Basic summary: The successor to Polar’s previous M400 watch, with a boatload of feature updates that easily make it the most conveniently functional multi-purpose watch we’ve tested. Its principal update is a new 6-LED wrist-based optical HR sensor, and heart rate data opens the door to Polar’s vast ecosystem of assessments and smart coaching capabilities. Other key updates include vibrating alerts and a significant increase in battery life. The watch is very lightweight and comfortable for use as an all-day activity tracker and sleep tool, and has become our favorite for everyday training in all conditions except extended duration racing.
- Weight: 51 g
- Thickness: 12 mm
- Display size: 128 x 128 px high resolution display
- Integrated GPS with SiRFInstantFix satellite prediction technology
- 6 LED optical heart rate sensor with heart rate algorithm
- 24/7 HR monitoring (with Fall 2017 firmware update)
- Activity sensor and accelerometer
- Vibration alerts
- Silent alarm
- Waterproof (suitable for swimming)
- Thin, lightweight performance wristband
- 8 MB flash memory
- Rechargeable 240 mAh lithium polymer battery
- Three GPS recording rates: 1 second, 30 seconds, 1 minute
- GPS battery life: 8 hours on 1-second intervals, 30 hours at 1-minute interval
Run training features:
- Manual and auto laps
- Vibration alerts
- Full sport profile customization
- Display screen shows 1 to 4 lines of data
- Wrist-based HR display and running cadence
- Full feature set for time, speed, distance, altitude, cadence, HR
- Customized HR or speed training zone indicators
- Interval workout customization
Smart coaching ecosystem features:
- Smart coaching for marathon distance or below
- Personalized structured workout programs
- Progress report follow-ups at designated intervals
- Race time prediction analysis for distances up to the marathon
- Running index calculated after each run, correlates with VO2 max
- Training targets for calorie burn, time, distance, heart rate or speed parameters
- HR-based calorie burn estimates
- Training benefit snapshot after each session
- Recovery status after each session
- Cumulative training load analysis
- Fitness test done in five minutes of rest
- Sleep tracking and analysis
- Bluetooth compatible with Android and iPhone
- Custom USB cable for data sync with PC or Mac
- Auto sync data transfer through Polar Flow app
- Firmware updates through Bluetooth Smart
- Full smartphone notification capability
- Screen customization through Polar Flow app or desktop application
- Online communities: Polar Flow with automatic transfer to Strava, Training Peaks, and most other external platforms
Polar has historically differentiated itself as the sport-science driven gadget company; they were founded in support of the Finnish national XC ski team, and they mastered the science of heart rate monitoring well before it became a popular add-on feature for sport watches and GPS devices. The magic of Polar products takes place “behind the curtain,” with extensive algorithms and massive databases that help analyze and customize training programs for virtually any user, from novices to world-class endurance athletes.
Their longstanding Achilles heel has been merging their sport science technology into devices that are thoughtfully designed and highly functional; some past Polar watches were cumbersome to wear, tricky to navigate, or difficult to read. Fortunately, the M430 suffers from no such drawbacks, and is perhaps Polar’s best combination of style, science, and functionality to date.
Ostensibly, the M430 is a successor to Polar’s popular M400, which was designed as a running-specific GPS watch, but it adds an impressive new feature set that places it competitively in the category of daily activity trackers. It also received a significant battery life upgrade that makes it a fully functional ultrarunning watch for virtually all of your training, and for race efforts of 50k to 50 miles depending on your speed.
The headline upgrade is a 6-LED wrist-based optical HR sensor, which combines with a set of algorithms to provide high accuracy and stability. However, there are a number of other updates that make the M430 a standout in this category, from both structural and operational standpoints. One favorite of ours is the silent vibration alarm, so you can sneak out of bed at 4 a.m. without waking up your spouse. The M430 has a new, thinner and more flexible wrist strap that is comfortable to wear all day, and has extensive air channeling to prevent sweat buildup underneath. On the backside, a new cable interface replaces the micro-USB that was used on the previous model. (Sadly, the interface makes it impossible to wear the watch while re-charging on the go, so you’ll lose HR tracking if you’re refueling the battery during a longer ultra.) It also has a whole new lineup of sleep metrics – so you can see how soundly you rested before 4 a.m. – and a VO2 Max fitness test that requires no activity whatsoever.
None of these upgrades come at the expense of either size or performance, and the M430 functions quite well as an everyday training watch. You can choose from an almost limitless number (OK…a little over 100) of sport profiles, and each of those profiles can hold up to eight customized data screens. Each data screen can accommodate up to four items – so if you do the math, there is a ton of information you can have at your disposal for every workout. The display is easy to read with three lines of data, but becomes a little scrunched with four. Pretty much everything an ultrarunner would want to see is available – even cadence data, which some coaches swear by as a key metric for efficiency, and which historically needs a separate foot pod to track. Much of Polar’s ability to collect all data from the wrist is thanks to an updated accelerometer, which can also combine with biometric data in order to give you fairly accurate pace and distance readings even on a treadmill.
Of course, we prefer running outside – and on the track or trails, we love the M430’s button arrangement and general ease of use for marking splits or pausing/resuming activity. At the track, it’s easy to take manual lap splits with the push of the red button at middle right, and your split time stays on the screen long enough to read it clearly. On the trail, you can easily scroll through multiple data screens, and you can have automatic mile splits flash as well as concurrently taking manual splits at landmarks. In the automatic lap setting, you get a quick snapshot view of other metrics like HR, current pace, and cadence along with each mile marker. When activity is paused, there’s a unique screen so you don’t confuse it with the regular data screens, but you can still see critical info like overall mileage, elapsed time, time of day, and heart rate.
After your workout, data is stored in the Polar Flow app, and a slew of metrics are immediately viewable; most of this data will also flow to Strava or most other third-party platforms. From an ultrarunner’s standpoint, the strength of Polar’s back-end metrics is that you can easily assess your training load, fitness adaptations, and recovery needs over an extended period of time. The training load feature is particularly handy when ramping up to high mileage and tapering down for a race; instead of just “going by feel,” you have objective data to tell how fatigued your body is and how prepared you are to race; the photo above reflects a taper period before a 50K tune-up race this summer. (The race itself took 10 hours, and was recorded on a different watch.)
If you want to assess the relative intensity or effort of an individual workout in comparison to others, it’s easy to do through HR zone analysis on the Polar Flow app. You can see what duration of your run was spent at fat-burning, aerobic or anaerobic intensity. The more you use the watch, the more accurate this information becomes, as the device and app build a database of your individual exercise responses, your distinctive biomechanics, and your overall HR parameters and fitness level.
Since the M430 is also firmly in the activity tracker category, it’s important for the size and comfort to be compatible with wearing all day and night. For the most part we’re really impressed with how the M430 feels over the long term; its profile is small enough to wear under a dress shirt, although the body is somewhat “boxy” and gets caught on sleeves at times. At a light weight of 51g, it doesn’t feel heavy or bulky on your wrist. The wristband rests comfortably against the skin and makes it easy to sleep with – and the resulting sleep data is another great metric for ultrarunners to track on a regular basis during high training cycles.
Although the vibration mechanism is an excellent new feature of the M430, it’s also the source of our biggest complaint, in that the vibration itself is fairly weak. It’s not uncommon for us to not even feel it when automatic laps are taken while running. If you’re a particularly heavy sleeper, the silent alarm may not be strong enough to wake you right away. And if you’re old-school and prefer the beeping alert option, you won’t find it on the M430. Finally, while we’re getting nitpicky about the alarm, it also takes too many button pushes to access and set up.
The only other potential drawback to the M430 compared to other watches in its category is that it doesn’t have the capacity to carry or play music files onboard as some others do. Since we don’t frequently advocate for running with music, this isn’t a significant downside for us.
The Polar M430 is a very impressive successor to the M400, with a pleasantly unexpected degree of user-friendliness and functionality during workouts and everyday use. It also brings the full power of Polar’s sport science expertise to guide your workouts and provide a number of important metrics that ultrarunners should appreciate throughout the course of extended training cycles.