Biomechanics Of Swimming

Sports Biomechanics

1. BIOMECHANICS OF SWIMMING Biomechanics of swimming Presented by: Dr Nishank Verma MPT-Sports Jamia Millia Islamia

2. INTRODUCTION Swimming is a movement through water using one’s limbs and usually without artificial apparatus. It is a full body sport and requires the coordinated activation of muscles in legs, core and upper body. One unique aspect of swimming mechanics is that power comes from shoulder girdle . In swimming, the body is being over the arms. Thus, the arms are the propulsive mechanism and the shoulders are quite vulnerable specially if the scapula cannot act as a stable base for GH control.

3. In a survey of 532 collegiate swimmers, not only did half of the swimmers have a history of 3 or more weeks of shoulder pain that forced them to alter their training , more than half of the injured swimmers also had recurrence.

4. Most of the injuries swimmers experience are chronic in nature and are due to repetitive microtrauma or overuse because of the repetitive nature of the swimming stroke. The elite swimmer experiences higher injury rates than the recreational swimmer primarily because training tends to stretch the body to its limits of endurance. Site of pain: 44% swimmers: anterior superior region pain 26%: diffused pain 14%: antero inferior region pain 10%: postero superior region pain 4%: postero inferior pain

5. On Average, injury rate about 50% 10 strokes per 25 – yard pool (5 each arm) 320 laps per day (8,000 yards) 5 x 320 = 1,600 revolutions per arm each day! 8 x 1,600 = 12,800 revolutions per arm each week! 12,800 x 50 = 640,000 revolutions per arm each year! 640,000 x 15 (years) = 9,600,000 revolutions per arm each age-group career!

6. Swimming Strokes What is a Swimming Stroke? A swimming stroke is a method of moving the arms and legs to push against the water and propel the swimmer forward.

7. Types of Strokes Freestyle Butterfly Breaststroke Backstroke Medley

8. FREESTYLE Arms follow the windmill motion with one hand going into water when the other hand exits the water. When hand in water pull through making an ‘S’ shape Breathe when hand is out in front. Kick with feet together moving up and down Make sure you don’t lift head to high, because you want to be in a streamline position.

9. Butterfly Stroke The most difficult and exhausting stroke. The body is in a prone position. Involves the dolphin kick with a windmill-like movement of both arms in unison. Pull through the water making an S shape Make sure hands leave water at the same time.

10. Breaststroke The body is in a prone position. Involves frog kicking alternates with a simultaneous movement of the arms from a point in front of the head to shoulder level. Push inwards with hands into chest area. Then bring hands out to front again Kick is similar to a frog, bring feet up to behind and spread outwards then kick with feet going together again at the end.

11. Backstroke Involves alternate over-the-head arm strokes and a flutter kick in a supine position Keep head straight do not move it around. Move hands in windmill motion, while one hand is inside the water the other hand is outside the water. When one hand is entering the water make sure the other hand is exiting the water. You must enter the water with little finger first.

12. STROKES(biomechanical implication) The shoulder is the primary area of interest to clinicians working with swimmers because of its vulnerability to injury. The visually apparent mechanics related to potential shoulder injury in the freestyle, backstroke, and butterfly strokes is that of humeral position relative to the axis of the body. humeral hyperextension is defined as a combination of humeral abduction and extension (i.e., the humerus is behind the long-axis of the body while the arm is abducted). This position places stress on the anterior joint structures. Too much or too little body rotation changes the position of the humerus relative to the body axis, and thus is related to humeral hyperextension.

13. Humeral hyperextension Freestyle style Butterfly stroke backstroke

14. FREESTYLE STROKE Phases : hand entry forward reach early pull-through middle through Late pull through hand exit Early recovery middle recovery Late recovery MECHANICS : 70% painful symptoms are identified during the first half of pull-through. 18% identified during the first half of recovery.

15. The arm motion in this stroke is reciprocal. Hand entry - The hand enters the water forward of and lateral to head and medial to the shoulder. The elbow is flexed and positioned above the hand so that fingers are the first to enter the water. Forward reach - The hand then reaches forwards under the water and palm begins to rotate down and at maximal elbow extension, hand initiated S-shaped pulling pattern (early pull-through)

16. EARLY PULL THROUGH PHASE : marked by the initiation of the backward arm movement . The palm and forearm should face the backward direction with the fingertips pointing down MID PULL THROUGH PHASE : The point at which the humerus is perpendicular to the body. LATE PULL THROUGH PHASE : The hand continues back and passes next to the hip until it exits the water , leading with the elbow.

17. HAND EXIT RECOVERY PHASE : when the arm is swung above the water to bring the arm into position to pull once again .

18. Shoulder pain occurs in early pull through to mid pull through and hand exit to mid recovery phase .(cause-humeral hyperextension) The lower extremities do a reciprocal diagonal sweep called flutter kick . Swimmers roll to left once the left arm reaches mid pull-through and to the right when right arm reaches mid pull-through. Breathing pattern : roll the head to the side of dominant arm as the arm exits the water. They prefer to breath alternately on the right and left sides during every third hand exit.

19. MUSCLE ACTIVITY Three force couple During hand entry and forward reach : suprasinatus Anterior and middle deltoid During early pull through phase: pectoralis major teres minor During late pull through: lattiimus dorsi subscapularis

20. During hand entry and forward reach , the upper trapezius elevates the scapula while the rhombiods retract it. The serratus anterior is active in order to protract and upwardly rotate the scapula .(also stabilizer of the scapula in a protracted position) this muscle action positions the glenoid fossa for the humeral head as the arm is abducted and flexed by supraspinatus and anterior and middle deltoid when the hand reaches forward in the water.

21. The pectoralis major is responsible for the initial and powerful humeral adduction, internal rotation and extension . Teres minor fires to provide an antagonistic external rotation force. Lattisimus dorsi becomes the primary muscle of propulsion after mid pull-through. Subscapularis forms a force couple with the latissimus dorsi . Throughout the propulsive motions serratus anterior is also active as it pulls the body over the arm and through the water. It also maintains the scapula in a position of upward rotation and also assists with joint congruency of the humerus and glenoid .

22. The posteior deltoid becomes active after the latissimus dorsi reaches its peak, it contributes to final part of pulling. As the hand begins to exit the water, the group of muscles that were active at hand entry once again begin to function. The muscles that function at hand exit continue with their activity during recovery. In swimmers with normal shoulders , the serratus anterior continually fires above 20% of its maximum . This muscle appears to be stabilizing the scapula in a protracted position as the arm pulls the body over itself . When a muscle continually fires above 20%, it is susceptible to fatigue . in swimmers with painful shoulders , the serratus anterior demonstrates significantly less muscle action during a large portion of pull-through

23. Although the serratus anterior diminishes its action during pull-through, the rhomboids increase their activity . It may be that, in an attempt to stabilize the scapula during the absence of the serratus anterior, the primary muscles available are the rhomboids. Decreased subscapularis activity during mid recovery. the primary “power” muscles of the shoulder during swimming (the latissimus dorsi and the pectoralis major ) demonstrate no significant differences when comparing normal versus painful shoulders. So it appears that these muscles may not be integral in the prevention of injury.

24. EMG ACTIVITY DURING FREESTYLE STROKE

25. COMMON FREESTYLE MECHANICAL CHANGES CAUSED BY FATIGUE, SORENESS AND PAIN

26. NORMAL SHOULDER PAINFUL SHOULDER HAND ENTRY FORWARD REACH PULL-THROUGH

27. HAND EXIT AND RECOVERY ROTATION

28. Ways by which an injured swimmer can reduce humeral hyprextension CATCH-UP When arm phases overlap slightly so that the recovery arm is on to the late recovery while the underwater arm Is still in the early pull through. Reduces body rotation during the early to mid pull through Reduces the chances of humeral hyperextension

29. During the hand exit to mid recovery: Humeral hyperextension can be reduced by swinging the arm wider and decreasing the elbow flexion. The recovery should be relaxed and controlled, and it is acceptable to swing the hand around the side. Recovery phase should be led by the elbow.

30. BUTTERFLY STROKE MECHANICS : The butterfly stroke is a bilateral activity . butterfly stroke typically consisting more of an S –shaped pulling pattern and the upper body pivoting up and down about the hips, instead of rotating about the central axis as in freestyle and backstroke. No body roll in this stroke. Breathing occurs by lifting the head out of the water. Dolphin kick : legs move together similar to the tail of dolphin. The legs move up then down for two cycles during each complete arm cycle . When the arm begin the actual pulling, the legs kick upward.

31. The hands enter the water with the arms extended forward and in front of the shoulder. The upper body presses down at the same time the arms enter the water to generate a more dynamic motion on entry and support the swimmer’s forward motion. The hands and arms should remain extended forward during the upper body press, as opposed to aiming downward. There is potential for the humerus to be internally rotated during the arm exit and early recovery phase.

32. MUSCLE ACTIVITY the rhombiods , upper trapezius , serratus anterior, supraspinatus , anterior and middle deltoid all exhibit peak of muscle activity during hand entry. But the peak is a little later than in freestyle stroke. This later peak is due to wider hand entry in butterfly stroke. Activity increases in pectoralis major and teres minor Decrease in activity of latissimus dorsi and subscapularis . Due to excessive scapular elevation needed to replace the lateral body roll of freestyle and to clear hand above the water- more activity in upper trapezius , deltoid and supraspinatus .

33. Wider arm position, which produces an outward rather than upward position of the elbow and an increase in external rotation- more activity in posterior deltoid and infraspinatus and less activity in supraspinatus and subscapularis . At the end of the recovery phase , the teres minor also exhibits decreased muscle activity in the swimmer with a painful shoulder.

34. In swimmers with painful shoulder , there is less activity in the serratus anterior muscle. This muscle is not firing enough to stabilize the scapula or to assist with the pulling of the body over the arm. The decreased firing may be attributable to fatigue . With an unstable or “floating” scapula, the teres minor is unable to control the humeral rotation caused by the powerful pectoralis major. These two muscles which attach to scapula lacks synergistic interplay to assist the propulsion ahead.

35. With a floating scapula during butterfly stroke, there is no stable base and The teres minor and serratus anterior cannot function adequately

36. BACKSTROKE MECHANICS: The backstroke is similar to the freestyle stroke in that the arms stroke reciprocally and are supported by a trunk rotation and a leg kick. backstroke is performed supine . diagonal flutter kick The face is above throughout the stroke, thus no specific breathing pattern. The body rolls in the direction of the arm that is entering the water in order to minimize the lateral motion of the legs and hips. PHASES : Hand entry is by little finger leading towards water. The beginning of the pull-through is marked by the hand entry of the swimmer with the arm extended above the head

37. The mid pull-through phase begins when the humerus is perpendicular to the body. The arm continues to move toward the feet late pull-through , the elbow straightens out with a slight downward press before lifting out of the water to start the recovery phase.( it is important that hand exit the water with the thumb first) recovery phase - The elbow is fully extended throughout and travels straight over the top of the water and overhead to the point of hand entry.

38. MUSCLE ACTIVITY - The muscles most active during the powerful pull-through are the teres minor and the subscapularis . Positioners : the three heads of deltoid, supraspinatus are responsible for placing the shoulder girdle in a position for hand entry and hand exit. Pullers : latissimus dorsi , rhomboids, posterior deltoid, subscapularis and teres minor are active during propulsive phase. depressed activity in the teres minor in the backstrokers with painful shoulders , the rhomboids also exhibit less action. Supraspinatus demonstrates suppressed activiy toward mid pull though in the swimmers with painful shoulder.

39. BREAST STROKE MECHANICS: it is unique in that the arms do not exit the water . the legs are more of the propeller or power drivers than are the arms. This stroke uses a bilateral arm motion in which the arms reach forward and then sweep outward (the beginning of the pull-through ), while the elbows begin to flex. When the hands are in line with the mid-chest, the hands move inward in a circular pattern until they meet in front of the chest and are thrust forward ( recovery ) once again.

40. the body motion in the breaststroke is centered around the hips. Breathing is done by lifting and lowering the head. The kicking motion most frequently used in competition is the whip kick , a symmetric, bilateral action or frog kick. The kick motion starts with the legs fully extended horizontally . The knees bend and move forward as the heels are brought as close to the buttocks as possible . When the heels reach their highest point, the feet rotate outward so that the toes point to the side, and will also move wide of the knees.

41. The knees and feet push backward and inward from that position until reaching full extension with the legs together again. Forward propulsion is generated primarily by the force of the inside of the feet and lower leg pushing directly against the water.

42. Muscle activity The pectoralis major is responsible for powerful humeral adduction and extension to provide propulsion . Serratus anterior is active throughout pull through to stabilise scapula and recovery to stabilize, protract and upwardly rotate the scapula for the forward reach. The three heads of deltoid fires sequencially during recovery in order to position the arms forward. Painful shoulder: breaststroke swimmers with painful shoulders demonstrate an increase in activity in the subscapularis and the latissimus dorsi .

43. The increased subscapularis activity , along with a decrease in the action of the teres minor , leads to a relative increase in internal rotation. The increase in latissimus dorsi action may assist with humeral head depression to relieve the impingement. (during pull through) Activity of serratus anterior also decreases during pull through phase lack of stabilization and upward rotation upper trapezius increaes its activity in order to upward rotate the scapula and relieve impingement During recovery : decreased middle deltoid activity drop elbow to avoid impingement

44. BIOMECHANICAL IMPLICATIONS IN PREVENTING INJURY A hand entry that crosses the midline of the long axis causes mechanical impingement in the anterior shoulder, including the long head of the biceps and the supraspinatus . This is exacerbated by a thumb-first entry that further stresses the biceps attachment to the anterior labrum. A crossover pull-through usually results from a crossover entry and increases the time in the impingement position. Proper body roll, however, can resolve most of the impingement risks, unless the athlete has glenohumeral instability or anterior capsular laxity and concomitant anterior subluxation .

45. Asymmetric body roll or unilateral breathing may increase impingement by causing a compensatory crossover pull-through on the side with less roll or on the nonbreathing side. Improper head position, forward-sloping shoulders, and scapular instabilities are also implicated in arm, shoulder, upper-back, and neck pain that may or may not be associated with neurologic signs and symptoms.

46. Rotating on the axis The correct stroke pattern must be accompanied with equal body rotation to avoid injury. The body must rotate at least 45° from its long axis equally in both directions. The head position should be neutral on the spine PREVENTION IMPROVING MECHANICS

47. Conditioning and flexibility Encouraging the young athlete to participate in a variety of activities that help develop total-body conditioning, muscular strength, and muscular endurance is essential. Preventive Rehabilitation A preventive rehabilitation program should include strengthening the scapular stabilizers, appropriate stretching, and spinal stabilization with core strengthening

48. Strengthening exercises should focus on endurance training of the serratus anterior, lower trapezius , and subscapularis muscles. The four most widely accepted and effective exercises used in clinical practice are scapular elevation ( scaption ), push-ups with a plus, and press-ups. These exercises can be incorporated into a dryland training program for swimmers and should be progressed to three sets done to fatigue. upper-body ergometry can greatly enhance the endurance component of the strengthening of the scapular stabilizers.

49. Muscles at risk during the swim sroke and suggested exercises stroke Muscles at risk Strength or endurance Suggested optimal exercise freestyle Serratus anterior subscapularis Strength Endurance Strength and endurance Push-up Military press Scaption Boxing Medial rotation butterfly Serratus anterior Teres minor Strength and endurance Same Lateral rotation with low loads, more reps backstroke Teres minor Subscapularis Rhomboids supraspinatus Strength and endurance Strength strength Retraction with an isometric hold flexion breaststroke Supraspinatus Upper trapezius Strength strength Shoulder shrugs

50. Serratus anterior Teres minor subscapularis rhomboids

51. Strength training is most effective when done as an isolated workout session. Strengthening exercises done before swimming can fatigue the rotator cuff and possibly increase the risk of injury. Stretching : Swimmers have selective tightness of certain muscles, which may predispose them to anterior impingement. Isolated stretches of the pectoralis major and minor, posterior capsule, and latissimus dorsi are most effective. There should be omission of anterior capsule stretching. Core strengthening: facilitates total kinetic chain transference and ultimately performance.

52. Stretchings a swimmer should NOT do(omission of anterior capsule strtching )

53. Back stretch Hamstring sand back stretch Dorsiflexor stretch Pectoral stretch

54. Warm up/Cool down : Warm up : To prepare all the muscles to be used later when swimming for speed and conditioning, all strokes except the butterfly should be incorporated into the warm-up. The butterfly is too powerful a stroke to be considered warm-up intensity(15-20 minutes). Cool down : rhythmic freestyle and backstroke laps are good choices, avoiding breaststroke and butterfly because they are too intense. A good cool down session will avoid strain on your heart and will reduce muscle soreness.

55. Training and cross-training : Both dry-land and pool-based exercises should focus on building strength and endurance of the muscles involved in swimming as well as increasing core strength, cross-training, and flexibility. Both aerobic and anaerobic training will reduce muscle fatigue and increase endurance. Technique : Proper swimming technique involving stroke, kick, and breathing as well as overall form, force, and streamlining greatly improve the ability to swim without injury.

56. Any position of the body angled from horizontal will increase form drag. Wave drag is decreased in deeper pools and pools using wave-dispersing lane lines.. Body hair, swim suit materials, and swim caps all have an effect on frictional drag. Some swimmers shave their bodies to reduce this force. Streamlining your stroke , reducing drag, timing of force so that it’s at the portion of the stroke that utilizes it most effectively, and directing force so that your effort efficiently propels you in the direction you want to go are all important factors not just in increasing speed, but reducing the counterforces that fatigue body parts and lead to overuse injuries.

57. Factors contributing to overuse injuries Physical factors joint alignment problems, muscle imbalance, inflexibility, muscle weakness, and ligament instability. Nutritional factors During high-intensity workouts, glycogen levels fall to low levels, and if depleted, the body must break down stored fats; an inefficient method of obtaining energy during high energy demand which contributes to fatigue. Stroke mechanics Poor stroke mechanics Training factors There is increased stress to the joints if technical stroke flaws exist. Training too hard and too fast is likely to put the swimmer at risk of injury.

58. Possible mechanisms of shoulder pain in swimmer’s TRAINING MUSCLE WEAKNESS DEFICITS IN NEUROMUSCULAR CONTROL CAPSULAR ABNORMALITIES Faulty stroke mechanics Early fatigue Abnormal loading of soft tissues Serratus anterior and lower trapezius Abnormal loading of GH joint and surrounding soft tissues Temporal problems of neuromuscular dynamic stability of ST jt cause inadequate scapular stabilization. Posterior capsule tightness creates obligate translation of humerus can lead to impingement syndrome. Sudden increase in training loads repetitive microtrauma Inadequate time for tissue recovery Posterior rotator cuff muscles Inadequate GH dynamic stability Early fatigue Temporal problems of neuromuscular dynamic stability of GH jt cause inadequate GH dynamic stability. Anterior inferior hypermobility of GH jt leads to microinstability which in turn can lead to secondary impingement syndrome.

59. Lack of periodization in training High level of swimming experience Elite swimmers train near or at their threshold of injury High percentage of time training with the front crawl stroke

60. It is a condition that has a microtraumatic overuse onset. It has been described as an inflammatory condition caused by the mechanical impingement of soft tissues against the coracoacromial arch. Bak states that shoulder pain in swimmer’s has been regarded as synonymous with coracoacromial ligament subacromial impingement, that is, anterior shoulder pain due to rotator cuff or long head biceps tendinopathy . He also concedes that concomitant glenohumeral instability plays an additional role in creating signs and symptoms of swimmer’s shoulder(secondary rotator cuff impingement due to underlying instability) SWIMMER’S SHOULDER

61. Sources of impingement During pull through phase of front crawl stroke During recovery phase of front crawl stroke The shoulder is placed in a position of horizontal adduction that mechanically impinges the long head of biceps against the anterior part of coracoacromial arch. The fatigued muscles of the rotator cuff act to externally rotate and depress the head of humerus against glenoid and they become less efficient. Supraspinatus becomes mechanically impinged between GT and middle and posterior portions of coracoacromail arch.

62. Double squeeze phenomena (decreased subacromial space) Intraarticular compression by Antero superior glide of the humerus Position of shoulder during pull through Similar to provocative impingement tests- hawkins kennedy and neer impingement: increased internal rotation at the GH joint

63. Stocker and coworkers state that more than 50% of swimmers with shoulder pain in both impingement type groups perceived that increased intensity or distance provoked their shoulder pain. This finding is significant and illustrates that fatigue may be a condition to avoid. A number of swimmers might also have a primary impingement due to abnormal acromial morphology or a selective hypomobility of posterior capsule. Electrical activity measured in 25 breaststroke swimmers showed an increase in activity of the internal rotators muscles in swimmers with painful shoulders. There was decreased activity in the teres minor, supraspinatus and upper trapezius muscles. These factors increased the risk of impingement

64. Classification scheme that divides the swimmer’s shoulder into four phases based on the severity of the symptoms Pain only during workout; does not interfere with performance. Pain during and after workout, which resolves with ice and does not affect performance. Pain during and after workout, which affects performance. Pain severe enough to prevent competitive swimming.

65. Role of laxity in swimmer’s shoulder Shoulder stability is controlled by static and dynamic factors. Loss of static component requires greater contribution from the rotator cuff, which can result in muscle overload and eventual muscle fatigue. The most common pattern of instability is anteroinferior . The risk of subluxation is increased in backstroke if the hand contacts the wall for the turn with the arm in this position of abduction and external rotation. Thoracic outlet syndrome Freestyle, butterfly and backstroke all require a controlled repetitive power motion at the very extreme of abduction and external rotation of the shoulder. Tightness and pain about the shoulder, neck and clavicle at the hand entry position should alert the physician to the possibility of thoracic outlet syndrome.

66. The instability continum Stretching of anterior fibres microtrauma Muscle fatigue or weakness hyperlaxity instability subluxation impingement Rotator cuff tear

67. Signs and symptoms of swimmer’s shoulder SIGNS SYMPTOMS Altered and reduced arc of ROM Pain progression Weakness of supraspinatus and infraspinatus Pain only present during and after workouts Weakness of scapulothoracic stabilizers Pain present that interferes with performance Poor neuromuscular control of ST jt Pain prevents participation Increased shoulder laxity anteroinferiorly Pain at rest or at night Multidirectional instability Dead arm feeling Trunk and abdominal(core) stability deficits Feelings of instability

68. In freestyle swimmers Deviating the head from the axis of rotation i.e. looking or breathing forward repetitively can cause unnecessary neck problems due to the neck adopting an extended and rotated position, which is known to stress the neck Poor body rotation results in over-rotation of the neck in order to breathe In backstroke swimmers prolonged contraction of the anterior neck to keep the face above the water line, a position, which may predispose cervical spine hyper flexion. These muscles are prone to fatigue and can result in muscle soreness afterwards. In butterfly swimmers A weak kick, poor body strength, or a combination of both may result in imperfect clearance of the head and face out of the water causing the swimmer to hyperextend in order to breathe Cervical spine

69. LUMBO-PELVIC COMPLEX Torsional strain can occur when the body does not roll as a whole unit during the stroke causing abnormal loading at the point in the spine where the rolling stops. This predisposes the swimmer to overuse or acute injury or both. Tight hip flexors can reduce hip extension resulting in hyperextension of the lumbar spine and anterior pelvic tilt. In addition, anterior pelvic tilting results in the pelvis assuming a lower than normal position in the water, creating increased drag.

70. The hyperextension motion of the lumbar spine seen with butterfly and breaststroke can predispose to facet joint irritation, otherwise known as “Butterfly back syndrome” If this compression becomes repetitive and chronic, it may progress to low grade joint inflammation , leading to reflexive spasm of the back muscles and pain can occur. With continued repetitive stress, low back problems like stress fractures of the pars interarticularis ( spondylolisthesis ) can occur. Scoliosis

71. BREASTSTROKER’S KNEE Most common in swimmers who swim a lot of breaststroke. Mostly due to the position of the knee during breaststroke kick. The rotation in the kick affects the medial collateral ligament, which runs along the inner side of the knee. If painful exercise does not stop, it can lead to a MCL tear. http:// www.nsmi.org.uk /articles/swimming- injuries.html

72. REFRENCES Athletic injuries and rehabilitation James E. Zachazeuski Spinal musculoskeletal injuries associated with swimming henry pollard, matt fernandez Prevention and treatment of swimming injuries Tamara mitchell Swimming biomechanics and injury prevention james N. johnson Knee pain in competitive swimming Scott A. Rodeo Bilateral and antero -posterior muscular imbalances in swimmers Ted becker

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