What is the best training app for triathletes who also lift?

For the three endurance disciplines, TrainingPeaks or Intervals.icu, because both handle swim, bike and run properly. For the lifting and the energy accounting, something else — and being honest, no single tool currently does all four well, which is why most triathletes who lift run two.

Does Base support swimming?

Not as a prescribed and graded discipline. Run and ride are supported; swim is not. The energy cost of swimming is still captured, because measured maintenance does not care which discipline the calories went to, and the recovery signals are systemic and discipline-blind. But there is no swim band and no swim grade.

How do triathletes track strength training?

Usually badly, because endurance platforms model load as intensity relative to a threshold and resistance training has neither term. A heavy lower-body session that costs two days of run quality enters the model as almost nothing.

Should triathletes lift weights?

Yes. Strength work improves running economy, reduces injury risk, and preserves the lean mass that high-volume endurance training otherwise erodes. Two sessions a week during a block, three or four in the off-season.

What is the biggest tracking gap for triathletes?

Energy. Fifteen hours a week of training produces a cost no activity multiplier can estimate, and chronic under-fuelling is the mechanism behind most of what goes wrong in this population — lost muscle, poor recovery, bone stress injuries and the wider RED-S picture.

The Best Apps for Triathletes Who Lift

The swim gap, stated first

Base does not support swimming as a prescribed and graded discipline. Run and ride are; swim is not.

For a triathlete that is a real limitation and it should shape your choice. What still works: the energy cost of swimming is captured, because measured maintenance derives from your weight trend and does not care which discipline the calories went to. The recovery signals — HRV, resting heart rate, sleep, RIR drift — are systemic and discipline-blind.

What does not work: there is no prescribed swim band and no swim session grade. If threshold-based swim prescription is central to your preparation, an endurance platform that handles all three should be your primary tool, and this page will not argue otherwise.

What each option covers

	Swim	Bike	Run	Lifting	Energy
TrainingPeaks	Yes	Yes	Yes	Effectively no	Basic
Intervals.icu	Yes	Yes	Yes	Manual estimate	Limited
Garmin Connect	Yes	Yes	Yes	Records only	Imported
Hevy / Strong	No	No	No	Excellent	No
MacroFactor	No	No	No	No	Measured
Base	No	Yes	Yes	Full, with RIR	Measured

Read across the rows and the shape of the problem is obvious: nothing has a complete row, and the two gaps that hurt most are lifting in an endurance platform and energy anywhere.

Why lifting is invisible to endurance platforms

Not a missing feature — a structural limit.

Training Stress Score is intensity relative to threshold power or pace, multiplied by duration. A resistance training session has neither term: a set is thirty seconds, and there is no threshold power for a squat.

So a heavy lower-body day that costs you two days of run quality enters the model as almost nothing. Your form curve says fresh, Thursday's brick session falls apart, and nothing predicted it.

Manual load entry exists and does not fix it. Entering a guess into a model whose other inputs are measured makes the output harder to interpret, not easier — you now have a fatigue curve where some of the fatigue is measured and some is invented.

Why energy is the bigger gap

Triathlon training volume produces a very large energy cost, and low energy availability is the mechanism behind most of what goes wrong in this population: lost muscle, poor recovery, bone stress injuries, hormonal disruption, the whole RED-S picture.

Running costs roughly 1 kcal per kilogram of bodyweight per kilometre. A 155 lb (70 kg) triathlete at fifteen hours a week is easily 1,000 to 1,500 kcal a day above a sedentary baseline.

No activity dropdown reaches that. "Extremely active" in a standard calculator does not, and the gap between what such a tool suggests and what you need can exceed a thousand calories a day.

The only method that works at this volume does not predict anything:

weightChangeLb = trendWeight(today) - trendWeight(14 days ago)
energyBalance  = weightChangeLb * 3500 / 14
maintenance    = avgDailyIntake - energyBalance

Fourteen days, ten of them logged, eight weigh-ins. Re-measure every four to six weeks as volume ramps. The full method.

The stacks that work

If you have a coach: whatever they use, plus something for the lifting and the energy. The coach-athlete workflow outweighs every other consideration and TrainingPeaks owns it.

Self-coached, swim is central: Intervals.icu for all three endurance disciplines — free, deep, and it ingests from anywhere — plus a lifting log, plus a measured-maintenance nutrition tool. Three apps, and the reconciliation is yours.

Self-coached, swim is the smallest part of your week: Base for the bike, the run, the lifting and the energy, with your watch platform holding the swim record. Two tools, and the cross-discipline arithmetic is automatic.

Off-season, when swim volume is lowest: the swim gap costs least here, which is also the window where building muscle is realistic and the energy accounting matters most.

The modality fact worth knowing

The concurrent-training research finds a clear moderator that changes triathlon programming: running interferes with lower-body strength and hypertrophy at statistical significance, and cycling does not.

The explanation is eccentric loading. Running is thousands of eccentric contractions per session; cycling is almost purely concentric; swimming is close to zero.

So your fifteen hours are not fifteen hours of equal cost to your lifting. Schedule strength work around your run volume, not around your total volume. That single reframing is worth more than most tooling decisions. The research.

What to look for, whatever you choose

Does it measure maintenance or predict it? At fifteen hours a week, prediction is not merely imprecise — it cannot resolve the quantity.
Does anything read lifting fatigue alongside endurance load? Two signals firing at once is the deload trigger worth using, and two of the four come from a training log.
Does it grade your easy sessions? Most triathletes run their easy runs too hard, and it is invisible without a prescribed band to grade against.

What to do next

Whichever stack you pick, do the fourteen-day maintenance measurement first. The triathletes who lose muscle through a season are almost always the ones who never made it, and it is orthogonal to every other tooling decision on this page.