Fatigue in an AMRAP: velocity, holds and movement choice

The format changes how you slow down

Twelve trained athletes performed the same work under three formats on separate days: as many rounds as possible, every minute on the minute, and rounds for time. Movement velocity was measured throughout.¹

Read the two columns together, because separately they mislead. The AMRAP was the slowest format but not the one that decayed hardest within a set — rounds for time was. The authors attribute the AMRAP's lower velocity to its prolonged duration prompting a self-regulated tempo.

That is a meaningfully different story from "the clock drives you to failure". In an AMRAP you are choosing a speed you can repeat, which isthe pacing decision showing up in the barbell rather than in the round times. Twelve participants, so hold it lightly.

Rest protects movement quality

Thirty-four subjects completed three different workout types with jump testing before, during and after: a 20-minute AMRAP of pull-ups, push-ups and air squats; a metabolic piece of skipping intervals with rest built in; and a five-minute weightlifting piece at a light load.²

Jump performance was reduced after the AMRAP and after the weightlifting piece. After the interval piece it had recovered by the end — the rest periods were long enough to restore the immediate energy stores that jumping depends on.

The practical reading is not that AMRAPs are bad. It is that continuous formats leave you measurably more fatigued at the end than interval formats doing comparable work, which matters if you have planned something demanding immediately afterwards, or if tomorrow is abenchmark retest.

Holding is harder than acting

There is a real and under-appreciated distinction between two isometric tasks that look identical. Holding means reacting to an external load — supporting a weight against gravity.Acting means initiating force against something immovable — pushing or pulling on a fixed resistance.

At matched intensity they do not last the same. In a controlled task at 60% of maximal torque, time to failure was significantly shorter for the holding action than for the acting one.³

Now the caveats, because they are large. That was twelve subjects, one joint — the elbow flexors — at a single fixed intensity, in a laboratory. Nobody has tested whether it transfers to a plank hold in minute fourteen of a twenty-minute AMRAP. I am reporting a mechanism that looks relevant, not a finding about AMRAPs.

It is worth knowing anyway, because ourmovement library is full of holds — plank, hollow, side plank, bottom squat, superman, bear crawl hover. All of them are the holding kind. If the distinction transfers, they will fail sooner under fatigue than their duration suggests.

What this suggests about picking movements

Stated as suggestions, because that is the strength of the evidence.

• Put holds early, not late. Aplank hold that is comfortable in round two may be unholdable in round eight, and a hold you fail out of mid-rep is worse than one you never programmed.
• Expect the technical movement to break first.Velocity falls as the workout runs,¹ and the movements that need precision have the least room to lose.
• If you want to preserve quality, build in the rest.That is what the interval format did in the jump study.² An AMRAP is the wrong tool for a session about movement quality — use it for the thing it is good at.
• Do not stack a hard AMRAP before a test.Jump performance was still down at the end of one.² That is the measurable case for aneasy day before a retest.

What the research does not show

• A specific velocity-loss figure for AMRAPs.The comparison above reports directions and rankings, not a percentage you should expect. If you have seen a precise number quoted for AMRAP velocity decay, ask which study it came from.
• That the holding-versus-acting difference applies to bodyweight holds in a workout.It has been shown in a lab, on one joint.³ Everything past that is extrapolation, including mine.
• Anything about long-term adaptation. These are acute studies — what happens during and immediately after one workout. Whether repeated AMRAP exposure changes fatigue resistance is a different question and these do not answer it.
• Much about women. Twelve participants with two women;¹ thirty-four subjects described as men.² Sex differences in fatigability are a real research area and this literature is not where you will find them.

Related questions

Programme around it

Every workout in the library lists its movements up front, so you can see where the holds and the technical work fall before you start the clock rather than discovering it in round eight.