Smartlife categorises its outputs into measures and insight. Measures are interesting in their own right, but only with the ability to interpret them correctly. Measures are the building blocks of actionable insight, by which we mean easy-to-interpret feedback that leads to an action or change in behaviour that can have a positive impact on your health and / or performance. Here we define the measures and insights we will be offering.

Please note that not all measures and insights are available in the current app release.

Cardio Measures

+ Heart Rate (HR)

The number of times the heart beats in a minute, expressed as beats per minute (bpm).

A number of additional measures are derived from heart rate as follows:


The maximum HR achieved within a session.


The mean HR achieved in a session.


The maximum number of beats per minute that your heart can achieve.

This typically varies with age and can be estimated using the formula 220 – age. However, this is not very accurate so it is best determined by a test. To determine your own maximum HR:

  1. Put on your Smartlife garment and activate the sensors in the app
  2. Start an exercise session
  3. Warm up at a steady pace for 3 to 5 minutes
  4. Increase the intensity and run or cycle at a maximal but steady pace for 3 mins
  5. Reduce the intensity to easy for 2-3 mins
  6. Repeat maximal interval for another 3 mins (HR will typically peak higher in the second interval)
  7. Enter the peak HR for the session into your profile in the Smartlife app or website


Your normal heart rate when you are at complete rest.

Resting HR varies from person to person, and with environmental, emotional, and medical factors (e.g. temperature, stress, or medication). Resting HR is a good indicator of overall health and fitness. In general, a normal resting heart rate for adults ranges from 60 to 100 beats a minute, however a well-trained athlete could have a resting heart rate closer to 40 beats a minute.

To calculate your own resting heart rate:

  1. Put on your Smartlife garment and activate the sensors in the app
  2. Lie down and rest for at least 15 minutes (first thing in morning is ideal)
  3. Observe or record your heart rate for 1 minute
  4. Enter the average HR into your profile in the Smartlife app or website

Alternatively, for a quick estimate, measure your pulse at the wrist for 15 seconds then multiply by 4.

Note, it’s important to measure your resting HR under the same conditions each time. Some factors to consider are:

  • Time of day
  • Body position (sitting vs lying down)
  • Caffeine/alcohol consumption
  • Time since eating


The reduction in HR during the first minute of recovery following peak exercise.

HRR is a good indicator of cardiac health and fitness. A healthy, well-trained person will recover faster than an unhealthy or untrained person. Smartlife calculates a score and grades it from poor to excellent. NB This score is only applicable if the exercise session recording was stopped after high intensity exercise, otherwise the heart will already have had time to recover.


The increase in heart rate when standing up from a lying/seated position.

When standing up from a lying/seated position blood moves into the body’s lower extremities due to gravity. Normally, to maintain blood flow to the heart and brain and to prevent blood pressure dropping, the autonomic nervous system (ANS) constricts the blood vessels and raises the heart rate. This is called the baroreflex.

An OHR of less than 20 is considered indicative of a normal ANS response.

+ HR Variability (HRV)

The variation in the time interval between heart beats.

The heart is controlled by the autonomic nervous system (ANS). The ANS has two branches, the Sympathetic Nervous System (SNS), which speeds up the heart rate (often thought of as the “fight or flight” response) and the Parasympathetic Nervous System (PNS), responsible for slowing the heart rate (for “rest and repair”).

HRV reflects the balance of the SNS and PNS in response to various internal and external stimuli. A high HRV with a stronger PNS influence, indicates an optimal balance.

Breathing Measures

+ Breathing Frequency (BF)

The number of breath cycles in a minute expressed as breaths per minute (brpm).

A breath cycle is a complete inhalation followed by a complete exhalation (or vice versa).

A number of additional measures are derived from breathing frequency as follows:


The maximum BF achieved within a session.


The mean BF achieved in a session.

+ Breathing State (BS)

The stage of a breath cycle: in, out, or held.

+ Ventilatory Thresholds (VT)

The workloads at which there is a marked change in breathing.

There are two ventilatory thresholds as shown in the chart below.

The first, VT1, is the workload at which lactate starts to accumulate in the blood and the breathing rate starts to increase. At this point talking becomes less comfortable.

The second, VT2, is the workload at which lactate accumulates more quickly and breathing becomes rapid. This usually coincides with the lactate/anaerobic threshold.

How Smartlife Works

+ VO2 Max

The maximum amount of oxygen that an individual can utilize during intense exercise.

This can only accurately be measured in the lab using gas analysis equipment under maximal exercise conditions. However, Smartlife estimates this from performance data.

+ Minute Ventilation

The volume of gas inhaled or exhaled from the lungs per minute.

Movement (Gait) Measures

+ Steps

The number of steps taken during a training session.

A step is the sequence of movements from the heel strike of one foot to the heel strike of the opposite foot when walking or running.

+ Cadence

The step or pedaling rate, measured as number of steps/revolutions per minute.

Cadence describes the rhythm of your movement.

In running and walking, it is the step rate expressed as the number of steps per minute (SPM), where each foot strike counts as one step. The optimal cadence for any given runner is related to their height, weight, leg length, and speed.

In cycling, cadence is the pedaling rate expressed as revolutions per minute (RPM), where one revolution is a full turn of the crank. The optimal cadence for a cyclist is between 80 and 100 based on biomechanical efficiency.

+ Stride Length

The length of an entire gait cycle.

A stride is the sequence of movements from the heel strike of one foot to the heel strike of the same foot when walking or running.

+ Ground Contact Time

The length of time each foot remains planted on the ground during a gait cycle.

+ Vertical Oscillation

The vertical distance travelled in a stride.

+ Speed

The rate of forward movement.


+ Exercise Readiness

The preparedness of the body to cope with ongoing physical demands.

This preparedness relates to the level of psychological or physical strain (stress/fatigue) resulting from demanding circumstances (e.g. exercise or mental tasks). Stress and fatigue are signs of poor emotional, mental, or physical wellbeing and are associated with reduced autonomic nervous system (ANS) function.

Good ANS function has been shown to positively correlate with mental and athletic performance and negatively correlate with the risk of overtraining and physical injury.

Use the Exercise Readiness test to determine if your body is well rested and ready to take on a high intensity workout, or if rest and recovery would be more beneficial.

+ Exercise Intensity

An approximation of the physiological effects of different intensities of physical activity.

As the intensity of physical activity increases, there are changes in its physiological effects.

Lower intensities are characterised by predominantly aerobic (with oxygen) metabolism and burn a higher proportion of fat to carbohydrate. They are beneficial for endurance training and improving cardiovascular fitness.

Higher intensities are characterised by predominantly anaerobic (without oxygen) metabolism, using a greater proportion of carbohydrate for fuel. These intensities burn more energy overall as well as leading to improvements in VO2 max and lactate thresholds which improve the capacity of the body to cope with high intensity activities.

Smartlife defines three personalised Training Zones based on percentage of your HR reserve (the range between your resting and maximum HRs).

Training Zones

Use Exercise Intensity to see, at a glance, if you’re working at a sufficiently strenuous intensity to achieve your goals.

+ Energy Expenditure

The amount of energy used by the body during a training session.

Energy, measured in calories (kcal), is consumed in the form of food and drink and expended through basic bodily functions at rest (e.g. breathing, temperature regulation, cell production, brain function etc), through digestion (the thermic effect of food), and through activity.

Energy balance is the net result of calories consumed and expended. Over- or under-consumption of calories relative to energy expenditure will affect performance in the short term, and body weight (fat and muscle) in the longer term.

Use Energy Expenditure to inform how many calories you need to consume to refuel after an intense training session, or to track if your energy balance is over or under target in relation to fat-loss goals.

Note, high intensity training sessions will also result in burning more calories than usual for a few additional hours after exercise. This is due to increased energy demands during recovery to return the body back to a resting state and adapt to the exercise performed, an effect known as excess post-exercise oxygen consumption (EPOC).

+ Breathing Rhythm

The ratio of inhalation to exhalation.

Breathing Rhythm aims to achieve two things: (i) full oxygenation and carbon dioxide clearance; and (ii) even distribution of impact stress.

Firstly, taking long and controlled breaths in from the belly helps to maximise the volume in your chest cavity and draw in the maximum amount of oxygen. Taking long and controlled breaths out has the reverse effect, squeezing out all of the carbon dioxide ready for the next breath.

Secondly, an odd ratio ensures that the impact stress from your foot strike is distributed alternately over both sides of your body. As you breathe in your diagphragm and core muscles contract and as you breathe out they relax. This means your core is most stable during an inhalation. Therefore, when your foot hits the ground during an exhalation the impact stress on your body is at its greatest.

Use Breathing Rhythm to check that you are taking slow, controlled breaths and distributing the impact stress equally across both sides of your body. A target ratio of 3:2 is recommended i.e. breathe in for 3 steps and out for 2 steps.

+ Exercise Economy

The resources expended, energy or oxygen, by the body, per unit of activity (e.g. a mile).

Efficient runners and cyclists use less energy per mile resulting in better (faster) performance.

Use Exercise Economy to gain insight into how efficiently you are moving and make minor adjustments to your gait to improve your running or cycling economy.

+ Training Load

The cumulative amount of stress placed on the body due to the frequency, duration and intensity of physical activity.

While training too often at a low intensity will have little benefit, training too often at a high intensity can result in injury and illness. Studies show that training load is a good predictor of injury and illness in athletes.

Use Training Load to monitor and adjust your training schedule to ensure you avoid injury or illness from over-training.

+ Aerobic Fitness

The ability of the heart, blood cells and lungs to supply oxygenated blood to the working muscles and the ability of the muscles to use that oxygen to produce energy for movement.

Aerobic fitness not only improves athletic performance by enabling these systems to meet energy demands, but is also beneficial to health by decreasing the risk of cardiovascular diseases and stroke, lowering blood pressure, and improving autoimmune function. Aerobic fitness can be improved through exercise.

Track improvements in your Aerobic Fitness over the course of an exercise/health programme to judge how well it is working.

+ Cardio Age

The relative age of the heart compared to true age.

As people age their arteries lose flexibility and their circulation becomes impaired, resulting in higher blood pressure and an increased risk of cardiovascular disease and stroke.

People who do more exercise tend to have a cardiovascular age more like that of a young person.

Measure your Cardio Age on a regular basis and track your improvements over the course of an exercise/health programme to judge how well it is working.