Is Intervals.icu good for hybrid athletes?

For the endurance half it is outstanding and free, with depth that rivals paid platforms. For resistance training it does what every endurance platform does — records that a session happened without modelling its cost against your endurance load in a way that changes a prescription.

Can Intervals.icu track strength training?

It can log the activity and supports custom fields and manual load entry, so a determined user can approximate something. What no amount of manual entry fixes is that the underlying load model is defined in terms of intensity relative to an endurance threshold, which resistance training does not have.

Is Intervals.icu better than TrainingPeaks?

For a self-coached, data-literate endurance athlete, arguably yes, and it is free. TrainingPeaks wins decisively on the coach-athlete workflow and the plan marketplace, which is what most people are actually paying for.

Does Intervals.icu track nutrition?

It has some fuelling and weight tracking, and it does not derive maintenance calories from your weight trend against your intake. A calorie figure there carries the same problem as any prediction-based number.

What is the best free training analysis tool?

Intervals.icu, comfortably, for endurance. It ingests from most sources, models load properly, and gives you more analytical depth than most people will use.

Base vs Intervals.icu for Hybrid Athletes

What Intervals.icu owns

Depth, free. CTL, ATL, form, power curves, pace curves, HRV tracking, custom charts, a full API. It is closer to a research tool than a consumer app, and that is the appeal.

Ingestion. It will take data from most platforms and devices, so it sits happily on top of whatever you already use rather than demanding you move.

Openness. Custom fields, custom charts, and an API that people genuinely build on. If you want to compute something it does not compute, you can.

A genuinely useful HRV implementation with a considered approach to baselines.

The structural gap

Load in this model is intensity relative to threshold, multiplied by duration. A resistance training session has neither term in a meaningful sense: a set is thirty seconds, the rest is three minutes, and there is no threshold power for a squat.

You can enter a manual load figure. That figure is a guess, and layering a guess onto a model whose other inputs are measured makes the model's output harder to interpret rather than easier — you now have a fatigue curve where some of the fatigue is measured and some is invented, and no way to tell which part is driving a reading.

The consequence for a hybrid athlete is the familiar one:

Three heavy lower-body sessions and moderate running produces a form curve that says fresh.
Adding lifting volume while holding endurance steady produces a flat, sustainable-looking build.
A bad threshold session after a heavy squat day appears in the model as an unexplained underperformance.

The comparison

	Intervals.icu	Base
Endurance load model	Deep: CTL, ATL, form, curves	Deliberately crude: acute-to-chronic on minutes
Data ingestion	Excellent, from almost anywhere	Platform health store
Customisation and API	Extensive	None
Swim	Yes	No
Resistance training in the model	Manual estimate at best	First-class
Set, rep, RIR logging	No	Yes
Nutrition	Limited	Full, with measured maintenance
HRV	Good implementation	Drives a decision: RIR offset and deload
Cross-discipline deload trigger	No	Two-signal
Price	Free	Beta

Why Base's endurance model is cruder on purpose

Intervals.icu models endurance load well. Base uses total endurance minutes against a four-week average, which is much less sophisticated. That is a deliberate trade and the reasoning is worth stating rather than glossed over, because on this axis Intervals.icu is simply better.

TSS-style load requires either power or a well-calibrated threshold on every session. In practice a real training history has holes: the run where the watch died, the treadmill session, the ride without a power meter, the hike. A model with holes under-reports exactly the weeks that were unusual, which are the weeks it exists to flag.

Minutes needs nothing. And the thing it catches — a large sudden jump — is coarse enough that a coarse measure finds it. Base is not trying to periodise a season. It is trying to notice that this week is 1.6 times your recent normal, and to say that this also has a cost on the lifting side.

If season periodisation is what you want, Intervals.icu does it and Base does not.

What running both looks like

This is a genuinely good stack and worth recommending explicitly.

Intervals.icu for endurance analysis: the curves, the power and pace history, the season view. Base for the cross-discipline decisions: whether the surplus survived the training week, whether two fatigue signals are firing, what today's lifting should ask for given how recovered you are.

They overlap on almost nothing, which is unusual in this category and makes the combination cheap.

When Intervals.icu alone is enough

Endurance is your training and lifting is genuinely support work.
You are a triathlete — swim is a real gap in Base.
You want the analysis and will do the interpretation yourself. That is what the tool is for.
Free matters.

When the gap costs you

Lifting has its own progression and its own goals.
Your form curve and your legs disagree, repeatedly.
Nothing in your stack can tell you whether your calorie target accounts for the training you actually did.

What to do next

Keep Intervals.icu — nothing here replaces it for endurance analysis. The question is whether the two decisions it structurally cannot make are ones you currently make well. The energy one is where most hybrid athletes lose a year.