Comparison

HRV4Training vs CapnoTrainer

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

Head to head
About

HRV4Training

Quantify stress, balance training and lifestyle, and improve performance with scientifically validated heart rate variability insights. This app accurately assesses HRV using your phone's camera or compatible devices, offering actionable interpretations for optimizing your training plan.

Highlights
  • HRV-based stress quantification
  • Training and lifestyle balance
  • Performance improvement insights
  • Camera-based HRV assessment
  • Integration with wearables
  • Training load analysis
  • VO2max and Lactate Threshold estimation
Features
Read full description

The first scientifically validated Heart Rate Variability (HRV) app. HRV4Training provides HRV based insights to help you quantify stress, better balance training and lifestyle, and improve performance. HRV4Training does not require a heart rate monitor, since it can accurately assess your HRV using the phone's camera. HRV4Training also works with Apple Watch, the Oura ring and all compatible Bluetooth SMART sensors. HRV4Training is also the first app that goes beyond simple measurements and provides insights on: 1) acute or day to day HRV changes in response to different stressors (alcohol, travel, sick days, training, menstruation, etc.) 2) long term multi-parameter trends to look at the big picture 3) correlations between physiological measurements and annotations 4) training load analysis, fitness, fatigue, readiness to perform and injury risk 5) VO2max estimation for runners linking the app to Strava or TrainingPeaks and using a heart rate monitor during their workouts 6) Training Polarization analysis (or 80/20) 7) Lactate Threshold Estimation for runners linking the app to Strava or TrainingPeaks and using a heart rate monitor during their workouts 8) Weekly and monthly summaries to track progress. All data is processed inside the app in order to provide you with actionable interpretations that can help optimizing your training plan and performance. Supported devices for the camera measurement: iPhones 5, 5S, 6, 6S, 6+, 6S+, SE, 7, 7+, 8, 8+, X, XS, XS Max, XR, 11, 11 Pro, 11 Pro Max, 12 mini, 12, 12 Pro, 12 Pro Max, 13 mini, 13, 13 Pro, 13 Pro Max, 14, 14 Plus, 14 Max, 14 Pro, 15, 15 Max, 15 Pro, 16, 16 Max, 16 Pro Currently unsupported devices for the camera measurement: iPhones 4S, iPads and iPods - These devices require a chest strap. Other features: - HRV-based advice helps you to adapt your trainings based on objective measures of recovery - TAGS: lets you tag your sleep, mental energy, muscle fatigue, stress and all other parameters that can help you understand what is influencing your physical condition and physiological stress - Works with Bluetooth SMART heart rate monitors (a Polar H7 is recommended) or simply your phone's Camera - Integrates with the Health app (writes heart rate, and sleep, read sleep time) - Configurable test (single or orthostatic, choose test duration between 1, 3 or 5 minutes) - Extracts and stores the following features while lying down and/or standing: heart rate, mean of beat-to-beat intervals (AVNN), standard deviation of beat-to-beat intervals (SDNN), square root of the mean squared difference of successive R-Rs (rMSSD), number of pairs of successive R-Rs that differ by more than 50 ms (pNN50), low frequency power (LF, 0.04-0.15 Hz), high frequency power (HF, 0.15-0.40 Hz) - Shows the PPG signal view to ensure signal quality during the test if the camera is used instead of a bluetooth SMART sensor - HRV4T Recovery Points to provide a single, straightforward metric to analyze your physical condition - Population summaries and people like you comparisons to put your data into perspective - Analysis of compliance and consistency - Data export via email or Dropbox - Integrates with TrainingPeaks, Oura, Strava and Coros HRV4Training requires to register an account with your email address, so that your data can be backed up safely and retrieved in case anything happens (app issue, changing phone, etc.). HRV4Training does not provide medical advice. It is intended for informational purposes only. Consult a medical professional before making health or lifestyle decisions. Please find an overview of the relevant scientific literature in our guide, here: https://marcoaltini.substack.com/p/the-ultimate-guide-to-heart-rate

About

CapnoTrainer

Features
Read full description

CapnoTrainer iOS app is a great substitution for CapnoTrainer desktop app in case you would like to record session remotely. The app connects to your instrument's Bluetooth and allows you to record session and provide multiple different graphical analysis.

Screenshots

HRV4Training4 screens
CapnoTrainer4 screens

Verdict

The call

The clearest difference is price: CapnoTrainer at Free against HRV4Training's $9.99. CapnoTrainer also leads on update cadence (every 3 weeks vs every 6 weeks) and iOS requirement (13.0 vs 15.6). HRV4Training's advantage is chart position (#22 vs unranked). On ads, in-app purchases 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

CapnoTrainer is free to download; HRV4Training costs $9.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

HRV4Training ships an update every 6 weeks, CapnoTrainer every 3 weeks. The most recent releases landed on October 15, 2026 and September 29, 2026 respectively.

Scorecard4 real differences · 7 level
HRV4Training versus CapnoTrainer: the parameters behind the verdict, then further details
ParameterHRV4TrainingCapnoTrainer
Price$9.99Free — better
Rating3.6 (288 ratings) — better—
Positive reviews61.2% of reviews—
Number of ratings288 — better—
Update frequencyEvery 6 weeksEvery 3 weeks — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaid—
Best chart rank#22 — better—
DevicesiPhone, iPodiPhone, iPad, iPod — better
Requires iOS15.613.0 — better
Further details — not scored
Size35 MB54 MB
Age rating4+4+
DeveloperA.S.M.A. B.V.Muhammad Arshad Khan

Bugs and requests

HRV4Training

Reported bugs

3 issues
  • App crashes frequently, especially with iOS updates
  • Syncing issues with Strava, TrainingPeaks, and Apple Health
  • Camera-based measurements often unreliable or inconsistent

Requested features

4 requests
  • Allow multiple measurements per day
  • Improve integration with Apple Watch and other wearables
  • Add more customization options and data visualization
  • Expand support for non-athletic use cases

CapnoTrainer

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

HRV4Training

No in-app purchases

None

CapnoTrainer

No in-app purchases

Questions

Is HRV4Training free?
HRV4Training costs $9.99, with no in-app purchases.
Is CapnoTrainer free?
CapnoTrainer is free to download, with no in-app purchases.
Do HRV4Training or CapnoTrainer have ads?
Neither HRV4Training nor CapnoTrainer shows ads.
Which is updated more often, HRV4Training or CapnoTrainer?
HRV4Training ships an update every 6 weeks, and CapnoTrainer every 3 weeks. Most recently, HRV4Training was updated on October 15, 2026 and CapnoTrainer on September 29, 2026.

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