Okay, this might seem like a strange match-up but the Garmin Fenix 5s and the Suunto Spartan Trainer Wrist HR, less than half the cost of the Fenix 5s, shares many of the same features.  They’re both great outdoor GPS fitness trackers that also measure dozens of different kinds of gym workouts. Those of us that love to hike, go trekking, or just get lost a lot while doing either will appreciate the great navigational features of both watches and that’s where these two devices rise above the competition.  I was torn between these two and ended up getting both, mostly because I love to review products like these for you guys but also out of curiosity.

Garmin Fenix 5s

Unfortunately, right now I don’t have a review of those great hiking features because Illinois is in the grasp of a frigid air mass parked on top of it but I am performing several indoor gym workouts, comparing the two head-to-head. [Update: I’ve been hiking with both watches and they’re good! See the video at the end of this post.]

General Similarities and Differences

The watches operate in much the same fashion with both watches using 5 buttons to access menus and select various settings and features.  Neither have touch screens and both have very similar displays in that they are designed to use very little battery power and offer excellent readability outdoors in bright sunlight.  In dimmer conditions they both have a backlight.  The screen sizes are also very similar, if not exactly the same.  As far as smartwatch features go they do display notifications from your phone but neither offers any ability to interact with those notifications.  Also, neither has on-board music storage which kinda stinks for many but isn’t a dealbreaker for me personally.  Both are also able to record pool and open water swims and if you enjoy water sports like kayaking, canoeing, sailing, fishing, etc., both watches can handle getting wet.

The Fenix 5s can pair with ANT+ and Bluetooth sensors while the Suunto Spartan Trainer Wrist HR can only pair with Bluetooth sensors. The Fenix can pair with more than one ANT+ or Bluetooth device while the Suunto can only pair with one Bluetooth sensor at a time so keep that in the mind if you want to use a chest HRM and a cadence sensor.  Probably, only the most serious athletes are going to need this capability however.

In future reviews I’ll get down to all the specs of each device but I really just want to show how each of these watches performs during gym workouts because that’s probably what you’re most interested in.



About the Heart Rate Sensors

Before I get to the results I need to discuss wrist heart rate sensors.  I didn’t know what to expect from the Garmin Fenix 5s in regards to its heart rate monitor.  I had read some reviews claiming it was inaccurate but then I had read some that claimed it was great.  Similarly, I wasn’t sure about Suunto but I was expecting a very good HR sensor because it uses one of the best optical HRM in the wearable industry but my first tests with it were absolute disasters.  I didn’t know if I had a faulty unit but after trying everything I knew to improve the results of the HR sensor I was ready to ship it back.  Then I finally did what Suunto suggested to prevent erratic heart rate readings after I looked up the manual and things improved immensely.

Preventing Erratic Heart Rate Readings on the Spartan Trainer and Fenix 5s

To get accurate HR readings it is necessary to warm up in order to get your heart rate up a little before recording a workout. Actually, Garmin suggests doing the same thing as well for the Fenix 5s because it too may show funky, erratic HR data for the same reason.  All I changed was to begin walking on the treadmill for 3-5 minutes before actually beginning my recorded workouts and then both watches performed very well.  The difference for the Suunto was like night and day.  When I just jumped on the treadmill and began recording the workout without warming up first the HR readings were highly inaccurate within the first 4-5 minutes, showing my heart rate at 150 bpm+ when in reality it was less than 110 bpm.

I have noticed this behavior with the Fitbit Blaze as well.  It has always been inaccurate early in my workouts while the Samsung Gear Fit 2 and Gear Sport have no problems right from the start but some wrist HR sensors apparently need a warm up, so you might want to keep that in mind.




While I did this workout I kept an eye on both watches and they performed almost identically as far as the heart rate data went.  They were usually showing the same HR number or only differed by 1-2 bpm with the Suunto usually just a little bit higher than the Garmin.

Below: Early in the workout.  (Sorry for the blurred images but I was taking the pics while walking.)  The Garmin Fenix 5s was on my left wrist and the Suunto on my right.

Below:  Very similar readings after running on the treadmill.  I like the graphical display on the Fenix with the color coded categories.  It motivates me to get my heart rate up more during workouts.  The display on the Suunto is better in person than the photo shows.

Below are the screens of data after the workout on the Fenix 5s

Below is the data provided by the Suunto after the workout.

And if you want lots of data, Garmin will give it to you in their app!  All this from a short run on a treadmill.

But Suunto does a pretty good job too for us data geeks.

So looking over the data for each, the estimated average heart rate and max heart rate was exactly the same for both watches.  Estimated distance was fairly close but estimated recovery time was considerably different with the Fenix 5s estimating 17 hours and the Spartan Trainer estimating 5 hours.  Cadence is measured a little differently by the devices with Garmin using steps per minute and Suunto using revolutions per minute. Like every fitness tracker I’ve ever used calorie estimation always varies.  It’s a hard metric to nail down from person to person but I was mainly interested in how well the heart rate sensors compared and well, from this test they were identical.

Fenix 5s Spartan Trainer Wrist Hr
Time 22:49 22:41
Calories 143 178
Avg Pace 17:04 min/mi 16:04 min/mi
Est. Distance 1.34 mi 1.41 mi
Avg Speed 3.5 mph 3.74 mph
Avg Heart Rate 121 bpm 121 bpm
Max Heart Rate 150 bpm 150 bpm
Avg Cadence 119 spm (steps per minute) 70 rpm (revolutions per minute)
Recovery Time 16 hours 5 hours


Weight Lifting / Resistance Training / Pilates

The following workout was a mix of several different types of strength training exercises including weight lifting, crunches, planks, lunges, squats, rolling wheel, leg lifts, etc.  I was pleasantly surprised by how well both watches did throughout the various exercises.  As expected they both performed the least well during weight lifting but did pretty darn good for nearly everything else.  I compared the HR data against a chest HRM.

Below:  Chest heart rate monitor data

Below:  Again Garmin does provide more metrics for workouts, especially when using the Fenix.

Below:  Suunto doesn’t provide as many metrics for weight training but probably the data most people need.  You’ll also notice that Suunto provides PTE (peak training effect) and EPOC peak.  According to Suunto PTE indicates the impact of the workout based upon your individual max aerobic performance.  The more fit you are the harder you have to work to get a higher PTE number.  In my case, 1.9 is kinda low.  EPOC refers to Excess Post-Exercise Oxygen Consumption.  The is the amount of extra oxygen the body needs to recover after a workout.

Okay, so looking over the data the average heart rate for the chest HRM seems too low to me.  I’m not sure if it calculates the average differently but 88 doesn’t seem right since I watched my HR throughout the workout and it was very close to what the two watches were displaying most of the time.  At any rate, the Fenix 5s and the Spartan Trainer Wrist HR performed very similar to each other.  I did weight lifting first and that’s where the data between the chest HRM and the two watches differ the most.  For most of the other exercises my estimated HR was close between all three.

I would give the highest accuracy compared to the chest HRM to the Fenix 5s but the Suunto wasn’t far behind by much at all.  Like I already mentioned, I was surprised how well both did because other watches have done much worse with these types of workouts.

Chest HRM
Fenix 5s
Spartan Trainer Wrist HR
Avg Heart Rate 88 bpm (this seems too low) 110 bpm 111 bpm
Max Heart Rate 135 bpm 133 bpm 131 bpm
Calories 86 106



I was actually using a Gazelle, yeah those funny looking things but they work similarly to an elliptical machine and they’re a good challenge for wrist HR sensors because wrist muscles are used to varying degrees throughout the workout.  This is the piece of equipment where many fitness trackers struggle but again I was surprised by how well both watches performed against a chest HRM.  They performed very well, good enough that I won’t need to use a chest HRM for a reasonably accurate HR measurement.  The Suunto actually performed a little better than the Fenix 5s but I was impressed with both.

I did have some problems with my chest heart rate monitor though.  I didn’t get a good, reliable signal from it until I was about 7-8 minutes into the workout.  From that point on it was showing data very similar to the two watches.  In this test the watch HRMs of both outperformed the chest HRM. Notice the weird spike below in the chest HRM.  That shouldn’t be there.

Chest HRM Data

Fenix 5s

Spartan Trainer Wrist HR

Initial Thoughts

Overall, I like how both watches work.  Of course, the Fenix 5s is the more sexy of the two watches but I think the Suunto is cute and fun to wear. And for you guys, the Suunto comes in more manly colors if you don’t want to wear a “cute” watch.

I have to add that Garmin has greatly improved their app.  I had so many problems with Garmin Connect over the years when I was using the first generation Vivoactive.  It became so frustrating I switched to Samsung.  However, it has been improved both in appearance and more importantly in reliability, although Bluetooth connections sometimes still fail.  The same can be said for Suunto’s app as well, so it’s a toss up between the two.

The Fenix 5s will likely be my everyday watch because, well, it looks like an everyday watch and the size is perfect for my wrist.  (Plus, I paid a lot for it so I’m going to wear it a lot!)  I’m glad Garmin made a watch for those of us with smaller wrists, a.k.a women but not just women because a lot of men wear the 5s as well.  It’s not a dainty watch, just one that’s more practical to wear because it’s not the size of a dinner plate.  With that said, I have a soft spot in my heart for the Suunto Spartan Trainer Wrist HR (even if its’ name is too long).  I really like the looks of it and I think it is actually more comfortable to wear than the Fenix 5s. I’m eager to get these two watches out on the trail and compare their navigational features.  That review will be coming, with full video reviews to boot.

Final Thoughts

Okay, I think I’ve done enough tests to confidently declare that both heart rate sensors of the Fenix 5s and Suunto Spartan Trainer Wrist HR are very good.  In fact, they behave almost the same and I think you can leave your chest heart rate monitors off for many different types of workouts with each watch as long as you’re wearing the watch properly.  Others may have different results than I did but both fitness watches worked great for my needs in the gym.

Of course, for weight lifting and other types of workouts that involve a lot of flexing of the wrist then you’ll want to switch to a chest HRM but thankfully the sensors are good enough for a wide variety of other types of workouts.

Now I just need to get these two outdoors and try out GPS accuracy, navigational features, heart rate accuracy when performing outdoor workouts, etc.  Unfortunately the weather keeps getting worse instead of better.  It’s going to be -10 below zero in a few hours!  But as soon as I can get outdoors in weather that won’t kill me I’ll be out there.

I also plan to do some video tutorials for using both watches.  The Suunto is fairly straightforward but there’s some features that probably some explaining, especially if you’re new to these types of fitness trackers.  The Fenix 5s has a bit of a learning curve because of its many features and capabilities.  The watch just does a lot, hence the reason for its higher price tag, so I’ll be showing you how to get the most out of it over the next few months.

Anyway, at this point I can confidently recommend both/either watches based upon my experiences with them.  For the workouts I’ve done so far, they have performed equally as well.  The Spartan Trainer Wrist HR holds up well to the much pricier Fenix 5s.  I’m not going to give preference to either one just yet.  I need to get them on the trail first and then we’ll see.

Check the latest prices for the Suunto Spartan Trainer Wrist Hr on Amazon > http://amzn.to/2CoCSEo

Garmin Fenix 5s on Amazon > http://amzn.to/2Cw4ZS6

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Last Update: March 29, 2018