Strength Endurance Test: Single Leg (SL) Side Plank

The Single-Leg Side Plank Test is a more demanding variation of the side plank where the client supports their body laterally while one leg is elevated or held unsupported. It challenges lateral trunk endurance, shoulder support, hip abductor endurance and pelvic control. Side bridge testing has been widely used to assess lateral trunk endurance, and research supports its use when protocols are standardised.  

Introduction

The single-leg side plank increases the demand of the standard side plank by reducing support and increasing hip and pelvic control requirements. It can be useful for athletes, runners and clients who require lateral trunk and hip endurance.

This test should be used as a performance and monitoring tool rather than as a standalone diagnostic assessment.

Equipment Required

• Mat or flat surface
• Stopwatch or Measurz stopwatch
• Optional inclinometer for trunk/pelvis angle
• Optional Measurz AR measurement to document limb position
• Optional Measurz metronome for related dynamic side plank variations
• Optional Measurz rep counter if leg lifts are added
• MAT isometric tools for related hip abductor/adductor or shoulder strength tests
• Measurz platform for time, side, symptoms and retest comparison

Step-by-Step Protocol

1. The client begins in a side plank position with elbow under shoulder.
2. The body forms a straight line from shoulder to ankle.
3. The top leg is lifted or the support leg is the only lower-limb contact, depending on the chosen version.
4. Start timing once the correct position is achieved.
5. Stop when the client loses alignment, drops the pelvis, rotates, places the leg down, reports intolerable symptoms or chooses to stop.
6. Record time on each side.

Scoring and Interpretation

The primary score is time held in seconds for each side. Compare left versus right, dominant versus non-dominant, and baseline versus retest.

Normative Data, Benchmarks or Reference Values

Formal norms for the exact single-leg side plank are limited. Use side bridge research and standard side plank values as context only.

Practical Guide

• Excellent: 60+ seconds
• Good: 40–59 seconds
• Moderate: 20–39 seconds
• Developing: 10–19 seconds
• Low current tolerance: under 10 seconds

Reliability and Validity

The side bridge test is one of the most common tests for lateral trunk endurance. McGill’s endurance work reported high reliability for side bridge endurance testing, while later research found the side bridge can be valid and reliable but may show high within-subject variability when small changes matter.  

Common Errors and Limitations

Common errors include pelvic drop, trunk rotation, shoulder shrugging, poor elbow placement, inconsistent leg position and comparing different versions directly.

How to Record This in Measurz / MAT

Record side, time, version, leg position, pain score, symptoms, compensations, reason for stopping and retest date. Use the stopwatch for timing and inclinometer/AR measurement for setup consistency.

FAQs

What does it measure? Lateral trunk, hip and shoulder endurance.
Is it harder than a standard side plank? Yes.
Should both sides be tested? Yes.
Are there formal norms? Limited; use baseline and side-to-side comparison.

Key Takeaways

• This is a demanding side plank variation.
• The primary score is hold time.
• Side-to-side comparison is important.
• Standardisation is essential.
• Measurz can track time, side and compensations.

References

McGill, S. M., Childs, A., & Liebenson, C. (1999). Endurance times for low back stabilisation exercises: Clinical targets for testing and training from a normal database. Archives of Physical Medicine and Rehabilitation, 80(8), 941–944.  

Barbado, D., et al. (2022). Is the side bridge test valid and reliable for assessing trunk lateral flexor endurance in healthy females? Biology, 11(7), 1043.