FURTHER DISCUSSION

Trainers and sports therapists need to prevent shoulder injuries in athletes by implementation of exercise intervention to modify suboptimal physical characteristics (Oyama et al., 2008). Research has contributed to understanding the kinematics of sport and the load on the athlete’s shoulder. Few studies have, however, looked at the physical makeup of the athlete using clinically measurable methods. If screening and exercise intervention is going to be used to prevent athletes from injury, then it is important to determine whether altered motion patterns observed in athletes are

158 of athletes who place high demands on their shoulders is to enhance athletic performance, extend longevity, and prevent injury (Silliman & Hawkins, 1991). But the demands on the shoulder during athletics often times exceed the physiological limits of the shoulder and results in injury (Silliman & Hawkins, 1991). Understanding the sporting activity, the anatomy of the shoulder girdle and the biomechanics of the shoulder girdle are all essential to restore normal anatomy and physiology, and clinical research is essential to this understanding (Silliman & Hawkins, 1991). Clinical measures as used in this study are important for sports therapists and trainers. The demands that sport places on the shoulder are great, and require interaction between the GHJ and Scapula kinematics (Kibler, 1998). A high incidence of shoulder problems is reported in the literature in athletes, but other than identifying the repeated throwing action as a contributing factor, there is little evidence regarding causation (Webster, Morris, & Galna, 2009). Repeating clinical evaluation throughout rehabilitation informs the choice of treatment. Screening and prehab of physical characteristics in the shoulder needs to be sport-specific and the link between physical characterises and sport proficiency needs to be established (Sell, Tsai, Smoliga, Myers, & Lephart, 2007). Scientific evidence is necessary to produce normative data regarding what physical characteristics improve performance in sports, as this will give clinicians parameters for training programs.

159 4.2 Sport specific adaptations in the elite golfer’s shoulder

INTRODUCTION

Shoulder problems in golf

In professional golf, the shoulder is the third most commonly injured area (Gosheger, Liem, Ludwig, Greshake, & Winkelmann, 2003). The lead shoulder is three times more likely to be injured than the dominant shoulder (D. H. Kim, Millett, Warner, & Jobe, 2004). A study (Jobe & Pink, 1996), reported that 93% of shoulder injuries in the golfer were due to Rotator Cuff disease or sub-acromial impingement. The professional golfers swing, which is complex and repetitive, can be repeated as much as 2000 times per week (Jobe & Pink, 1996).

GHJ rotation in golf

Kinetics and kinematics using 3D analysis techniques of the swing are bountiful (Hume, Keogh, & Reid, 2005). Using 3D swing analysis, the dominant shoulder external rotation at top of back swing ranged from 78°-102° and in follow-through, external rotation in the lead shoulder ranged between 59°-80°. This depended on age and level of proficiency the player (Burden, Grimshaw, & Wallace, 1998; Hume et al., 2005). Range of motion in all directions in the lead shoulder is considered to determine the length of the back swing (Hume et al., 2005). From these data an asymmetry could be expected in passive range of the golfers’ GHJ rotations. Kinematic assessment of flexibility during the golf swing is prolific (Hume et al., 2005; Mitchell, Banks, Morgan, & Sugaya, 2003) but there are few studies which investigate physiological GHJ rotational ROM which is important because the passive GHJ ROM will determine the range the golfer can achieve during the swing (Keogh et al., 2009; Sell et al., 2007).

160 Rotation of shoulder affects club-head speed and hence ball distance (D. M. F. Smith, 2010). In older golfers, greater shoulder ER correlated to lower handicaps (Keogh et al., 2009), More proficient players are noted to have more dominant shoulder ER than less able players (Sell et al., 2007). Physical screening of golfers to assess shoulder flexibility is important as this flexibility is required to ensure power during the dynamic movement of the golf swing (D. M. F. Smith, 2010) but it needs to be based on results from scientifically rigorous and reliable screening (D. M. F. Smith, 2010). To date, no literature has investigated this variable in the professional elite open golfers.

In previous literature reporting GHJ ROM in golf, the sample population, though referred to as “elite golfers” only had handicaps less than five (Brumitt, Meria, Nee, & Davidson, 2008). A study compared sides in 24 male golfers, finding no statistical difference between sides for IR and ER. This study concluded that in golf no unique passive GHJ ROM pattern existed. In this same study (Brumitt et al., 2008) the mean age of the included golfer was 39.67 range with a range from 24 to 57 and this may have skewed results as older golfers are reported to have as much as 38° less GHJ ER than younger players (Mitchell et al., 2003). GHJ rotation ranges are reported to be greater in more proficient golfers (Sell et al., 2007).

The anatomical makeup of the body of a golfer will determine the dynamics of the golf swing (D. M. F. Smith, 2010).Data relating to the physical characteristics of proficient professional elite players would therefore be useful. It would help to understand what the optimal physical attributes in the shoulder of golfers are. Golfers have to be able to achieve and sustain movement positions

161 between and during the swing to execute an effective swing and shot, and so limited ROM in the shoulder could result in a poor swing technique

Pectoralis minor length in golfers

High levels of pectoralis muscle activity are observed with EMG during the acceleration phase of the golf down swing (Jobe & Pink, 1996). High muscle torque at each joint in the kinetic link aggregates to produce a resultant torque which dictates club head velocity which in turn is linked to driving distances (Keogh et al., 2009). The overall resultant torque or angular velocity and the length of the lever determine linear velocity and, in the case of golf, the club head speed. The golfer’s arm length and the length of the club are finite (Hume et al., 2005). To generate a longer lever on the back swing, however, the golfer may use the extremes of external (in the dominant shoulder) and internal (in the lead shoulder) rotation in the shoulder. This challenges the pectoralis muscles in the golfer to generate power but also to allow extremes of shoulder ROM during the golf backswing. This muscle is required to have strength and flexibility in golfers. The stretch-shorten cycle and the X factor stretch in golf have been proposed as underlying mechanisms for improving power and generating greater club head speeds (Hume et al., 2005). The short stretch cycle theory is that a short stretch followed by a contraction (shortening) of the muscle increased elastic energy, enhancing the power of the concentric contraction (Hume et al., 2005). In the backswing the golfer maximises the short stretch cycle by stretching the hip, trunk and shoulder musculature (Hume et al., 2005). The pectoralis muscle would be a strategic part of this kinetic link.

162 Scapular position in golf

No previous literature quantifying Scapular position in golfers was found. The turn of the hip relative to the shoulder is the X-factor in golf and a longer X-factor is associated with a longer driving distance. Computer simulation suggests that a greater distance is shot off the tee if the length of the back sing is increased. As mentioned previously, the resting pectoralis muscle length, and the dominant shoulder GHJ ER ROM, and the lead shoulder GHJ IR may affect the X-factor stretch in golfers. Because Pectoralis Minor extensibility is a factor which can influence Scapular upward rotation. In the same vein, it is proposed that the degree of upward Scapular rotation in the golfer may also enhance the X-factor length.