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