The benchmarks that calibrate your sessions: pace, FTP, CSS and SWOLF

Why a wrong benchmark is expensive

A maximal aerobic speed overestimated by ten percent makes every interval session too hard. You endure them, recover badly, and the plan turns counterproductive without any number announcing it.

That is why measuring the benchmark is not a one-off formality at the start but regular maintenance — as much a part of the plan as a session.

Aerobic power: running speed and cycling FTP

These two benchmarks play the same role in two sports: they set the ceiling from which every intensity is derived.

• — Maximal aerobic speed is the lowest speed at which you consume maximum oxygen. In running, everything is calibrated as a percentage of it.
• — It is measured with a maximal six-minute test: the average speed held is a direct and honest estimate.
• — FTP is the power holdable for roughly an hour on a bike. It is estimated from a maximal twenty-minute effort, keeping about 95% of the average power.
• — Both are reassessed every two to three months, or after a marked block.

A botched test beats a value inherited from two years ago: redo it rather than guess.

CSS: the swimmer's threshold

Critical swim speed is the swum equivalent of threshold: the pace holdable for roughly thirty minutes. It is the reference from which swim sets are built.

• — It is measured with two maximal efforts: a four hundred and a two hundred metres, separated by full recovery.
• — The difference in times divided by the difference in distances gives the corresponding time per hundred metres.
• — Instructions are then expressed as offsets: "CSS plus five seconds" for volume, "CSS minus two" for hard work.
• — It moves faster than running speed for a swimmer improving technically: revisit every two months.

It is the easiest benchmark to measure yourself, since it needs only a pool and a stopwatch.

SWOLF: efficiency, not intensity

SWOLF is not an intensity benchmark but an efficiency one: it adds the time for a length to the number of strokes it took.

• — It only compares against yourself, in the same pool: between two swimmers it means nothing.
• — Read length by length, it shows technical degradation across a set.
• — It falls when technique improves, at equal speed.
• — It never calibrates a target: it is a tracking indicator.

It is swimming's most misused metric, because people compare it between swimmers when it depends on height and wingspan.

Training load: the ratio that warns

Beyond the four benchmarks, a fifth number is worth tracking: the ratio of the current week's load to the average load of the previous three to four weeks.

That ratio is not calculated in your head, but it is calculated very well from activities already recorded.

Frequently asked questions