How much training load is too much?

Every injury-prevention article eventually produces a number: keep your acute-to-chronic ratio under 1.5. The number is real, the research behind it is more contested than the number suggests, and the useful version of the advice is simpler than either.

What the ratio is

Acute load is roughly this week's training. Chronic load is your rolling average over the previous four weeks or so. The ratio is one divided by the other, and it asks a single question: is what you are doing now a lot, compared to what you are used to?

Gabbett's work popularised it, along with the finding that risk rises steeply above a ratio of roughly 1.5 in the original cohorts, and the accompanying and more interesting claim: high chronic load is protective. Athletes who had built up to a lot of training were more robust than those who had not. The danger is not volume. It is the spike relative to your own history.

That reframing is the part worth keeping. "Am I doing too much?" has no absolute answer. "Am I doing much more than I have recently been doing?" has one.

Where the 1.5 number is weaker than it sounds

The methodology has taken sustained criticism since: the way the ratio is computed, how loads are coupled between numerator and denominator, and how thresholds were derived have all been challenged, and some of the original sport-specific findings have not replicated cleanly elsewhere.

What survives the criticism is the underlying direction rather than the exact cut-off. Rapid increases in load relative to your recent norm are associated with more injuries; gradually built high loads are not the same risk. Treating 1.49 as safe and 1.51 as dangerous was never supported by anything. Treating a sharp jump as worth noticing always was.

The version you can actually use

Ramp gradually. Roughly 10% a week is the familiar heuristic, and while the specific figure is not strongly evidenced, the principle behind it — that your connective tissue adapts more slowly than your cardiovascular system — is sound. Weeks after time off should start lower than where you stopped.

Build a down week in. Every third or fourth week at roughly half volume. This keeps chronic load high without letting acute load stay high, which is the combination you want.

Count everything. The most common way to blow up a ratio is not to count the lifting, or the cycling commute, or the walking. An incomplete load count produces a comfortable ratio and an uncomfortable Achilles.

Weight intensity, not just duration. Ninety easy minutes and forty hard ones are not the same load. Anything that multiplies duration by an intensity factor beats counting hours.

Watch the direction, not the decimal. A ratio drifting up across three weeks matters. Today's value to two decimal places does not.

What PeakU does with this

Computing this by hand fails at the first step, which is the complete count. PeakU takes workouts from Health Connect, strength sessions from Hevy and runs from Strava, puts them on one intensity-weighted scale, and computes acute and chronic load across the lot.

The ratio is shown with its drivers rather than as a bare number, so you can see whether it moved because of the long run or because of two heavy lower-body days. Running plans are audited against ramp rate and hard-day spacing before you ever see them, and when readiness drops the plan reflows rather than holding a ramp your body has stopped agreeing to.