Pull Ups are perhaps one of the best upper body strength exercises. Training predominantly your ability to lift your own body weight (plus if you invest in training hard enough a bit more) they are an exercise that deserves it’s place in most strength and conditioning coaches toolbox.
That said with the advent of higher intensity conditioning programmes which are en-vogue pull ups have transcended away from being a strength exercise in to what could be termed a high rep conditioning exercise. When programmed with high rep bench pressing, press ups or shoulder press it adds a lot of stress to a joint that craves stability.
When you perform high repetition work we create fatigue- this is great for conditioning. Not so great though if stronger and more dominant muscles start to do the work of other muscles. This is where we get muscle imbalances and ultimately injury. Almost everyone reading this probably has had a niggle or injury in the neck or shoulder so it makes sense that your training does not cause these niggles…. indeed it should act against the imbalances developed in day to day life should you be a full time athlete or indeed a full time desk athlete.
There are a number of reasons I avoid high rep upper body training in compound exercises in my programmes.
Take the example of a pull up…
1. Bad form uses momentum to mask fatigue.
2. If momentum is masking muscular fatigue then where is force being generated from?
3. At the base of the movement the shoulder joint is being forced forward (out of socket) to induce a recoil to propel you upwards.
4. All though in some “kips” the individual generates force from the legs being in front of the body and throwing them backwards. In this context the shoulder is not hyper extended at the base of the movement. That said it is still a major challenge not to hyper extend the shoulder at the base of the movement- especially if performing multiple repetitions.
To refine this point I want to go back a bit to human anatomy.
Your shoulder joint or specifically the top of your humerus is held in place by a multitude of musculature. This musculature is designed to stabilize the humeral head and control movement. I have in the past heard it described as a golf ball on a tee with the wind blowing in 5 different directions.
NB This is a great read if you are a personal trainer/ strength coach/ anatomy geek. Skip a few paragraphs if the why doesn’t interest you too much
The rotator cuff aims to internally and externally rotate the humeral head as well as playing a role in maintaining the humeral heads position during movement. If you generate force by momentum what is holding on to your humeral head to stop it’s hyperextending if it can’t keep it’s position?
Specifically from a muscular sense the dynamic stabilisers muscles such as the supraspinatus which resists superior and inferior translation of the humeral head and subscapularis which resists anteroinferior translation. During movement the rotator cuff muscles are active throughout. Infraspinatus, subscapularis and teres minor produce an inferior shear force to counteract movement. Supraspinatus generates a compressive force across the glenohumeral joint. The force couple resulting from these actions maintains the humeral head centred on the glenoid to within 1mm throughout the range of motion. This is known as dynamic functional stability.
Non anatomy geeks resume here…
In a “normal” shoulder (which is often hard to find in the average office worker and definitely not in the swimmers and tennis players I work with) the actions of the internal rotators (subscapularis) and external rotators (infraspinatus) are balanced but the internal rotation action is enhanced by the action of pectoralis major.
If an individual over uses the shoulder, fatigue is likely to take place in the external rotators before the internal rotators resulting in an imbalance. This will cause the control of the humeral head position to be lost (it sort of highlights that doing a load of theraband external rotations and labeling it as shoulder rehab perhaps is not the best course of action as well as it does not influence dynamic stabilistation of the humeral head).
The humeral head impinges against the coracoacromial arch with resultant compression of the subacromial bursa and pain in the epaulette region and the upper arm/front of the shoulder. Sorry slipped in to anatomy again…. in simple terms this is an instability impingement and everything gets sandwiched together causing pain.
In individuals who work with the hands overhead e.g. throwing athletes and swimmers the role of the external rotators is pertinent as it acts as a humeral head depressors keeping the humeral head in place. Repetitive activity at this level resulting in fatigue of the external rotators meaning depression is not maintained and impingement may occur. This also highlights how shoulder laxity develops in to instability when fatigue becomes an issue.
It’s not all just about the rotator cuff though. Shoulder instability can be found if the scapular stabilisers are fatigued. Specifically subscapularis and the serratus anterior which control the scapular which if fatigued means that during scapular elevation impingement may occur as a product of scapular instability.
Again in more simple terms…. Your shoulder blades stability effects how the rotator cuff works- poor shoulder blade strength and stability therefore can result in poor humeral head stability.
It has been suggested that once instability impingement occurs then stretching of the anterior capsule takes place and a tightening of the posterior capsule occurs. Often in shoulder problems the stock recommendation is to “stretch your chest”. This may result in more anterior stretching and begin to put movement in to an unstable range of movement. This so-called capsular tightening predisposes to further anterior translation (forward movement) of the humeral head thus contributes to impingement.
So in round up…. stability of the shoulder blade leads to stability of the humeral head. Humeral head position is a product of maintaining stability. Excessive strengths or weaknesses acting upon the scapular or humerus can cause a imbalance which may lead to injury.
But how does this relate to high repetition training? There is always going to be an adaption to training but the key is to maintain suitable joint integrity. In high rep circuits the prime mover big muscles will overpower the stability based muscles. Typically we will say the exercise is in poor form as the exercise is performed in poor posture.
The one question you need to ask when training the upper body (as pretty much every movement from pull ups to bicep curls and the Olympic lifts will effect shoulder joint positioning) is what is the effect on scapular stability or numeral head stability, does the movement look good enough to broad cast or has fatigue masked form. Form should always be maintained when you consider the risk and reward of the exercise choice, intensity and volume.