It’s ultimately dealer’s choice when it comes to how clinicians approach measuring strength. Traditionally, dynamometry devices and manual muscle testing have been reliable methods of strength measurement; however, the brawn of these devices lie in the measurement of isolated muscle strength in clinical and research settings. On the other hand, the repetition maximum (RM) method is used to assess the strength of an individual during compound movements that involve multiple planes. This yields reliable data in order to prescribe the appropriate amount of resistance for training, as well as a  benchmark to measure both gains or losses in strength.

What’s the best way to perform the RM method?

From here, the debate rages on. Should clinicians be using isotonic resistance like free weights and machines or elastic resistance like the TheraBand CLX to perform these repetition maximums? The validity of torque and force elongation of elastic resistance compared to isotonic is seemingly a common roadblock of using bands. No worries though; we’ve got plenty of research to bust this myth. Notably, a throwback study done by Dr. Robert Topp (1998) established the TheraBand Strength Index, a chart that provides a repeatable measurement of any movement or functional activity involving multiple joints and planes of motion that can be used as an assessment of strength.

elastic resistance strength index for rm method

To accompany this data and continue to put your mind at ease, Phil Page PhD, PT, ATC, CSCS, FACSM recently compiled five research studies that prove strength can be measured with elastic resistance in certain muscle groups and populations using multiple variations of the RM method.

Successfully measure the strength of these five muscle groups with elastic resistance

measure strength of muscle with elastic resistance

1. Elbow Flexors

A study published In 2006 concluded that TheraBand resistance was a valid and reliable measure of elbow strength in older adults, making it a viable alternative to testing with dumbbells in the Senior Fitness Test (Manor et al. 2006).

2. Shoulder Flexors

Swedish researchers found moderate to excellent agreement between elastic and isokinetic strength measures, and excellent agreement and no difference between 1RM elastic resistance and peak isokinetic force, concluding that it’s possible to evaluate muscle strength with the use of elastic resistance bands in healthy older individuals (Nyberg et al. 2014).

3. Knee Extensors

Although there were a few variations between individuals who completed his study, Dr. Nyberg (2016) concluded that 1RM testing with elastic resistance bands could be a very valid measure of knee extension strength in older adults.

4. Knee Flexors

In 2015, Guex and colleagues found high validity and reliability using TheraBand elastic resistance to test maximal strength of knee flexion and extension in healthy, younger subjects.

5. Shoulder Abductors

Most recently, Dr. Lars Andersen and colleagues (2016) used an isometric force transducer to measure maximal strength of shoulder abductors at 90 degrees of abduction and reported outstanding validity and reliability.

Key takeaways from these studies

While all of these studies do prove that elastic resistance is a valid and reliable measurement of strength in these muscle groups and populations, Dr. Page warns that we should take this information for exactly what it is.

“It’s important to remember these studies provided validation and reliability for specific shoulder and knee muscles within specific populations. These results allow us to use TheraBand elastic resistance to measure strength within individuals and within studies, but we may not be able to compare different methods between individuals or studies” (Page, 2016).

At the end of the day, the portability, cost and convenience of elastic resistance bands exceed isotonic resistance. This means that your patients will be able to utilize this tool inside the clinic, at home or on the road. And, let’s be honest; the less limitations, the better.

This study was featured in an article originally published in the Journal of Performance Health written by Phil Page PhD, PT, ATC, CSCS, FACSM. Read the full article now or take a peek at the entire Journal here!


Andersen LL, Vinstrup J, Jakobsen MD, Sundstrup E. Validity and reliability of elastic resistance bands for measuring shoulder muscle strength. Scand J Med Sci Sports. 2016.

Guex K, Daucourt C, Borloz S. Validity and reliability of maximal-strength assessment of knee flexors and extensors using elastic bands. J Sport Rehabil. 2015;24(2):151-155.

Manor B, Topp R, Page P. Validity and reliability of measurements of elbow flexion strength obtained from older adults using elastic bands. J Geriatr Phys Ther. 2006;29(1):18-21.

Nyberg A, Hedlund M, Kolberg A, Alm L, Lindström B, Wadell K. The accuracy of using elastic resistance bands to evaluate muscular strength. European Journal of Physiotherapy. 2014;16(2):104-112.

Nyberg N, Lindstrom, B., Aronsson, N., Naslund, M.,Wadell, K. Validity of using elastic bands to measure knee extension strength in older adults. J Novel Physiother Phys Rehabil. 2016;3(1):16-21.

Page P 2016. Can I assess strength with elastic bands? J Performance Health 1(1):26-31

Topp R, Mikesky A, Thompson K. Determinants of four functional tasks among older adults: an exploratory regression analysis. J Orthop Sports Phys Ther. 1998;27(2):144-153.

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