In Parts 1 & Part 2 of ‘Understanding Hand Exercise and Grip Strength’ educational series, we went over the 18 muscles of the hand. This is such key information as a starting point.

9 muscles open the hand and 9 muscles close at hand. It sounds so simple, but now you ALSO realize that these muscles have great reach, not only within the hand but to the fingers, thumb, wrist, carpal tunnel, forearm, and elbow. The veil is off. Hand strength and grip training is no small subject. It relates to everything that happens to the mid and lower arm… and maybe even further.

Now let’s shed some clear and bright light on another new and vital grip concept that you will likely have little idea of, yet utilize every day. It is referred to as the ‘kinetic chain of grip,’ or in other words,‘the sequence of muscle contractions that occur in order to grip something, grab something, or move the fingers and thumb to perform various actions.’ It is how your hands work. And, once you know it, you will wonder how you as an individual or we as a health- and fitness-conscious world ever trained the hands as we did.

‘The kinetic chain of grip’ refers to the cooperative contraction of distinct muscle groups to produce a final desired action of grip. In order for grip to occur, the body, in its wisdom, must stabilize its base so as to connect ‘the peripheral with the proximal.’ In simpler terms, it would appear to do no good to grip a baseball with the fingers and thumb alone if the wrist were not stabilized. The ball, fingers, and thumb would simply just hang there. That picture makes sense to most people… especially pitchers (lol).

Now the slightly tricky part…

What would happen if the finger and thumb extensor muscles are also not providing stabilization, meaning… not contracting? What would happen to the ball then? Would the player have control of it?

Try it. Go grab a ball, or tennis racquet, or pen or keyboard and feel what happens when you grip them or use your fingers. Feel the ‘back of your hand’ where your finger extensor tendons are. Review ‘Part 2 (The 9 Muscles That Open the Hand)’ here. Are they contracting? The answer is a resounding ‘yes.’ They have to be. Otherwise the hand would fall limp.

One might say that this doesn’t make sense because finger extensor muscles and tendons are supposed to open the hand not close it? Right?

Right! The finger extensor muscles DO contract to open the hand… but they ALSO contract ‘in cooperation with the finger flexor muscles‘ in a supportive role when gripping and grasping, as in sports, music, computers, gaming, workplace and hobby. The finger extensor and finger flexor muscles are constantly in a ‘cooperative co-contraction’ when gripping.

This is what is meant by the ‘kinetic chain of grip.’ The finger extensor muscles contract cooperatively to support the finger flexor muscles… i.e. to grip. It is a kinetic chain. And the kinetic chain of grip can be shown clearly on surface electromyography (sEMG). In fact, it is how we discovered the clear consistent evidence of the kinetic chain of grip. To this day, we have done dozens of sEMG pattern tests in doing our grip research. The images are consistent, revealing and super-interesting.

The above sEMG signal above shows the sEMG pattern of a dental hygienist while doing a teeth cleaning. Did you ever think that a dental hygienists has a tough physical job? Probably not. You were likely thinking other thoughts while having your teeth cleaned – lol! But dentists, dental hygienists and dental assistants do have a difficult physical job, as do many repetitive grip professionals and workers. In fact, dental hygienists have one of the most demanding physical jobs of any profession.

For real!… as my daughter says.

And one of the main reasons is because of the constant presence of the kinetic chain of grip.

Notice the green signal that indicates the contraction of the finger extensor muscles on the sEMG chart above. The red is the finger flexor muscle signal. When the hygienist is cleaning teeth, BOTH the finger extensor AND flexor flexor muscles are contracting… the whole time… otherwise the hygienist would drop their dental cleaning tool.

Notice the intensity of the green finger extensor muscle pattern. This might surprise many people. It is a huge burden on the entire profession, and we will explain why in more detail in later posts in this series. Indeed, much more to cover on workplace injuries to to repetitive gripping later.

The baseball catcher sEMG below shows the detailed pattern of both finger extensor (green) muscle pattern contraction in support of the finger flexor (red) muscle pattern when the catcher provides a target for the baseball pitch (spike on left of the graph) and when the catcher catches the pitch (red and green simultaneous spikes near right of graph).

Again the intensity of the finger EXTENSOR muscle signal (green) might surprise you. Most would expect the finger FLEXOR muscle signal (red) to be strong, because historically athletes think of grip only and use ‘squeeze-only’ training devices to prepare for sports.

There is little difference in the study of the kinetic chain of grip in music. The above sEMG pattern depicts the pattern of the finger extensor muscles (green) versus the finger flexor muscles (red) when viewing a guitar player’s fret hand. Note the intensity once again of the green signal that represents the finger extensor muscles, or ‘support muscles’ in the kinetic chain of grip.

These patterns surprise experts and lay people alike. The finger extensor AND flexor muscles contract together in cooperation in order to grip. Indeed, the finger extensor muscle fire pattern is almost always very intense in grip activities.

In summary, the kinetic chain of grip refers to the fundamental concept that the finger extensor muscles contract to support the finger flexor muscles in any grip, grasp or finger action. And as well, the thumb extensor and abductor muscles contract to support thumb flexion muscle actions (more on the thumb later).

It makes sense that, if the finger extensor muscles are not contracted, the finger flexor muscles would simply fall contracted limply towards the ground. It is a rather simple complex, though not at all well known. I often compare cooperative grip contraction (‘the kinetic chain of grip’) to pairs figure skating. We are watching the female skater eloquently complete all of the thrilling tricks, but the partner skater is working well and hard in support to equally create the outcomes we are dazzled by.

The finger extensor muscles are the vital motor for grip. If one expects advanced strength, stamina, and grip performance, finger extensor muscles must be trained properly through their full range of motion. When an athlete’s, musician’s or worker’s grip fatigues it is a more clear indication of poor finger extensor muscle training than finger flexor muscle training. In other words, it is an indication of a kinetic chain that is broken.

Finger extensor muscles must be trained properly by all who depend on grip.

Now that we understand the kinetic chain of grip, we complicate matters a lot. We are a repetitive grip society. We must start to understand where these mechanical problems of the fingers, thumbs, hand, wrist, carpal tunnel, and elbow come from. We must also be prepared to change our training approaches to correct these very debilitating and costly problems.

One of the most common of those problems is tennis elbow or lateral epicondylitis. It is the eye-opening topic of Part 4. But do we understand tennis elbow? Are we approaching tennis elbow exercises and training properly? Thanks for reading!

Next:
Understanding Hand Exercise & Grip Strength – (Part 4) Discussing Tennis Elbow Cause and Treatment

Dr. Terry Zachary is an advocate for proper and complete hand exercise & grip strength training in sports, music, the workplace, modern computer, electronics/gaming/esports, therapy/rehab/wellness, and hobby. Dr. Zachary discovered that repetitive gripping imbalances have gone under the radar as a cause of muscle imbalance, weakness, poor blood flow, and poor lymph drainage for over 5 decades. He developed Handmaster Plus to provide the world with fast, easy and complete hand training to create maximum strength, balance, performance, and overall health. The result is healthy, stable fingers, thumbs, wrists, carpal tunnels, forearms, and elbows… and healthier lives.

Dr. Zachary can be reached at terry@doczac.com. For information on Handmaster Plus, visit www.handmasterplus.com