Dr. E demonstrating the general use of the Activforce 2
Dr. E demonstrating the use of the Activforce 2 to measure end range strength after restoration of shoulder motion.
Hand-held dynamometers are a valuable tool for measuring muscle strength in rehabilitation settings. They are portable, affordable, and easy to use, making them a convenient option for clinicians. Dynamometers measure the amount of force that a muscle can generate during a maximal isometric contraction. This type of contraction is performed when the muscle is activated but does not shorten. For example, when you grip a dynamometer as hard as you can, you are performing a maximal isometric contraction of your grip muscles.
There are many benefits to using hand-held dynamometers for strength testing in rehabilitation. These include:
Portability and affordability: Dynamometers are small, lightweight devices that can be easily transported from one location to another. They are also relatively inexpensive, making them a cost-effective option for rehabilitation settings.
Ease of use: Dynamometers are relatively easy to use, even for clinicians with limited experience. The instructions are typically clear and concise, and the devices are designed to be user-friendly.
Objective and reliable measures: Dynamometers provide objective and reliable measures of muscle strength. This means that the results of dynamometer testing are not influenced by the clinician's subjective judgment.
Ability to track changes over time: Dynamometer measurements can be used to track changes in muscle strength over time. This information can be used to assess the effectiveness of rehabilitation interventions and to make adjustments to the treatment plan as needed.
Identification of patients at risk: Dynamometer measurements can also be used to identify patients who are at risk for falls or other complications. This information can be used to develop targeted interventions to reduce the risk of these complications.
While there are many benefits to using hand-held dynamometers, there are also some limitations to consider. These include:
Can only measure isometric strength: Dynamometers can only measure isometric strength, which is the amount of force that a muscle can generate when it is activated but does not shorten. This means that dynamometers cannot be used to measure dynamic strength, which is the amount of force that a muscle can generate during a movement.
Not as sensitive as other methods: Dynamometers are not as sensitive as other methods of measuring muscle strength, such as isokinetic dynamometry. This means that dynamometers may not be able to detect small changes in muscle strength.
Can be difficult to use with some patients: Dynamometers can be difficult to use with some patients, such as those with limited range of motion or pain.
The amount of force that is considered a significant difference in strength using dynamometers can vary depending on the muscle group being tested, the individual's age and gender, and the clinical setting. However, in general, a difference of 10% or more between two measurements is considered to be significant.
For example, if a patient's grip strength is measured at 20 kilograms on the first test and then 22 kilograms on the second test, the difference of 2 kilograms would be considered significant. This means that the patient's grip strength has increased by 10%.
It is important to note that the amount of force that is considered a significant difference may also vary depending on the specific clinical setting. For example, in a research setting, a smaller difference in force may be considered significant than in a clinical setting.
Here are some factors that can affect the amount of force that is considered a significant difference in strength using dynamometers:
The muscle group being tested: Some muscle groups are naturally stronger than others. For example, the grip muscles are typically stronger than the shoulder muscles.
The individual's age and gender: Muscle strength tends to decline with age, so a smaller difference in force may be considered significant in older adults than in younger adults. Men are also typically stronger than women, so a smaller difference in force may be considered significant in men than in women.
The clinical setting: In a research setting, a smaller difference in force may be considered significant than in a clinical setting. This is because the research setting is typically more controlled, so there is less variability in the results.
Overall, hand-held dynamometers are a valuable tool for measuring muscle strength in rehabilitation settings. They are portable, affordable, and easy to use, making them a convenient option for clinicians. Dynamometer measurements can be used to track changes in muscle strength over time and to identify patients who are at risk for falls or other complications. Check out the best, comfortable, and affordable handheld dynamometer below, the Activeforce 2!
References
Kaufman KR, et al. Hand-held dynamometry for the assessment of muscle strength in rehabilitation. J Rehabil Res Dev. 2006;43(1):121-131.
Panjabi M, et al. Reliability of hand-held dynamometry for the measurement of isometric muscle strength in the upper and lower extremities. J Orthop Sports Phys Ther. 1999;29(6):333-340.
The American Physical Therapy Association. Hand-held dynamometry. Guide to Physical Therapist Practice. 2nd ed. Alexandria, VA: APTA; 2001.
Hsu YC, et al. A systematic review of reference values for hand-held dynamometry. J Rehabil Med. 2012;44(7):551-559.
Mital S, et al. The reliability of hand-held dynamometry in the assessment of muscle strength in people with Parkinson's disease. Clin Rehabil. 2007;21(6):547-555.