During the IX Winter Olympic Games in Innsbruck, Austria, athletes from 12 nations competed for the first time in the sport of luge. Since this time, luge has grown in popularity within the European nations and continues to be an Olympic sport with athletes from the United States competing yearly at the World Cup level (19). The majority of research conducted on the sport of luge over the past 20 years has originated from Germany, but little has been published (18). In 1988, one of the only off-season conditioning programs for luge was published in the United States (8). Most recently, researchers from Austria published articles addressing the performance factors specific to the luge start, which according to the experts is a critical component for success in achieving a fast time (18,2). Both these articles have focused on year round conditioning and screening of athletes, addressing general overall strength needed to excel in the sport of luge (18,2). It is obvious that strength and explosive power are key attributes needed for any athlete to be successful in his/her given sport. Specific to luge, it is well accepted that a fast start is critical to achieving a fast overall race time, considering that the difference between finishing first and second may only be separated by one thousandth of a second (18,2). Luge athletes train year round to develop explosiveness in the hopes of improving their start times (18). The importance of sport-specific training cannot be understated. However, neglecting the scapulothoracic stabilizers may predispose the athlete to shoulder injury, which could have a negative effect on an athlete's start technique. The purpose of this article is not to present a year round strength and conditioning protocol but rather to focus on some elements specific to the shoulder girdle complex as it applies to the luge start.
THE LUGE START
There are roughly 5 phases to the start, although a sixth has been described (Table). They are the (a) block, which consists of grasping 2 handles (sled is forward placing the shoulders in extension); (b) compression (sled is back, there is an excessive trunk flexion, which places the shoulders in a position of horizontal abduction and internal rotation); (c) pull; (d) extension; (e) push, ultimately leading to a series of 3-4 paddles (the 6th phase) accomplished through shoulder flexion, extension, and internal rotation (18). The explosiveness and repetitive nature of these movements may eventually lead to an overuse injury, especially if there is a muscle imbalance present.
The rotator cuff muscles—specifically the subscapularis, infraspinatus, and teres minor—stabilize the humeral head, allowing the deltoid and supraspinatus to initiate abduction, which creates a force couple needed for efficient movement at the glenohumeral joint (GHJ) (9,1,11). Likewise, the force couple for scapular stabilization consists of the upper and lower trapezius in concert with the rhomboids and serratus anterior (SA) (11). Under ideal conditions when all these muscles are firing in sequence, normal biomechanics of the scapulothoracic (SCT) joint and GHJ exist. This has been described as scapulohumeral rhythm and occurs with flexion, abduction, and elevation of the shoulder coupled with rotation of the scapula (16). Both these joints must move unimpeded and in synch to obtain the necessary range of motion (16) needed to accomplish sport techniques, such as throwing, rowing, and paddling.
In the overhead throwing athlete, force production is initiated through a well-timed sequence of movements summating from joint to joint and terminating at the distal segment, the hand (11). In regard to the luge start, force is generated primarily by the explosive phases of compression, pull, and extension. The athlete is using his/her body like a slingshot off the handles summating with a series of paddles on the ice. It has been described in the overhead throwing athlete that fatigue of both the rotator cuff and SCT stabilizers will negatively affect the ability of the supraspinatus to stabilize the humeral head and alter scapulohumeral rhythm during elevation of the arm (14). This alteration may eventually lead to impingement, which inhibits the ability of these muscles to fire in sequence (14,11,17). Likewise, fatigue and/or weakness affecting both the rotator cuff and SCT stabilizers could result in the disruption of this critical sequence of movement important for the execution of the luge start. Both these conditions—weakness and fatigue—can alter the scapulohumeral rhythm and positioning, ultimately leading to injury to the GHJ (17,14,11). During the competitive season, it is not uncommon for luge athletes to have 2 practice sessions per day throughout the week before a race. This would entail approximately 6-8 starts at 3-4 paddles each depending on the length of the start ramp. In addition, athletes may then return to the track to specifically practice their start technique in a specially designed facility. Likewise, this may include approximately an additional 10-20 starts at 3-4 paddles.
Senior-level luge athletes may perform approximately 250-300 starts during a season. It would appear that the need for prehabilitation and rehabilitation exercises adopted by overhead throwing athletes to strengthen the SCT and GHJ could benefit the luge athlete. Paine and Voight (17) stated that exercises incorporated for rehabilitation of the shoulder should focus on “muscles that control the position of the scapula.” Once incorporated, this will help maintain scapulohumeral rhythm during GHJ movements (17).
The well-timed sequence of GHJ and scapula positioning requires coordinated muscle activity and balance to obtain functional stability (4). Cools et al. (3) examined 12 exercises commonly used in the clinical setting to rehabilitate the SCT joint and GHJ and determined that the following 4 were instrumental in maintaining SCT balance: (a) side lying external rotation, (b) side lying forward flexion, (c) prone horizontal abduction with external rotation (T-raise), and (d) prone extension. The exercises presented above should be considered when designing a year round strength and conditioning program for a world-class luge athlete, especially when addressing issues specific to the start technique. Prone extension, side lying external rotation, and T-raise demonstrated early activation of the middle and lower fibers of the trapezius before activation of the posterior deltoid and fibers of the upper trapezius (6,3). Activation of these portions of the trapezius act to stabilize the scapula during active movements at the GHJ (6), which can be applied directly to the luge start. In regard to the compression position of the start, upward rotation of the scapula is achieved through synergistic activity of the trapezius and SA (7). There are a variety of exercises—SA punch, dynamic hug—that could be incorporated to activate the SA. However, the testing procedure used to assess maximum electromyographic (EMG) activity while performing these exercises has come under scrutiny (7). Performing scaption above 120° in a standing position generated higher EMG activity of the SA (7). This exercise should be included, and specific to a luge athlete be performed in a seated position (Figure 1). Athletes experiencing shoulder pathology could perform this exercise in a supine position, thus minimizing the effects of gravity and progress to a seated position of scaption below 80°, which would activate both the SA and supraspinatus (7).
Having witnessed luge athletes from numerous countries, they typically perform a variety of common rowing exercises to strengthen their upper and mid back, for example, prone barbell row, low cable row, and 1-arm dumbbell row. Interesting enough, EMG research has demonstrated that there is low activation of the lower trapezius during these movements (3). It has been demonstrated that the middle trapezius and lower trapezius are activated earlier than the upper trapezius during the prone extension, side lying external rotation, and T-raise (6). In addition to the rowing exercises described above, luge athletes also incorporate into their year round strength training program weighted pull-ups and front lat pull-downs. The nature of the sport is very “lat dominated” because of the start technique and subsequent paddle maneuver. Incorporating the 4 GHJ and SCT exercises presented could help in maintaining proper positioning of the scapula during the compression phase. Overdevelopment of the upper trapezius as a result of presetting the scapula in an elevated position while performing weighted pull-ups could alter the timing pattern of the SCT muscles during dynamic movements, thus negatively affecting SCT kinematics (6,4). Performing a prone arm raise above the head in line with the fibers of the lower trapezius (also referred to as a Y-raise; Figure 2) could be added to isolate the lower trapezius (7), thus counteracting any perceived muscle imbalance, while simulating the positioning of the arms and scapula relative to the compression phase.
Traditionally, forward flexion at the GHJ is performed in a standing position. In doing so, it has been reported that there is higher activation of the upper trapezius because of the effects of gravity (3). Therefore, it is recommended that individuals with an upper trapezius-lower trapezius muscle imbalance perform this exercise in a controlled manner while in a side lying position to activate fibers of the middle trapezius (3).
It is recommended that side lying external rotation be performed in the position described above with the arm abducted to 30° to ensure normal biomechanics and sufficient vascular supply to the rotator cuff (12). In regard to prone extension, one could progress to performing shoulder extension while seated on a bench using rubber tubing (Figure 3), which is a more functional position specific to the paddle portion of the start. Additionally, the luge athlete could progress to performing this exercise seated on a bench while in the compression position at a high rate of speed simulating 3-4 explosive paddles (Figure 4). The focus should be flexion at the hips while maintaining a lordotic curve of the lumbar spine throughout the exercise. Caution should be used here because the cumulative effects of repeated loading of the lumbar spine, while in a flexed position (as seen in the luge start), could ultimately lead to tissue failure and subsequent disc loading (13).
The side lying forward flexion exercise could be adapted and performed with tubing, while seated on a physioball (Figure 5). The focus here should be on explosive speed to assist with the push phase off the handles, positioning the arms to engage in the paddle sequence. Another exercise that could be implemented is a power push-up using a band wrapped around the athlete's upper back (Figure 6) and incorporating maximum scapular protraction while the elbows are fully extended (15). Again, this could be incorporated to assist with the push phase of the start, while activating the SA as well (7,15).
CONCLUSIONS AND RECOMMENDATIONS
The nature of the luge start is extremely explosive. Combined with the repetitive motion of the paddle maneuver, this may lead to an overuse syndrome, affecting the SCT joint or GHJ. There is evidence that when primary impingement of the supraspinatus is present, overtime, there is both a decrease in fast twitch fiber diameter and the number that could lead to a loss in reaction and precision of movement at the GHJ (10). In addition, activation of the middle and lower fibers of the trapezius during active movement are delayed in patients exhibiting impingement or instability at the GHJ (6,4). Patients who have been diagnosed with an impingement have also presented with a delay in the firing pattern of the middle and lower trapezius on the uninvolved side as well (4). This is evidence for the need to include bilateral SCT and GHJ strengthening exercises, especially because it applies to the sport of luge where the start phase and the subsequent paddles are critical for achieving a fast time. The need for uninterrupted coordinated movement of the SCT and GHJ muscles may be advantageous for the purpose of summating and generating force (11,6). It would appear that a kinematic and kinetic analyses of the luge start to establish timing patterns and force production of the SCT muscles seems warranted.
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Keywords:© 2011 National Strength and Conditioning Association
luge start; scapulothoracic stabilizers; glenohumeral joint; rotator cuff