Grip strength is the force applied by the hand to pull on or suspend from objects and is a specific part of hand strength. Optimum-sized objects permit the hand to wrap around a cylindrical shape with a diameter from one to three inches. Stair rails are an example of where shape and diameter are critical for proper grip in case of a fall. Other grip strengths that have been studied are the hammer and other hand tools. In applications of grip strength, the wrist must be in a neutral position to avoid developing cumulative trauma disorders (CTD's).
Grip strength is a general term also used by strength athletes, referring to the muscular power and force that they can generate with their hands. In athletics, it is critical for rock climbers and in competitions such as the World's Strongest Man. Grip strength training is also a major feature in martial arts, and can be useful in various professions where people must work with their hands.
Types of gripEdit
The hand is an amazing human instrument, and can be used to grip objects in several ways. These different ways, and different types of grip strength, are typically quantified based on the way the hand is being used.
The crush grip is what is most commonly thought of as "grip". It involves a handshake-type grip, where the object being gripped rests firmly against the palm and all fingers. A strong crush grip is useful in bone-crushing handshakes or for breaking objects with pressure.
In a pinch grip, the fingers are on one side of an object, and the thumb is on the other. Typically, an object lifted in a pinch grip does not touch the palm. This is generally considered a weaker grip position. The pinch grip is used when grabbing something like a weight plate or lifting a sheet of plywood by the top edge.
A support grip typically involves holding something, such as the handle of a bucket, for a long time. This type of strength is epitomized by the "Farmer's walk", where the bucket is filled with sand or water, and carried over a long distance. A great deal of muscular endurance is necessary to have a good carrying grip.
There has been extensive medical and ergonomic research looking at grip strength. This has led to the generation of normative data Average values exist for both men and women.  Averages also exist for different types of grip in different positions. 
Grip strength is often used in medicine as a specific type of hand strength. The purpose of this testing is diverse, including to diagnose diseases, to evaluate and compare treatments, to document progression of muscle strength, and to provide feedback during the rehabilitation process as a measure indicating the level of hand function. For example, it is used to indicate changes in hand strength after hand surgery or after a rehabilitation program. By asking subjects to maintain a maximum contraction for longer periods, it can be used as a measure of fatigue. It is also able to predict a decline in function in old age.  Since the above-mentioned grips involve the action of a large number of different joints and muscle groups, grip strength is not always very sensitive to measure individual muscle groups in medicine. For this purpose, dynamometers have been developed that provide more specific information on individual muscles in the hand such as the Rotterdam Intrinsic Hand Myometer (RIHM).
Hand grip is an important, though often overlooked, component of strength in sports. However, the grip strength is most often a secondary or auxiliary function of the sport. Sports in which grip strength are included within the secondary focus include the following: climbing, horse racing, judo, brazilian jiu-jitsu, weightlifting, Fencing, and arm wrestling and baseball, as well as tennis.
As a separate disciplineEdit
From their beginnings as odd performances at fairs and circuses, grip feats have recently gained acceptance as a sport in their own right, with competitions being held with increasing regularity. Events include one-arm deadlift, nail bending, the closing of torsion spring hand grippers, v-bar (vertical bar) lifting, and standardized pinch apparatuses. Other common events may include Rolling Thunder lifts, thickbar deadlifts, and "Blob" lifting.
The major contests are:
- Champion of Champions
- European Grip Championships
- British Grip Championships
- Münsterland Grip Challenge
- Global Grip Challenge
- Loddekopinge Grip Challenge
- Meisterhaft Pinzettenherren Pjasjma
- Australian Grip Championships
- German Grip Championships
- Backyard Bastard Bash
Exhibitions and feats of strengthEdit
Aside from functional uses of a powerful grip, traditional strength feats such as ripping decks of cards or phonebooks in half experienced renewed popularity after Clayton Edgin posted a video tutorial at an online magazine Heavy Sports.
Grip strength training requires a different type of training regimen than other muscular training. The reasons are primarily based on the interplay of the tendons and muscles and the lack of "down time" or rest that most people's hands get.
It is generally considered that all aspects of the hand must be exercised to produce a healthy and strong hand. Only working on closing grip will cause an imbalance between closing and opening (antagonist) muscles, and can lead to problems such as tendinitis and carpal tunnel syndrome.
For closing gripEdit
- Thickbar work on a two-inch or thicker bar—such as deadlifts, pullups, and the farmers walk—trains the support grip.
- Grippers train the crushing grip.
- Plate pinches grabbing plates smooth side out and pinching them.
- Sledgehammer lever — levering a sledgehammer using the wrists to train fingers and wrists.
- Plate curls/wrist curls — grabbing a plate and doing wrist curls or regular curls with them with the fingers on the bottom and thumb on top, trains the wrists and fingers and thumb for pinch grip.
- Blockweights — cut off ends of hex dumbbells that are grasped in a pinch grip fashion from different sides of the blockweight with one end grasped by fingers and other by thumb; trained with either singles, timed holds, or tosses from hand to hand.
For opening gripEdit
- Extensors; these are the muscles that oppose the flexors of the hands and should be trained to achieve a good balance between opposing muscle groups; shoving your hand in something like rice and extending it, or placing something such as rocks in a coffee can, putting your hand in there, and extending it to pick up the coffee can, are ways of training your hand extensors.
- Some grip companies are also selling high-resistance rubber bands which are meant to be opened to work the extensor grip
- Fingertip pushups would utilize both opening and closing grip muscles to keep the finger from sliding, as well as more focused bone density in the hand, though they are very strenuous and dangerous unless approached progressively.
- Hand stands free from a wall with fingers pointing behind would use gripping stretching to stabilize the hand to prevent the body from falling towards the front, and extensor muscles to prevent the body from falling towards the back.
- Metal-rod exercises strengthen the grip indirectly but very effectively through strength training using a metal rod or pole.
Noted grip strength athletesEdit
- John Brookfield (1995). Mastery of Hand Strength. Ironmind Enterprises. ISBN 0-926888-03-X.
- John Brookfield (2002). The Grip Master's Manual. Ironmind Enterprises. ISBN 0-926888-11-0.