Strength Endurance Test: Side Plank

The Side Plank Test, also known as the side bridge test, assesses lateral trunk endurance by recording how long a client can maintain a side plank position. McGill’s trunk endurance research reported high reliability for side bridge testing and highlighted ratios between side bridge, flexor and extensor endurance as useful trunk endurance comparisons.  

Equipment Required

• Mat
• Stopwatch or Measurz stopwatch
• Optional inclinometer for trunk position
• Optional Measurz AR measurement for setup consistency
• Measurz platform for time, side and symptom tracking

Protocol

1. Client lies on one side with elbow under shoulder.
2. Legs are stacked or staggered, but the version must be recorded.
3. Client lifts hips into a straight-line side plank.
4. Start timing once aligned.
5. Stop when hips drop, trunk rotates, shoulder position fails, symptoms become intolerable or the client stops.
6. Test both sides.

Scoring and Interpretation

Record time in seconds for each side. Compare:

• Right versus left
• Dominant versus non-dominant
• Baseline versus retest
• Side plank versus other McGill endurance tests

Normative Data, Benchmarks or Reference Values

Practical adult guide:

• Excellent: 90+ seconds
• Good: 60–89 seconds
• Moderate: 30–59 seconds
• Developing: 15–29 seconds
• Low current endurance profile: under 15 seconds

McGill’s work suggests side bridge scores can be interpreted relative to trunk flexor and extensor endurance rather than as isolated values only.  

Reliability and Validity

Research supports side bridge testing as a common trunk lateral endurance assessment, but later studies note that variability may be high when trying to detect small individual changes.  

Common Errors

Pelvic drop, trunk rotation, poor elbow placement, shoulder shrugging, breath holding, inconsistent leg setup and inconsistent stopping criteria.

Measurz / MAT Recording

Record side, time, leg position, elbow position, pain, symptoms, compensations and retest date. The Measurz stopwatch supports timing, while AR measurement or inclinometer can help with setup consistency.

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.