Training Load (ACWR) Calculator

This calculator implements the Acute:Chronic Workload Ratio, a training-load monitor Tim Gabbett popularized in his 2016 British Journal of Sports Medicine paper "The training-injury prevention paradox: should athletes be training smarter and harder?" You enter four weeks of load in any consistent unit (RPE multiplied by minutes is the usual convention). Acute Load is simply This Week's Load echoed back, while Chronic Load is the rolling average of all four weeks — including the current one. ACWR divides the two, and because the current week appears in both the numerator and (at quarter weight) the denominator, it is the only input that can swing the ratio hard in either direction: a spike this week raises the acute number four times faster than it raises the average underneath it.

The three prior weeks each carry identical weight in the chronic average, so per unit of load they pull on the ratio — downward, since they only inflate the denominator — with exactly the same strength as each other. The Risk Level output bands the ratio: below 0.8 flags detraining, 0.8 to 1.3 is the sweet spot associated with the lowest injury rates, 1.3 to 1.5 advises caution, and above 1.5 marks elevated injury risk. What the ratio cannot see: how the load was distributed within the week, monotony of session types, or non-training stressors like sleep and illness.