Handgrip Strength: Measurement Protocols, Interpretation, and Improvement

How to measure handgrip strength?

Measuring handgrip strength typically involves using a hand dynamometer, following a standardized protocol to ensure accuracy and reliability, which provides valuable insights into overall health, muscular strength, and functional capacity.

Understanding Handgrip Strength

Handgrip strength, often referred to as crushing grip, is a fundamental measure of muscular strength and a robust indicator of overall health. It reflects the maximum force one can exert with their hand and forearm muscles. Its importance extends beyond just lifting heavy objects; research consistently links strong handgrip to:

• Longevity and Mortality: Higher grip strength is associated with a reduced risk of all-cause mortality.
• Cardiovascular Health: It serves as a predictor of cardiovascular events and hypertension.
• Functional Independence: Essential for daily activities like opening jars, carrying groceries, and maintaining balance.
• Bone Mineral Density: Correlates with bone health and can indicate sarcopenia (age-related muscle loss) and frailty.
• Athletic Performance: Crucial for many sports, including weightlifting, climbing, and martial arts.

While there are various types of grip (e.g., crushing, pinching, support), the standard measurement focuses on crushing grip strength, which is what most hand dynamometers are designed to assess.

The Gold Standard: Dynamometers

The most accurate and widely accepted method for measuring handgrip strength involves using a hand dynamometer. These devices quantify the maximum isometric force produced by the hand and forearm muscles.

• Types of Hand Dynamometers:

  • Hydraulic Hand Dynamometer (e.g., Jamar Dynamometer): Considered the gold standard in clinical and research settings. It uses a hydraulic system to register force, providing consistent and reliable measurements. They are durable but typically more expensive.
  • Electronic Hand Dynamometer: These devices use strain gauges to measure force and display the reading digitally. They often offer additional features like peak hold, average calculations, and sometimes data storage. They can be very accurate but require calibration and battery power.
  • Spring Dynamometers: Less common for scientific or clinical use due to potential for less consistent readings and difficulty in calibration compared to hydraulic or electronic models. They are often more affordable and used for general fitness tracking.

• Preparation for Testing:

  • Warm-up: A light warm-up of the hands and forearms (e.g., gentle stretching, opening and closing the fist a few times) can help optimize performance and prevent discomfort.
  • Posture: The subject should be seated comfortably in a chair without armrests, with their feet flat on the floor.
  • Arm Position: The arm being tested should be positioned with the shoulder adducted (close to the body), the elbow flexed to 90 degrees, and the forearm in a neutral position (thumb pointing upwards). The wrist should be in a neutral position or slightly extended (0-30 degrees).
  • Dynamometer Adjustment: Ensure the dynamometer's handle is adjusted to fit the individual's hand comfortably. The second metacarpophalangeal joint (knuckle) should be aligned with the handle.

Step-by-Step Measurement Protocol

To ensure reliable and comparable results, a standardized protocol, often based on guidelines from organizations like the American Society of Hand Therapists (ASHT) or the American College of Sports Medicine (ACSM), should be followed.

1. Subject Positioning:

   • The subject sits upright in a chair without armrests.
   • The shoulder is adducted (arm at the side).
   • The elbow is flexed to 90 degrees.
   • The forearm is in a neutral position (palm facing medial, thumb up).
   • The wrist is in a neutral position (0-30 degrees extension).
   • The dynamometer is held in the hand, not touching the body or chair.

2. Instruction and Execution:

   • Instruct the subject to "Squeeze as hard as you can!"
   • The squeeze should be a maximal isometric contraction, sustained for approximately 3-5 seconds.
   • Encourage maximal effort throughout the squeeze.

3. Number of Trials:

   • Typically, three trials are performed for each hand.
   • Allow a rest period of 30-60 seconds between trials for the same hand to minimize fatigue.
   • It's common practice to alternate hands between trials (e.g., Right 1, Left 1, Right 2, Left 2, Right 3, Left 3) to allow for adequate recovery.

4. Recording the Score:

   • Record the peak reading from each trial in kilograms (kg) or pounds (lbs).
   • The final score is often the average of the three trials for each hand, or sometimes the highest score from the three trials, depending on the specific protocol being followed. Consistency is key.

Interpreting Your Handgrip Strength Scores

Interpreting your handgrip strength requires comparing your scores to established normative data, which varies by age, sex, and population.

• Reference Norms: Consult published reference charts to understand where your score falls relative to your age and sex demographic. These charts can be found from health organizations, research papers, or specialized fitness resources.
• Clinical Significance:
  • Sarcopenia/Frailty: Low grip strength, especially in older adults, is a key diagnostic criterion for sarcopenia and frailty, indicating a higher risk of falls, disability, and poor health outcomes.
  • Cardiovascular Risk: Below-average grip strength can be an independent predictor of cardiovascular disease and mortality.
• Performance Significance: Athletes in sports requiring significant grip (e.g., powerlifting, grappling, climbing) will typically aim for scores well above average.
• Left vs. Right Hand: It's normal for the dominant hand to exhibit slightly higher grip strength (typically 5-10% more) than the non-dominant hand. Significant asymmetries (e.g., >10-15% difference without a clear explanation) could warrant further investigation.

Alternative and Practical Methods

While dynamometers offer the most accurate measurement, some practical, albeit less precise, methods exist for general tracking or home use.

• Grip Trainers/Grippers with Resistance Scales: Some advanced grip trainers come with built-in scales or adjustable resistance levels that can give an approximate idea of the force exerted. These are useful for self-monitoring progress in grip training but are not clinical measurement tools.
• Bathroom Scale Method (Caution Advised): This is a highly unscientific and imprecise method. It involves placing a bathroom scale on a table and pressing down on it with your hand. The reading gives a rough force, but it's inconsistent, difficult to standardize, and not comparable to dynamometer readings. It's generally not recommended for accurate assessment.

Factors Influencing Handgrip Strength

Many variables can affect handgrip strength measurements:

• Age: Grip strength typically peaks in the 20s and 30s, then gradually declines with age.
• Sex: Men generally have higher absolute grip strength than women.
• Dominance: The dominant hand is usually stronger.
• Body Size: Taller and heavier individuals often have greater grip strength.
• Physical Activity Level: Regular strength training, especially exercises that engage the forearms and hands, improves grip strength.
• Nutritional Status: Malnutrition can lead to muscle weakness, including reduced grip strength.
• Medical Conditions: Conditions like arthritis, carpal tunnel syndrome, neuropathy, or stroke can significantly impair grip strength.
• Time of Day: Minor fluctuations can occur throughout the day due to fatigue or hydration status.
• Fatigue: Previous strenuous activity can temporarily reduce grip strength.

Improving Handgrip Strength

If your grip strength is below desired levels, it can be improved with targeted training.

• Compound Lifts: Exercises like deadlifts, rows, and pull-ups naturally engage the grip muscles.
• Direct Grip Training:
  • Farmer's Carries: Walking while holding heavy dumbbells or kettlebells.
  • Plate Pinches: Pinching two weight plates together and holding them.
  • Bar Hangs: Hanging from a pull-up bar for time.
  • Crush Grippers: Using specialized spring-loaded grippers.
• Consistency and Progressive Overload: Like any strength training, regular training and gradually increasing the resistance or duration are key to progress.

When to Seek Professional Guidance

While self-measurement can be insightful, consider seeking guidance from a healthcare professional or certified fitness expert if:

• You observe a sudden or unexplained significant decrease in grip strength.
• There's a marked asymmetry between your hands without a known cause.
• You experience pain, numbness, or tingling during grip strength testing or daily activities.
• You are an older adult concerned about sarcopenia or frailty.
• You need help interpreting your scores in the context of a specific health condition or athletic goal.

Measuring handgrip strength is a simple, non-invasive, and powerful tool for assessing overall health and physical capacity. By following standardized protocols, individuals can gain valuable insights into their strength and track progress over time.