That’s the question I asked when working with a personal trainer last year. To determine my abdominal strength I was asked to perform as many bent-knee sit-ups as possible in 1 minute with feet anchored. Wait, this was the test we used when I was in high school in the 1960s! Surely there is a more contemporary and effective measure of abdominal strength.

So I called on my strength and conditioning industry friends for their expert recommendations. Here are the responses from Todd Durkin, Wayne Westcott, Douglas Brooks, and Paul Chek:

We use external resistance (such as the Nautilus Abdominal Machine) to test abdominal muscle strength. We find the heaviest weight that can be performed with correct technique for 5 repetitions (5 repetition maximum) or 10 repetitions (10 repetition maximum), and use this as our baseline strength measure. After several weeks of training, we reassess the 5 rep or 10 rep maximum to attain the pounds and percentage improvement over baseline. Although it is easier to do standard body-weight abdominal exercise tests, form is always a major variable and the assessment typically tends more towards muscle endurance rather than muscle strength.
— Wayne Westcott

I would say the best test you can do is a “simple” plank test (elbows & toes). It is going to test your entire trunk. Perform the max time you can stay up and maintain good form. Retest every 30 days and you will easily measure improvement.
— Todd Durkin

I would recommend eight assessments to help determine abdominal conditioning and where you’d need to start your training.
Prone TVA
Multifidus in Prone
Standing TVA Activation
Janda’s Upper Abdominal Strength
Forward Flexion Activation
Lower Abdominal Strength
Lower Abdominal Coordination
Oblique Dominance
These eight assessments provide a good understanding of abdominal conditioning (both inner and outer units) and guide the design of a strength training program that is appropriate, fun, and safe. You cannot perform these assessments alone, however. You’ll need a practitioner to assist.
— Paul Chek

We use a 7-level plank assessment. Initially the goal is 15 seconds per hold and build to 30 seconds. Or, go for 30 seconds at each stage and try to reach level 7 — 2.5 minutes. As soon as a perfect plank is lost (form break) or either hip turns up toward the ceiling the test is ended.

Start with a prone bent elbow plank; after that you move to right arm extended; then left arm extended; next right leg lifted; then left leg lifted; next opposite arm and leg lifted and, lastly, switch sides for the opposite arm and leg lifted…test over.
— Douglas Brooks

As you can see, a multitude of approaches can be used to measure muscle strength and endurance from a relative and functional strength perspective.

If you have questions about the best test for assessing your clients’ cardiorespiratory and muscular fitness, flexibility, balance, and body composition, the Fitness Assessment and Exercise Prescription for all Ages CE course is an excellent reference tool. Check it out today!