Training load and acute-chronic ratio calculator
Injury risk rises when this week is much harder than the last month has been. The acute-to-chronic ratio makes that comparison.
%
Acute to chronic ratio
1.125
- Ratio after the planned increase
- 1.238
- Load ceiling at a ratio of 1.3
- 520
- Headroom left this week
- 70
- Planned load next week
- 495
- Average daily load
- 64.3
Show the working
- This week load = 450
- Four-week average load = 400
- Planned increase = 10
- Acute to chronic ratio = 450 / 400 = 1.125
- Planned load next week = 450 * (1 + 10/100) = 495
- Ratio after the planned increase = 400 > 0 ? 495 / 400 : 0 = 1.2375
- Load ceiling at a ratio of 1.3 = 400 * 1.3 = 520
- Headroom left this week = 520 - 450 = 70
- Average daily load = 450 / 7 = 64.2857
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- ACWR = this week load / four-week rolling average
The 0.8 to 1.3 sweet spot comes from team-sport injury studies. It is a population association, not a personal guarantee.
Load can be anything measured consistently: minutes, TRIMP, kilometres or session RPE times duration.