How Safety Guards Work

How Pheidi protects you from training load spikes and injury risk.


Single-Session Spike Guard

No single run can exceed 110% of the longest run in the preceding 4 plan weeks. If a planned distance would spike above this threshold, it is automatically capped to the safe maximum.

Research: BJSM 2025, n=5,200 — single-session spikes are the strongest predictor of running injuries.

Acute:Chronic Workload Ratio (ACWR)

Pheidi continuously monitors your training load ratio by comparing your last 7 days (acute) against your last 28 days (chronic, averaged per week). A minimum of 3 weeks of completed workout data is required before the ratio becomes available.

ACWR Range Risk Zone Guidance
< 0.8 Under-training You can safely increase load
0.8 – 1.3 Green Sweet spot — building fitness safely
> 1.3 – 1.5 Yellow Caution — training load is ramping quickly
> 1.5 Red High injury risk — dial it back


Research & evidence

Science behind this feature from pheidi.training.


See also