In 1841, Sir Joseph Whitworth, an english mechanical engineer and inventor published, A Paper on a Uniform System of Screw Threads.  He presented the need for a universal and an accepted standard for screw threads, which would address the cost of repairs of machinery, the speed of repairs of equipment, the worldwide enormous waste of screws and bolts because of their variability, the power of the screw and its threads related to pitch, depth and form - and the positive effect of global mass-production of standardized parts.

Whitworths foresight led to having almost every lid, door knob, thread, nut, screw and bolt turn in a particular way and led to the saying righty-tighty, lefty-loosey, which helped in remembering to turn clockwise to the right to tighten and counter clockwise to the left to loosen.

When we grasp a circular object with five-digits the maximum torque in the closing clockwise direction is larger than in the opening counter clockwise direction.  The thumb contributes the largest force share and the little finger the smallest. Each finger's contribution is due to the moments (moment = force x perpendicular distance) in the direction of the opening and closing movements.  Standardizing the direction of tightening a screw versus loosening based on hand power assures a firm secure fit.


Pendulum Grip Cart Wrist Rollers

What does this all mean in regards to exercise and how do we apply it when it comes to grip training.  Having different objects of varying shapes and sizes to manipulate when training is important for ensuring hand and finger strength is developed maximally.  The diameter of the circular wrist roller that is used affects maximum torque and grasping force.  Circular gripping tools that are large or very small are more difficult to interact with.

There is a smaller moment production capability of our hands when opening.  Hence, when exercising a circular wrist roller it should be done periodically in both directions. For example, use an opening movement one workout to raise the weight and closing movement to raise the weight the next training period.  Understanding the best muscular gains of the fingers and hands are based on their performance capabilities in particular situations.


Train Opening and Closing Movements

In the above picture both athletes uninstructed are beginning the exercise in clockwise rotation excluding the little finger.  This is natural  as greater leverage can be gained by altering the grip.  The athletes adjust finger spacing and increase contact surface area, which allows them to produce as much force as possible to complete the raising portion of the repetition.  As explained, the athletes in the next training session should raise the weight counter clockwise augmenting muscular adaptation to Get even Stronger workout to workout.