Review: Garmin 645 Music

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Grand Canyon

I gave the new Garmin 645 Music a heck of an adventure in the last month! We did runs, swims, gravel rides and a big ‘ol hike in the Grand Canyon. Here’s my review of this watch that I grew to love quickly!

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I’ve been doing triathlons for over 15 years and was an early adopter of the Garmin multisport watches that debuted in the mid-2000s. Hello, Forerunner 205! I’ve stuck with Garmin’s line ever since; in fact, my current model is the 920XT, which is packed with fun and useful still multisport features

The Garmin Forerunner 645 Music, however, is my first foray into the running-specific line and, I have to admit, it feels great wearing a fitness watch that doesn’t look like a small desktop computer on my petite wrist! The soft wristband has plenty of notches, and it’s easy to adjust to make it looser or more snug, depending on preference.

Initial Thoughts

My first few days with the 645 Music were very similar to the experience of buying a new car and not knowing where everything is just yet. It certainly has all the bells and whistles, but it takes a few days to feel comfortable once you get beyond the initial test drive. Charging and set-up are simple enough, and done via USB and a quick sync with Garmin Connect. Because I wanted to familiarize myself with the watch as quickly as possible, I carried the instruction booklet around with me for a few days until the buttons and features started to become second nature.

Simply put, the watch made me want to keep moving even outside of my usual training sessions.

When turning on the watch, the first thing you can customize is the actual watch face. I had a fun time personalizing everything from accent colors to settings to data displays. For now, I’ve settled on viewing the time, date, battery life and amount of steps I take in a day (you can also download more watch faces and apps from Garmin’s Connect IQ store.)

Various functions and widgets are pre-programmed, including heart rate, steps, calorie burn and other informative data for both the recreational and serious fitness enthusiast. I’ve never fancied myself a step-counter, but the moment I programmed it on the front of my watch face, it became a real motivator. The same is true for total calorie burn. Throughout the course of the day, I found myself wanting to continue to best my previous efforts. Simply put, the watch made me want to keep moving even outside of my usual training sessions.

Activity Tracking

Speaking of training, this isn’t a traditional multisport watch, meaning there is no specific “triathlon” activity built in. However, it does track multiple activities like indoor swimming, cycling, hiking, running and other customizable activities. To start an activity on the Forerunner 645 Music, simply press the start/stop button. This will take you to the activities screen where you can select your sport of choice. This is your entry point into the data-tracking depths of your preferred activities.

Like other Garmin products, you can customize your data screens and select your preferred metrics to view on each screen—there are more metrics than an average (or even elite) athlete would ever need! In fact, I spent a lot of time setting up my preferred data screens for each discipline, and I recommend all users familiarize themselves with this area of the watch. I took this watch on swims, bike rides, runs and even one epic hike in the Grand Canyon. To celebrate, I even created a customized activity just for the adventure.

Once I spent time programming the data screens to display the metrics that were useful to me, I found the 645 Music to be simple and easy to use during all activities. Display screens were large and bright even in the burning Grand Canyon sun, and you can also select various tones and vibrations to signal and alert you at each lap, distance, pace or time. You don’t want to spend the entire workout focusing only on your watch, right? Let it tell you what’s happening.

For instance, in “Run mode,” I have it programmed to beep at every mile. On the bike, I have it set to beep every 5 miles, as well as every 10 minutes to remind me to hydrate. Yes, that’s the obsessive long-course triathlete in me, but these are the features I encourage all users to take advantage of. Tones and alerts are valuable training tools for any athlete, whether it is your first half marathon or your 30th IRONMAN.

Every time I turned on the watch or selected an activity, it found the GPS signal in a matter of seconds—even in the Grand Canyon (although it did lose some accuracy in the deepest parts of the canyon).

Heart Rate

As someone who has been a victim of severe chafing with traditional chest heartrate straps, I welcomed the wrist monitor with open arms. I even did some old-school testing to compare it to a traditional chest strap, and found it to be super accurate.

One of my favorite screens shows average heartrate over the last four hours. If you’ve ever wanted a glimpse of your resting heartrate, this is a great way to find out. It’s also another great motivator to get up and move if you’ve been sitting at your desk for hours at a time. Sitting is the new smoking, and you can even have the watch tell you when to get up and get after it.

Battery Life

If you’re only using the watch feature and have GPS and notifications turned off, the watch can last almost a full week without needing a recharge, even when keeping it on your wrist 24/7. It does use more battery when you are in activity mode with GPS, but it still lasted through over 13 hours of continuous activity during the Grand Canyon hike, with over 20,000 feet of elevation change throughout the day. In fact, I’m not sure who was working harder—me or the Forerunner 645 Music! While it didn’t last the entire 17-hour day, I wasn’t disappointed or surprised because let’s be honest, how many activities should actually last that long anyway?

Run Pod

Run Pod

The Run Pod accessory easily latched onto the back of my shorts and provides a customized gait analysis, including data points such as run cadence, stride length, vertical oscillation and more. Honestly, a few of these tracking points are well-beyond what a recreational runner needs to know or would likely know how to dissect without working with a coach. However, it does provide several pieces of valuable feedback that may help improve your run. For instance, cadence is an important measurement of running efficiency and most will say an efficient cadence is around 90 foot strikes per foot, per minute. If you use the run pod and it shows your cadence as 70, for example, you aren’t as efficient as you could be, so you can use the pod to track, improve and increase your cadence and see what it does to your overall pace.

Vertical oscillation is another important cue because when you run, you want to move your energy forward rather than up and down. If you’re bouncing up and down, you’re expending a tremendous amount of energy over time while going in the wrong direction.

Note: I recommend using the pod on very specific sessions like track or speed work where the surface is smooth and the elevation is consistent. Use the feedback you receive to make small incremental changes. Attempting to change too much at once may lead to injury. Remember every runner is different, and a 5-foot woman will not run the same as a 6-foot-4-inch male.

Bluetooth Enabled for Music and Notifications

I’m not much of a music-while-running woman, but I do love to zone out with a good podcast during some of my longer runs. It was super convenient to be able to download both music and podcasts directly to the watch via a simple connection to Garmin Express (outlined in the Quick Start Manual) without having to also bring along my phone.

I also turned on notifications for a few days, but I made the mistake of enabling all apps, and therefore quickly became annoyed with the incessant buzzing and vibrating with news and text updates. Instead, enable the notifications just for urgent needs like calls and texts, so you don’t get interrupted every time Taylor Swift tweets.


This watch—and other Garmins I’ve used through the years—provides consistent and accurate data tailored just for me based on my programmed physiofactors and completed workouts. I’ve come to trust Garmin through the years and have completed many successful training runs and races using its products. It’s hard to imagine a time when GPS data didn’t exist, and now I’m the woman who runs laps in the parking lot to get my mileage totals even (you know you do it, too).

Yes, it is possible to drown in the details of all the feedback, but that’s why I recommend spending time with the watch before using it for a major event. Decide which data points are most important and use the watch to get to know yourself a little better. You don’t need to evaluate and analyze every data point, but the more you know your zones, heart rate and pacing, the better you will perform.

The Forerunner 645 Music is a stylish and functional watch that is also an invaluable training tool for both athletes who don’t want a lot of data, as well as those who do. It can be as simple as a time, pace and distance tracker or as detailed as a comprehensive biofeedback tool. Use what you need for each specific activity, and don’t get bogged down by too many details. After all, fitness is supposed to be fun, right?


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