There are a variety of tools that you can use to improve your force output. Proper warm-ups, mobilization techniques, good sleep, adequate fuel, fish oils, and a list of other things can improve your overall capacity on any given day. Most athletes would argue that technique and form are paramount as well. I would agree. This being the case it makes a lot of sense to try and understand the biomechanics of force production in a particular joint in order to improve capacity under load. Simply relaxing one muscle or activating another will improve the mechanics of the joint and maximize force production. In other words you may be missing out on some PR’s.
Today we’re going to focus on the mechanics of the shoulder. Remember, this is not an article on technique. Additionally, many lifts are compound movements requiring multiple joints to function optimally so improving the function of the shoulder solely will be unlikely to make dramatic changes. For some, however, it may be all they need to get the extra pull they’ve been missing.
This article is more about the current composition of your body. The way your body fires in certain movements, and possible hindrances to maximum output. This article will show you common imbalances and provide you with a quick program to eliminate those mechanical flaws.
Most people are under the impression that the rotator cuff is responsible for rotating the humerus, but the primary role of the cuff is to stabilize and elevate the arm in the scapular plane. Mild contraction of the rotator cuff is all that is necessary to stabilize the joint during movement. The rotator cuff helps to keep the head of the humerus centrally located while big movers do the work. Before we get into specifics we have to discuss “force coupling” in the joint for better clarity.
There are two major force couples to understand in the shoulder. These are the 1) deltoid/rotator cuff, and the 2) scapular rotators. Three of the four muscles of the rotator cuff (subscapularis, infraspinatus and teres minor) compress the humeral head into the glenoid for fluid, congruous movement. This force opposes the elevation from the deltoids allowing the humerus to depress in the fossa and allow for full overhead positioning. This force couple allows for maximum output overhead. The required deltoid power in abduction of the arm has been shown to be 41% less when the cuff is firing as a couple with the deltoids. That’s a HUGE number.
Toning it back a bit, if your rotator cuff is not active in your movement you will decrease your capacity on your pulls, pushes and presses. Basically, if the rotator cuff is not working correctly the shoulder cannot achieve maximum force output.
In the second group, the serratus anterior couples with the upper trapezius and lower trapezius muscle to produce upward rotation of the scapula. With proper rotation, the tension-length ratio of the deltoid is maintained.
From Dr. Phil Page’s book Assessment and Treatment of Muscle Imbalances, “Proper balance of the trapezius and serratus force couple is believed to reduce the superior migration of the scapula, improve posterior scapular tilt, facilitate optimal glenohumeral congruency, and maximize the available subacromial space…to avoid impingement.”
In English, if your serratus anterior, lower traps and middle traps are not activated at the right time, the upper trap will tend to become overactive in the movement leading to scapular elevation as opposed to upward rotation. If the lower trap is inhibited the shoulder will lose strength causing the infraspinatus (part of the rotator cuff) to overwork from lack of deltoid force. Any of you have trigger points or tenderness right here?
Let’s back up a second and understand that “activation” is not necessarily strength. Our lifestyles, traumas, pathology, posture and repetitive motions can essentially lead to altered movement patterns. These are biomechanically inefficient patterns. This has nothing to do with weakness either. Some muscles are simply prone to becoming inactive. What you’re reading about is essentially the cause of most secondary impingements, tendonoses, thoracic outlet syndromes, and rotator cuff damage. Aside from setting you up for injury it could also be hindering your force output.
Ensuring that your upper trap, levator scap and pecs are not shortened or overactive is the first step. Shortened muscles will inhibit their antagonists. After that it’s important to make sure that the serratus anterior, lower trap, middle trap and rotator cuff are active in your shoulder movements. If the joint is balanced it will be able to work with maximal force.
Below is an outline of a brief program that can help to minimize your chance of having imbalances in the shoulder. Remember that this is not a fix-all program. If you truly have muscle imbalance disorders, which nearly everyone that walks into my clinic has, you may need a qualified professional to evaluate you. This is at least a good catch-all to get you going. The video at the end of the article has a quick pre-workout activation program to get the shoulder girdle prepared for activity along with some simple ROM exercises. The general rules are:
1) Keep the upper traps, levator scapulae and pecs loose and relaxed. There are a million stretches, soft tissue systems and PNF techniques to accomplish this.
2) Increase ROM in the posterior capsule of the shoulder if you’re reduced in internal rotation.
3) Activate your middle trap, lower trap, serratus anterior and rotator cuff while bracing through the abdomen.
4) Perform the activation exercises bilaterally.
5) Don’t work these muscles to fatigue as that will be counterproductive. Focus on proper mechanics.
6) Remember the muscles just need to activate, you’re not trying to PR on these exercises. Once they are activated they will do their jobs. Do a handful of reps with each exercise.
A few more things that you need to know. Core activation and abdominal bracing supersede shoulder imbalances. If you’re not activated in your abdominals you have no chance of fully stabilizing in the shoulder girdle. This goes for your lifts as well. On the resistance movements in the video utilize a 1:2 concentric to eccentric ratio with respect to the movement. Eccentric contraction facilitates muscle activation more quickly. Do not perform static stretching prior to performance as it may hinder you. Do not work to fatigue with the activation exercises. And most importantly, never pass up an opportunity to PR!
Stretches for upper trap, levator scap, pecs (Use contract-relax if you know how)
Posterior Capsule mobilization
Oscillatory Movement (activate LT and SA) with FlexBar
Side-lying external rotation, flexion, extension (activate MT, LT, and SA)
Full can (to activate rotator cuff)
Retraction with external rotation (activate scap rotators and rotator cuff)
Serratus Hug (activate SA)
Dr. Kevin Kerchansky, DC, DACRB, CSCS, CICE
Dr. Kerchansky is the Director of Physical Rehabilitation at Triad Pain Management Clinic, a multidisciplinary, functional rehabilitation facility in Tempe, Arizona. He is a Board Certified Diplomate to the American Chiropractic Rehabilitation Board, and has been certified to testify in court as an expert in Clinical Biomechanics. Dr. Kerchansky is a post-doctorate educator at Northwestern Health Sciences University, currently conducting seminars around the country on the Functional Rehabilitation of injuries. His pursuits have also led him to credentialing through the NSCA, USAW, CrossFit, and various other sport systems.
Cools et al., 2003. Scapular muscle recruitment patterns: Trapezius muscle latency with and without impingement symptoms. Am J Sports Med 31(4): 542-9.
Cram and Kasman. 1998. Introduction to surface electromyogdaphy. Gaithersburg, MD: Aspen.
Liu et al 1997. Roles of deltoid and rotator cuff muscles in shoulder elevation. Clin Biomech (Bristol, Avon) 12(1): 32-8.
Lucas 1973. Biomechanics of the shoulder joint. Arch Surg 107(3):425-32
Ludewig et al. 2004. Relative balance of serratus anterior and upper trapezius muscle activity during push-up exercises. Am J Sports Med 32(2): 489-93
Mottram 1997. Dynamic stability of the scapula. Man Ther 2(3): 123-31
Otis et al. 1994. Changes in the moment arms of the rotator cuff and deltoid muscles with abduction and rotation. J Bone Joint Surg Am 76(5): 667-76
Perry 1978. Normal upper extremity kinesiology. Phys Ther 57(3): 265-78
Sarrafian 1983. Gross and functional anatomy of the shoulder. Clin Orthop Relat Res 173: 11-9
Sharkey, Marder and Hanson 1994. The entire rotator cuff contributes to elevation of the arm. J Orthop Res 12(5): 699-708.
Sherrington, C.S. 1907. On reciprocal innervation of antagonistic muscles. Proc R Soc Lond B Biol Sci 79B:337