Having opposable thumbs is divine. It allows us to grip. Its part of what makes us human and special.
We pick up our kids, carry groceries, open jars and hang on for dear life. Among athletics, we lift weights, throw balls, and grip bats, clubs, and rackets. Anything we do that requires holding something is limited by our grip.
Simply gaining awareness of the importance of grip and being mindful of using will yield immediate improved strength and in some cases skill.

The Ignition Switch
There is this super cool magic trick that the body does called the Law of Irradiation. This is the ability of one muscle, when it tenses strongly, to recruit the tension of nearby muscles.
Make a fist, squeeze as hard as you can, feel the muscles in your arms start to tense.
Squeeze your glutes as hard as you can and feel your quads start to engage.
Instant Strength. It’s Magic.
Phrases like “break the bar” or “screw your feet down” are common coaching cues before big lifts. This generates hip and shoulder rotation for stable positions that are ready to move heavy loads.
But in order to generate torque, you need a strong connection point.
If you opt for a weak finger hold, you’ll notice you can’t lock the shoulders in as well. This limits performance and results in compensations at the elbow, shoulder or spine.
The same is true with a “disengaged” foot. Feel your foot relationship with the floor and the whole system gets stronger.

The research shows that even a slight grip, can significantly increase rotator cuff (supraspinatus and infraspinatus) activity, which improves the ratio of muscle forces between the rotator cuff and deltoid
This helps reduce the risk of impingement and sets up the shoulder for performance.
Make Big Gains With A Strong Grip
Lift, carry, hang, and climb…that’s the best way to build strength, along with strong hands to support it.

Here are a couple of specifics to put into practice…
1. Hold Onto Things
When we grip an object to do work, whether its a barbell, dumbbell, pull up bar etc. we want that  object to become a part of us. We “absorb” an object with a strong grip which makes it much easier to move as opposed to a loose grip that allows the object to be wobbly and less stable.  Consider a strong grip on a dumbbell for a bicep curl and how it engages the entire arm.
Please be advised, if you are not using a hook grip, You are doing it wrong!

When holding onto a pull up bar, a solid palm grip not only improves safety on the bar but it activates the shoulder.

2. Grip Work For Shoulder Work
There is a strong correlation between grip and shoulder strength
Partly because lifting weights improves both the grip and rotator cuff, but there’s also evidence to show that grip exercises provide a training effect for the shoulder as well.
If you’re struggling with some shoulder pain, grip intensive exercises like farmer carries and deadlifts can provide a training effect for the shoulder, with minimal risk of furthering any irritation.
You can also use this evidence to close out your shoulder training days. Throw some carries and hangs on the tail end of your shoulder days, to increase workloads, without piling more repetitions on the joint.

Get a grip on things…
Irradiation of the upper extremity from gripping a handle or weight is a natural part of movement and necessary for proper shoulder function.
For those reasons, if you want to improve the capacity of your rotator cuff and shoulder complex, exercises that use a grip are better options for strength, function, and overall shoulder health.
A strong grips makes you stronger overall.