Frontier X vs Train.Red APP
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Frontier X
Track your heart health and exercise performance with a smart chest strap monitor. Gain detailed insights into heart rate, rhythms, and training load. Receive personalized feedback and alerts to optimize your workouts and understand your body better.
- Heart Health Monitoring
- Real-time Heart Rate & HRV
- Breathing Rate & Strain Tracking
- Activity Recording (24hrs)
- Personalized Vibration Alerts
- AI-enabled Training Insights
- Metabolic Profile Analytics (Premium)
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With your Frontier X/X2/X3, track your activity including exercise, rest or sleep to get detailed insights on heart health and exercise performance. This companion app allows you to connect with Frontier X2/X3 - a revolutionary chest strap wearable smart heart monitor and view your recorded data. Trusted by world-class athletes across the globe, the Frontier X2/X3 is a chest-worn Smart Heart Monitor that provides in-depth real-time feedback on your heart health. It can monitor your: - Heart Health - Heart Rate - Heart Rate Variability (HRV) - Breathing Rate - Strain - Rhythms - Training Load - Calories - Stress, and a lot more. • Accurately record your activity like exercise, running, cycling, resting, sleeping, meditation, etc for up to 24hrs with comprehensive heart health insights. • Spot changes in your heart health with Rhythm and Strain. • Train in the right zone without distractions with real-time, personalized, and discreet vibration alerts. • Add health event tags to help you understand how lifestyle choices and behavior affect your health. • Seamlessly integrate with Bluetooth-enabled wearables and third-party devices such as GPS sports watches, bike computers, and more. • AI-enabled algorithms - Receive post-activity training insights, recommendations, and weekly goals. • Frontier X integrates with HealthKit to export your Frontier X activities into the Health app and to read heart rate and biometric data. • IP67 Waterproof up to 1.5 M • Battery: 14+ days of typical use Now get deeper insights and data with Frontier Premium Subscription*: Metabolic Profile Analytics: Track training intensity and the impact of lifestyle changes on metabolic health with key metrics like VO₂ Max, VO₂ Zones, Oxygen Uptake, and Ventilatory Thresholds (VTs). VO₂ Max: Get the most accurate real-time VO₂ Max data. While other wearables estimate using motion and heart rate, our advanced algorithms provides precise VO₂ Max readings outside of a lab, tracking cardiovascular efficiency and endurance potential. Readiness Score: Determine if your body is ready for peak performance or needs recovery. Advanced algorithms use heart rate, heart rate variability (HRV) to guide your daily activities and training. Sleep Stage Analysis: Get a comprehensive understanding of your sleep quality (Webapp). With Frontier's Premium subscription and Metabolic Profile Analysis, tracking your VO₂ max becomes simpler and more precise. *A Paid Frontier Premium subscription is required to access the full feature set . The Premium feature subscription comes with a complimentary 7 days free trial, and continue at a minimal monthly cost starting from USD 14.99, or opt for an annual plan for substantial savings. Please note that prices may fluctuate based on your geographical location, currency, and current exchange rates The Terms of use are available in the app and our website: https://in.fourthfrontier.com/pages/terms-of-use About Fourth Frontier Fourth Frontier is an innovative health-tech company focused on revolutionizing heart health monitoring with its cutting-edge wearable technology. We are the World’s First Smart Heart Monitor. With over 5 billion heartbeats recorded from 120,000+ users across 50+ countries, we are empowering users to understand and manage their heart health in real-time. These features make the Frontier App a comprehensive tool for heart health management and fitness improvement. Download the app today and access the most accurate heart health data available. Apps available for iPhone and Apple Watch.
Train.Red APP
This app monitors muscle oxygen saturation to provide real-time physiological insights for athletes and coaches. It helps optimize performance, track recovery, and analyze training data with actionable metrics.
- Muscle oxygen saturation monitoring
- Real-time physiological insights
- Performance and recovery tracking
- Workout analysis and data export
- Team/organization structure
- Live data overlay
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About this app The official app for the Train.Red muscle oxygen sensors, the new metric for performance. To move, your muscles need energy. The most efficient way to get this energy requires oxygen. We measure the oxygen saturation in your muscles to help you improve. Not every athlete has a team of scientists helping them with their physiological data, we measure data from your muscle and translate this into useable insights, in real-time. - Monitor your physiological power and perform easy exercise tests as an endurance athlete. - Know when your muscle is fully recovered and ready for the next set when doing strength. What’s more? - Cloud functionality to allow workout analysis at home, even when you perform in the gym. - A Team/organisation structure that allows multiple athletes to use the sensors. - Actionable insights after your training or scientific analysis with access to raw data. - Live view with data overlay to match measured fatigue with movement patterns. - Muscle States, Protocols, Dashboard, Training Menu, Muscle Stress Score, and much more. How to start with Train.Red: Create a user profile and connect your sensor. No sensors yet? The Train.Red app requires the Train.Red sensors for full functionality (https://train.red/). Connected your FYER or PLUS? Nice, you are ready to BE AHEAD. What does Train.Red do for me: Whether you’re an athlete, coach, scientist, physio, or anyone involved in sport, Train.Red has something to offer you. Simply because your muscles play a key role in human movement. We track your muscle oxygenation, more specifically, the hemoglobin concentration changes. The Train.Red sensors measure: - SmO2, Muscle Oxygen Saturation (%) - O2Hb, Oxyhemoglobin (mM) - Hhb, Deoxyhemoglobin (mM) - Thb, Total hemoglobin (mM) - HbDiff, the Hemoglobin Difference (mM) If this sounds like Abracadabra, no worries. We display the oxygen saturation in your muscle live and use the other metrics to provide you with actionable insights in real-time. Our AI and advanced analysis options translate this data into 5 different muscle states showing you if your muscle is recovering, or approaching its limits. If this physiological data sounds familiar, perfect. We allow exporting your data to .csv or .fit files for an in-depth analysis of all your data. Every single training session is stored in our cloud and can be analyzed or exported afterward. How do I use Train.Red? The Train.Red sensor is a light-based wearable that you wear directly on your skin. You’re free to place the sensor anywhere on your body but know that this is a hyperlocal metric that will only tell you something about the exact location you place the sensor. We recommend wearing the sensor on a primary involved locomotor muscle, a place on your body that is active during the activity you’re performing. e.g. on your thigh during cycling or squats, the middle part of your upper leg during running, or on your lower arm during climbing. Of course, you are free to use more than one sensor! You can connect up to 4 sensors simultaneously and measure multiple areas at once. You’re not bound to this smartphone application. The Train.Red hardware is integrated into 3rd party apps allowing you to easily synchronise your data from multiple sources. Train.Red sensors can be connected to most Wahoo’s, Garmin’s, Suunto’s and several other devices. More information can be found on our website https://train.red/
Screenshots
Verdict
The clearest difference is in-app purchases: Train.Red APP at none against Frontier X's 2. Train.Red APP also leads on rating (5.0 vs 4.6). Frontier X's advantage is ratings volume (318 vs 1). On price, update cadence, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Frontier X sells 2 in-app purchases, starting at $14.99 per month. Train.Red APP asks for nothing beyond the download.
Train.Red APP holds the better App Store score, 5.0 against 4.6. That said, the two scores are not equally well evidenced: Frontier X has 318 ratings behind it against 1, so its average is the more settled of the two.
Both ship on a similar rhythm, roughly every 3 weeks. The most recent releases landed on October 26, 2026 and October 20, 2026 respectively.
| Parameter | Frontier X | Train.Red APP |
|---|---|---|
| Price | Free | Free |
| Rating | 4.6 (318 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 81.8% of reviews | — |
| Number of ratings | 318 — better | 1 |
| Update frequency | Every 3 weeks | Every 3 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone, Apple Watch | iPhone, iPad, iPod — better |
| Requires iOS | 16.0 | 15.0 — better |
| Further details — not scored | ||
| Size | 569 MB | 70 MB |
| Age rating | 4+ | 4+ |
| Developer | Fourthfrontier | Train.Red B.V. |
Customer experience
Frontier X
Train.Red APP
Bugs and requests
Frontier X
Reported bugs
4 issues- ECG stopped working
- Inaccurate breathing rate and other metrics
- Inability to edit activity details for indoor workouts
- Syncing issues with Garmin devices after firmware updates
Requested features
6 requests- Add interval markers
- Improve integration with Apple Fitness/Fitness+
- Add support for ANT+
- Improve compatibility with other fitness apps and devices
- Add more customization options for workouts
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- Improve data visualization and analysis tools
Train.Red APP
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Frontier X
- Monthly7 Days trial$14.991 Month
- Yearly7 Days trial$119.991 Year
Train.Red APP
No in-app purchases
Questions
Is Frontier X free?
Is Train.Red APP free?
Which has better reviews, Frontier X or Train.Red APP?
Do Frontier X or Train.Red APP have ads?
Which is updated more often, Frontier X or Train.Red APP?
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