in order to increase their awareness regarding the prevention, early identifi­ cation and successful management of injuries that may occur. REFERENCES 1. Brady TA, Cahill BR, Bodnor LM. Weight Training - Related Injuries in the High School Athlete. Am J Sports Med 1982:10(l);l-5. 2. Ciullo JV, S teven s GG. The Prevention and Treatment of Injuries to the Shoulder in Swimming. Sports Medicine 1989:7;182-204. 3. Collins HR, Wilde AH. Shoulder Instability in Athletics. Orthopaedic clinics o f North America 1973:4(3);759-773. 4. Greipp JF. Swimmer's Shoulder: The Influence of Flexibility and Weight Training. The Physician and Sports Medicine August 1985:13(5);92-1051. 5. Hawkins RJ, Kennedy JC. Impingement Syndrome in Athletes. Am J Sports Med 1980:8(3);151-158. 6. Jobe FW, Jobe CM. Painful Athletic Injuries of the Shoulder. Clinical Orthopaedics and Related Research 1983:173;117-124. 7. Kennedy JC, Hawkins R, Krissoff HB. Orthopaedic Manifestations of Swimming. Am J Sports Med. 1974:6(6);309-322. 8. Lohr JF, Uhthoff HH. The Microvascular Pattern of the Supraspinatus Tendon. Clin Orthop 1990:254;35-38. 9. McMaster WC. Anterior Glenoid Labrum Damage: A Painful Lesion in Swimmers. Am J Sports M ed 1986:14(5);383-387. 10. McMaster WC, Long SC, Caiozzo VJ. Shoulder Torque Changes in the Swimming Athlete. Am J Sport Med 1992:20(3);323-327. 11. McMaster MC, Troup J. A Survey of Interfering Shoulder Pain in United States Competitive Swimmers. Am J Sports M ed 1993:21(1);67- 70. 12. Micheli LJ. Overuse Injuries in Children's Sports: The Growth Factor. Orthopaedic Clinics o f North America 1983:14(2);337-360. 13. Neer CS. Anterior Acromioplasty for the Chronic Impingement Syn­ drome in the Shoulder. J Bone Joint Surg 1972:54A(l);41-50. 14. Nuber GW, Jobe FW, Perry J et al. Fine Wire Electromyography Analysis of Muscles of the Shoulder during Swimming. American Journal o f Sports Medicine 1986:14(1);7-11. 15. Pappas AM, Sgoss TP, Kleinman PK. Symptomatic Shoulder Instability due to Lesions of the Glenoid Labrum. Am J Sports Med 1985:11(5);179- 288. 16. Rathbun JB, Macnab I. The Microvascular Pattern o f the Rotator Cuff. J Bone Joint Surg 1970:52B(3);540-553. 17. Richardson AB, Jobe FW, Collins HR. The Shoulder in Competitive Swimming. Am J Sports M ed 1980:8(3);159-163. 18. Warner JJP, Micheli LJ, Arslanian LE et al. Patterns of Flexibility, Laxity and Strength in Normal Shoulders and Shoulders with Instability and Impingement. Am J Sports Med 1990:18(4);366-375.+ 18 SA J o u r n a l P h y s io th e ra p y , V o l 51 N o 4 N o v e m b e r 1995 P a g e 61 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )