Suunto Blog

Every Heartbeat Matters: A New Heart Rate Algorithm for Suunto Run You are eight kilometers into a tempo run, holding what feels like the right effort, and you glance at your wrist to check that you are where you want to be. It tells you whether to hold the pace, ease back, or press a little harder. When you train by heart rate zones, every reading feeds a decision. Runners have told us how closely they watch that number, and how much it matters that it reflects what their body is actually doing. We have been listening. On August 20, 2026, Suunto Run receives a firmware update with an all-new wrist heart rate algorithm, developed by Suunto, built to make your running heart rate more accurate and more worth acting on. What Is New in This Update A new firmware version for Suunto Run, releasing August 20, 2026. An all-new wrist-based heart rate algorithm, developed in house by Suunto. Focused specifically on heart rate accuracy while running. The interface and the way you use your watch stay exactly as they are. Free, and delivered straight to the watch you already own. This is an improvement to how your watch reads and interprets your pulse, not a redesign of how you use it. There is one thing to do: install the update. What This Means on Your Next Run Wrist heart rate works by reading blood flow through the skin, and running is a demanding environment for that measurement. Arm swing, changes in pace, cold weather and the sharp climb in effort at the start of a session all make the signal harder to read cleanly. The new algorithm is designed to handle those moments better. In practice, that means: Fewer readings that clearly do not match the effort you are putting in. A more dependable view of how your body responds through a session. More confidence when you use heart rate zones to steer intensity. A more reliable data foundation for managing your training load over time. For runners who work to zones, that last point matters most. A zone-based session only works if the number driving it holds up, and this update is about strengthening that foundation. What the Data Shows Suunto ran internal comparative testing across a range of running scenarios, measuring Suunto Run against a reference heart rate device. Data points that deviated by more than 5 bpm from the reference device were reduced by approximately 45 percent compared with the previous algorithm. In plain language: across the test data, the readings that stood noticeably apart from the reference device became considerably less common. The improvement shows up in the outliers, in the moments where the number on your wrist looked out of step with the run you were having. Full figures and testing detail are in the Testing Notes at the end of this article. Based on Suunto internal testing against a reference heart-rate device. Results may vary depending on the user, activity and wearing conditions. How to Get the Update Installing takes a few minutes: Update the Suunto app on your phone to the latest version. Make sure your watch has enough battery to complete the installation. Connect Suunto Run to the Suunto app and check for a software update in the app or on the watch. Follow the on-screen prompts to complete the installation. The update will be rolled out gradually. Availability timing may vary by market and user. Getting the Best from Wrist Heart Rate A few habits help your watch read you well, whichever algorithm is running: Keep the watch in steady contact with your skin, with the strap snug enough to stay in place while you run. Remember that wearing position, skin condition, ambient temperature and the type of movement can all influence a wrist-based reading. For sessions where you want the most detailed heart rate data, pair Suunto Run with a compatible heart rate belt. Wrist heart rate is a training tool, and a good one. It is not a medical device, and it is not designed to replace one. Every Reading, Taken Seriously You care about every heartbeat. We take every reading seriously. Update your Suunto Run and get more accurate, more dependable heart rate data on your next run. Testing Notes Suunto conducted internal comparative testing of the new and previous wrist heart rate algorithms across multiple running scenarios, using a reference heart rate device as the comparison benchmark. Data points with an error greater than 5 bpm: 7.394 percent with the previous algorithm, 4.036 percent with the new algorithm, a relative reduction of approximately 45 percent. Accuracy within ±5 bpm: improved from 92.606 percent to 95.964 percent. Accuracy within ±10 bpm: improved from 96.468 percent to 97.803 percent. These results come from Suunto internal testing and are not an independent third-party certification. A reference heart rate device serves as a comparison benchmark rather than an absolute measure of heart rate. Results may vary depending on the user, activity and wearing conditions.

Trail running is more than running on dirt. Unlike road running, where pace and distance often define performance, trail running brings new challenges: changing terrain, elevation, technical sections, and unfamiliar routes. A good trail running watch should help you understand more than just your pace. It should help you manage your effort, navigate with confidence, and stay prepared for every climb, descent, and adventure ahead. So, what should you look for when choosing the best watch for trail running? Let's take a look. Part 1: What should you look for in a trail running watch? Trail running demands more from a watch than simply tracking distance and pace. The right trail running watch should help you make better decisions before, during, and after your run, from planning your route and managing your effort to understanding your performance and preparing for future adventures. Here are the key features to consider when choosing a trail running watch. 1. Navigate unfamiliar trails with confidence Trail running often takes you beyond familiar paths, where staying on course can become a challenge. Unclear trail markings, technical terrain, low visibility, and fatigue can all make it easier to lose your way. A good trail running watch should help you plan and navigate before and throughout your adventure: Before your run Plan your route and understand the course ahead. Review elevation profiles to prepare for major climbs and descents. During your run Follow your route with reliable navigation and offline maps. Check your direction, remaining distance, and elevation information to better manage your effort. With dependable navigation, you can spend less time worrying about where to go and more time focusing on the trail ahead. 2. Manage effort beyond just raw pace Long-distance trail running is about managing your energy, not just maintaining speed. Starting too fast or underestimating elevation changes can leave you exhausted before the finish, turning a strong start into a difficult final stretch. Unlike road running, pace alone doesn't show the full picture. The same pace can feel completely different depending on elevation, terrain, and fatigue levels. A good trail running watch combines pace, heart rate, elevation data, and training insights to help you understand your effort, adjust your intensity, and maintain a sustainable rhythm throughout the course. With the right data, you can make smarter decisions on the trail and save your energy for when it matters most. 3. Adapt your strategy to the terrain Trail races rarely follow a steady rhythm. Long climbs, technical descents, and changing altitude can quickly affect your pace and energy levels throughout the course. A trail running watch helps you turn route information into real-time decisions. By tracking elevation gain, ascent and descent, altitude, and your current effort, you can understand where you are on the course and adjust your strategy for what comes next. Whether you're saving energy for the final climb or managing a long descent, the right data helps you approach every section with confidence. 4. Go further with reliable battery life Trail running adventures don't always follow a fixed schedule. Long-distance races, challenging terrain, and unexpected conditions can extend your time on the trail, making reliable battery life essential. A good trail running watch should provide enough power to support your entire adventure, even when using GPS and navigation features for extended periods. Long-lasting battery life gives you the confidence to explore further, track your progress, and stay supported from the start of your run to the finish. 5. Stay reliable in harsh conditions Trail running rarely happens in perfect conditions. Rain, mud, dust, cold temperatures, and rough terrain can all challenge both the runner and the equipment. A reliable trail running watch should be built to handle changing outdoor conditions. Water resistance, durable construction, and reliable performance help ensure your watch continues to provide essential data when the trail gets tougher. From wet mountain races to long days in the backcountry, dependable equipment allows you to stay focused on the adventure ahead. Part 2: Choosing the right Suunto watch for your trails Every trail runner has a different mix of goals: short local races, long technical mountain routes, or multi-day adventures far from the trailhead. Suunto offers several watches that share the same core trail running experience, including navigation, training insights, and durable outdoor design, but differ in size, battery life, and focus. Suunto Race S Lightweight and compact for confident trail running Suunto Race S delivers the full Suunto trail running experience in a lighter and more compact design. It is ideal for runners who want advanced navigation, training, and recovery tools in a watch that stays comfortable from daily training to race day. Key features: Lightweight and compact design Offline maps and route navigation Dual-band GNSS for accurate positioning Training load and recovery insights Bright AMOLED display Up to 30 hours of battery life in Training mode (All-Systems GNSS + Multi-Band) Ideal for:Trail runners who prioritize a lightweight, comfortable watch without compromising on trail running features. Suunto Race / Race 2 Larger display and longer battery for demanding trail runs Suunto Race and Race 2 deliver the same core trail running experience as Race S, with a larger display and longer battery life for runners who spend more time on the trail and prefer more screen space during activities. Key features: Larger AMOLED display for easier viewing of maps and training data Up to 50h battery life for Race and 55h for Race 2, ideal for extended training sessions, long races, and full-day adventures Offline maps and route navigation Comprehensive training and recovery insights Dual-band GNSS for accurate positioning Ideal for:Trail runners who prefer a larger display and longer battery life for training, racing, and longer adventures. Suunto Vertical / Vertical 2 Built for long-distance trails and outdoor exploration Suunto Vertical and Vertical 2 are designed for runners who take trail running beyond race day. Combining exceptional battery life with advanced navigation and outdoor-focused features, they are built for long mountain routes, remote environments, and multi-day adventures. Key features: Up to 65h GPS battery life for the Vertical series, built for ultra-distance races and multi-day adventures Offline maps and advanced navigation Altitude and weather tools for changing mountain conditions Durable construction for demanding outdoor environments Designed for trail running, hiking, mountaineering, and exploration Ideal for:Outdoor athletes who combine trail running with hiking, mountaineering, and multi-day adventures, and need maximum battery life and navigation reliability. Part 3: How Suunto supports your trail running journey Trail running doesn't start when you press the start button, and it doesn't end at the finish line. From planning your next adventure to reviewing your performance afterwards, Suunto supports every stage of your trail running journey. Build your training plan and prepare for race day Consistent training is the foundation of every successful trail run. Suunto helps you understand how your body responds to training, so you can balance workload, recovery, and performance as you prepare for your next race or adventure. With Suunto, you can: Monitor training load and recovery Track fitness progress over time Follow structured workouts and training plans Get personalized guidance from Suunto Coach to help you prepare for race day Plan your route and understand the challenge ahead Good preparation starts before you step onto the trail. Whether you're exploring a new route or preparing for race day, planning ahead helps you better understand the terrain and make more confident decisions. With Suunto, you can: Build or import GPX routes in the Suunto app Discover popular trails with heatmaps Review elevation profiles to understand key climbs and descents Sync routes and offline maps to your watch before you head out Stay confident during your adventure Once you're on the trail, your watch becomes your guide. Reliable navigation, accurate positioning, and dependable outdoor tools help you stay focused on your run instead of worrying about what lies ahead. With Suunto, you can: Follow your planned route with offline maps and clear route guidance Stay on course and retrace your steps whenever you need to head back Track your location with dual-band GNSS for accurate positioning in challenging environments Receive storm alerts based on changing pressure trends, and rely on a durable design built for demanding outdoor conditions Manage your effort from start to finish Trail running is about managing your energy, not just your pace. Real-time performance data helps you adjust your effort as the terrain changes, so you can make smarter decisions throughout your run. With Suunto, you can: Monitor pace, heart rate, and elevation in real time Track distance, ascent, and remaining route progress Use nutrition and hydration reminders during long activities with SuuntoPlus apps Pace yourself for climbs, descents, and the finish Learn from every adventure and keep improving Every run tells a story. Reviewing your performance helps you understand what worked well, identify opportunities to improve, and prepare more effectively for your next challenge. With Suunto, you can: Analyze your route, pace, heart rate, and elevation after each activity Review long-term training load, recovery, and performance trends over time Track your progress across similar workouts and training blocks Relive and share your adventures in the Suunto app with route maps, photos, videos, and stories Over time, Suunto becomes more than a trail running watch. It becomes a record of where you've been, how far you've come, and where you're ready to go next. Conclusion Choosing the right trail running watch starts with understanding your needs. From everyday training to ultra-distance adventures, the right watch gives you the confidence to plan better, run smarter, and explore further. Find the Suunto watch that fits your journey and enjoy every mile on the trail.