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