Glossary of Terms

What Does It Mean

(Select your language using the flags below if required)

Please visit our FAQ page for any questions and answers as a first port of call. It contains 95% of answers to support questions here. We've looked through thousands of support emails and these are easily the most common ones all answered.

Glossary of Terms

Wellness Terms

  • Daily bpm - your daily heartbeat is measured when you are not exercising or sleeping

  • Sedentary bpm - is a subset of the daily heartbeat readings where you have been still for at least 5 minutes prior to the heartbeat sample

  • Sleep bpm - is measured from the time you went to sleep and awoke

  • Sleep Time - measures your sleep duration from the time you fell asleep to the time you awoke, excluding any waking periods

  • Recharge - is measured from the time you slept compared to your goal which is setup in Settings. Recharge is your body's time to recover from your activities and get ready for the next, measuring how restless you were overnight and calculating how much of your sleep requirement has been met

  • Restfulness - indicates how much of your sleep was restful, with little or no tossing or turning. It excludes any waking periods

  • Waking bpm - your waking pulse is considered one of the gold standards when measuring your resting heart rate. This is automatically captured when you start to wake from sleep if using the HeartWatch sleep function or using our AutoSleep app

  • HRV (Sleep) - Heart Rate Variability (HRV) is a method for assessing the effects of stress on your body, by measuring the variances between your heart beats. This is automatically captured by your Apple Watch overnight or by performing a breathe session on your Watch

  • HRV (Waking) - Heart Rate Variability (HRV) is a method for assessing the effects of stress on your body, by measuring the variances between your heart beats. This is automatically captured by your Apple Watch overnight or by performing a breathe session on your Watch. We recommend the breathe session to apply protocol to the measure.

  • BP (am) - Blood Pressure is the measurement of the pressure of the blood in the artery in the morning (am)

  • BP (pm) - Blood Pressure is the measurement of the pressure of the blood in the artery in the afternoon (pm)

  • SpO2 (Sleep) - this is your blood oxygen average while you are sleeping, which represents the percentage of the haemoglobin in your red blood cells that are carrying oxygen from the lungs to the rest of the body

  • SpO2 (Daily) - this is your blood oxygen average while you are awake, which represents the percentage of the haemoglobin in your red blood cells that are carrying oxygen from the lungs to the rest of the body

  • Respiration Rate - is the number of breathes you take each minute while sleeping. We use an abbreviation named BrPM, which stands for Breathes Per Minute

  • Glucose (Sleeping) - Blood glucose is the amount of glucose in your blood. It comes from what you eat and drink as well as your body releasing stored glucose from your liver and muscles. Sleeping glucose requires a device that allows continuous glucose readings which you are sleeping and writes the data to Apple Health.

  • Glucose (Waking) - waking Glucose is similar to fasting glucose, where a blood sample will be taken after an overnight fast

  • Glucose (Daily) - Daily Glucose is during the day. This is aimed more at users who take multiple readings during the day. Blood glucose levels are measured in millimoles per litre of blood (mmol/L).

  • Temperature - your body temperature. Your bodyโ€™s a bit like a little oven that is always on. It generates heat to keep you alive.

  • ECG - an electrocardiogram is a test that records the strength of electrical signals that make the heart beat.

  • % Elevated - when you have been still for 5 minutes prior HeartWatch will measure your heart rate and record it as a sedentary heart rate. % Elevated is the percentage of these readings above 100 bpm.

  • MinMax bpm - the maximum and minimum heart rate in your day. This excludes workouts.

Activity Terms

  • Move - your energy expenditure for the day, shown in calories or kilojoules, whichever you elected in settings

  • Exercise - the duration in minutes on the amount of exercise captured

  • Stand - the amount of stand hours

  • Steps - shows the number of steps walking or running for the day

  • Distance - shows the distance travelled (kms/miles) for the day

  • Weight - shows your body weight measurement (kgs/lbs) for the day

  • BMI - Body Mass Index (BMI) is a measurement of a personโ€™s weight with respect to his or her height

  • Waist - using a soft measure this is the length around your middle section, it is a simple check to monitor if you're carrying excess body fat around your middle

  • Fat % - refers to the proportion of fat you have, relative to lean tissue like muscle, bones, body water, organs, etc. Body composition monitors can help you measure your fat %

  • Lean Mass - is calculated as the difference between total body weight and body fat weight

  • Fat Mass - the actual weight of fat in your body

  • Habit Status - Research and common sense all indicate that you need to repeat a behaviour over a period of time to form a new habit, be it 21 days, 12 weeks or 6 months. Habit Status has been designed exactly for this habit tracking, automatically showing your current status along with recommending move, step & distance goals based on your individual results and goal level to monitor your habit changes.


  • Energy Cals/Kjs - A calorie (cal) or kilojoule (kj) is a unit of energy. A calorie is the amount of heat needed to raise the temperature of one gram of water by one degree Celsius. Our bodies store and burn calories as fuel

  • Time - this is the duration of the workout, shown in hours and minutes

  • Recovery - your heartrate change following exercise. Your Recovery Heart Rate, the speed at which your heart rate returns to normal after exercise, can indicate physical cardiac condition. HeartWatch activates a 2min recovery at workout ends.

  • VO2 Max - is the maximum rate of oxygen consumption measured during incremental exercise. Maximal oxygen consumption reflects cardiorespiratory fitness and endurance capacity in exercise performance.

  • Workout Avg - the average heart rate during the workout

  • Workout Max - the maximum heart rate during a workout

  • Duration - the duration of the workout from start to finish

  • RPE - this stands for Rate of Perceived Effort, which is a 0 to 10 self reflection rating of how hard the workout was directly after the exercise, ideally captured in a 2-5 minute window

  • Load - this represents your response to exercising, quantified by the intensity and duration of each workout you perform

  • Distance - the distance travelled, which can also be split in HeartWatch by activity type

  • Pace - how fast you are moving and is usually expressed in relation to how fast you could run a km or mile

  • Location - this is a map of the GPS coordinates captured during an outdoor session such as bike ride or outdoor run

  • Altitude - in relation to sea level the amount gained or lost during a workout

Daily Heart Rate - What it Means

This section explains some key concepts behind the design of HeartWatch and how heart rate data is represented.

Daily/Regular Heart Rate

Regular heart rate is a term used in Heart Watch to isolate the readings your watch takes in the background every two to ten minutes from those readings you take during a workout or those taken during sleep.

Workout readings are more likely performed under physical stress and an elevated heart rate. By isolating regular heart rate from workout heart rate, Heart Watch can present a more accurate picture of your day to day heart health.

Daily bpm Zones & What The Colours Mean

It is generally understood that a regular resting heart rate is from 60-100 bpm though resting heart rates from 50-60 bpm are common amongst healthy individuals.

By default, HeartWatch uses the following colours and zones to present your regular heart rate data, both in heart badges and charts.

Keep in mind that this is not medical advice. If unsure of anything, always consult a medical professional.

  • Red: Greater than or equal to 100bpm. A sustained resting heart rate above 100bpm may indicate tachycardia. If your regular heart rate badge is mainly red, you should consider seeing a health professional.

  • Purple: Greater than or equal to 80 & less than 100bpm. Though this does fall within the parameters of a regular resting heart rate, it is on the high side. Depending on your level of activity or consumption of stimulants, this may indicate that you aren't particularly fit/healthy if you are consistently seeing that your badge is nearly all purple. To help in determining how active you have been, HeartWatch overlays your active energy level when you press the badge to see the details of what makes it up.

  • Blue: Greater than or equal to 55 and less then 80bpm. This is recognised as a healthy resting heart rate. Ideally your badge should be at least half blue. The more blue, the healthier your heart is likely to be. You should however, consider the type of day you have had though. If you have been very active, then purple may be a reflection of what you have been doing (see above).

  • Pinkish Brown: Lower than 55 and greater than or equal to 40bpm. If you can see a significant pinkish brown centre in your badge, and you are experiencing fatigue, weakness, dizzyness or feel faint, then this may indicate bradycardia. If you don't have any symptoms, and particularly if you are a well trained athlete this likely isn't a problem. Again, consult your doctor especially if you are experiencing symptoms.

  • Brown: Lower than 40bpm. Unless you are a very highly trained athlete, a brown centre in your badge or even seeing a percentage of readings in brown is likely not a good thing. If you are experiencing any fatigue, weakness, dizzyness or feeling faint then even more so. Probably a good idea to see your medical professional.

Waking Heart Rate - What it Means

Studies have shown that your waking heart rate is an important measure of your basic fitness level and a strong predictor of your cardiovascular health. A normal adult range is from 60 to 80 beats per minute. Athletes can have a range between 35 to 50 beats per minute. Generally speaking, the better shape you are in, the fewer beats per minute.

Having a high waking heart rate can be an indication of poor cardiovascular health and can indicate things such as hardening of the arteries and restrictions in the diameter of your blood vessels.

For athletes, monitoring the variance in waking heart rate can be useful in monitoring overtraining.

Taking Waking Pulse if you wear or don't wear Watch to bed

There are two ways to capture your waking heart rate, depending on whether you use HeartWatch's sleep tracking feature or not.

If Using Sleep Tracking

If using sleep tracking in the Watch app, there is a handy Take Pulse option when you finish sleeping. Using this will ensure the most accurate way of tracking your waking pulse.

If Not Using Sleep Tracking

Whilst still in bed, put your Apple Watch on to your wrist & enter its PIN. This will trigger an immediate heart rate reading in the background on your Apple Watch. However, reaching across and moving around might cause your heart rate to elevate slightly. The way around this is to open the HeartWatch watch app, choose the Pulse option and touch the gauge. This will let you capture five live readings and then buzz you when it finishes.

Waking Pulse Customisation

By default, if you do not use sleep tracking, HeartWatch will use the first reading after 4AM that it finds. You are able to customise this in the settings menu (the red cog in the top right corner of the iPhone app) by changing the hour to something more appropriate for you.

If you do not want to see the Waking Section then you can also stop it from being displayed by turning off the switch under the Show Waking Section heading within the Settings menu.

Workout Heart Rate - What it Means

When you start and end a workout on your Apple Watch, Heart Watch will use this information to isolate and present this heart rate information in a separate section. Each workout will appear with its own badge and all workouts for a day consolidated under a zonal summary.

Ideally you should start the workout using the HeartWatch watch app as this will also show you which zones you are in.

Workout Zones & What They Mean

For workouts, the zones are based on percentage of max heartbeat which is very popular with โ€œzonalโ€ style training.

Percentages are used to give a common reference over different ages & levels of fitness and to allow individual adjustment based on training level.

By default, HeartWatch uses the following zones:

  • Aqua = moderate zone (50-60% of max) - wonโ€™t increase fitness/strength/endurance but good for health, recovery, warm ups, cool downs etc.

  • Green = fat burning zone (60-70% of max) - lowish effort, predominantly uses fat for energy.

  • Yellow = aerobic fitness zone (70-80% of max) - builds functional capacity, lung capacity, respiratory rate, numbers & size of blood vessels etc, metabolises fats & carbs around a 50/50 rate.

  • Red = anaerobic threshold / intense zone (80-90% of max) - getting faster & fitter via more intensity.

  • Bright Red = extremely intense (90-100% of max) - full on effort for short bursts only during interval training. Purely anaerobic.

Anything below 50% of your max heart rate will show in the default resting colours. Something to look out for is if you are also seeing light or dark brown readings and experiencing light headedness during your workout. Rapid fluctuations from red to brown are of particular concern. This may indicate an underlying heart problem that you should discuss with your medical practitioner.

As with any exercise, be sensible. Unless you are an elite athlete, or experienced trainer, it is likely sensible to stay yellow or lower as you build your fitness and adapt to training loads.

Workout Customisation

In the HeartWatch settings menu (the red cog in the top right corner of the iPhone app), you can customise how the various heart rate zones are presented in the workout section. Each colour can be associated with a percentage of your maximum heart rate. Your maximum heart rate itself may also be changed, by default, it is based on your age.

Sleep Tracking - What it Means

The sleep section relies on you capturing both heart rate & when you started and finished sleeping. This is made somewhat easier in HeartWatch as there is a sleep tracking option built into the Watch app.

However, you don't have to use this. If you have a favourite iPhone app (or even another Watch app like AutoSleep) that you use for sleep tracking/alarm that writes sleep data into HealthKit, you can still use this. You do however have to wear your Watch whilst sleeping otherwise you won't be tracking your sleeping heart rate nor your restless energy.

Using AutoSleep with HeartWatch

If you are using our automatic sleep tracking app AutoSleep then you can learn how this works on the AutoSleep page by clicking here.

HeartWatch Inbuilt Sleep

If you are using HeartWatch's inbuilt sleep tracking feature using the Watch app, then the following information explains what it all means.

About Restlessness Tracking

Your Apple Watch captures your active energy and basal energy whenever you are wearing it. This includes while you are asleep. This is, like heart rate data, written to the Health database on your iPhone. The HeartWatch app reads your sleep start and finish, the basal energy you used and any active energy. It uses an algorithm to compare the active energy to the basal energy and determines how restless you were during your sleep. This is then graphed over your heart rate in a top down format (where the top y axis = 0). It also uses a z axis by plotting activity that has occurred in overlapping times to form a deeper green which indicates greater intensity of movement. In practice, any waking events can be seen as bars that have descended the red line.

Sleep Recharge Estimate

This restlessness data is then used along with how long you have slept to determine to what extent you've "recharged your batteries".

By default, this works based on an average of 8 hours quality sleep. If you feel that you require more or less hours of sleep per night, then you can change this in the info section.

The trailing week recharge battery symbol is based on the weighted average of up to your last seven days' sleep. This a fairly non-scientific analysis of your sleep but does provide a handy indicator as to whether you are starting to incur a sleep deficit. You'll likely notice anything below 90% and especially feel the effects of anything below 80%.

Future updates of the app may include automatic sleep recording and a deeper analysis of sleep zones. We'd love to hear your feedback.

What is Basal Energy

Basal energy expenditure (BEE), also known as basal metabolic rate (BMR) is the amount of energy needed to carry out fundamental metabolic functions, such as breathing, ion transport, normal turnover of enzymes and other body components, etc.

So while sleeping (and also throughout the day), there is a base (basal) rate of energy that you burn while doing absolutely nothing.

The Apple Watch records this whenever you are wearing it.

Now, active energy is any energy you burn over and above that required as basal energy. This is due to needing to fuel physical movement.

Again, your Apple Watch also captures this.

How is Restlessness Calculated

For restlessness calculations, HeartWatch identifies the basal energy requirement that your body had while asleep. It then looks at active energy expended during this time and uses an algorithm to identify the intensity of this activity versus baseline.

The simple percentage you see is, the active energy you have burned over and above your basal energy requirements which provides a nice way of seeing how restless you were.

The green energy graph you see overlaid over the sleeping heart rate is where and when this occurred, the strength and intensity.

The energy graph has a reverse y axis, where the top = 0 and the bottom is maximal. It also has a pseudo z axis by overlaying entries that overlap each other to cause a brighter shade of green

Home or next topic - Whats New