The Relationship Between Grip and the Rotator Cuff

A handshake, a grip, physical contact between two people with one of the most densely innervated areas of the body; there is something intimate and telling about it. There is something ultimately manly about a strong grip. You reach out to shake hands and feel a firm strong hand and inherently have respect for this person. If they grip the hell out of your hand, you grip back feeling challenged and in attempt to not come off as a weakling guuurrly man. You all know when you were kids you used to see who could squeeze each other’s hand the hardest before the other person squealed in mercy over the sound of bones crunching. I personally remember my own dad’s grip more than anything. He worked hard labor his whole life and the guy looked like Popeye. Never lifted a weight in his life, had small skinny biceps and legs, but damn he could turn coal into diamond with a simple squeeze of his hand. 

It has been hypothesized that the handshake is a modern day version of an ancient practice in which people grabbed each other’s arms and checked their hands to ensure that no weapons were being carried. The arm-grabbing then turned into hand-grabbing in which one person clasped the other person’s hand in an ‘arm-wrestling’ type position, commonly observed in gladiators of the Roman Empire. The current version is less aggressive and is used in all kinds of meetings be it business or social and helps people 'open up' to each other. It conveys the message, ‘I carry no weapons. I am harmless. You can trust me. We are on good terms.’

With handshakes being such an integral part to our culture one may wonder what else our grip could tell us. Interestingly, there has been some research recently that shows a relationship between grip strength/hand function and rotator cuff strength/shoulder function that should pique the interest of any physical therapist of strength and conditioning professional. Any good strength coach knows the importance of a good grip. If you can’t hold onto the weight, you can’t lift heavy enough to stimulate growth to the more proximal and stronger muscles. Additionally, every physical therapist realizes that the shoulder joint is incredibly complex, and shoulder pain is one of the most common outpatient MSK complaints. In fact some studies have shown that the lifetime prevalence of shoulder pain can range anywhere from 6.7-66.7%.  

So what is the connection between the hand and the rotator cuff? First we will take a look in 1995 and 1996 where Sporrong et al found that in normal healthy subjects, strong hand gripping in various shoulder planes of elevation increased the EMG activity in RTC musculature.  Interestingly, there was a stronger effect found in the higher shoulder elevation conditions. Again in 2011 we see here that even submaximal gripping at 50% MVC elicited significant supra and infraspinatus activity as well as fatigue. Next, a 2004 study conducted by Budoff, revealed that in a sample size of 57 individuals with injury to the hand or wrist there was “A statistically significant decrease in strength was found in the ipsilateral shoulder for both elevation in the plane of the scapula (supraspinatus) and for elevated external rotation (infraspinatus)”.  This is an interesting correlation because it appears to be a bottom up relationship. Injury of the hand somehow was shown to relate to weakness in the shoulder. To follow up on that study, in 2008, Roberts et aldemonstrated what appears to be a proprioceptive relationship between the hand and the shoulder which begins to connect the dots on how a hand injury could have subsequent effects more proximally. Roberts found “for the first time that propriospinal pathways may connect the hand to the rotator cuff of the shoulder. The modulation of facilitation/suppression during the grip-lift task suggests that inhibition of propriospinal premotoneurons is down-regulated in a task-dependent manner to increase the gain in the feedback reflex loop from forearm and hand muscles as required.” What does that mean in regular words? Basically it means that proprioceptive feedback from the peripheral nerves (ulnar in this study) have a direct impact on the excitability of the RTC (infraspinatus in this study) to aid in stabilization of the shoulder during usage of the arm and hand. Finally, and most recently, we see herethat Horsley et al demonstrated that there is a direct correlation between hand grip and rotator cuff strength for the external rotators of the shoulder. 

Hell, this is unrelated, but there even appears to be prognostic value of grip strength for all-cause mortality seen herepublished in the Lancet medical journal. Amazingly grip strength was a stronger predictor of all-cause and cardiovascular mortality than systolic blood pressure. But I digress…..

From the above we can see there that there appears to be quite the relationship between the rotator cuff and grip strength. Likewise, we know that the rotator cuff often plays a role in shoulder dysfunction and rehab, whether it be the injured tissue, or the tissue we tend to focus intervention on when there is shoulder pain. We all know the importance of the RTC, but many of us don’t really understand the function. Most people tend to over simplify the rotator cuff into its individual parts. It’s easy to say the supraspinatus abducts, infraspinatus and teres minor externally rotate, and subscapularis internally rotates. However, looking at the RTC in isolation like this is severally short sighted. The main function of the rotator cuff is primarily to stabilize/compress the head of the humerus in the glenoid through all ranges of active shoulder motion. This makes a lot of sense when you think about what your shoulder should reflexively be doing if you pick of something heavy that requires a strong grip. It should be activating to keep your shoulder stable and from popping out of socket! Much bigger and stronger muscles perform all of the same motions that each independent portion of the RTC performs. The pec major, teres major, anterior deltoid, and lat all internally rotate while the posterior deltoid also helps to externally rotate. So why do we have these redundancies in the body, and why do we have the habit of solely isolating these small motions for rotator cuff specific work?

It seems to me that it could be of great value to start working on rotator cuff recruitment with various gripping, carrying, and proprioceptive exercises at multiple arm elevations. This is where I feel like strength professionals definitely have the drop on rehab professionals. The importance of a strong grip has long been implemented into traditional well round strength programs. Deadlifting twice one’s body weight requires an exceptional amount of grip strength. Farmers walks, pull ups, heavy rows, cleans, etc all require extreme gripping, which in turn as we have come to learn means extreme RTC recruitment to approximate the head of the humerus into the glenoid under the high decrease of traction forces. Additionally, cues to squeeze and crush the bar are regularly used to help a lifter create a more stable base while pressing and move the weight through a cleaner path without struggle. 

(me walking in from the grocery store….team one trip!)

I strongly encourage rehab professionals to take a page out of this book and start using gripping for your patients with shoulder pain. You might be surprised at the results you get. If pain has caused altered muscle recruitment patterns/decreased EMG/decreased stability of the shoulder with movement repetitively activating the RTC with isometrics by gripping is often enough to decrease pain through shoulder elevation as well as start to progressively load an inflamed tendon.  Start with the arm at the side, and then steadily progress to varying elevations and shoulder positions as pain decreases and fear reduces. 

After coming into all the grip research I have personally began implementing prolonged hangs and farmers walks into my training regularly. For example, next time you are in the gym, try to complete 10 pull-ups with a 10 second dead hang between each one. I can assure you that it won’t be your lats that give out first. Additionally, I will sometimes add a heavy dumbbell hold or short farmers walk into my warm up prior to lifting chest, shoulders, or back to strongly activate the RTC and hopefully elicit some degree of post activation potentiation. No research on this yet, but my own humble expert opinion feels that my shoulders have been much happier since I regularly started implementing these activities. 

It is definitely a very interesting connection between the hand and shoulder emerging. I will be patiently waiting for research to continue to be produced in this area and see how we can further evolve our interventions. Until then…..

You better not try to crush my hand with your handshake next time I see you!

Thanks,

Jarod Hall, PT, DPT, CSCS

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