ACWR, the metric professionals use
The Acute:Chronic Workload Ratio is the ratio between the last 7 days of training load (acute load) and the rolling 28-day average (chronic load). It's the reference metric used in professional sport to prevent overuse injuries.
ACWR between 0.8 and 1.3 = optimal performance zone. ACWR > 1.5 = red zone, significantly elevated injury risk.
ZON calculates this automatically for every athlete, without the coach or athlete needing to do anything extra.
What ZON measures and calculates
Session load
For every completed session, ZON calculates a training load based on:
- Total volume (sets × reps × load)
- Session duration
- Declared intensity (athlete's RPE)
- Effort type (strength, cardio, mixed)
Rolling ACWR
ZON maintains 7-day and 28-day windows continuously for each athlete and calculates the ratio. The result is displayed in the athlete profile (coach side) and in statistics (athlete side).
Collective load dashboard
On your Roster view, ZON shows the ACWR status of every athlete at a glance: green indicator (optimal zone), yellow (attention), red (overload). In seconds, you know who needs a lighter week.
The consistency calendar
Complementary to ACWR, the consistency calendar displays an annual heatmap of training days, similar to GitHub contribution graphs, but for physical performance.
At a glance:
- High-frequency weeks vs drops
- Recovery patterns (is there always a dip after intense periods?)
- Consistency over 6 or 12 months
Daily check-in as a recovery signal
ACWR measures objective load. The daily check-in measures subjective recovery. ZON cross-references both:
- Athlete in green ACWR zone but 3 consecutive high-fatigue check-ins → under-recovery alarm signal.
- Athlete in yellow ACWR zone but positive check-ins → the body is adapting, you can maintain.
This combined reading is what distinguishes data-driven coaching from intuition-based coaching.
For coaches and for athletes
ACWR is visible on both sides:
- Coach side: in the athlete profile on the Roster, with a collective view on the dashboard
- Athlete side: in the Statistics section of the ZON app (iOS / Android), with a pedagogical explanation of what their zone means
The athlete understands why the program is lighter. The coach has the data to justify it.
Available on iOS and Android (private beta) for athletes, and ZON Web for coaches. Automatic calculation, no additional input required.