Shoulder Stabilziation for Striking: are you Focusing on the Right Muscles?

When considering upper body striking, martial artists tend to focus on the pectoral, triceps and deltoid muscle groups, and the glenohumeral (GH) joint, which is the most obvious shoulder joint. The GH joint consists of the humerus and the glenoid fossa of the scapula (the “socket” of the shoulder blade). Since this joint is essentially like a ball resting on a shallow dish, and not a deep socket like the hip joint, ligaments and the attached muscles provide most of the stability. There are also three other joints in the shoulder complex that play important roles in maintaining stability for the GH joint, with the scapulothoracic being most prone to abuse in combative training. This joint is formed by the fibrous connection of the scapula to the posterior torso wall, which allows the scapula to glide and rotate as the GH joint requires.

The serratus  anterior and the trapezius provide the ability to adduct (pull close to the ribcage), retract, depress, and upwardly or downwardly rotate the scapulae.  They maintain alignment of the glenoid fossa  with the head of the humerus.  A strong, reasonably flexible rotator cuff group is important, but the trapezius needs to be able to provide rotation and stabilization so that the GH joint stays centered and the rotator cuff isn’t impinged. The trapezius and serratus need to work synergistically with the GH joint movers. Striking in general requires the same coupling of scapular and humeral actions that has been reported for other overhand actions  (Kibler, et. al., 2007) such as the tennis serve.

In cases where scapular stabilization is inadequate, winged scapulae are common. This is an indication that the GH joint is not centered in it’s “socket”, and the common shoulder motions of striking or pushing are likely causing damage to the rotator cuff tendons. Athletes and martial artists who regularly engage in standing striking actions and strength training for this region often develop kyphosis and anteriorly translated, internally rotated shoulders with winged scapulae, which may be a postural adaptation related to practice (Kritz & Cronin, 2008). Functional efficiency might be improved as a result, but the risk  of chronic injuries including thoracic outlet syndrome, biceps tendinitis, glenoid lesions, and rotator cuff damage is increased.

The trapezius, lower fibers are the inverted triangle.

Compound exercises such as the deadlift and pullups can be effective in strengthening the middle and lower fibers of the trapezius (which retract and depress the scapulae), but some specific training is needed to develop coordination between the GH joint’s actions and the stabilization of the scapulae. The upward rotation provided by the upper trapezius and lower trapeezius is especially important. By pulling at opposite ends of the spine of the scapula, the upper and lower trap rotate the glenoid “socket” upward. When reaching overhead, you can (hopefully) feel the shoulder blade rotate as the humerus moves past parallel. “Scaption” exercises with light weights or resistance cables are effective ways to develop this synergy. “Scapular snow angels” are also useful: lie on the floor supine, pass a light resistance cable under the feet and cross so that you are holding the opposite end in each hand, palms facing away from you at about hip level, with some slight tension. Depress your shoulder blades and retract them slightly as you begin abducting your arms (raising them to the sides). As you reach shoulder height, elevate your scapulae as if trying to stretch as far out to the sides and overhead as possible; don’t simply shrug your shoulders to your ears, stretch outward as you elevate.

The serratus anterior is the other important stabilizer during striking. This muscle runs under the scapula (mingling with the rhomboids) and attach to the medial ribcage. They slide the scapula around the chest wall so that the glenoid “socket” remains behind the humerus, as opposed to oblique to the humerus. The SA of a martial artists or fighter may be hypertrophied (larger) from regular striking and pressing exercises, but this does not necessarily enable it to provide dynamic stabilization. A quick assessment can be done by observing an individual as she performs pushups against a wall, leaning at a moderate angle. If the scapulae protrude (wing) from the ribcage, the serratus and lower trapezius fibers are underactive and the pectoralis minor is likely to be tight. In this case, the serratus is maintained in a stretched position, and cannot pull the scapula flat to the ribcage. If retraction is good but winging still occurs, the rhomboids may be tighter and shorter than the SA, and some lengthening and tissue work (via lacrosse ball) may be required to complement the SA strengthening. A basic corrective strengthening exercise can be done by adducting the scapula (pulling it around the ribcage) while lying supine. Hold a light dumbbell or resistance cable in one arm, and reach upward as far as possible without the rest of the back leaving the floor. If you place your fingers on the side of the ribcage a few inches under your armpit, you should feel several muscles contract over the ribs.

It’s important to note that the trapezius and SA are active in both exercises. Strengthening of each is part of the goal, and promoting better coordination between them is the other. If limited prorioception makes it difficult for an individual to notice the correct movement pattern vs. the impaired one, contact with the wall, floor or a partner’s fingers can provide feedback as they attempt to depress, retract, rotate (upwardly or downward), and adduct the scapulae. A basic corrective program should target stretching for the pec minor and major before the  exercises, although other muscles that attach to the scapulae may be involved. Begin both sets of exercises with:

  • a light load (1-5 lbs.)
  • higher reps (in the 12-15 rep range)
  • moderate volume (3-4 sets)
  • a low tempo exercises, emphasizing the isometric and eccentric phase of scapular rotation and adduction (arms returning to sides)
  • perform relevant stretches and exercises before training to promote better shoulder joint synergy, and on off days to reinforce it in daily life.

A coach or partner can observe your scapulae to ensure that they maintain a neutral position throughout, instead of winging. After performing the exercises without loss of form, integrate the scapular movement pattern into light shadow boxing, or upper-body elevated pushups, with an emphasis on maintaining scapular rotation as the humerus moves into striking positions.

References:

Ebben,, W.P., & Blackard, D.O. (1997). Developing a strength-power program for amateur boxing. Strength and Conditioning,19(1), 42-51.

Kibler, W.B., Chandler, T.J., Shapiro, R., & Conuel, M. (2007). Muscle activation in coupled scapulohumeral motions in the high performance tennis serve. British Journal of Sports Medicine, 41, 745-749.

Kritz, M.F., & Cronin, J. (2008). Static posture assessment screen of athletes: Benefits and considerations. National Strength and Conditioning Association, 30 (5), 18-27.

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