health / training-readiness

Training Readiness Explained: How Garmin, WHOOP, Oura and Polar Score Recovery

What goes into the readiness and recovery scores of Garmin, WHOOP, Oura, Polar, Fitbit (Google), Samsung, Apple and COROS, taken from each maker's own manuals and help pages.

How do watches calculate training readiness? Every brand compares last night with your own baseline, but none publishes its formula or weights, and baseline windows differ, so scores are not comparable between brands. To check your own readiness from how you feel, use the Should I Train Today checker.

For information only, not medical advice. These tools do not diagnose anything.
Whatever your watch says, do not train with fever, symptoms below the neck, chest pain, fainting or dizziness or palpitations. Rest and see a doctor. The Should I Train Today checker asks about these first and calculates no score if any applies.

How each brand scores readiness

Each row is in the maker's own words, shortened. "not published" means the maker's pages do not say; "not confirmed" means we could not open the maker's page to check.

ScoreScale and zonesInputsBaseline windowWeights publishedWhen updatedSource, checked
Garmin Training Readiness1 to 100: Prime 95 to 100, High 75 to 94, Moderate 50 to 74, Low 25 to 49, Poor 1 to 24sleep score (last night), recovery time, HRV status, acute load, sleep history (last 3 nights), stress history (last 3 days)not publishednot publishedcontinuously, throughout the dayGarmin, 5 Nov 2026
Garmin HRV StatusBalanced, Unbalanced, Low, Poor; no numberHRV from wrist heart rate while you sleepseven-day average against your own baseline rangesingle inputmeasured while you sleepGarmin, 5 Nov 2026
Garmin Body Battery5 to 100, reserve energy; not a readiness or HRV scoreheart rate variability, stress level, sleep quality and activitynot publishednot publishedthrough the day: sleep charges it, activity and stress drain itGarmin, 5 Nov 2026
WHOOP Recovery0 to 100%: green 67 to 100, yellow 34 to 66, red 0 to 33HRV, resting heart rate, respiratory rate, sleep hours against sleep needed, sleep stages, skin temperature, blood oxygen, menstrual cycle phase if applicableHRV against your 30-day baselinenot publishedcalculated each night during sleep, score in the morning; does not change over the dayWHOOP; WHOOP, 5 Nov 2026
Oura Readiness0 to 100. Help centre: Optimal 85 to 100, Good 70 to 84, Fair 60 to 69, Pay attention 0 to 59. Blog: Optimal 85 or higher, Good 70 to 84, Pay attention under 70nine contributors, among them resting heart rate, HRV balance, body temperature, sleep and activityHRV balance: past 14 days against your three-month average; "long-term" means the past two monthsnot publishednot publishedOura; Oura; Oura, 5 Nov 2026
Polar Nightly Recharge, ANS charge-10 to +10, around zero is your usual levelheart rate, HRV and breathing rate in roughly the first four hours of sleepyour usual levels from the past 28 daysorder only: heart rate has the biggest influence, breathing rate the smallestmeasured during the nightPolar, 5 Nov 2026
Fitbit (Google) Daily ReadinessApp: 0 to 100, High 65 or above, Moderate 30 to 64, Low 29 or below. Watch tile: 1 to 100, Low 1 to 29, Moderate 30 to 64, High 65 to 100HRV, recent sleep, resting heart ratepersonal baseline from 7 nights, more accurate after a monthnot publishedafter you wake upGoogle, 5 Nov 2026
Samsung Energy Scorenot confirmedsleep time average and consistency, bed and wake time consistency, sleep timing, previous day activity, sleeping heart rate and HRVnot publishednot publishednot publishedSamsung, 5 Nov 2026
Apple Vitals and Training Load, no single scoreVitals: each metric against its typical range; Training Load: well below to well aboveVitals: overnight health metrics; Training Load: workout effort and durationVitals: a typical range per metric, length not published; Training Load: the most recent seven days against 28 daysnot publishedVitals: a notification when at least two overnight metrics are outside their typical rangeApple; Apple, 5 Nov 2026
COROS Recovery Timer and EvoLab loadRecovery: a time until full recoveryRecovery: Base Fitness, Training Load, remaining energy since your last workout; no HRV or sleep in that listBase Fitness: 42-day rolling average of Training Load; Load Impact: 7-daynot publishedafter each training sessionCOROS; COROS, 5 Nov 2026

Oura prints two sets of bands: its help centre has four, with Fair at 60 to 69, and its blog three, with Pay attention under 70. Fitbit's help page gives two scales, 0 to 100 in the app and 1 to 100 on the watch tile. Both are shown in each case. WHOOP's support centre renders with a script, so its Recovery article was checked by hand in a browser on 5 Nov 2026. On a phone the table scrolls sideways.

Body Battery vs Training Readiness vs HRV Status

Three different Garmin numbers, often confused. Body Battery is not a readiness score and not an HRV score.

What it measuresWindowWhen it changes
Body Batteryavailable reserve energy; from heart rate variability, stress level, sleep quality and activitynot publishedthrough the day: sleep charges it, activity and stress drain it
Training Readinesshow ready you are for training each day; from sleep score (last night), recovery time, HRV status, acute load, sleep history (last 3 nights), stress history (last 3 days)not publishedcontinuously, throughout the day
HRV Statusyour seven-day average night time HRV against your baseline range; from HRV from wrist heart rate while you sleepseven-day average against your own baseline rangemeasured while you sleep

From Garmin's Forerunner 965 owner's manual. HRV Status needs three weeks of consistent sleep data before it shows a status.

Why the brands disagree

Different baselines. Where the makers state a window, they state different ones: Garmin HRV Status, seven-day average against your own baseline range; WHOOP Recovery, HRV against your 30-day baseline; Oura Readiness, HRV balance: past 14 days against your three-month average; "long-term" means the past two months; Polar Nightly Recharge, ANS charge, your usual levels from the past 28 days; Fitbit (Google) Daily Readiness, personal baseline from 7 nights, more accurate after a month; Apple Vitals and Training Load, no single score, Vitals: a typical range per metric, length not published; Training Load: the most recent seven days against 28 days; COROS Recovery Timer and EvoLab load, Base Fitness: 42-day rolling average of Training Load; Load Impact: 7-day. Garmin Training Readiness, Garmin Body Battery, Samsung Energy Score: no window on the pages read.

Hidden weights. 8 of the 10 scores in the table publish no weighting at all, and Polar gives only an order. A review of 14 scores from 10 makers found that "None of the manufacturers disclosed their exact algorithmic formulas" (Doherty et al. 2025).

Different sensors. Wrist and ring devices read the pulse optically (PPG), not from an ECG, and the two are not the same: the PPG-derived PRV consistently underestimated rMSSD, SDNN, and pNN50 (Kantrowitz et al. 2025, Frontiers in Physiology). Against ECG, one study found Apple Watch read HRV 9.6 ms low on average and Garmin 22.4 ms low (Miller et al. 2022, Sensors). Compare readings only within one device.

What the research says

Adjusting training to a daily HRV reading has been tested. A meta-analysis found a small advantage over a predefined plan for VO2max, a standardised mean difference of 0.20, not statistically significant (Manresa-Rocamora et al. 2021). How you feel matters too: in a review of 56 studies, subjective measures tracked training load more sensitively and consistently than objective ones, and the two "generally did not correlate" (Saw et al. 2016). And the composite scores themselves are largely untested: the makers do not disclose their formulas and few offer validation evidence (Doherty et al. 2025).

What can throw a score off

In the makers' own words:

  • Garmin: "Illness, alcohol consumption, and stress can prevent you from fully charging your Body Battery overnight."
  • Polar: on breathing rate, "Higher values than usual may indicate a fever or impending illness"; and stress, exercising late at night, "illness, or alcohol can keep your heart rate up" during the early hours of sleep.
  • Oura: "Significant changes in average body temperature may indicate illness or other physiological strain, the luteal phase of the menstrual cycle, or a change in pregnancy status." And: "Late night meals, caffeine, alcohol, or exercise before bedtime can also contribute to a high resting heart rate."
  • Apple: Vitals notifications come with context for factors "like medications, elevation changes, or illness".
  • Samsung, on Energy Score: "Intended for general wellness and fitness purposes only."

Related tools

Check today from how you feel with the Should I Train Today checker, follow your own HRV trend with the HRV calculator, or see a transparent weighted score with the recovery score calculator. All health tools are on the health page.

Frequently asked questions

Is Body Battery the same as Training Readiness?

No. Garmin describes Body Battery as available reserve energy, on a scale of 5 to 100, reserve energy, built from heart rate variability, stress level, sleep quality and activity. Training Readiness is a separate score, 1 to 100, built from sleep score (last night), recovery time, HRV status, acute load, sleep history (last 3 nights), stress history (last 3 days). HRV Status is a third measure: your seven-day average night time HRV against your baseline range.

Why do Garmin and WHOOP show different scores?

They use different inputs, different scales and undisclosed weights. Garmin Training Readiness runs 1 to 100 from sleep score (last night), recovery time, HRV status, acute load, sleep history (last 3 nights), stress history (last 3 days); WHOOP Recovery runs 0 to 100% from HRV, resting heart rate, respiratory rate, sleep hours against sleep needed, sleep stages, skin temperature, blood oxygen, menstrual cycle phase if applicable. Neither publishes how the inputs are weighted, and the sensors themselves differ from an ECG by different amounts, so the two numbers are not on a common scale.

How many nights does my watch need to learn my baseline?

It depends on the brand, in the makers' own words: Garmin HRV Status, three weeks of consistent sleep data; Oura Readiness, up to two weeks; Polar Nightly Recharge, ANS charge, three nights; Fitbit (Google) Daily Readiness, 7 nights of sleep; Samsung Energy Score, at least the previous day's activity and sleep, with heart rate during sleep. Garmin Training Readiness, Garmin Body Battery, WHOOP Recovery, Apple Vitals and Training Load, no single score, COROS Recovery Timer and EvoLab load: not published.

Should I train if my score is green but my legs are sore?

Take the more cautious option; that rule is this site's convention. In a review of 56 studies, subjective and objective measures "generally did not correlate", and how athletes felt tracked training load more sensitively than the measured markers (Saw et al. 2016). Soreness is information the watch does not have.

Does alcohol lower readiness?

The makers say it can. Garmin: "Illness, alcohol consumption, and stress can prevent you from fully charging your Body Battery overnight". Polar: stress, exercising late, "illness, or alcohol can keep your heart rate up" during the early hours of sleep. Apple says Vitals changes may be linked to "elevation changes, alcohol consumption, or even illness".

Does the menstrual cycle affect readiness?

Oura says so for body temperature: "Significant changes in average body temperature may indicate illness or other physiological strain, the luteal phase of the menstrual cycle, or a change in pregnancy status". WHOOP lists "Menstrual Cycle Phase (if applicable)" among the inputs to Recovery. The other makers' pages read here do not say how the cycle enters their score.

Is HRV-guided training better?

Slightly at most. A meta-analysis of heart rate variability guided endurance training found a small advantage over a predefined plan for VO2max, a standardised mean difference of 0.20 that was not statistically significant (Manresa-Rocamora et al. 2021).

Last updated: November 2026

Where these numbers come from

  • Scales, zones, inputs, baseline windows and update times: Garmin, WHOOP, Oura, Polar, Google, Samsung, Apple, COROS.
  • What can throw a score off: Garmin, Polar, Oura, Apple, Samsung.
  • Optical sensors against ECG: Kantrowitz et al. 2025, Frontiers in Physiology, Miller et al. 2022, Sensors.
  • HRV guided training, subjective measures, and undisclosed formulas: Manresa-Rocamora et al. 2021, Saw et al. 2016, Doherty et al. 2025.
  • Site convention: taking the more cautious option when a score and how you feel disagree

Pages opened

Every page was opened and its quoted passage checked on 5 November 2026. Makers change their pages; the maker's current page decides.