Cartwright Professional Assessment Tool

Back & Leg Dynamometer Strength Assessment

Compare a leg-strength result measured with a back and leg dynamometer against published age- and sex-specific adult reference percentiles.

Age Adult reference groups cover 18–29 through to 80+ years.

Sex used for reference comparison Published leg-strength percentile tables are sex-specific.

Best leg-strength result

Enter the highest force recorded from two correctly performed trials.

Test method Reference values apply to a standard back-leg-chest dynamometer leg-strength protocol.

Important: posture and chain length affect dynamometer results. For comparison with these reference values, follow the protocol shown below rather than using a different back-strength or combined-lift position.

Evidence-based 4,096-adult reference study Age & sex percentiles Published BLC protocol

Recorded leg strength

—

kg force

Reference position — Enter your assessment result to compare it with the reference data.

Age group —

Reference sex —

Reference median —

Difference from median —

Age-specific reference percentiles

These are the published 5th, 25th, 50th, 75th and 95th percentile values for the selected age and sex group.

5th —

25th —

50th —

75th —

95th —

The calculator reports the published percentile band rather than inventing an exact percentile between reference points.

How to perform the leg strength test

Reference protocol

Complete approximately five minutes of warm-up activity.
Stand on the dynamometer platform with the feet wider than shoulder width.
Flex the knees to approximately 120–140°.
Adjust the chain to the participant and test position.
Keep the back straight with the hips and core braced.
Pull upward forcefully using the legs without leaning backwards.
Perform two maximal attempts separated by one minute.
Record the highest result in kilograms of force.

Need a professional back & leg dynamometer?

The Takei Back and Leg Dynamometer provides objective measurement of isometric leg and trunk strength and is available from Cartwright Fitness in analogue and digital versions.

View Takei Back & Leg Dynamometer View Takei Equipment

Understanding your leg strength result

A back and leg dynamometer measures maximal isometric force: the force produced while pulling against a resistance that does not move. The result is strongly influenced by the muscles of the lower limbs, hips and trunk as well as the precise testing position.

This assessment compares the measured result with published adult leg-strength percentiles. It deliberately reports a percentile band rather than calculating an artificial exact percentile between published values.

Reference-population limitation: the normative data used here come from Vietnamese adults participating in the Vietnam Osteoporosis Study. They provide a useful published benchmark, but they should not be presented as universal norms for every ethnic, geographic, athletic or occupational population.

Why test position matters

A back-leg-chest dynamometer can be used in different body positions to emphasise different muscle groups. Changing knee angle, trunk position, handle height or chain length changes the mechanical conditions of the assessment.

For that reason, a result obtained using a dedicated back-strength position should not be compared directly with the leg-strength percentiles in this calculator. Use the same protocol when tracking an individual over time.

Frequently asked questions

What does a back and leg dynamometer measure?

It measures maximal isometric pulling force. Depending on the body position and chain setting, the test can involve the legs, hips, back and upper body to different degrees.

What is a good leg dynamometer result?

There is no single value that is appropriate for every adult. Strength varies substantially with age, sex, population and testing protocol. This calculator therefore compares a result with age- and sex-specific published percentile values.

How many attempts should I perform?

The normative study used for this calculator performed two measurements separated by one minute and retained the highest recorded value.

What knee angle should I use?

The reference protocol used knees flexed to approximately 120–140° while maintaining a straight back and braced hips and core.

Can I use pounds instead of kilograms?

Yes. Enter the recorded value in pounds and the calculator converts it to kilograms before comparison with the published reference data.

Can I use these percentiles for a back-strength test?

No. These percentiles were produced using a leg-strength protocol performed on a back-leg-chest dynamometer. A different trunk or back testing posture changes the assessment and should not be interpreted against these leg-strength reference values.

Are the reference values universal?

No. The reference study involved Vietnamese adults. The values are a useful evidence-based benchmark, but population differences should be considered when interpreting individual results.

Can I compare results from different dynamometers?

Use caution. Device construction, calibration, chain position and testing posture can influence measurements. Longitudinal monitoring is strongest when the same device and standardised protocol are used.

Scientific methodology & references

Primary normative reference:
Do KT, Luong QN, Nguyen HG, et al. Reference Values of Handgrip and Lower Extremity Strength for Vietnamese Men and Women: The Vietnam Osteoporosis Study. Journal of Cachexia, Sarcopenia and Muscle. 2025.

The study included 4,096 adults aged 18 years and over and measured leg strength using a Baseline Back-Leg-Chest dynamometer. Published reference tables provide the 5th, 25th, 50th, 75th and 95th percentile values for men and women across 10-year adult age groups.

Supporting reliability reference:
Ten Hoor GA, Musch K, Meijer K, Plasqui G. Test-retest reproducibility and validity of the back-leg-chest strength measurements. Isokinetics and Exercise Science. 2016;24(3):209–216. DOI: 10.3233/IES-160619.

The supporting study found high adult test-retest reliability for BLC dynamometry, but used a different BLC body position. It supports the measurement approach rather than supplying the normative percentiles used by this calculator.

Methodology reviewed: September 2026
Calculator version: 1.0
Purpose: Professional education and benchmarking
Reference population: 4,096 Vietnamese adults aged 18+
Reference points: 5th, 25th, 50th, 75th and 95th percentiles

This assessment is not a diagnostic test and should not be used as a standalone assessment of sarcopenia, disability or clinical disease.

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