You can record your heart rate manually by holding your wrist and counting your pulse, but this hasn’t stopped technology companies producing devices to do the job with electronics. Most of these devices collect heart data all day long and record it on a smartphone app which builds up a richer set of data than you might get with a stopwatch and pencil. One of the most useful metrics they collect is your RHR (resting heart rate) a reading taken when you are relaxed, most typically first thing in the morning. In most cases a low RHR indicates a strong, healthy heart which has to beat fewer times to circulate blood around the body. However in older people a low RHR might indicate diseased heart muscle or overmedication. Some day-to-day variation in your RHR (or indeed in many of the metrics these devices measure) isn’t something to be worried about, explains Dr Satpal Arri of the British Heart Foundation Centre of Research Excellence, King’s College London, “A certain amount of variability is normal, healthy in fact – as you get older variability tends to decrease.” So by all means listen to your heart, but don’t become obsessed.

Garmin Forerunner 735XT

Measures: RHR, HR, recovery time, V02 max, movement, sleep; £359

Garmin’s latest exercise tracking watch records your runs, rides, steps and swims using GPS or an accelerator. The rear of the watch features an optical sensor that uses a light to measure blood flow, which is processed by an algorithm to create HR data. The watch displays HR and RHR but these are better displayed on Garmin’s Connect smartphone app where you can see historical data. The watch also had a recovery adviser feature, which advises you how many hours you should wait before exercising again – for running the times seemed consistent but for cycling I found them to be a little haphazard – the software company says that power meter data is required for an accurate result. When running, the watch will also produce a V02 max (the maximum value of oxygen you can use) score, which they claim is 95% accurate when compared to lab tests. You’ll need to purchase a power meter to generate a cycling V02 max figure.

Accuracy: You need to wear the watch day and night to get an accurate RHR reading. Wearing it on and off, or only using it when exercising, will affect the averages the software calculates. For example, my RHR for one month when I only wore the watch on a couple of occasions was 10bpm, whereas days when I only wore it while running or cycling would push the average into the 60s. It’s surprising that the algorithm can’t recognise and remove these biases.

Verdict: This is a powerful tool for tracking and improving your sporting performance – probably the best sports watch on the market – but for simple monitoring of your RHR you might be better off using a smartphone app such as Instant Heart Rate.

FitBit Surge

Measures: RHR, HR, movement, sleep; £199

Much like the Garmin, this unit will track exercise and steps, and collects HR data using an optical sensor. The interface is a little confusing, requiring a mix of buttons, presses and touchscreen swipes to operate it. The rubber wristband tended to cut into my wrist and felt sweaty.

Accuracy: Worn side by side, the FitBit and the Garmin record the same HR. However, the Surge’s software does more to remove outliers when calculating a RHR – mine rarely varied by more than a BPM each day. That said, if you don’t wear the watch the app will tell you that your RHR is the same as the last time you were wearing it – a big assumption. The app itself is easy to navigate and visualises your data clearly.

Verdict: If you’re mainly interested in monitoring your general health, ie your RHR, sleep and a bit of exercise, this is a good choice.

Withings Body Cardio Scale

Measures: HR, pulse rate velocity, weight, fat mass, bone mass, muscle mass, water; £149

This wireless-connected scale generates a slew of data to pore over. Integrating it into your morning routine is pretty simple – just stand on it for few seconds. The scale sends a small electrical current through the body, measures impedance and then, using sophisticated algorithms, generates body fat percentage, muscle mass and so on. The measurements are displayed briefly on the scale itself and then turned into graphs and the like on Withings Health Mate app.

Accuracy: It’s moot how useful the HR data collected by the scale is. A reading taken while standing isn’t a RHR; anything you do between your bed and the scale, such as a bathroom visit, taking a shower, walking up stairs or even talking, will influence your HR. However, the scale’s USP is that it takes a reading of your pulse wave velocity – a measure of how quickly blood is travelling along your arteries, and therefore how stiff or supple they are. A reading over 10 is associated with an increased risk of cardiovascular events.

“PWV is a research tool, but not normally something we would measure in routine practice. However, it is a validated measure of risk,” says Arri.

Verdict: If you’re looking for a device to monitor your cardiovascular health, you’re probably better using this in combination with a blood pressure monitor or a device that measures your RHR.

Read an in-depth of the Body Cardio here.

Withings Blood Pressure Monitor

Measures: blood pressure, HR; £109

Easily the coolest looking blood pressure monitor you can own. Unlike most, there are no cables; it communicates with your smartphone via Bluetooth. Once charged, the sleeve inflates around your arm to take a reading – you can also set it up to take three readings in one session, from which it takes an average. The results are displayed on Withings Health Mate app, so you can track the readings over time.

Accuracy: Produced consistent results over a couple of months. It also records your heart rate, which is a good indicator of how “rested” you were when the reading was taken.

Verdict: A great piece of design, simple to use, and if you’re concerned about your blood pressure, it produces useful data. “Having a blood pressure monitor at home is a good idea, because high blood pressure doesn’t have any symptoms – the patient will feel fine. If well people who are worried can pick it up early with one of these devices, we can treat them early,” says Arri.

Kito+

Measures: HR, ECG data, blood oxygen, respiration rate, skin temperature; £99

This consists of a credit-card sized device that slips into one of two specially designed iPhone cases (for the 6 and 6S) and a small black connector for charging up the card-shaped bit. To take a reading, you fire up the Kito app and place your fingers on the sensors at the rear of the card. You can then see a graph of electrical activity created by your heart beating on your iPhone screen, which is pretty incredible.

Accuracy: A hospital ECG would be able to detect whether a patient had a heart attack recently – this device isn’t sensitive enough to do that, but it can help patients monitor an abnormal heart rhythm. “Typically we give patients who report palpitations, blackouts or light-headedness monitors that they can use for 24 hours or a week but if they don’t have an episode during that period, we don’t capture any data. With something like this a patient can check for themselves when they feel something happening,” says Arri.

For such patients a device that captures ECG data is more useful than those with an optical sensor. “When you’re in an irregular rhythm, your peripheral heart rate becomes unreliable. Because an ECG monitors electrical activity, it will pick up those extra beats that aren’t translated into a peripheral pulse.”

Verdict: A useful device if you have an irregular heart rhythm.