Comparison Polar V800 vs Polar RS400

— Pedometer. This category comprises devices primarily designed to count the number of steps taken by the user. Additional measurements in the design are directly related to step counting and may include movement speed, distance traveled, energy consumption, etc. Steps are typically counted based on accelerometer data, responding to the characteristic shaking during walking. Some pedometers use GPS modules instead of accelerometers, measuring distance traveled rather than individual steps. Another specific variety is designed for swimmers, measuring strokes instead of steps. Despite this difference, they share key features with traditional pedometers and are included in the same category.

— Heart rate monitor. Devices designed to track the user's heart rate and the corresponding calculations based on this data. They are not able to work with step counting — unlike pedometers and combination metres, see below. There are both devices with a built-in sensor, and with a remote one.

— Heart rate monitor/pedometer. Combined models integrate the functionalities of both heart rate monitors and pedometers, measuring both the number of steps and heart rate, along with related parameters. These devices offer versatility, but their development involves technical challenges that can impact measurement quality and overall cost. As a result, there are relatively few...models of this type available on the market.

— Pulse oximeter. These devices can measure both heart rate and blood oxygen saturation and typically resemble a characteristic "clothespin" attached to the finger. Using non-invasive methods, they determine blood oxygen levels without causing skin damage. While suitable for sports applications, they also find use in medical settings, serving as a means to monitor a patient's condition in the absence of more advanced medical equipment. However, due to the inconvenience of the finger "clothespin" during vigorous activity, these devices are more aligned with medical instruments in their intended use.

— Heart rate sensor. These models are external heart rate sensors meant for connection to other devices such as heart rate monitors, exercise equipment, or smartphones. They are not designed for stand-alone use. While these cardiac sensors have limited capabilities, this is not a drawback but a specific feature inherent in their application format. The expectation is that additional measurements will be conducted by an external device, and the sensor's role is to provide the necessary data for this purpose.

Measurements and calculations that can be carried out with the device.

— Heart rate. Heart rate measurement in real-time is a crucial feature for devices with a heart rate monitor function and is primarily the main function for heart sensors and pulse oximeters. In fitness, heart rate is a key parameter, aligning with various training goals such as fat burning, maintaining shape, or cardiovascular strengthening. Many models can also detect critical situations like heart rhythm disturbances or excessive heart rate, providing user warnings. However, it's important to note that not all heart rate monitors or combined devices offer continuous monitoring; some models require touching the sensor for measurements. Therefore, for constant pulse data, ensure the selected device supports continuous monitoring.

— The level of oxygen in the blood. The pulse oximeter function measures blood oxygen saturation levels using a specialized sensor in a non-invasive manner, without puncturing or damaging the skin. It's important to acknowledge that the oxygen level sensor is not a certified medical device. However, it effectively responds to critical decreases in saturation, such as those experienced by climbers at high altitudes or individuals with specific respiratory conditions.

— Perfusion Index (PI). A parameter found exclusi...vely in pulse oximeters (see “Type”). Perfusion Index (PI) is a measure of blood flow in the finger being measured. The PI indicator is measured as a percentage and can vary from 0.3 to 20%. A value in the range of 4 – 7% is considered normal. If you deviate from this range, the saturation measurement results may be distorted.

— Number of steps. Step count measures the number of individual steps taken by the user, aiding in achieving recommended activity levels for a healthy lifestyle, fitness, or physical therapy. The function calculates steps taken in various ways, such as recording results for multiple sessions or days, displaying total and average numbers, remembering target values, and signaling their achievement. It's important to note that not all devices with a pedometer function (refer to "Type") support step count measurements. Some devices, designed for professional sports where movement speed is crucial, may prioritize other metrics over step count.

— Distance travelled. The function measures the total distance covered by the user. Basic models calculate distance in real-time, while more advanced ones can summarize results and work with target values. There are two main measurement methods: classic pedometers determine distance by multiplying the number of steps by the set step length (refer to "Individual settings"), while models with GPS use satellite navigation data (see "Features"). The first method has a larger error, but it's often not critical. The second method is more accurate but is costlier and may not work well in areas with weak satellite signals, such as dense urban areas or indoors.

— Movement speed. Measurement of the current movement speed. Like the distance traveled, this indicator can be calculated in two ways — by the number of steps or by data from the GPS module; see above for details on both methods. The simplest measurement option provides measuring the speed only at the current time, however, additional features may be provided — for example, building a schedule for a workout.

— Energy expenditure (calories). The function measures the amount of energy expended during a workout, commonly referred to as "burned calories". Monitoring energy consumption is crucial in weight management training programs as it helps track metabolism. However, it's essential to note that modern heart rate monitors and pedometers do not directly determine actual energy consumption. Instead, they estimate the number of calories based on factors such as heart rate, movement speed, number of steps, user's personal characteristics (refer to "Individual settings"), and other indirect parameters. Despite being approximate, these calculations are generally accurate enough for practical application.

— The amount of burning fat. The function calculates the amount of burned fat during a workout, typically measured in weight units such as grams. Similar to energy consumption, the device doesn't directly measure the actual fat burned but estimates it from various auxiliary data. The accuracy of these measurements is relatively low, and this parameter is not a primary focus in fitness. However, tracking the amount of fat eliminated can serve as additional motivation for users.

— Average/maximum heart rate. Calculation of the average and maximum value of the heart rate for a certain period of time (usually for one training session). These calculations are based on general information about the heart rate; about its meaning, see above.

— Activity time. The function measures the total duration of the user's physical activity, specifically recording only the time during which the device sensors detect the activity. Breaks in sessions are excluded from the recorded time. For instance, if you walked 1000 steps in 20 minutes with a 3-minute break, the recorded activity time would be 17 minutes. This feature distinguishes it from a regular stopwatch (refer to "Features") and enables accurate tracking of the duration and intensity of training loads.

Sensors and measurement modules provided in the design of the gadget.

— GPS module. A GPS receiver helps pinpoint a device's current coordinates. Its applications range from calculating distances in sports gadgets to more advanced functions such as full-fledged navigation with optimal route determination, depending on the device's features.

— Altimeter. The altimeter, detecting device height, operates through various principles. In GPS-equipped models, it uses a geographic database to determine height based on coordinates. Those with a barometer calculate altitude from pressure differences, often referencing a starting point or a hypothetical sea level. While the GPS method is more precise in measuring ground surface height, it overlooks objects like stairs or towers. Barometer-based measurement is affected by weather changes but provides the actual height of the device.

— Thermometer. A sensor that detects the ambient temperature. This data can be useful both for assessing general comfort levels (personal impressions can be deceiving, especially if you will be outside for a long time), and for specific tasks — for example, improvised weather forecasts (in combination with barometer data and other observations).

— Barometer. A s...ensor measures atmospheric pressure, commonly used to forecast weather changes. Its applications extend beyond this, including the ability to gauge height differences even when a dedicated altimeter is not present. It's worth noting that this function is applicable only to gadgets capable of displaying atmospheric pressure data on the screen; altimeters with barometric sensors lacking this feature are not included in this category.

— Compass. A traditional compass is a device for determining the cardinal directions, one of the basic instruments for any navigation. In modern heart rate monitors and other sports gadgets, usually, a digital compass is used, which displays data directly on the display.

— Clock. Classic clock — a function of displaying the current time. The clock provides not only time tracking, but also some other features — for example, they are mandatory for devices with an alarm clock (see below).

— Alarm clock. The presence in the device of the alarm clock function — the sound signal at a specified time. In the simplest models, this signal can only be programmed for one specific time, more advanced devices allow you to remember several alarms, and if you have a calendar (see below), you can also set them on certain days (for example, only on weekdays or even on specific dates) .

— Calendar. The device includes a calendar function, displaying at least the current date, and some models may offer advanced features like viewing monthly dates in table form. Calendar data is often used by other functions, ranging from the built-in training diary to the alarm clock.

— Stopwatch. The device can function as a stopwatch, measuring time intervals with high accuracy, down to tenths or even hundredths of a second. The stopwatch starts and stops at the user's command, and many models offer special measurement modes, including recording intermediate results or the time of each individual lap. This makes stopwatches significantly mor...e convenient for measuring time intervals than regular watches.

— Timer. The ability to operate the device as a timer — that is, in the countdown mode, with a signal at the end of the specified segment. This feature will be useful when performing exercises that are clearly limited in time: setting a timer and waiting for a signal is more convenient than constantly looking at the clock.

— Lap counter. The device has the capability to record data (time, speed, calories burned, average heart rate, etc.) for each individual lap, such as during running. Typically, this is achieved with a designated "Lap" button that, when pressed, captures data for that lap and initiates a new countdown. This function enables monitoring of training dynamics, identifying the most effective laps, while simultaneously recording overall training data. Some devices also offer a lap countdown feature, where the user sets a specific number of laps, and the device signals the end of the workout after that set number is completed. This simplifies the process of tallying the total number of laps.

— Multisport. The device includes a "multisport" function designed to enhance usability during multisport activities — training or competitions involving various sports stages. While non-specialized devices can be used for such activities, those with the dedicated "multisport" feature offer greater convenience. Optimized for this mode of use, they feature built-in software modes like "Running" or "Rowing" that can be easily switched between. These devices save complex data in a format conducive to further processing and analysis.

Data transfer standards supported by the device.

— Wi-Fi. Originally designed for computer networks and internet access, Wi-Fi is now commonly used for direct communication between devices, notably in fitness devices. While internet connectivity is possible, it's typically for specific tasks like firmware updates or saving data to network storage. The prevalent Wi-Fi version, 802.11n, theoretically offers a communication range of up to 100m indoors and 200m in open areas (though real-world figures are more modest). Newer generations boast even greater ranges. Wi-Fi modules are essential in various portable electronics like smartphones and tablets, but it tends to be less power-efficient compared to Bluetooth and ANT+.

— Bluetooth. Developed as a universal standard for direct device-to-device connectivity, Bluetooth technology comes in several compatible versions. The latest version, Bluetooth 4.0, offers a connection range of up to 100m and incorporates a low-energy communication standard, making it more energy-efficient than Wi-Fi. This efficiency is especially beneficial for compact electronics like heart rate monitors and pedometers with limited space for a sizable battery. However, Bluetooth modules are somewhat less common than Wi-Fi, with certain tablets and laptops lacking support. This is a consideration when selecting a model with this data transfer method.

— ANT+. Designed specific...ally for sports equipment and remote control applications, ANT+ is a low-power wireless transmission technology. It facilitates connections between heart rate monitors or pedometers and various devices, including exercise machines, smartphones, and tablets. For devices with USB On-The-Go support, communication is possible through a special adapter. Higher-priced models may have built-in ANT+ support, eliminating the need for additional equipment.

The degree of water protection provided for in the design of the device.

The specified underwater depth for device functionality is often given, but it's important to note that these values are somewhat arbitrary and don't accurately reflect real-world water resistance. The assessments only consider static pressure, neglecting dynamic pressure created by movement, including immersion.

Effectively, genuine water resistance can only be claimed at a minimum of 30m. Even then, such capabilities only withstand minor exposure like rain. Brief water exposure, like swimming, might be permitted at 50m (not universally). For depths of 2 — 3m, 100m is necessary, and serious diving requires a minimum of 200m (or 300m for depths exceeding 20m).