Strength Endurance Test: McGill Endurance Tests

The McGill Endurance Tests assess trunk flexor endurance, trunk extensor endurance and lateral trunk endurance using timed isometric holds. McGill’s original database reported high reliability coefficients for the trunk extensor, flexor and side bridge endurance tests, supporting their use when protocols are standardised.  

What Is This Assessment?

The battery commonly includes:

• Trunk flexor endurance test
• Trunk extensor endurance test
• Right side bridge
• Left side bridge

The goal is to measure trunk endurance and compare endurance balance across the anterior, posterior and lateral trunk.

Equipment Required

• Bench or table
• Mat
• Straps or support where appropriate
• Stopwatch or Measurz stopwatch
• Optional inclinometer for trunk angle
• Optional Measurz AR measurement for setup consistency
• Measurz platform for timing, ratios, symptoms and progress tracking

Protocol Summary

Trunk flexor endurance: Client holds a supported sit-up position at the defined angle until form failure.
Trunk extensor endurance: Client holds the trunk unsupported over a bench with pelvis supported.
Side bridge endurance: Client holds right and left side bridge positions to form failure.

The ACE protocol describes these as timed isometric tests designed to assess endurance of trunk flexors, extensors and lateral stabilisers.  

Scoring and Interpretation

Record each hold time in seconds:

• Flexor time
• Extensor time
• Right side bridge
• Left side bridge
• Right:left side ratio
• Flexor:extensor ratio
• Side bridge relative to extensor/flexor endurance

Normative Data, Benchmarks or Reference Values

McGill’s research reported sex differences and endurance relationships, including that women had longer extensor endurance than men, while side bridge endurance represented different proportions of extensor and flexor endurance between sexes.  

Practical Guide

• Compare all four scores together rather than one score alone.
• Large right-left side bridge differences may indicate asymmetrical lateral trunk endurance.
• Very large flexor-extensor differences may suggest imbalance in trunk endurance profile.

Reliability and Validity

McGill’s database reported reliability coefficients of .99 for extensor, .93 for flexor, .96 for right side bridge and .99 for left side bridge when repeated sessions were included.  

Common Errors

Changing trunk angle, poor support, inconsistent stopping criteria, unrecorded symptoms, poor side bridge alignment and comparing modified protocols with standard versions.

How to Record This in Measurz / MAT

Record each test time, side, body position, symptoms, compensations, ratios and retest date. The Measurz stopwatch supports timing, and AR measurement/inclinometer can support setup consistency.

Key Takeaways

• McGill tests assess trunk endurance as a battery.
• Ratios are often more informative than single scores.
• Reliability is strong when protocols are standardised.
• Measurz can track scores, ratios and progress.

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.  

American Council on Exercise. (n.d.). McGill’s torso muscular endurance test battery protocol.