Dead Bug Hold

How This Calculator Works

This calculator measures your core stability and endurance using the dead bug — one of the most common and joint-friendly tests of how well your deep trunk muscles can keep your spine stable while your limbs move. You perform one standardized timed hold on each side, enter how many seconds you held each side in good form, and the calculator classifies it against Amatal’s age- and sex-graded estimated standards, then computes your category, an estimated Dead Bug Age, and an estimated percentile for your age and sex.

How These Standards Were Set

Because no dead bug norms exist, Amatal set each tier as the hold time we expect at that level, then checked the numbers against the closest real data available:

• Below the plank at every level. Extending an arm and the opposite leg makes the dead bug harder to hold than a plank, so every dead bug threshold sits well below the matching threshold on Amatal’s Plank Hold Test, at every tier, age, and sex (roughly 30–55% of the plank time).
• The gap between men and women. Women’s thresholds are about 10% lower than men’s. Real data on similar holds disagrees: on McGill’s trunk flexor hold, young men and women scored about the same, while plank data shows women about 30% lower. The 10% gap sits between the two.
• Tier spacing and age decline. Each tier asks for roughly 1.4–1.7 times the time of the tier below, and the Elite threshold falls about 45% from age 18 to 65, a pattern similar to other endurance tests on the site.

The percentile labels and Dead Bug Age are built on these same estimates, so they carry the same limits. If real dead bug norms are published, the numbers can be updated without changing how the calculator works.

Step 1: Enter Your Details

The calculator needs four inputs: your sex, your age, and your hold time on each side.

• SexCore-endurance standards are reported separately for men and women to account for typical differences in body proportions, limb leverage, and strength-to-weight ratio. — selects which scale you are compared against.
• Age — determines the performance standards expected for your stage of life.
• Right Arm + Left Leg — the seconds you held with your right arm overhead and left leg straight, in good form.
• Left Arm + Right Leg — the same for the other side.

The Test Protocol

The standards apply to one version of the dead bug only. Other versions change the difficulty a lot, so use this protocol every time:

• Setup: Lie on your back. Bend your hips and knees so your thighs are vertical and your shins are parallel to the floor (a "tabletop" position). Reach both arms straight up toward the ceiling. Let your lower back rest in its natural, neutral position, lightly touching the floor, and brace your core. Do not force it flat by tucking your pelvis; a small natural curve is normal.
• Hand check (optional): Before you start, slide one hand under your lower back so you feel light pressure on it, then move the hand away. If the gap under your back clearly grows during the hold, your back has lifted. A partner can keep a hand there and tell you when the pressure is lost.
• Test position: Lower one arm overhead and straighten the opposite leg until both hover just above the floor. Keep the other arm pointing at the ceiling and the other leg in tabletop. Start the timer once you are in position.
• Test both sides: Hold one side to the end, rest about 2 minutes, then hold the other side (left arm and right leg after right arm and left leg, or the reverse). Enter both times.
• When time stops: Stop the timer the moment your form breaks in any of these ways:
  • Your lower back lifts away from its starting position (the gap under it grows).
  • The extended arm or leg touches the floor.
  • The arm pointing up or the bent leg drifts out of position.
  • Your hips or torso rock or rotate.
  • You feel pain (stop right away).
  Only time held in good form counts.

Scoring Both Sides

Your tier, percentile, and Dead Bug Age are all based on your shorter hold, because your weaker side is the one that limits your core stability. The thresholds are hold times for one side, so they apply to whichever side is scored.

The calculator also shows the side difference: how much shorter your weaker side held, as a percentage of your stronger side.

A difference of about 5% or less is treated as balanced. That cutoff comes from McGill’s guideline for his side-bridge test, a related core endurance hold. No dead bug data exists for side differences, so use it as a guide, not a rating.

How Your Category Is Determined

Results are placed on the same five-tier scale used across this platform, so every assessment on the site reads consistently:

Your result is compared against the minimum required for each tier at your age and sex, and you are placed in the highest tier you qualify for:

• Low — below the typical range for your group. A clear starting point with substantial room to build core endurance and control.
• Intermediate — around the expected average for your group. Typical of recreationally active adults with some core conditioning.
• Advanced — above average for your group. Reflects consistent core and stability training.
• Superior — well above average. Characteristic of well-conditioned individuals with strong trunk control.
• Elite — top tier for your age and sex. Among the strongest core-endurance performers in the demographic.

The Smooth Age Model

Rather than slotting you into a wide age bracket — which would make your standards jump abruptly the day you change brackets — the calculator builds a smooth, continuous curve. Core endurance, like other muscular fitness, declines gradually with age, not in sudden steps.

To model this, the standard is anchoredThe model uses representative reference ages — 18, 25, 35, 45, 55, and 65 — and treats each as a single point on the curve. at a series of representative ages (18, 25, 35, 45, 55, 65), then interpolates a smooth value for every age in between:

Ages below 18 are held at the youngest values, and ages beyond 65 are extrapolated by continuing the downward trend out to 75. This produces the smooth band chart and the per-five-year standards table. Because there is no published dead-bug norm dataset, every value in the model — at every age — is a modeled estimate, not a directly published figure.

How to Read the Standards Table

The standards table lists one row for every five years of age, and one column for each of the five levels. The header labels are color-coded to match the chart bands — on a phone the headers shorten to single letters (L · I · A · S · E); tap any header to see its full name.

• Each cell is a single number — the minimum. It shows the fewest seconds needed to reach that level at that age. If your result equals or exceeds it, you've reached that level.
• The Low column is the exception.Low has no real minimum — it runs from zero up to the Intermediate threshold. The number shown is just a representative point inside that range. Because Low spans from zero up to the Intermediate cutoff, the number shown there is a representative midpoint for display only, not a threshold you need to hit.
• Your row and level are highlighted. The row closest to your age is shaded, and within it, the cell for your achieved level is filled with that tier's color.

Dead Bug Age

Your Dead Bug AgeThe age at which your result would be considered typical (median) performance. Conceptually similar to the "fitness age" used in cardiovascular testing. is the age at which your result would be average. If you outperform the typical person of your actual age, your Dead Bug Age is younger; if you fall short, it is older.

The calculator scans the smooth age model to find the age whose typical performance equals your result, giving you a single-number summary of where your core endurance sits relative to the aging curve.

Percentile Estimate

The percentile estimates the share of people in your age-and-sex group who perform below you. Because the model is built from tier boundaries rather than a full population distribution, the percentile is approximated by mapping each tier threshold to its corresponding percentile and interpolating between them:

Your result is placed along this scale to produce an approximate percentile. Because the tier cutoffs are themselves Amatal estimates, no measured population sits behind this percentile. It shows where your time falls on Amatal’s scale, not a ranking against real test-takers.

How Age and Sex Change Your Score

These two inputs do not just describe you — each one directly changes the numbers your result is measured against:

• Age changes the thresholds. The calculator recomputes the requirement for every tier at your exact age. Because endurance standards decline with age, the same result is judged against lower requirements as you get older — so an identical hold time can place you in a higher tier at 55 than it would at 25. This is why the entire standards table and chart shift downward from left to right.
• Sex selects a different scale. Choosing male or female swaps in a separate set of values. The requirements for each tier differ between the two, so the same result is scored against different benchmarks depending on which scale applies.

Why Core Endurance Matters

Core endurance is more than a gym metric. The deep trunk muscles the dead bug challenges are what keep your spine stable while your arms and legs move — transferring force between your upper and lower body and protecting your lower back during lifting, bending, and carrying. Influential work by spine researcher Stuart McGill has argued that, for everyday back health, the muscular endurance of these stabilizers matters more than their peak strength: it is the ability to hold good position over time, not maximal force, that most consistently distinguishes healthy backs from painful ones in his research.

Important context: this is an association drawn largely from clinical and laboratory populations, not proof that training the dead bug will prevent injury for any one person. Still, trunk muscular endurance is a meaningful marker of functional fitness — and the dead bug is so widely used precisely because it trains anti-extension control of the spine with very little compressive load, making it accessible to nearly everyone, from rehab patients to advanced athletes.

Data Sources and Verification

None of the sources below contains dead bug norms. They support why timed trunk endurance matters and how such tests are run, and two of them serve as reference points for checking Amatal’s estimates. The tier numbers themselves are Amatal’s (see How These Standards Were Set above).

• McGill, S.M., Childs, A., & Liebenson, C. (1999). Endurance times for low back stabilization exercises: clinical targets for testing and training from a normal database. Archives of Physical Medicine and Rehabilitation, 80(8) — reference times for the trunk flexor, extensor, and side-bridge holds (not the dead bug). Used here only as a reference point for the gap between men and women, and for the ~5% side-bridge guideline used as a guide for the side difference.
• McGill, S.M. (2015). Low Back Disorders: Evidence-Based Prevention and Rehabilitation (3rd ed.). Human Kinetics — the case for trunk muscular endurance over peak strength in spinal health.
• ACSM’s Guidelines for Exercise Testing and Prescription (11th Edition, 2021). American College of Sports Medicine — general principles for muscular endurance testing. It does not include the dead bug.
• Amatal Plank Hold Test. Used as the upper reference: every dead bug threshold is set below the matching plank threshold.

Limitations and Important Caveats

This calculator provides an estimate, not a clinical measurement. Several factors affect how precisely it reflects your true core endurance:

• Estimated standards. The biggest caveat: every threshold is an Amatal estimate, because no published dead bug norms exist. Treat your category as a benchmark, not a ranking against real test-takers.
• One protocol only. The standards apply only to the timed hold described above. Other versions (legs fully straight, both limbs moving, alternating reps, a different tempo) change the difficulty a lot and cannot be scored here.
• Estimated percentile and Dead Bug Age. Both are calculated from the estimated tiers and age curve, not from a measured population, so read them as guides, not statistics.
• Form and control variability. How strictly you judge your lower back lifting or a limb drifting varies from person to person. Inconsistent judging is the largest source of error in self-administered core tests, so a partner watching your lower back helps.
• Body leverage. Limb length, body weight, and proportions influence how demanding each rep or hold is, independent of core fitness. Two equally fit people can score differently.
• Your own trend is the most reliable result. Fatigue, sleep, time of day, and recent training all affect a single test. Retest every 4–6 weeks under the same conditions, test both sides each time, and compare against your own previous times.

Disclaimer:
This calculator scores your hold against Amatal’s estimated standards and a modeled age curve. No published dead bug norms exist, so your tier, percentile, and Dead Bug Age are estimates. Real core endurance depends on training history, technique, body proportions, recovery, and individual variation. Always warm up before any fitness test and stop immediately if you experience pain — particularly in your lower back — dizziness, or unusual discomfort. This tool is for general informational purposes only and should not be considered medical, fitness, or training advice. Consult a healthcare provider before beginning a new exercise program, especially if you have a pre-existing condition (including any history of back problems), are over the age of 45, or have been sedentary for an extended period.