Acute:Chronic Workload Ratio (ACWR)
The acute:chronic workload ratio (ACWR) compares the training load you did this week (acute) to your rolling average load over the last four weeks (chronic). A ratio around 0.8–1.3 is often described as a workload 'sweet spot'; ratios above ~1.5 represent a sharp spike in load.
Why it matters
ACWR turns 'am I ramping up too fast?' into a single number. Rapid spikes in training load — doing far more this week than your body is conditioned for — are associated with higher injury and overreaching risk in the sports-science literature (Gabbett, 2016, BJSM). Keeping the ratio in a controlled range lets everyday athletes progress steadily instead of in boom-and-bust cycles.
How it's measured
Each session is scored as load = session RPE (0–10) × duration in minutes (sRPE). Acute load is the sum of the last 7 days. Chronic load is the average weekly load over the last 28 days. ACWR = acute ÷ chronic. An exponentially weighted moving average (EWMA) variant weights recent days more heavily and is considered more sensitive to sudden changes.
ACWR Calculator — get your acute:chronic ratio and zone
Frequently asked questions
What is the ACWR sweet spot?
Many practitioners use roughly 0.8–1.3 as a target range, with ratios above ~1.5 flagged as a load spike worth managing. These thresholds are guidelines from group data, not hard guarantees — individual tolerance varies, so use them as a prompt to review your plan, not a rule.
How do I calculate ACWR?
Sum your training load (session RPE × minutes) for the last 7 days to get acute load, average your weekly load over the last 28 days to get chronic load, then divide acute by chronic. You can do this instantly with the umo ACWR calculator.
Is a low ACWR bad?
A ratio well below 0.8 means you are doing much less than your body is conditioned for — fine during an intentional taper or rest, but sustained low load gradually erodes fitness and leaves you less prepared for a return to hard training.
Educational, performance-oriented content for athletes — not medical advice. Thresholds and reference ranges come from group data and vary between individuals.