When you are being measured for a bowling ball, the pro shop takes care to check the flexibility of the thumb and fingers, check for fatty tissue, and for bone length. While this has become the accepted method of fitting a bowling ball, and when done by the skilled pro, it has been quite successful over the years. The hand is a very complex mechanical device with much more than bone, flesh, and fat. To understand this most necessary of all bowling aids, you need to get a feel for what makes up the human hand, how it moves, and what it does. You need to look under the skin to examine its construction and functions.
Before you run off thinking that this is a short course in medicine, it is not. It is just a brief overview of human movement from something called kinesiology. Over time, people have wondered exactly what made or allowed animals and humans to move as they do. Kinesiology developed as an academic discipline to study motion. Unlike most areas of study, kinesiology does not look at a single restricted area. It draws from anatomy and physiology, anthropology, psychology, and physics. In fact, kinesiology utilizes some of the same principles of physics to study human motion that ball designers use to study ball motion. This latter adaptation of physics (statics) to human functioning is also known by a broader name: biomechanics.
Just studying the hand, wrist, and forearm would have no particular value to most people, so in this instance, the discussion will be adapted to bowling. This is easily done since bowling is one of the most obvious examples of a sport that requires precise movement of the hand and wrist, development of fine motor skills, and the use of every bone and joint in the hand, wrist and arm.
If you look at Illustration 1, you can see the bony structures of the hand, wrist, and lower arm region. There are 29 bones and more than 25 joints shown in this illustration. What the drawing does not reveal is the network of more than 30 muscles, plus all of the cartilage, nerves, ligaments, tendons, and soft tissue that cooperate to determine strength and specific ranges of motion.
There are two types of joints in this region of the body, condyloid and ginglymus, or as bowlers might call them, ball and socket and hinge. The type of joint is the major determinant of what you can and cannot do.
For example, the three bones of the wrist that permit motion—the triquetrum, lunate, and scaphoid—are ball and socket joint allowing a full range of motion. This is the joint that allows you to cup a ball (flexion), break your wrist back on delivery (extension), or cock your wrist to the right (abduction) or left (adduction). If you attend a Fred Borden class or read one of his books where he mentions load and unload, you will need to have the joint flexibility that allows you to cup and break your wrist to carry out his instructions.
In most people, the normal range of motion in this joint is 70 to 90 degrees of flexion (With the back of your forearm laying flat on a table, you should be able to cup your wrist and have the fingers pointing straight up). Normal extension is 65 to 85 degrees (With your forearm facing up, you should be able to bend your wrist back so that the fingers point in a downward rather than outward direction. Normal abduction (horizontal movement of the hand to the right) is 15 to 25 degrees (a slight point of the fingers to the right), and normal adduction (movement to the left) is 25 to 40 degrees. If you can do all of these things, then you have normal wrist flexibility. If not, and you don’t know why, you might mention it at your next physical.
Although there are three joints in each finger, flexibility concerns for most bowlers reside in the joint between the distal phalanx and the middle phalanx. This is a hinge joint, and it will only flex (bend toward the palm) from zero to forty degrees for most people. This can have obvious implications to the fitting process. A person with zero flexion (the finger remains straight) could not throw a fingertip ball—unless they were forced into it, at some risk to their well-being. In days of old, forcing a grip was common, but as more is learned about the hand and fingers, more and more pro shop operators are moving to relaxed grips that do not force any joint.
The thumb is the tricky digit. It only has two joints, both hinge type, in the hand, but it also has a condyloid joint where the metacarpal and trapezium connect. This latter joint permits the illusion of gripping positions that are not proper. You may have heard the term “double-jointed” used by people who have an extensive range of motion in this joint. For bowling, only the interphalangeal (nearer to the tip of the thumb) and the metacarpophangeal (where the thumb connects to the hand) joints should be considered in the fitting process and both of these are hinge-type joints.
Getting that grip
Why should you not consider allowing the joint between the wrist and thumb to become a basis for fit? The thumb wants to grip in a certain manner, the point of maximum grip strength. If you allow the thumb to simply open and close on its hinges, it will assume the most natural position. If you force it to assume a position to the right or left of its natural position, the gripping pressure will be reduced. Muscle and joint strength are deterrents to injury.
Should you exercise?
If you are a three-game-a-week bowler, it may not be necessary for you to exercise beyond that which you do for basic health. If you are a tournament player, however, you should consider a program to develop task specific muscles, both for strength and endurance. Although not all muscles in the hand, wrist, and arm play an important role in bowling execution, there are several notable ones that do.
Of primary importance to bowlers:
Flexor carpi radialis
Flexor carpi ulnaris
These three muscles that combine to form the forearm allow you to curl your wrist or hold your wrist straight when you have a heavy object pressing against it. Sufficient strength is necessary for all bowlers to keep the wrist from bending back under the weight of the ball, but it is even more crucial for the cranker (wrist cupper). In a previous issue of BTM, Jeff Briggs advocated wrist curls against a form of hand-held resistance (bands) to develop these muscle.
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor carpi ulnaris
These three muscles that combine to form the back of the forearm serve a lessor specific purpose in bowling. The are primarily used in wrist extension (bending the hand back). In a previous issue of BTM, Jeff Briggs advocated a wrist extension exercise again using a hand-held resistance. That exercise is prescribed to develop these muscles.
Flexor digitorum sublimis
Flexor digitorum profundus
Located in the back of the forearm, these two muscles are used in any gripping activity. Squeezing any object (such as a soft rubber ball) will help to develop these two muscles.
Flexor pollicis longus
Allows the thumb to flex and is therefore essential in any gripping activity. Also, developed by squeezing any object (such as a soft rubber ball).
Divides into the four tendons that run up the back of the hand that allow the fingers to extend.
Extensor pollicis longus
Extensor pollicis brevis
Abductor pollicis longus muscle
Abductor pollicis brevis muscle
Combine to extend and abduct the thumb, to allow the release of the ball in bowling.
The rest of fit
With the bones (length or shortness) of the thumb and the flexibility of bowling specific joints, most of the fit can be determined. There is one area related to muscles though and that is gripping strength.
Even in a “relaxed” grip, men and women are not alike. As politically unpopular as it is to say, the two sexes aren’t equal. In every area, there will be differences. Sometimes women have superior results. Sometimes men do. (All men are not equal to all other men nor are all women equal to all other women either).
One area that is rarely considered in bowling is gripping strength. Bowlers use a cylindric grasp, which can be measured in pounds. In studies conducted on male and female populations from 3 to 90 years of age, it was revealed that men have on average twice the gripping strength of women of the same age. This was true for all adult age groups except 30-39 year olds.
When you analyze the hand for bowling, several things must be taken into account:
- Bone length of the thumb
- Flexibility of the joints of the thumb and fingers
- Muscularity of the individual
- Gripping strength
- Nerve health
- Fatty content
- Range of motion of wrist joints
The fingers, thumb, hand, and wrist are too often taken for granted in bowling, but without strong healthy bones, muscles, and other tissue, bowling would be uncomfortable or even impossible.