How to Detect Undertraining and Overtraining Using the Acute:Chronic Workload Ratio (ACWR)
- Nadine Rücker
- Jul 16, 2025
- 3 min read
Overview
Staying fit isn’t just about working harder. It’s about balancing your workouts so your body adapts and grows stronger, without injury or burnout. The Acute:Chronic Workload Ratio (ACWR) is a simple but powerful way to track this balance, helping you stay in the “sweet spot” of training.
You don’t need a fancy device. A timer, your sense of effort, and our spreadsheet are enough. But if you do use wearables like Garmin, they can calculate training load automatically based on physiological data like EPOC (excess post-exercise oxygen consumption).
🧠 What Is Training Load?
Training load reflects how much strain your body experiences during exercise. It consists of:
External load: measurable things like distance, time, or weights lifted
Internal load: how your body responds—heart rate, fatigue, and how hard the session felt (your Rate of Perceived Exertion, or RPE)
The Session RPE Method
The simplest way to calculate training load is the Session RPE method, which is used by athletes and coaches worldwide. After your workout, ask yourself:
“How hard was that session?”
On a scale from 0 to 10, rate your effort:
RPE | Description |
|---|---|
0 | Rest |
1-3 | Light Effort |
4-5 | Moderate |
6-7 | Hard |
8-9 | Very Hard |
10 | Maximum effort |
Then multiply your RPE by how long the session lasted (in minutes):
Training Load = RPE × Session Duration
Example: A 50-minute workout that felt like a 7 → 7 × 50 = 350 load units.
This method works for running, cycling, strength training, yoga—anything.
📈 Acute vs. Chronic Load
To understand whether you’re improving safely or overdoing it, compare your short-term load (acute) to your long-term average (chronic):
Acute Load: Total training load over the past 7 days. Shows your recent stress.
Chronic Load: Average training load over the past 28 days. Reflects your fitness base.
⚖️ The Acute:Chronic Workload Ratio: Finding the Sweet Spot
The Acute:Chronic Workload Ratio (ACWR) compares your recent load to your usual workload.
ACWR = Acute Load ÷ Chronic Load
ACWR Value | Meaning | Action |
< 0.8 | Undertraining | Increase load gradually |
0.8–1.3 | Optimal zone | Keep going—safe progress |
1.3–1.5 | Elevated risk zone | Gains possible, but caution |
> 1.5 | Overtraining | Back off to avoid injury |
Stay in the 0.8–1.3 range for steady improvement
Spikes above 1.5 raise your risk of injury
Long dips below 0.8 might mean you’re losing fitness
⌚ Can Wearables Help?
Some devices, like Garmin watches, calculate training load using EPOC, a physiological measure derived from heart rate and activity duration. Garmin’s app even displays an acute load, chronic load, and sometimes an ACWR or load ratio. These are helpful tools—but you don’t need them. Your body awareness and consistent tracking give you the same insights.
🛠️ How to Track It Yourself
Track every workout: Note the duration and how hard it felt (RPE)
Sum your weekly load: Add up the last 7 days for your acute load
Average your last 4 weeks: Add up the last 28 days and divide by 4 for your chronic load
Calculate ACWR: Divide acute by chronic
Watch for trends: Stay between 0.8 and 1.3 and avoid sudden spikes
💡 Why It Works
This approach works across sports and fitness levels. Whether you’re training for a marathon, lifting weights, or just staying active, tracking your load helps prevent:
Overtraining and burnout
Injury from doing too much, too soon
Plateaus from doing too little, too often
Summary
You don’t need high-tech gadgets to train smart. By tracking how long and how hard you work out—and comparing your recent load to your usual routine—you’ll uncover powerful insights into your body’s needs.
Train consistently. Progress gradually. Listen to your body.
Comments