Why does ZoneSense require a heart rate belt?
To get accurate measurement of one’s heartbeat requires a heart rate belt. This data is essential for detecting differences between R-R peaks in heart rate. Optical heart rate monitors can only perform this type of measurement reliably at rest, such as during sleep.
Can ZoneSense be used with any heart rate belt?
Yes, any heart rate belt that provides beat-to-beat data can be used with ZoneSense. However only Suunto hr belt works in swimming with its inbuild memory.
Can ZoneSense be used with an arm heart rate monitor?
Arm heart rate monitors use optical heartrate. This cannot be used to measure the beat to beat data accurately during exercise, therefore ZoneSense is not available for these sensors.
How can I get ZoneSense on my watch?
To install ZoneSense, go to the Suunto App SuuntoPlus Store, select the ZoneSense Sports app, and save it to your watch. Next time you start your workout, select ZoneSense. For subsequent sessions in the same sport mode, ZoneSense is automatically selected.
Which watches support ZoneSense?
ZoneSense works with all Suunto watches with heart rate belts for post-analysis. This includes older models like Suunto Ambit and Spartan. Live data with ZoneSense is supported on the latest Suunto watches with the latest software, including Suunto 9 Peak Pro, Suunto Vertical, Suunto Race, Suunto Race S, and Suunto Ocean (later in autumn).
What does ZoneSense show on the Suunto app?
ZoneSense SuuntoPlus sports app shows your intensity graphically as green, yellow and red. Time in currently spend in given intensity and cumulative time in each intensity in workout. The cumulative time doesn’t include the first 10 minutes of training, as this period cannot be measured (read about this on next question).
The athlete can press the upper right button on their watch to change the fields shown, to follow other values such as pace, vertical, speed, power instead of cumulative time in zones.
Is it normal that ZoneSense SuuntoPlus sports app doesn’t show the intensity of my training’s first 10 minutes?
Yes. The ZoneSense DDFA (Dynamical Detrended Fluctuation Analysis) index cannot be measured accurately during the first 10 minutes as the body is typically then still warming up. The real-time measurement and after analysis therefore don’t show the data during this time.
Is it normal that cannot see my friend's ZoneSense numbers?
The ZoneSense analysis is visible only for your own workouts, and is hence personal.
Can I see ZoneSense data in my old workouts?
Yes you can. However, these numbers should be treated with caution, and most accurate data is received from new workouts with ZoneSense enabled.
My old workouts with ZoneSense data looks a bit off, what is the reason?
As ZoneSense is published in mid September 2024, each new workout is used to understand your personal sport specific baseline level of the DDFA. This will make the ZoneSense analysis more accurate over time. The older workouts prior enabling ZoneSense will have ZoneSense data, but as these do not include personal baseline analysis, the ZoneSense has error that can shift the ZoneSense graph 10-20% higher/lower.
Is there a way to make ZoneSense measurement more accurate?
As ZoneSense measures each workout, it will analyze the athlete’s normal aerobic baseline heart-rate variability with the DDFA index, used in as a parameter of the ZoneSense measurement. The intensity state of aerobic (green), an-aerobic (yellow) and vo2max (red) ranges are then evaluated based on the shift from this normal aerobic level, a.k.a. the workout baseline. The workouts that have very little aerobic effort will not contribute to this baseline definition. To have the best possible accuracy with ZoneSense, please ensure that you have easy aerobic sessions in your training regularly to analyze the effort of different types of training.
How can I get the best possible aerobic & an-aerobic threshold as heartrate evaluated?
You can use ZoneSense as an intensity measurement without the need to analyze the intensity with pace, power or heartrate. But there are workouts such as short intervals where pace and power are more suitable as they react to intensity changes immediately.
Naturally, the athlete can use heartrate as a measure of intensity, as well as power and pace. There is an analysis feature with ZoneSense where Suunto App defines the aerobic and an-aerobic threshold as heartrate with the DDFA. This analysis maps the heartrate to the ZoneSense DDFA index shifts cross aerobic and an-aerobic thresholds. To get a result from this analysis, the athlete needs to do a workout where intensity is tough and challenging. The intensity needs to grow from aerobic area to an-aerobic level, to get the aerobic threshold as a heartrate result. Similarly, to get the an-aerobic threshold, the athlete needs to do a workout that will have intensity in vo2max range.
To get a threshold result, the athlete can do a workout where he/she increases the intensity of the effort step by step. Increasing the intensity gradually ensures that there is enough measurement data in each effort level and therefore as the athlete goes over thethresholds it’s possible to identify heartrate at this intensity. This can be done in different sports such as running, cycling, rowing, even swimming. The idea of step-by-step protocol is to stay in each intensity for several minutes for example jogging easily for 3mins, then increasing each 3 minutes the pace and repeat this until max effort.
Sports and use cases
Why should I start workouts at an easier effort with ZoneSense?
ZoneSense establishes a personal intensity scale by measuring “DDFA index” during easy aerobic efforts. This baseline is updated with each workout but cannot be identified in high-intensity efforts. Accurate measurements therefore require regular easy workouts to keep the personal DDFA level up to date.
This personal baseline level can change throughout the year and can have differences even on day to day basis. Therefore, the best possible accuracy in the measurement you can get with ZoneSense requires a warmup period at the start of the workout.
My workout did not seem to be in “right intensity”, what could be the reason?
ZoneSense is best when used while doing workouts with steady effort, or during long intervals. The short bursts of effort, for example 1 minute intervals, do not reach homeostasis in your body. Therefore the DDFA index used with ZoneSense does not represent the intensity at that time.
Each workout you do will impact how your personal ZoneSense measurement works. The normal easy aerobic level measured with DDFA is saved to your watch & personal profile.
As you do a new workout it will contribute to this baseline measurement. If you do a first run with Suunto and this would be with very high effort, the ZoneSense can try to measure this DDFA level as your normal state. This might provide the wrong type of output. Ensure you make easy efforts also with your Suunto watch and heartrate belt, so that your normal baseline is calibrated accordingly.
When should I use ZoneSense instead of pace, power, or heartrate to identify my training intensity zones?
ZoneSense is ideal for steady workouts, such as long aerobic, hard threshold sessions or long interval sessions that last over 3 minutes. For short intervals, like 1-minute sprints, use running pace or cycling power for more accurate measurement. ZoneSense requires the athlete to work on given intensity at least 2-3 minutes in order to properly show the intensity level.
However, with ZoneSense you will learn which effort level in power, pace, vertical speed, swim pace you can sustain in your aerobical, an-aerobical and vo2 max area. This information you can be useful in daily training when adjusting your effort in each workout.
How does ZoneSense work with team or racquet sports?
In sports where the athlete can be working out constantly, ZoneSense can indicate whether the activity is primarily aerobic or anaerobic. However, due to delays in the measurement of ZoneSense and the nature of short bursts in the most common team and racquet sports, the actual effort intensity might not be shown correctly with ZoneSense. For example a 1-minute max out sprint followed up by longer rest lag can be shown in ZoneSense as completely aerobic level intensity training.
However, if the higher efforts are repeated with short recovery periods, the cumulative impact will be shown in ZoneSense.
ZoneSense is evolving, and feedback from sports scientists, coaches, and athletes is welcome to improve its application.
How can ZoneSense be used for swimming?
The Suunto heart rate belt stores data within its sensor module, as the heartrate signal cannot be transmitted underwater. Once on land or at the edge of a pool, the beat-to-beat heart rate data is transferred to the watch. ZoneSense data is then available for post- analysis to learn the real intensity from the session.
Does ZoneSense work with strength training?
ZoneSense focuses on aerobic and an-aerobic efforts by analyzing DDFA – the Dynamical Detrended Fluctuation Analysis index. Strength training intensity is based on muscular effort, not cardiovascular, making ZoneSense less suitable for strength-based workouts.
Can ZoneSense consider muscular fatigue, heat or other stress factors?
ZoneSense measures the stress of the heart which correlates with the aerobic, an-aerobic, vo2max states, but there are examples that indicate that ZoneSense can consider other factors that impact performance. For example, the fatigue in a muscle seems to impact the athlete so that ZoneSense will reach higher intensity levels faster. This means that the performance level shows decline when having muscle fatigue and in order to keep working out in normal level they would need to ease the effort.
Could ZoneSense be used to measure intensity in challenging levels of altitude or in hot conditions?
In altitude or in hot conditions, heart rate, pace and power measurements do not represent the intensity defined in laboratory conditions. Challenging and abnormal conditions make it difficult for the athlete to understand what a suitable effort level would be. There is a possibility that ZoneSense can be used in different conditions, as it measures the stress level of the heart and therefore is considering different internal and external stressors. However, this aspect will require more research.
ZoneSense analysis
Why isn’t the start of the exercise shown in the analysis?
The initial part of the workout serves as a warmup, allowing the body to adjust to exercise mode. During this time, measuring heart rate variability does not accurately correlate with exercise intensity. As a result, ZoneSense does not display data during this period in live tracking or in post-analysis.
Why isn’t short intense effort shown as hard effort with ZoneSense?
ZoneSense measures stress with DDFA, which has inherent delays. When you start a sprint, it takes several seconds to minutes for your body and heart rate to adjust. In a normal ramp-up test protocol in laboratory conditions, this delay is managed by working in the same effort for more than three minutes. During this time, the body metabolism “matches” the effort intensity such as lactate level in blood. Similarly, ZoneSense requires
a set of data before producing a relevant DDFA value, resulting in a delay of up to 1-2 minutes.
When gauging the right intensity level in running, cycling, swimming with shorter intervals or sprinting, the best measurements of intensity would be speed, pace, and power measurements. However, these will require predefined zone levels. ZoneSense can be used in after analysis to understand the power and speed levels in given effort, illustrated with the ZoneSense DDFA index.
Science background
What is the difference between HRV, RMSSD, DFA-1and DDFA?
These are different metrics used to analyze heart rate variability (HRV):
- HRV: Heartrate variability means the variation in time intervals between heartbeats. When the heartrate is 60 beats per minute, the average time between beats is 1 second. When a person is relaxed the variability between beat to beat has a difference, for example time between beats is 950ms (about 1 second),1050 ms, 940ms and so on.
- RMSSD: The Root Mean Square of Successive Differences is the most common method to calculate the short-term heart rate variability. This is commonly used to measure stress levels during the night or daytime stress test. This is used in Suunto to analyze your recovery state with night time measurements.
- DFA -1: DFA-1 refers to the short-scale scaling exponent covering 4-16 beat-to-beat intervals. The scaling exponent is conventionally computed for the full time series, thus giving one number as an output.“DDFA, on the other hand, covers all the time scales from 4 beat-to-beat intervals to even thousands, and gives an output for each particular time scale (4, 5, 6, ..., 1000). Furthermore, those values are given dynamically as a function of time. As a result, DDFA gives as an output a two-dimensional map of scaling exponents. Thus, DDFA is significantly more accurate and reliable than DFA-1, and as a real-time method it is responsive to changes in physiological conditions.
- **DDFA**: Dynamical Detrended Fluctuation Analysis. The method evaluates how the heartbeat intervals change with respect to each other, and how these changes at some time affect the changes of heartbeat intervals during other times. Such dependencies between the intervals are called correlations. DDFA evaluates the characteristics of these correlations very precisely at every instant of time.
How do aerobic and anaerobic thresholds work with ZoneSense?
ZoneSense measures the DDFA index during and after training. The anaerobic threshold is identified as a -0.5 change from the "0 baseline," and the aerobic threshold is set at -0.2. These levels correlate with laboratory tests but are indicative values representing changes in your metabolic system. Consistent use of ZoneSense provides a simple method for tracking intensity without frequent lab tests. ZoneSense illustrates the metabolic state of the body by measuring the stress level of the heart.
In principle, your daily fatigue, hydration level, heat, muscle soreness, running terrain and many other aspects can impact your current state of your body, impacting this DDFA index. For instance, you can reach your aerobic threshold at a slower pace than some days before.
How does ZoneSense measure heart rate thresholds?
ZoneSense maps changes as aerobic and an-aerobic thresholds to corresponding heart rate values. Sudden changes in intensity can introduce errors, so it is best to consider several workouts before setting heart rate zones in your Suunto watch.
Learn more
Where can I learn more?
Visit Suunto ZoneSense Page for detailed information on ZoneSense, including news, articles, webinars, and scientific insights.
Interested in testing ZoneSense together with Suunto?
If you are a national team, sports scientist, or pro-club interested in ZoneSense, please reach out to Suunto here