Introducing Spleeft: VBT data integrated into the Intervals.icu workflow

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Hello everyone,

I’d like to briefly introduce Spleeft, an app focused on Velocity-Based Training (VBT) for strength training, and share a recent update that may be relevant for Intervals.icu users.

With Spleeft, athletes can measure barbell velocity directly using an iPhone or Apple Watch, or alternatively import VBT data from external devices such as ADREncoder, Vitruve, OVR Velocity, and similar systems. Athlete and coach are connected through iCloud, allowing shared access to the same strength training data without manual file exchange.

What’s new in this update

  • Intervals.icu integration
    You can now log in with your Intervals.icu account and import your activities into Spleeft.
    The idea behind this integration is not to replace Intervals.icu, but to be part of the coach’s normal workflow: quickly reviewing strength and velocity data alongside endurance training data. If something looks unusual, the coach or athlete can then open Spleeft for a deeper, set-by-set VBT analysis.

Why this matters for Intervals.icu users

Many coaches already use Intervals.icu as their central platform to review training data efficiently. Our goal is for strength training and VBT data to live naturally inside that same ecosystem, allowing velocity metrics to be reviewed at a glance, just like any other training signal.
(As a side note, I’m already thinking about asking @david whether displaying velocity with two decimals would be possible, as that would improve quick interpretation.)

What’s coming next

Following this update, our next step is to synchronize planned strength workouts from the Intervals.icu Workout Builder into Spleeft, so athletes can follow their prescribed gym sessions directly in our app while maintaining a seamless data flow back into their usual analysis tools.

If anyone here is working with VBT or structured strength training and has thoughts on workflows, metrics, or integrations, I’d be happy to discuss and get feedback. @Luisma_Gallego_Soy_P is on it!

Thanks for your time,
Ivan
Spleeft Dev

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*Note: cadence means the weight in kgs on the barbell

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If you add a Custom Stream as a clone of the normal ‘enhanced speed’ stream, you can set it up with two decimals.

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You can can also set it up in m/sec with two decimals, to get even more granularity

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Tx for building this integration.

Speed (and related charts) now display the number with 2 decimals when it is less than 10.

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Thanks a lot for your support!

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Spleeft is working really well; I’ve tested it and will give @Ivan_de_Lucas_Rogero feedback soon. I think it’s something that was needed in interval training: the ability to control strength work through speed. I think it’s a great addition to the ecosystem.

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Hi Ivan, are you planning to support kettlebell ballistics? Starting with swings. I’ve seen great success using kettlebells and focusing on power (velocity). There is a good thread on using an accelerometer on a kettlebell to estimate velocity and force and power.

For swings:

That thread evolved over time and requires reading thru it.

This one on snatches builds on the previous one, and good summary in first post:

The problem with snatches is any wearable on wrist likely needs to be removed. Or risk crushing by the kettlebell.