Training load: how much is too much

What it is

The acute:chronic workload ratio (ACWR) compares what you have done recently against what you are used to doing.

• Acute load — your training load over the last 7 days.
• Chronic load — your average weekly load over the last 28 days.
• ACWR — acute divided by chronic.

An ACWR of 1.0 means this week looks like a typical recent week. Above about 1.5 means this week is much bigger than what you are conditioned for, which is the state associated with raised injury risk. Well below 1.0 for a sustained period means you are detraining.

Calculate yours here — it takes about a minute.

A worked example

At 1.30 this player is at the top of the range that counts as steady. One more week at that size is fine. Another jump on top of it is the pattern to avoid.

The bands Train Smart uses, which are the ones most commonly quoted:

• Below 0.8 — under-loaded. You are doing less than you are used to. Fitness drifts, and it sets up a spike when you ramp back up.
• 0.8 to 1.3 — steady. Enough to build on, without a big jump.
• 1.3 to 1.5 — building quickly. Fine for a week. Do not stack another one on top.
• Above 1.5 — a spike. A big jump on what you are conditioned for. This is the range the research associates with raised injury risk.

The ratio needs history to mean anything. With only a week or two of training behind it the chronic number is tiny and almost any session looks like a spike — so a ratio built on less than a few weeks of regular training is noise, not a warning.

How to measure "load" without a GPS unit

The practical version, used across amateur sport, is session RPE: rate the session out of 10 for how hard it was, multiply by the duration in minutes. A 60-minute session you rated 7 is a load of 420. Add up the week.

It is crude. It is also good enough, and it correlates well with more expensive methods. Train Smart derives training load from your logged sessions and from the workouts your watch records — through Apple Health on iPhone, or Health Connect on Android.

What it can and cannot tell you

ACWR has been genuinely useful in making coaches think about ramp rates. It has also been criticised — the statistical methods behind some early findings have been challenged, and it is not a diagnostic. Treat it as one signal among several, not as a verdict.

The honest version of the finding is much simpler than the formula, and it survives all the criticism:

Big jumps in training load are risky. Build up gradually, and be careful in the week after a break.

The three situations that actually catch people

1. Coming back from a holiday or injury. Your chronic load has dropped to nearly nothing, so a normal week is now a huge spike. This is the classic scenario.
2. The start of pre-season. Same problem, at scale, across an entire squad at once.
3. A congested fixture block. Two games in a week plus a normal training week is a very large acute load and it is the one people do not count, because games do not feel like training.

What to do about it

• Increase weekly load gradually rather than in steps.
• After any break longer than a week, rebuild deliberately — expect it to feel frustratingly easy for a fortnight.
• Count games. They are the largest single load in most athletes' weeks.
• Use a planned deload rather than waiting for a forced one.

Train Smart tracks this automatically and flags it on your recovery card when your recent load has climbed sharply relative to what you are conditioned for.