Comparison

Train.Red APP vs O2CO2

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • Muscle oxygen saturation monitoring
  • Real-time physiological insights
  • Performance and recovery tracking
  • Workout analysis and data export
  • Team/organization structure
  • Live data overlay
Read full description

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/

About

O2CO2

Features
Read full description

Take a moment to breathe with O2CO2. Follow visual guides, sound cues and instructions in English or French to practise at your own pace. START FOR FREE • Cardiac Coherence in Balance mode: inhale for 5 seconds / exhale for 5 seconds, with adjustable session duration. • Guided Breathing: 3 loops of 24 breaths, at Relax pace, with a male voice. • Sound, music and volume choices in the included exercises. • Share your results at the end of a Guided Breathing session. • Exercise guides and access to the Masterclass, free for everyone. EXPLORE MORE WITH PREMIUM Both Premium plans include the same features: • Six additional exercises: Box Breathing, Sleep Breathing, Strengthen, Breathing 1:2, Alternate Nostril Breathing and Bee Breathing. • Every Guided Breathing setting: 1–15 loops or continuous mode, 8–96 breaths per loop, three paces, and male or female voice. • Four Cardiac Coherence rhythms: Balance 5/5, Relaxing 4/6, Balance + 5.5/5.5 and Energizing 6/4. • Guided Breathing session history and charts of your breath-hold times. Choose an automatically renewing annual subscription or a one-time purchase for lifetime access. The applicable price is shown before confirmation in the App Store. Payment is charged to your Apple account after confirmation. The annual subscription renews automatically unless cancelled at least 24 hours before the current period ends. Manage or cancel it in your Apple account settings. Restore purchases from within the app. PRACTISE AT YOUR OWN PACE Read each exercise’s instructions before starting. Choose your sound settings and find them again the next time you open the app. No account registration or advertising. Settings and history are stored on your device, and you choose which results to share. Terms of use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy policy: https://o2co2-confidentialite.eliott-romain.chatgpt.site/

Screenshots

Train.Red APP4 screens
O2CO24 screens

Verdict

The call

The clearest difference is in-app purchases: Train.Red APP at none against O2CO2's 2. 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. O2CO2 sells 2 in-app purchases, starting at $3.99 per year. Train.Red APP asks for nothing beyond the download.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 3 weeks. The most recent releases landed on November 3, 2026 and October 31, 2026 respectively.

Scorecard1 real difference · 8 level
Train.Red APP versus O2CO2: the parameters behind the verdict, then further details
ParameterTrain.Red APPO2CO2
PriceFreeFree
Rating5.0 (1 ratings) — better—
Number of ratings1 — better—
Update frequencyEvery 3 weeksEvery 3 weeks
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree—
DevicesiPhone, iPad, iPod — betteriPhone, iPod
Requires iOS15.0 — better15.1
Further details — not scored
Size71 MB353 MB
Age rating4+4+
DeveloperTrain.Red B.V.ELIOTT ROMAIN-SAVARD

In-app purchases

None

Train.Red APP

No in-app purchases

2 purchases

O2CO2

Subscriptions1
  • O2CO2 Premium Annual$3.991 Year
One-time1
  • O2CO2 Premium Lifetime$14.99

Questions

Is Train.Red APP free?
Train.Red APP is free to download, with no in-app purchases.
Is O2CO2 free?
O2CO2 is free to download, with in-app purchases available.
Do Train.Red APP or O2CO2 have ads?
Neither Train.Red APP nor O2CO2 shows ads.
Which is updated more often, Train.Red APP or O2CO2?
Train.Red APP ships an update every 3 weeks, and O2CO2 every 3 weeks. Most recently, Train.Red APP was updated on November 3, 2026 and O2CO2 on October 31, 2026.

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