An Anatomical Approach to Fitting and Drilling

A review of the hand and the motivations for the ADT grip

An Anatomical Approach to Fitting and Drilling

I recently devised an anatomically-guided fitting and drilling technique that I call the Anatomical Drilling Technique (ADT). With this grip, I believe the ball now feels like it is a natural extension of the hand. This fitting process was developed from reviewing the anatomy of the hand as well as researching how the hand naturally grips/grasps in an open position, such as when you are swinging and throwing a bowling ball.

With the ADT grip, the hand sits on the ball significantly better, reducing wrist tension and grip pressure and allowing a freer swing and cleaner release. There are also early reports that it has eliminated some pain and wrist discomfort both during and after bowling.

The Anatomical Drilling Technique began with two observations

I began work on the Anatomical Drilling Technique by thinking about how the hand sits and moves naturally in an open position. As you can see from the image, when the hand is in a normal open position, the thumb is outside the index finger and there is a substantial natural angle between the base of the thumb and the fingers. This angle is shown in the image by the two black dotted lines.

Note the large angle between the thumb and the fingers when the hand is in an opened position, as shown.

In sports science, the hand is split between the middle and ring finger into two sides: ulna on the pinky and ring side and radial on index and middle side. This naming convention emerged from the location of the lone forearm bones and the proximity of these bones to the hand. The ulna bone is located on the pinky side of the forearm and the radius bone is located on the thumb side. This is why a cocked wrist position is referred to as ulnar deviation.

To create a better fit, the grip should accommodate the natural angle from the base of the thumb to the center of the middle and ring finger. Historically, there have been efforts to adjust the ring finger line to accommodate this natural angle. For example, drillers have been using a Center Line Transposition (CLT) process for years. But, when observing the hand and reflecting on this anatomic reality, the angle of the base of the thumb through the finger line seemed larger than what had been traditionally utilized for CLT measurements. With this larger angular measurement, the fingers will face in a more natural position.

The sport of handball ...

Joe Slowinski

About Joe Slowinski

Joe Slowinski, a USBC Gold Coach, is a freelance bowling coach who works with bowlers around the globe. He is currently on assignment with the Philippines. Slowinski is the former Director of Bowling at Lincoln Memorial University, where he served as Program Administrator and Head USBC Collegiate Men’s and NCAA Women’s Coach. The Portland, Maine native has served as the Administrative and Men's Head Coach at Webber International University and served for four years as a Master Teaching Professional at the Kegel Training Center. Slowinski is also the former Director of Coaching and Coach Certification for the National Sports Council of Malaysia. He has coached international teams at the World Championships, Pan American Games, South American Games, and European Championships, helping Belgium win a Gold medal at the 2022 EBF Championship of Champions and coaching Brazil to Gold medals at the 2015 Pam American Games and the 2014 South American Games. He was the 2018 NTCA DII/III Coach of the Year and the 2010 NCBCA Men’s College Coach of the Year.