Applying Sherrington's Second Law To Kettlebell Arm Bars For Improved Shoulder Function

Charles Scott Sherrington was an early 20th century Nobel Prize-winning neurophysiologist who made huge contributions to our understanding of neuromuscular function, He contributed significantly to the fields of neurology, motor development, and exercise training. Unfortunately, his important neuromuscular findings are not known by many trainers, coaches, or therapists. However, Sherrington's laws provide crucial insight into how we move. Applying Sherrington's laws (which were discovered almost 100 years ago) can be very helpful to improve your health, movement patterns, and performance.

Sherrington's Second Law, known as the Law of Reciprocal Inhibition, states that when a muscle contraction is stimulated, there is a simultaneous inhibition of its antagonist (the muscle that provides the opposite function at a joint). For example, your leg muscles need to rhythmically contract and relax when walking or you will walk like Frankenstein! Reciprocal Inhibition is an integral part of human movement, but is not known widely understood or applied in fitness training.

How do you use this knowledge in the gym?

Sherrington's Law of Reciprocal Inhibition can be applied in the gym in many ways, but I found a very effective way to use it in my training. Shoulder dysfunction is a prevalent issue in our population. Many people have developed limited shoulder range of motion and poor stabilization of the inherently unstable shoulder joint. Hence, the great levels of shoulder aches and pains in the American population. Sitting all day with your arms by your side doesn't help.

The kettlebell Arm Bar is a relatively unknown exercise that is effective at restoring shoulder function (range of motion, stability, strength) and uses Sherrington's Law of Reciprocal Inhibition. Check out the video below of me performing the kettlebell Arm Bar.



The Pectoralis muscles (chest) and Latissimus Dorsi (upper back) muscles are usually very tight. Additionally, the smaller muscles that stabilize the shoulder can be underactive (hence the dysfunction). The kettlebell Arm Bars use Reciprocal Inhibition to facilitate the Pectoralis and Latissmus Dorsi to relax as you move from supine (lying on your back) to prone (lying on your stomach). With each repetition you alternate between Pectoralis and Latissimus contraction-relaxation. You will feel more stable and gain more range of motion with the shoulder as the larger, tighter muscles relax and the smaller, stabilizing muscles become more active.
The kettlebell Arm Bars have become a staple in my training and most of my clients' training. I find they are more efficient and effective than using multiple stretches and multiple stabilizing exercises.

While everything in fitness is marketed as new, revolutionary, and cutting edge, we often overlook a plethora of knowledge that already exists on neuromuscular function that can (and should) be applied to our training in the gym. I think we sometimes forget that muscles are simply the hardware, while neurological control of muscular movement (which can be extremely complex) is the software. The hardware's performance (and our performance) is dependent upon proper control by appropriate software. Trainees and trainers who fail to understand this relationship will be never be able to fully understand neuromuscular function and its significance to movement and performance. While neuromuscular laws like Reciprocal Inhibition will never make the cover of Shape magazine, using them with basic tool like the kettlebell can make your training highly efficient and highly effective.