A few years back, at the recommendation of a friend, I bought some Captains of Crush grip trainers. I remember back in school when some kids had taken these from their dads and stored them in their lockers. In between classes, they’d pull them out and lay down the gauntlet. It was a social test of strength, not to be taken lightly. 

I started doing some research to figure out a methodical way to increase grip strength. Quickly, I stumbled across medical literature that said grip strength was an excellent biomarker for overall health. In some cases, it’s being correlated with overall (and disease-specific) mortality. 

I spent a couple of weeks diving into studies and medical literature, and below are the notes that I took (edited slightly for narrative structure). 

Grip Strength as a Biomarker

A biomarker is something that can be used to represent the physiological state of an organism. 

Your doctor checks your knee reflexes with a reflex hammer just below the patella. This patellar reflex test can be used as a biomarker for nervous system health. 

In this same way, doctors and researchers use grip strength as a biomarker for overall health, particularly in malnutrition cases and the elderly. 

Research suggests grip strength is valuable as a biomarker because it is: 

"…largely consistent as an explanator of concurrent overall strength, upper limb function, bone mineral density, fractures, falls, malnutrition, cognitive impairment, depression, sleep problems, diabetes, multimorbidity, and quality of life."

Grip strength is tested using a dynamometer. Below is a list of grip strength benchmarks (also called norms) grouped by gender and age. 

This data comes from research done at the University of Wisconsin-Milwaukee. 

Female Grip Strength Norms (in lbs)

  • Ages 20-24: Right 55.9-84.9; Left 47.9-74.1
  • Ages 25-29: Right 60.6-88.4; Left 51.3-75.7
  • Ages 30-34: Right 59.5-97.9; Left 50.3-85.7
  • Ages 35-39: Right 63.3-84.9; Left 54.6-78
  • Ages 40-44: Right 56.9-83.9; Left 48.5-76.1
  • Ages 45-49: Right 47.1-77.3; Left 43.3-68.7
  • Ages 50-54: Right 53.9-77.4; Left 46.6-68
  • Ages 55-59: Right 44.8-69.8; Left 35.4-59.2
  • Ages 60-64: Right 45-65.2; Left 35.6-55.8
  • Ages 65-69: Right 39.9-59.3; Left 32.8-49.2
  • Ages 70-74: Right 37.9-61.3; Left 31.3-51.7
  • Ages 75+: Right 31.6-53.6; Left 28.7-46.5

Male Grip Strength Norms (in lbs)

  • Ages 20-24: Right 100.4-141.6; Left 82.7-126.3
  • Ages 25-29: Right 97.8-143.8; Left 94.3-126.7
  • Ages 30-34: Right 99.4-144.2; Left 88.7-131.7
  • Ages 35-39: Right 95.7-143.7; Left 91.2-134.6
  • Ages 40-44: Right 96.1-137.5; Left 94.1-131.5
  • Ages 45-49: Right 86.9-132.9; Left 78-123.6
  • Ages 50-54: Right 95.5-131.7; Left 84.9-118.9
  • Ages 55-59: Right 74.4-127.8; Left 59.8-106.6
  • Ages 60-64: Right 69.3-110.1; Left 56.5-97.1
  • Ages 65-69: Right 70.5-111.7; Left 57-96.9
  • Ages 70-74: Right 53.8-96.8; Left 46.7-82.9
  • Ages 75+: Right 44.7-86.7; Left 38-72

As you can see, grip strength typically peaks between ages 30-34 and degrades with age. 

Grip Strength as a way to quantify biological age 

Further, studies suggest that grip strength could be an accurate quantifier of biological age. 

Our age in years is a measure of chronological age, but everyone ages biologically at a different rate. Researchers can use a series of biomarkers to establish a biological age, which seeks to quantify our overall health on a timeline of functional capacity and physiological maturity. 

Since grip strength is positively correlated with functional capacity and physiological health (and many factors correlated with chronological age), it can be used to evaluate biological age. 

Does Training Grip Strength Increase Overall Health? 

It’s not clear to me that training your grip strength can help improve overall health or if it’s just a way to optimize the biomarker. 

I ran multiple queries on pubmed to find data that suggests increasing your grip strength through training improves the same metrics that it can help measure but could not turn anything up. 

Even if grip can only be used as a biomarker, there are still numerous reasons to improve your grip strength. 

Here are a few that are relevant to me: 

Reasons to Improve Grip Strength

  • Weight Lifting - You can’t lift what you can’t hold. 
  • Firearms/Shooting - Increased grip strength can help with accuracy. 
  • Rock Climbing - Better grip means better climbing and less falling. 

General notes on training grip strength 

Training grip fatigues the central nervous system (CNS) very quickly, so it’s quite unlike training larger muscle groups. The internet is filled with anecdotal evidence of people increasing grip strength immediately after squats and other large muscle group training or having optimal times of the day that coincide with their circadian rhythms. These anecdotes draw an interesting line to more research on CNS states. 

The concept of rate coding underscores the role that the CNS has to play with grip training. 

From a widely cited study, Rate Coding and the Control of Muscle Force:

The force exerted by a muscle during a voluntary contraction depends on the number of motor units recruited for the action and the rates at which they discharge action potentials (rate coding). 

Over most of the operating range of a muscle, the nervous system controls muscle force by varying both motor unit recruitment and rate coding. Except at relatively low forces, however, the control of muscle force depends primarily on rate coding, especially during fast contractions.

Additionally, another concept: post-activation potentiation (PAP), supports the idea of beginning with a warmup set before beginning a work set. 

“PAP is a phenomenon by which the force exerted by a muscle is increased due to its previous contraction."

How to increase grip strength with spring grippers 

Spring grippers, such as Captains of Crush, are small hand-held devices that allow you to increase your grip strength. 

Some variants are adjustable, but most are static in terms of poundage (difficulty). 

Most people should start with the Trainer and Sport. The most typical training modality is to use a warmup gripper and then use a work gripper that is difficult for you to close. 

Here’s an example training session using the sport and trainer CoC grippers: 

Set #1: Sport Gripper. 10 reps in each hand. 

Set #2: Trainer Gripper. 5 reps in each hand. 

Set #3: Trainer Gripper. 3 reps in each hand (using other hand to help if you’re unable to close single-handedly).

How to increase grip strength with a towel 

Many athletes use a simple bath towel to train and increase grip strength. Drape it over something that can handle your weight and grab it and hang. 

Popular exercises include towel pull-ups, towel dips, and towel rows. One advantage of using towels for these exercises is that you’re training your grip in addition to other muscle groups.

Here’s a video that shows how to use a regular doorway pull-up bar and a towel. 

How to increase grip strength with rice 

It’s popular within baseball and rock climbing circles to use buckets (or bags) of rice to train grip and forearm strength.

The idea is that resistance helps develop your forearms' extensors, which are often weak compared to the flexors. 

Essentially you fill a bucket, at least as deep as your mid-forearms, with dry rice. 

Here’s a video on the process.