Repetition Maximum Testing: Bicep Curl – Single Arm Test

A gym client may want to compare arm strength between sides. A field sport athlete may need upper-limb strength monitoring as part of a broader programme. A client returning to loaded elbow flexion may need a simple way to track left-right strength changes across training blocks.

The Bicep Curl – Single Arm Repetition Maximum Test provides a controlled way to assess unilateral elbow-flexion strength using a standardised dumbbell, cable, machine or supported curl setup. Rather than requiring a true 1RM attempt, the test can be performed using a submaximal repetition maximum, such as a 3RM, 5RM, 8RM or 10RM. The load and reps are then entered into Measurz to calculate the estimated 1RM.

The result is useful for strength tracking, but it should not be interpreted as a complete measure of arm function, grip capacity, elbow health, shoulder function, injury risk or sport readiness.

What Is the Bicep Curl – Single Arm Repetition Maximum Test?

The Bicep Curl – Single Arm Repetition Maximum Test measures the heaviest load a client can curl for a defined number of repetitions using one arm.

Depending on the protocol, this may be a 3RM, 5RM, 8RM, 10RM or another repetition maximum. The repetition target should be clearly recorded.

The test may be performed using:

Dumbbell curl
Cable curl
Single-arm machine curl
Preacher curl
Incline dumbbell curl
Supported single-arm curl
Other standardised elbow-flexion setup

In Measurz, the professional records the load, completed repetitions and side tested. Measurz then calculates the estimated 1RM from that result. This estimated 1RM can be used to monitor progress over time, compare sides and guide loading decisions.

If the client performs a true single-repetition maximum, the result should be labelled as a directly measured 1RM. If the result is calculated from a submaximal load and repetitions, it should be labelled as an estimated 1RM.

Why It Is Used

This test is used to assess unilateral elbow-flexion strength, compare sides and track strength changes over time.

It may be useful for gym clients, athletes, upper-limb strength programmes, general fitness assessments and training blocks where single-arm bicep curl strength is a meaningful monitoring variable.

It is especially useful when the professional wants a strength estimate without requiring a true maximal 1RM attempt. A submaximal RM test can be more practical for many clients while still giving a useful estimated 1RM through Measurz.

What It Measures

The test measures single-arm bicep curl performance under the selected setup.

It may reflect:

Loaded elbow-flexion strength
Single-arm bicep curl capacity
Side-to-side strength difference
Arm strength progress
Load tolerance
Control through the selected ROM
Pain or symptom response
Estimated 1RM progress across training blocks
Training load progression

It does not measure complete upper-limb function, isolated biceps strength, tendon health, grip strength, shoulder function, pulling performance, injury risk or sport readiness on its own.

Who It Is Useful For

This test may be useful for gym clients, athletes, personal training clients, general fitness clients and anyone completing upper-limb strength training.

It may not be appropriate when elbow or shoulder loading causes unacceptable pain, the client cannot maintain a repeatable curl technique, the test cannot be performed through a consistent ROM, symptoms increase during loaded elbow flexion, or the client is not ready for maximal or near-maximal repetition testing.

Equipment Required

Dumbbell, cable machine, single-arm curl machine, preacher curl setup or other standardised curl setup
Load stack, plates or dumbbells depending on setup
Measurz for recording load, reps, side and estimated 1RM
Optional metronome
Optional video
Optional bench or arm support depending on protocol

Step-by-Step Protocol

1. Choose the single-arm curl setup

Decide whether the test will use a dumbbell, cable, machine, preacher curl, supported curl or another clearly defined setup.

2. Record the setup

Record equipment type, side tested, grip position, body position, elbow position, shoulder position, support used, ROM, tempo and load method.

3. Choose the repetition target

Select the repetition maximum target, such as 3RM, 5RM, 8RM or 10RM. Use the same target for retesting where possible.

4. Define valid ROM

Set a clear start and finish range. A valid repetition should use the same elbow-flexion range each time without trunk swing, shoulder movement, elbow drift, wrist collapse or shortened ROM.

5. Warm up

Complete light warm-up sets on each side. Increase load gradually before testing.

6. Test one side at a time

Choose the testing order and keep it consistent. Allow adequate rest between attempts and sides.

7. Perform the test

Ask the client to complete the selected repetition maximum with controlled movement and the defined ROM.

8. Stop the attempt

Stop when the client reaches the target reps, cannot complete another valid rep, loses ROM, uses unacceptable compensation, reports limiting symptoms or cannot maintain control.

9. Record the maximum successful set

The score is the heaviest load completed for the target repetition range with acceptable technique and ROM.

10. Enter load and reps into Measurz

Record the completed load, repetitions and side tested in Measurz. Measurz calculates the estimated 1RM from the entered result.

Scoring and Interpretation

Record the load, reps, side tested and exact single-arm bicep curl setup. Measurz uses the completed load and reps to calculate the estimated 1RM.

The estimated 1RM should be interpreted as an estimate, not the same as a directly tested 1RM. If a true 1RM was performed, label it as directly measured. If the result comes from a submaximal load and repetitions, label it as estimated.

Interpretation should include:

Absolute load
Completed repetitions
Estimated 1RM
Side-to-side comparison
ROM
Setup
Tempo
RPE
Pain or symptoms
Compensations
Previous baseline

A lower estimated 1RM on one side may suggest reduced single-arm bicep curl strength under the tested setup, but it does not identify the cause. Pain, fatigue, elbow position, wrist position, grip, shoulder compensation, confidence, recent training and technique may all influence the result.

Normative Data, Benchmarks or Reference Values

No universal normative value should be applied across single-arm bicep curl setups and populations. Results vary by equipment type, grip, body position, elbow position, ROM, tempo, training history and whether the 1RM is directly measured or estimated.

Use baseline comparison, side-to-side comparison and progress across sessions as the primary benchmarks.

A noticeable side-to-side difference should be interpreted alongside symptoms, training history, grip capacity, shoulder function and related upper-limb strength tests. It should not be used as a strict pass/fail rule.

Common Errors and Testing Limitations

Common errors include using trunk swing, changing elbow position, moving the shoulder, shortening ROM, extending the wrist, changing grip, using momentum, changing tempo, testing while fatigued, not recording symptoms and comparing results across different curl setups.

A common recording error is failing to distinguish between a directly measured 1RM and an estimated 1RM. When load and reps are entered into Measurz, the result should be described as an estimated 1RM unless a true 1RM was directly tested.

The main limitation is that the test measures loaded single-arm bicep curl strength only. It does not fully assess grip strength, shoulder strength, pulling capacity, arm function, tendon capacity, sport performance or injury risk.

Practical Applications

Use this test to monitor single-arm bicep curl strength, compare sides, guide training loads and track response to upper-limb strengthening programmes.

The estimated 1RM can help track progress across training blocks, adjust loading and compare left-right differences when the same setup is repeated.

It is most useful when interpreted alongside grip strength, pulling strength, shoulder strength, upper-limb symptoms, training load and movement quality.

How to Record This in Measurz

Record protocol type, equipment used, side tested, grip position, body position, elbow position, ROM, tempo, load, reps, RM target, estimated 1RM, RPE, pain score, symptom location, compensation notes, reason for stopping and retest date.

Useful notes include shortened ROM, trunk swing, shoulder movement, elbow drift, wrist collapse, grip limitation, pain-limited stop, tempo failure, fatigue-limited attempt, side-to-side difference or setup change.

The key Measurz workflow is:

Enter the completed load
Enter the completed reps
Enter the side tested
Review the estimated 1RM calculated by Measurz
Record setup, ROM, symptoms, RPE and compensations
Use the same protocol for retesting

FAQs

What does the Bicep Curl – Single Arm Repetition Maximum Test measure?

It measures loaded elbow-flexion strength on one arm under the selected curl setup.

How does Measurz calculate the result?

The professional enters the completed load and reps into Measurz. Measurz uses this information to calculate the estimated 1RM.

Is the Measurz result a true 1RM?

Not unless the client completed a true 1RM. If the result is based on load and multiple repetitions, it should be labelled as an estimated 1RM.

Should left and right arms be compared?

Yes. Side-to-side comparison is one of the most useful parts of this test.

Can results be compared across different curl setups?

Only cautiously. Dumbbell, cable, machine, preacher and supported curl setups can all change the score.

Should pain be recorded?

Yes. Pain score, symptom location, ROM and whether symptoms limited the result should be recorded.

Is a true 1RM always required?

No. A 3RM, 5RM, 8RM or 10RM may be more appropriate for many clients. Measurz can use load and reps to estimate 1RM.

Key Takeaways

The Bicep Curl – Single Arm Repetition Maximum Test measures unilateral loaded elbow-flexion strength.
Measurz calculates the estimated 1RM from the recorded load and reps.
Side, setup and ROM must be repeated for meaningful retesting.
Do not treat an estimated 1RM as the same as a directly measured 1RM.
Do not treat the result as a complete upper-limb strength or function profile.
Record load, reps, side, setup, ROM, symptoms and RPE in Measurz.

References

Grgic, J., Lazinica, B., Schoenfeld, B. J., & Pedisic, Z. (2020). Test–retest reliability of the one-repetition maximum strength assessment: A systematic review. Sports Medicine - Open, 6, 31. https://doi.org/10.1186/s40798-020-00260-z

Hoeger, W. W. K., Hopkins, D. R., Barette, S. L., & Hale, D. F. (1990). Relationship between repetitions and selected percentages of one repetition maximum. Journal of Strength and Conditioning Research, 4(2), 47–54.

Suchomel, T. J., Nimphius, S., Bellon, C. R., & Stone, M. H. (2018). The importance of muscular strength: Training considerations. Sports Medicine, 48(4), 765–785.