# Train.Red APP vs O2CO2

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.

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.

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

## The numbers

| Metric | Train.Red APP | O2CO2 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/trainred-app/id6451237438/reviews)** | — |
| Number of ratings | **1** | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 3 weeks | Every 3 weeks |
| Monetization | Free | — |
| Size | 71 MB | 353 MB |
| Requires iOS | **15.0** | 15.1 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Train.Red B.V.](https://appshunter.io/developer/1646391181) | [ELIOTT ROMAIN-SAVARD](https://appshunter.io/developer/6813168270) |

## What reviewers say

### Train.Red APP

[App page](https://appshunter.io/ios/app/trainred-app/id6451237438)

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

**In-app purchases:** none


### O2CO2

[App page](https://appshunter.io/ios/app/o2co2/id6813168268)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| O2CO2 Premium Annual | $3.99 | per year |
| O2CO2 Premium Lifetime | $14.99 | one-time |


## Frequently asked 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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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*