Short answer
Training Readiness is a composite score, not a measurement. Garmin blends six inputs — last night’s sleep, recovery time, HRV status, acute training load, three days of sleep history and three days of stress history — into a 1–100 number with five labels from Poor to Prime. The pieces underneath have varying support: overnight HRV from the wrist agrees reasonably well with chest-strap references in validation studies, sleep staging is weaker, and the composite itself has no independent peer-reviewed validation against performance. Used as a trend across a week it is useful. Used as a verdict on one morning it is not, because a single number cannot tell you whether the cause was a bad night, a hot run or a glass of wine.
Every morning a number appears on your wrist and tells you whether to go hard. It is a good product. It is also the most over-trusted number in running, because it presents a blend of estimates with the confidence of a measurement. Understanding how it is built is the difference between a score that helps and one that runs your week.
How the score is built
Garmin publishes the inputs. Training Readiness combines six factors and weights them into a single value:
| Input | What it is | Where it comes from |
|---|---|---|
| Sleep | Last night’s sleep score | Wrist movement, heart rate, HRV and breathing during sleep |
| Recovery time | Hours the watch says you still need after your last hard session | Training Effect of recent workouts |
| HRV status | 7-day HRV average against your personal baseline | Overnight HRV, three weeks of history to set the baseline |
| Acute load | Training load over the last seven days versus what you can absorb | EPOC from workouts |
| Sleep history | The last three nights | Sleep tracking |
| Stress history | The last three days of daytime stress | HRV-derived stress via Firstbeat analytics |
The output is 1–100, labelled Poor, Low, Moderate, High or Prime. Note what is doing the heavy lifting: four of the six inputs are HRV or HRV-derived. Training Readiness is largely an HRV score wearing a sleep score as a hat.
What is actually validated
Overnight HRV: reasonably. A 2022 validation of six wearables against a chest-strap reference during sleep found Garmin’s overnight heart rate and HRV agreed closely with the reference, though less closely than the best ring in the same study. Wrist optical sensors do best when you are still, which is exactly when overnight HRV is taken. That is the strongest leg the score stands on.
The 7-day averaging: well. Plews and colleagues showed in elite athletes that rolling seven-day HRV averages track training adaptation far better than single-day readings, which are too noisy to act on. Garmin’s HRV Status is built on precisely that principle, and it is the right one.
Sleep staging: weakly. Consumer wrist devices detect sleep versus wake reasonably and sleep stages poorly. The sleep score inside Training Readiness inherits that limitation, and it can be moved by how still you lie as much as by how well you slept.
The stress model: proprietary. Daytime stress and Body Battery come from Firstbeat’s HRV-based method, described in the company’s own white papers rather than in independent trials. It is physiologically sensible — sympathetic dominance lowers HRV — but it cannot separate a stressful meeting from a hot walk to the car.
The composite itself: not at all. There is, to our knowledge, no independent peer-reviewed study showing that a high Training Readiness predicts a better session or that training by the score improves outcomes. The weighting is Garmin’s judgement. That is not a criticism of the judgement; it is a statement about the evidence.
The inputs are measured. The weighting is opinion. The number is the opinion, rounded.
Where it goes wrong
The score is at its worst precisely when you most want it to be right: after something unusual. Buchheit’s review of heart-rate-based monitoring makes the point that HRV responds to everything — training load, heat, illness, alcohol, travel, a late dinner — and the metric cannot tell you which. Training Readiness inherits that blindness. A long run in a 20°C dew point, two glasses of wine, and a week of poor sleep all produce the same low number with the same coaching message, and three completely different correct responses.
Three specific failure modes show up constantly in the forums:
Low readiness, feel great
Common after a hot or humid run yesterday. Heat elevates heart rate and suppresses HRV without the muscular fatigue that would warrant a rest day. The dew point, not the score, explains it.
High readiness, legs are wrecked
Cardiac and autonomic recovery run faster than muscular recovery. HRV can be back to baseline while your quads are still two days from a hard hill session. The score cannot see muscles.
The score tanks during a carb load
Glycogen storage, a heavier body and a busier gut all nudge overnight HRV down in race week. It is the plan working, not a warning. Why HRV drops during taper covers it.
How to use it
Read the week, not the morning. A single Low is noise. Three consecutive days trending down while your load has not gone up is a signal. That is how the underlying research says HRV should be read, and it is how the score should be read too.
Ask what changed. Before you obey a low score, list yesterday: the weather you ran in, what you ate, what you drank, how you slept, whether you are coming down with something. Nine times out of ten the answer is on the list, and the right response follows from the cause, not the number. Why was my run hard today? is the checklist.
Never override how you feel with a number that is already an estimate. If readiness says Prime and your body says no, the body has more information. If readiness says Poor and you feel sharp on an easy warm-up, run the session and watch the heart rate.
Training Readiness is a genuinely useful gauge of autonomic recovery, which is one input into whether to train hard. It is not a coach, and it does not know why. That gap — the why — is the one worth closing.
Kovr tells you why the score moved.
Kovr reads the same signals — sleep, HRV, load — and adds the two Garmin cannot see: what you ate and drank, and the temperature and dew point you ran in. So a low morning reads as “yesterday’s run was in a 21°C dew point — train as planned” instead of a red number with no cause. Keep your watch. Add the why.
Download Kovr on the App StoreFree with a 14-day trial · Garmin, Apple Watch & Oura
Sources cited
- Miller, D.J., Sargent, C. & Roach, G.D. (2022). A validation of six wearable devices for estimating sleep, heart rate and heart rate variability in healthy adults. Sensors — overnight HR and HRV from six wearables including Garmin against a reference, during sleep
- Plews, D.J., Laursen, P.B., Stanley, J., Kilding, A.E. & Buchheit, M. (2013). Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Medicine — seven-day rolling HRV averages track adaptation; single-day values are noise
- Buchheit, M. (2014). Monitoring training status with HR measures: do all roads lead to Rome?. Frontiers in Physiology — HRV responds to heat, illness, alcohol, travel and load alike, and cannot distinguish them
- Firstbeat Technologies (2014). Stress and Recovery Analysis Method Based on 24-hour Heart Rate Variability (white paper). Firstbeat Technologies Ltd — the HRV-based stress and recovery model behind Body Battery and stress scores
Frequently asked questions
Is Garmin Training Readiness accurate?
Its components vary: overnight HRV from the wrist agrees reasonably with chest-strap references in validation studies, the seven-day averaging is well supported, sleep staging is weak, and the composite score has no independent peer-reviewed validation against performance. It is a useful trend indicator and a poor single-morning verdict.
What does Garmin Training Readiness measure?
It blends six inputs: last night’s sleep score, recovery time, HRV status, acute training load, three days of sleep history and three days of stress history, into a 1–100 score labelled Poor, Low, Moderate, High or Prime.
Why is my Training Readiness low when I feel fine?
Usually because something suppressed overnight HRV without causing real fatigue: a hot or humid run, alcohol, a late meal, travel or the start of a carb load. The score cannot tell those apart from overtraining. Check what changed yesterday before you change the plan.
Should I skip a hard session if Training Readiness is low?
Not on one reading. Warm up easy and watch heart rate and breathing; if they are normal for the pace, run the session. Three consecutive low days with no increase in load is the pattern that justifies backing off.
Is Training Readiness the same as Body Battery?
No. Body Battery is an energy estimate that charges with sleep and drains with stress and activity across the day. Training Readiness is a morning score built for the question of whether to train hard, and uses HRV status and training load that Body Battery does not.
Which Garmin watches have Training Readiness?
Forerunner 255 and 265 series, 955 and 965, Fenix 7 and 8, Epix and Enduro series, among others. The Forerunner 165 does not include it; see our guide to what the 165 has instead.