Heart Rate Monitoring

What is heart rate?

Heart rate is the number of heart beats per minute; it serves as a fundamental indicator for measuring cardiac function, reflecting the cardiac rate and health status over a specific period. The normal heart rate range varies by age, gender, health condition, and physiological state (e.g., exercise, rest, emotions).

In adults, the resting heart rate typically ranges from 60 to 100 beats per minute, though individual variations may occur. For instance, athletes or regular exercisers may have a heart rate below 60 beats per minute due to enhanced cardiac function.

Resting Heart Rate (RHR) and Maximum Heart Rate (HRMAX)

Resting heart rate (RHR), also known as quiet heart rate, refers to the number of heart beats per minute in a conscious, inactive, and quiet state. Your resting heart rate varies from day to day.

The resting heart rate for healthy adults ranges from 60 to 100 beats per minute (bpm), with some athletes potentially having lower values. RHR values reflect fitness level and recovery status—the lower the value, the better the fitness and recovery. Generally, a lower RHR indicates good cardiopulmonary capacity and a higher VO2 max level. Moderate exercise can help lower resting heart rate.

Maximum heart rate (HRMAX) is the highest rate at which the heart can beat. Unlike resting heart rate, HRMAX is relatively stable, with values gradually decreasing with age.

During exercise loading, oxygen consumption and heart rate increase with exercise volume. When exercise load reaches maximum intensity and oxygen consumption/heart rate no longer increase, the highest heart rate achieved is defined as HRMAX. HRMAX is nearly unaffected by fitness status, so consistent training does not increase HRMAX.

Due to individual differences in age, fitness level, and cardiopulmonary capacity, HRMAX varies even among people of the same age. The QCY smartwatch automatically calculates your HRMAX when running at Heart Rate Zone 3 or higher. The HRMAX also can be estimated using the formula: 220 - age = maximum heart rate (bpm).

How does the QCY smartwatch measure your heart rate?

The QCY smartwatch is equipped with a multi-channel, high-bitwidth optical heart rate sensor. It continuously tracks your heart rate 24/7. The heart rate number displayed on the heart rate page is the real-time detected value, while the QCY App provides long-term tracking data trends for a deeper understanding of your health status.

Automatic Detection of Maximum Heart Rate

The new generation of QCY smartwatches automatically updates your HRMAX based on your fitness data. When the system detects a value exceeding your currently set HRMAX and meets the reliability threshold, your personal HRMAX data in the device and QCY App will be updated automatically. This update can be triggered by running at Heart Rate Zone 3 or higher for 12 minutes.

Heart Rate Zones and Personalized Heart Rate Zones

Heart rate zones enable you to adjust exercise intensity more effortlessly during workouts, gradually improving training efficiency, preventing overtraining during recovery, and appropriately modifying intensity. They also help enhance athletic performance in QCY smartwatch-supported activities like running, cycling, and swimming.

Everyone's heart rate zones vary by factors such as age and fitness level—not fixed. The QCY smartwatch features AI-powered automatic physiological parameter detection. In just 12 minutes of Heart Rate Zone 3 or higher running, it calculates personalized heart rate zones to optimize training efficacy and prevent overtraining injuries.

Application of Heart Rate Zones

Heart rate zones enable real-time monitoring of exercise intensity. Timely adjustments to training intensity, duration, recovery time, and repetitions ensure effective and sustainable training, while preventing undertraining or exercise-related injuries. They also serve as a basis for evaluating training efficacy over periods, eliminating the need to guess training intensity. The QCY smartwatch displays the corresponding heart rate zone in real-time during workouts.

Focusing on distinct training goals across heart rate zones allows you to develop a personalized regimen for enhancing muscle strength, endurance, power, and other fitness aspects. Generally, lower zones are ideal for warm-ups and recovery, while higher zones facilitate fitness level improvement. The following describes the preset heart rate zones of the QCY smartwatch. This description applies to regular training; if you have specific training objectives, it may not be applicable.

Heart Rate Zone 5 (Extreme)	90%-100% of HRMAX or 172-190 bpm	Training in the Heart Rate Zone 5 typically requires a sprinting pace that's difficult to sustain, accompanied by labored breathing. Zone 5 training enhances strength while improving anaerobic capacity and muscle endurance. Sprinting is a classic example of Heart Rate Zone 5 exercise.
Heart Rate Zone 4 (Anaerobic Endurance)	80%-90% of HRMAX or 152-172 bpm	Training in the Heart Rate Zone 4 requires a fast and near-uncomfortable pace, accompanied by rapid breathing. Zone 4 training enhances anaerobic capacity and lactate threshold. Fast run is a classic example of Zone 4 exercise.
Heart Rate Zone 3 (Aerobic Endurance)	70%-80% of HRMAX or 133-152 bpm	Training in the Heart Rate Zone 3 is performed at a moderate pace, making conversation slightly difficult. Zone 3 training enhances cardiopulmonary endurance. Easy run is a classic example of Heart Rate Zone 3 exercise.
Heart Rate Zone 2 (Fat Burning)	60%-70% of HRMAX or 114-133 bpm	Training in the Heart Rate Zone 2 features a comfortable pace, with deeper breathing while still allowing conversation. Zone 2 training is ideal for basic cardiopulmonary conditioning and recovery. Jogging is a classic example of Heart Rate Zone 2 exercise.
Heart Rate Zone 1 (Warm-up)	50%-60% of HRMAX or 104-114 bpm	Training in the Heart Rate Zone 1 is easy and effortless, accompanied by rhythmic breathing. Zone 1 training enhances the heart's blood delivery capacity and muscle oxygen consumption. Brisk walking is a classic example of Heart Rate Zone 1 exercise.

Pulse Oximetry

Blood oxygen refers to the oxygen content or saturation in blood. Pulse oximetry is the blood oxygen saturation (SpO2) measured by the QCY smartwatch via photoplethysmography (PPG) technology on the wrist. PPG pulse oximetry is one of the most widely trusted technologies for blood oxygen concentration detection. Understanding SpO2 provides valuable insights into health and physiological status. According to the Mayo Clinic, the ideal SpO2 for healthy adults at rest is 95%-100%, with levels below 90% considered low.

SpO2 helps assess the body’s adaptation to altitude during mountain sports or high-altitude activities—blood oxygen saturation typically decreases with increasing altitude. Additionally, SpO2 changes can reveal potential sleep disorders (such as sleep apnea) during sleep. Understanding your SpO2 levels helps evaluate bodily responses in different scenarios and alert you to significant health changes.

How does blood oxygen monitoring work?

Hemoglobin in the blood is key to understanding the oxygen content in your bloodstream. The oxygen saturation level in hemoglobin affects its absorption of two types of light: infrared and red. Wearable devices emit both infrared and red light, which sensors use to collect pulse signals. Using collected data and algorithms tailored to specific parameters, the QCY smartwatch estimates the user's blood oxygen level.

Why do you need to know your blood oxygen level?

Monitoring blood oxygen saturation (SpO2) helps users assess their health status in real-time, understand environmental factors, evaluate physical condition, and set appropriate activity or training goals.

When engaging in outdoor activities with rapid altitude changes, tracking SpO2 reveals how the body adapts. Combined with heart rate data, it enables calculation of additional physiological metrics, aiding in training efficacy assessment and early warning for potential altitude sickness in high-altitude environments.

Users can also leverage SpO2 trends to analyze sleep patterns and respond to potential sleep apnea.

Stress Detection

What does the stress index represent?

The stress index is derived from analyzing the user's heart rate variability (HRV). Generally, a lower HRV value indicates higher physical or mental stress, while a higher HRV signifies a state of relaxation or recovery. Factors such as training, physical activity, sleep, energy replenishment, and life stress can all impact your stress index.

The stress index ranges from 1 to 99: 1-29 indicates a relaxed state with low stress, 30-59 signifies normal stress, 60-79 denotes moderate stress, and 80-99 represents high stress. This feature helps you understand your daily stress levels and make timely adjustments.

The QCY smartwatch monitors your stress levels around the clock.

When the stress index exceeds 60, try...

1. Standing up and moving around to engage with your surroundings.
2. Listening to music and taking a short rest.
3. Sleeping or eating to replenish your energy. 

Moderate stress can drive personal growth, but excessive stress may pose health risks. There's no one-size-fits-all approach to stress relief—you need to experiment to find what works best for you.

All-Day Stamina

The all-day stamina feature on the QCY smartwatch is designed to help users monitor their overall physical energy throughout the day. Using the Gomore all-day stamina algorithm, this feature provides a numerical representation of the combined effects of physical activity, stress, rest, and sleep recovery. This analysis helps users establish training plans and healthy habits tailored to their individual conditions, enabling them to better manage the complex interplay between lifestyle, health, and physical fitness.

All-day stamina peaks in the morning upon waking. Various activities engaged in throughout the day continuously deplete stamina, while napping and resting can slow energy expenditure or even replenish it. Nighttime sleep is the optimal period for recharging the body's energy each day.

How does all-day stamina work?

The all-day stamina feature operates by continuously analyzing comprehensive data—including sleep patterns, daily physical activity, and stress levels during periods of inactivity—tracked by the wearable device. It identifies meaningful physiological metrics and records their impact on stamina.

Daily physical activities and exercise deplete stamina

When active, activity intensity affects the rate of stamina depletion—the higher the intensity and the longer the duration, the faster stamina is exhausted. Prolonged high-intensity training depletes energy more than a short walk.

Physiological stress levels also influence the rate of stamina recovery and depletion—the greater the stress, the faster stamina is consumed.

By recording the user's daily activity status, the QCY smartwatch provides in-depth analysis of activity impacts, offering references for establishing healthy training plans, controlling activity intensity, and maintaining physical health.

Sleep and naps help restore stamina

Sleep plays the most crucial role in stamina recovery. All-day stamina assessment integrates 24-hour activity data, stress levels during inactivity, and sleep patterns—whether a long night's sleep or a midday nap, stamina recovers as long as the body is asleep.

How does the physical fitness affect stamina?

Understanding how your fitness level impacts stamina and mastering the relationship between them can help you maintain optimal energy and lay the foundation for peak performance.

Fitness levels can be measured by VO2 max. VO2 max reflects an individual's ability of the heart, lungs, circulatory system, and muscles to work in concert to support aerobic energy production. The best way to improve fitness is through regular high-intensity exercise.

Exercise intensity correlates with the rate of stamina depletion. However, as fitness improves, the impact of exercise and high stress on the body diminishes, and physiological adaptability increases. The higher the fitness level, the more exercise one can perform without fatigue, and the greater the capacity to withstand physiological stress.

The QCY smartwatch integrates stamina feedback into all-day activity tracking and exercise monitoring.

Pay attention to low stamina levels

When facing life's challenges and unexpected events, we always need stamina to tackle these demanding tasks. A low stamina state means sometimes having to grit your teeth and push through, but prolonged low stamina can lead to various health issues and hinder you from reaching your full potential.

Experiencing low stamina for a few days is nothing to worry about—you can clearly understand your current state. For example: Being sick or having a poor night's sleep can lead to low stamina, and you just need to find ways to improve it. A low stamina state doesn't mean you can't exercise or take on challenging tasks, but it's not advisable in the long run.

Monitoring your stamina levels can bring training benefits and help you tackle physiological challenges. Please avoid subjecting yourself to excessive training load when fatigued or sleep-deprived.

Energy Expenditure and Sources

The two most common purposes for using smartwatches and health tracking tools are weight management and calorie tracking. Maintaining a healthy weight can significantly improve sleep quality, support heart health, reduce muscle and joint pain, and lower the risk of type 2 diabetes.

Calories vs. Energy Sources

Every activity we do each day requires energy, and even sleeping or sitting quietly burns calories. The body's energy needs increase with the intensity of physical activity. The QCY smartwatch helps you track the number of calories burned throughout the day.

During high-intensity activities, burned calories typically derive from carbohydrates and fats. The QCY smartwatch, in conjunction with Gomore Fitness, calculates calorie sources and the carbohydrate-to-fat ratio.

Tracking Calorie Consumption

The QCY smartwatch not only tracks calorie consumption during exercise but also monitors energy expenditure during daily activities, helping us build healthy habits and understand the dietary energy we need to consume.

Sleep Monitoring

How to improve sleep quality?

Establish a consistent sleep schedule with fixed times for going to bed and waking up.

Avoid consuming stimulating foods before bedtime, and refrain from overeating, as this keeps the digestive system active and disrupts sleep. Conversely, going to bed overly hungry can also affect sleep quality.

Engage in moderate exercise in the evening. Increasing the temperature difference between day and night can also facilitate deep sleep.

Numerous factors affect sleep quality, including age, environment, jet lag, previous night's sleep quality, medication use, alcohol consumption, and sleep disorders such as insomnia and sleep apnea.

Rate your sleep each night

The sleep monitoring feature on the QCY smartwatch calculates sleep scores by analyzing the user's heart rate variability (HRV), heart rate, physical activity, and time to fall asleep. The smartwatch detects whether the user is in light sleep, deep sleep, or rapid eye movement (REM) sleep, analyzes the quality of each stage, and performs complex calculations based on the user's daily physiological data and training information to generate a sleep score and recommendations. Sleep scores are primarily categorized into four types: 100 points: Represents excellent sleep quality with sufficient duration, predominantly consisting of restorative sleep. 80-99 points: Indicates good sleep quality with the body fully rested. 50-79 points: Signifies average sleep quality. 0-49 points: Denotes poor sleep quality that requires improvement. It is recommended to consistently track your sleep score daily, gradually adjust your sleep rhythm, and build healthy sleep habits. For more accurate measurements, wear the watch throughout the day.

Sporadic Naps

A sporadic nap generally refers to a short-duration sleep taken during the day.

A proper midday nap or short rest helps restore stamina, alleviate fatigue, and improve memory. Equipped with the Gomore health algorithm, the QCY smartwatch automatically detects sporadic naps, deeply analyzes your personal napping habits, and helps establish a healthy lifestyle.

Sporadic Nap Detection

For optimal detection, the nap duration—including wake time—should exceed 30 minutes but be less than 3 hours. Sleep exceeding 3 hours falls outside the definition of a nap and is classified as regular sleep. Naps shorter than 30 minutes may not be recorded. Naps should also be taken outside the normal nighttime sleep window. The QCY smartwatch supports sporadic nap detection from 8:00 a.m. to 10:00 p.m.

Shorter sleep durations make it difficult to achieve deep sleep and rapid eye movement (REM), which is why naps do not track the four sleep stages. This explains why multiple naps cannot provide the same restorative effects as a full night of uninterrupted sleep.

Sleep Apnea Research

Obstructive Sleep Apnea/Hypopnea Syndrome (OSAHS) is a disorder characterized by partial or complete collapse of the upper airway during sleep, leading to episodes of apnea and hypopnea due to various factors. The main symptoms include snoring during sleep and daytime drowsiness.

OSA may lead to:

• Snoring during sleep, accompanied by repeated awakenings and micro-arousals;
• Morning dry mouth and headaches;
• Daytime drowsiness, excessive sleepiness, and increased nocturia;
• Mental symptoms such as inattention, memory loss, irritability, anxiety, or depression.

Equipped with the Gomore OSA health analysis algorithm, the QCY smartwatch continuously monitors heart rate, blood oxygen levels, HRV, and activity sensor data during sleep, analyzing the risk of OSA to help you understand your sleep breathing conditions.

Note: This is not a professional medical device, and results are for reference only. In case of physical discomfort, please seek professional medical assistance promptly.

Respiratory Rate Detection

The respiratory rate measures your average breaths per minute (brpm) throughout the day, including both inhalation and exhalation. A low respiratory rate at rest is a strong indicator of good physical fitness. In a stationary state, the normal respiratory rate for adults is 12-20 breaths per minute.

If the respiratory rate during rest is significantly higher or lower than the average, it may indicate a health warning or air quality issues.

The QCY smartwatch uses PPG technology to track respiratory rate and provides overnight respiratory rate data during sleep.

Breathing Training

Breathing training helps reduce stress, improve focus, and enhance both work performance and sleep quality.

On the QCY smartwatch, you can practice four breathing techniques using the built-in breathing training mode: calm, relax, focus, and continuous.

Calm

The goal of calm breathing is to prepare you for sleep by gradually guiding you to a breathing rhythm of 4-second inhalation, 7-second hold, and 8-second exhalation.

Relax

The goal of relax breathing is to help you relieve stress by gradually guiding you to a breathing rhythm of 4-second inhalation, 4-second hold, 4-second exhalation, and another 4-second hold. When the watch detects an unusually high stress peak, it will issue a "Relaxation Reminder" and recommend that you perform this breathing exercise.

Focus

The goal of focus breathing is to help you enhance concentration, gradually guiding you to a breathing rhythm of 4-second inhalation, 4-second hold, 4-second exhalation, and another 4-second hold. Unlike the relax mode, the focus mode involves more sets of exercises.

Continuous

Continuous breathing training helps you regain balance and calmness, preventing excessive excitement or relaxation. You will gradually slow down your breathing until you achieve a balanced rhythm of 6-second inhalation and 6-second exhalation.

If you feel discomfort when first starting breathing training, do not give up. Once you get accustomed to the breathing rhythm and learn to control your breath more easily, you will begin to experience the many benefits of breathing training. Like any other training, breathing training requires consistent practice.

HRV Status

What is heart rate variability (HRV)?

Heart rate variability (HRV) refers to the variation in heartbeats. The heart does not beat in a completely regular rhythm. In fact, variations in heartbeats are healthy and normal. HRV is used to assist in measuring physiological data such as stress index, all-day stamina, VO2 max, and lactate threshold. QCY smartwatches with built-in optical heart rate sensors can also measure sleep HRV status.

How does the QCY smartwatch measure HRV?

The QCY smartwatch is equipped with a multi-channel, high-bitwidth optical heart rate sensor. It continuously tracks your heart rate 24/7 and records the time intervals between heartbeats, from which HRV values are generated. HRV data enables effective analysis of heart rate variability across different usage scenarios.

The QCY smartwatch can continuously measure and calculate HRV during sleep, and it also supports one-click measurement of various health data—including HRV—at rest. Through the HRV Status app, you can view the average HRV from overnight sleep while wearing the watch, as well as statistical charts composed of 5-minute heart rate variability data to understand your real-time HRV status.

Additionally, the watch can generate a statistical chart of average HRV values from 7 consecutive days of wear, assisting in analyzing your physical recovery over time.

HRV Baseline

When wearing the QCY smartwatch for sleep monitoring, the system automatically records and analyzes HRV status. After 3 consecutive weeks of wear, a personalized HRV status range is generated based on the average HRV values from this period. The HRV baseline changes over time.

The HRV baseline is a range of values (e.g., 45–55 ms) derived from historical measurement records, representing an individual's normal heart rate variability. After a period of exercise, the HRV baseline range may decrease. Additionally, the HRV baseline range declines with age.

HRV Status

The QCY smartwatch uses the established HRV baseline to determine if the average HRV over the past 7 days is balanced: When the average falls within the baseline range, it indicates the body is in a state of dynamic balance. If the average is outside the baseline—either above or below the baseline value—it signals an unbalanced HRV status.

When HRV is unbalanced and below the baseline, maintain normal HRV through moderate exercise, a balanced diet, and emotional well-being. If HRV consistently stays below the baseline, monitor your health.

An unbalanced HRV above the baseline may indicate a good recovery state, but be cautious: Excessive low-intensity training can lead to overtraining, causing HRV to rise above the baseline. Such excessive recovery training can also damage the body.

The HRV baseline is a continuously evolving process. Without long-term training, a significant or sustained decrease in the HRV baseline requires attention to health status and prompt adjustment for recovery.

VO2 Max and Physical Fitness

Physical Fitness

Physical fitness reflects the body's adaptability to the environment and health to a certain extent. It is generally evaluated from the perspective of cardiopulmonary endurance, with VO2 max as the standard metric.

VO2 Max

VO2 max is a single metric reflecting cardiopulmonary endurance, representing the maximal oxygen consumption per minute during high-intensity exercise. As a key metric for evaluating the body's ability to utilize aerobic energy for activities, a higher VO2 max indicates a greater capacity to inhale, transport, and utilize oxygen—converting energy stored in nutrients into physical performance through aerobic metabolism.

A higher VO2 max is preferable, and you can intuitively understand your level through the VO2 max rating on the QCY smartwatch.

How does the QCY watch estimate your VO2 max?

Fitness Age

Fitness age is an estimated measure of physical condition relative to chronological age. Fitness age tends to decrease with consistent training and improved physical fitness. It also serves as a reminder that a healthy diet and regular exercise help maintain good physical condition.

Estimating Physical Age Using VO2 Max

Fitness age reflects an individual's physical fitness level relative to others of the same gender and age group in a simple and understandable manner.

Cardiopulmonary endurance typically declines with age, but regular physical exercise can still slow down cardiopulmonary aging and even improve endurance to a certain extent.

Duration of Moderate to High intensity Activities

According to the WHO Guidelines on Physical Activity and Sedentary Behaviour, adults should engage in at least 150–300 minutes of moderate-intensity aerobic activity or 75–150 minutes of vigorous-intensity aerobic activity weekly to derive significant health benefits.

The QCY smartwatch easily tracks your daily/weekly duration of moderate to high-intensity activities, helping you understand the exercise intensity required to maintain basic vitality.

Water Intake Tracking

Maintaining adequate hydration offers numerous benefits, including:

• Supporting the physiological functions of organs and tissues
• Regulating body temperature
• Efficiently eliminating metabolic waste
• Replenishing body fluids to delay aging
• Preventing chronic diseases

The QCY smartwatch sets a default daily hydration goal. You can use the default value or customize your hydration target. You can also choose to enable/disable drinking reminders.

Vitality Value

According to the WHO guidelines, adults should engage in at least 150 minutes of moderate-intensity (MET 3–6) aerobic activity or 75 minutes of high-intensity (>6 MET) aerobic activity weekly, or an equivalent combination, to maintain health. The WHO-recommended effective activity level is approximately 500–1,000 MET-min. Therefore, when the accumulated effective activity (MET >3) reaches 500 MET-min over 7 days, the vitality value goal (100 points) is achieved.

Metabolic Equivalent (MET)

It refers to the ratio of the body's metabolic rate during different activities to the resting metabolic rate, calculated in METs. The MET values vary for different activities.

The vitality value follows a 7-day cumulative principle (today's score + scores from the past 6 days), so activity intensity does not need to be evenly distributed. The 7-day score correlates with activity frequency and duration and can exceed 100 points. Above all, maintaining healthy lifestyle habits brings the greatest benefits.

Altitude Sickness Assistance

Altitude sickness is a physiological stress response of the body to hypoxia at high altitudes. This reaction primarily occurs because the partial pressure of oxyge in the atmosphere decreases at high altitudes, directly affecting blood oxygenation and causing insufficient oxygen supply and hypoxia.

Altitude sickness typically occurs at elevations of 2,500 meters or higher and can be categorized into acute and chronic states. Common symptoms include: headache, dizziness, blurred vision, tinnitus, insomnia, fatigue, chest tightness, dyspnea, nausea, vomiting, palpitations, edema, etc. These symptoms typically appear within 24 to 48 hours of entering high-altitude areas.

The QCY smartwatch intelligently monitors altitude and automatically activates the altitude sickness assistance feature when the elevation reaches 2,500 meters or higher. A basic questionnaire is used to assess whether you are experiencing or at risk of altitude sickness, aiding in prompt response.

When the watch detects a potential altitude reaction, it will issue a warning, prompting you to closely monitor changes in blood oxygen levels and physical stamina. You can also initiate another questionnaire assessment for timely action.

We strongly recommend seeking immediate medical attention and professional healthcare advice if altitude sickness occurs.