Repetition Maximum Testing: Single Leg (SL) Leg Press

The Single-Leg Leg Press Repetition Maximum Test assesses machine-based unilateral lower-limb pushing strength. It is useful for tracking strength progress, comparing sides and guiding lower-limb strength programming.

Introduction

A client may squat evenly with light loads but show a clear side-to-side difference when each leg is tested separately. Another client may need a controlled machine-based strength test before progressing to more complex lower-limb tasks. The Single-Leg Leg Press Repetition Maximum Test provides a repeatable way to assess unilateral pushing strength under a controlled setup.

The result should be interpreted as leg press performance, not isolated quadriceps strength or proof of readiness for sport.

Quick Summary

Test name: Single-Leg Leg Press Repetition Maximum Test
Purpose: Assess unilateral lower-limb pushing strength
What it assesses: Machine-based single-leg press performance
Equipment: Leg press machine, load stack or plates, safety stops, Measurz for recording
Key finding: Maximum load completed for the target repetition standard
Best used with: Squat, leg extension, jump tests, sit-to-stand, hop tests and lower-limb strength tests
Key limitation: Machine setup and foot position strongly influence the result

What Is the Single-Leg Leg Press Repetition Maximum Test?

The Single-Leg Leg Press Repetition Maximum Test measures the maximum load a client can press through a defined range using one leg on a leg press machine.

It may be performed as a 1RM, 3RM, 5RM or another repetition maximum. The exact repetition target and machine setup must be recorded.

Why It Is Used

This test is used to assess unilateral lower-limb pushing strength, compare sides and track progress.

It may be useful when a controlled machine-based assessment is preferred or when bodyweight, free-weight or balance demands make other strength tests less suitable.

What It Measures

The test measures single-leg leg press performance.

It may reflect:

Unilateral pushing strength
Hip and knee extension contribution
Load tolerance
Side-to-side difference
Control through the selected range
Pain response
Strength progress over time

It does not isolate quadriceps strength, glute strength or sport performance.

Who It Is Useful For

This test may be useful for gym clients, athletes, older adults, lower-limb strength clients and anyone needing controlled unilateral strength tracking.

It may not be suitable when the machine position causes pain, the client cannot control the range, or maximal testing is inappropriate.

Equipment Required

Leg press machine
Load stack or plates
Safety stops
Measurz for recording
Optional metronome
Optional video

Step-by-Step Protocol

1. Set the machine

Adjust the seat/back position and safety stops. Record the exact setup.

2. Set foot position

Place one foot on the platform. Record foot height, width, angle and whether footwear is used.

3. Define depth

Set a consistent bottom position. This may be based on knee angle, machine stop, or agreed range that avoids pelvic lift.

4. Warm up

Complete light warm-up sets on each side. Progress gradually.

5. Test one side

Ask the client to lower under control, reach the agreed depth and press to the agreed finish position.

6. Progress load

Increase load after successful attempts. Allow adequate rest between heavy attempts and between sides.

7. Record the best successful result

The score is the heaviest load completed for the target repetition range with the agreed depth and technique.

Scoring and Interpretation

Record side, load, reps, RM target and machine setup. Interpret using absolute load, relative load, side-to-side comparison, pain, ROM and previous baseline.

A higher result indicates greater leg press performance under that machine setup. It should not be compared directly with squat or leg extension results.

Normative Data, Benchmarks or Reference Values

Leg press results vary widely between machines due to sled angle, carriage friction, plate loading, lever design and seat position. Universal norms are not appropriate unless the protocol and machine match.

Use baseline, side-to-side comparison and progress across sessions.

Reliability and Validity

1RM and repetition maximum testing can be reliable when familiarisation, loading progression and setup are standardised. A 2020 systematic review found 1RM testing generally shows good-to-excellent reliability across exercise types under consistent procedures.  

For leg press testing, machine setup, foot placement and ROM are critical for repeatability.

Common Errors and Testing Limitations

Common errors include changing foot position, using inconsistent depth, locking out aggressively, lifting the pelvis, not setting safety stops, changing seat angle and comparing results across different machines.

Limitations include machine specificity, reduced balance demand and difficulty comparing results between facilities.

Practical Applications

Use this test to track unilateral lower-limb strength, guide loading, monitor side-to-side differences and support programming decisions.

It is most useful when combined with squat, leg extension, sit-to-stand, hop, jump and movement-quality tests.

How to Record This in Measurz

Record side, load, reps, RM target, body weight, machine type, seat position, foot position, depth standard, safety stop position, pain score, symptom location, RPE, compensation notes and comparison side.

Useful notes include pelvic lift, shortened depth, knee discomfort, foot shift, slow lockout or side-to-side difference.

Related Tests or Internal Linking Suggestions

Single-Leg Leg Extension Test
Back Squat 1RM Test
Front Squat 1RM Test
Single-Leg Sit-to-Stand
Vertical Jump Test
Broad Jump Test
Y-Balance Test

FAQs

What does the Single-Leg Leg Press Test measure?

It measures unilateral machine-based lower-limb pushing strength.

Can leg press results be compared between machines?

Only cautiously. Machine design can strongly affect the result.

Should foot position be recorded?

Yes. Foot placement changes joint angles and muscle contribution.

Is this a quadriceps-only test?

No. It measures a lower-limb pressing pattern involving multiple joints and muscles.

Should both sides be tested?

Yes, when side-to-side comparison is relevant.

Key Takeaways

The test measures single-leg leg press performance.
Machine setup and foot position must be standardised.
Use safety stops.
Do not compare directly with squat or leg extension.
Record load, side, depth and symptoms 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.

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.

Weakley, J., Mann, B., Banyard, H., McLaren, S., Scott, T., & Garcia-Ramos, A. (2021). Velocity-based training: From theory to application. Strength and Conditioning Journal, 43(2), 31–49.