Training science

The biggest tier in the library is also the one nobody programmes

Sort all 272 movements in the Forta database by stimulus-to-fatigue ratio and the middle one returns 1.38. That is not a rounding curiosity — the band around it holds 81 movements, more than any other tier in the library, and almost nothing has been written about it.

Alfredo Silva · Sports Scientist MSc Physical Education · MSc High Performance Training 272 movements analysed

Two earlier posts on this blog covered the tails of this distribution. The ten most expensive movements — deadlift, clean and jerk, snatch — return 0.45 for every unit of neural cost they charge. Seventy-seven movements sit at the cheapest cost there is, and most of them aren't there to build muscle at all. Between those two extremes sits the actual centre of the library, and it turns out to be bigger than either tier on its own.

The shape, not just the ends

Line up all 272 ratios and split them into bands of 0.5. The result is not a bell curve. It has a shoulder around the median, then a trough, then a second rise:

The band from 1.0 to 1.5 holds 81 movements — three in every ten in the entire library, and the single largest band there is. Immediately above it, the distribution collapses: only 19 movements sit between 1.5 and 2.5, barely 7% of the database. It rises again from 2.5 upward, but that upper half is mostly the cable and machine isolation work already covered on this blog. The middle band is not a staging post between cheap and expensive. It is its own category, and it is the biggest one.

What actually sits at 1.38

Two cost levels make up almost all of it. Twenty-nine movements carry a neural cost of 4 and a stimulus of 5.5 — a ratio of exactly 1.375. Forty-seven more carry a cost of 6, mostly at a stimulus of 7, for a ratio of 1.167 to 1.25. Read the names and a pattern appears immediately: this is not a specialist tier. It is the default vocabulary of a training session.

No barbell PRs. No cable-machine hacks. Burpees, sled work, carries, push-ups, squats done with your own bodyweight or a single kettlebell, a plain pull-up. This is what most people picture when they picture "a workout" — and by movement count, it is the largest single thing in the Forta database.

The tier with the most exercises in it has had the least written about it. That mismatch is the actual finding here.

Why the middle gets skipped

The two earlier posts on this blog both had a clean story. The expensive tier reads as a warning: these movements cost you more than you think, spend them carefully. The cheap tier reads as a hack: eighteen exercises that build muscle almost for free. Both make a headline. The middle band doesn't, because there is no twist to report — a burpee costs what a burpee looks like it costs, and a goblet squat isn't secretly better or worse than it seems.

That is exactly why it gets under-discussed and, in practice, under-programmed. Content rewards the extremes: the max-effort feat and the efficiency hack. Actual training weeks are still built mostly from the middle, whether or not anyone writes about it — which means the tier doing the most work is the one with the least analysis behind it.

What to do with this on Monday

Not "avoid the tails" — the earlier posts already made the case for both of them. It is a matter of proportion. The default content of a normal week — most sessions, most sets — should sit in this cost 4–6 band, because it is where compound, transferable, moderately loaded work lives. Reserve the cost 8–10 tier for the days you can genuinely afford it, and the cost 2 tier for the days you can't afford anything else. The middle isn't a compromise between those two. It is the actual centre of gravity of a training week, and the numbers say so more plainly than the case for either tail.