Triathlon Training Zones: Heart Rate and Power for Swim, Bike, and Run
2026-06-14 · 7 min read
Rapid answer
Triathlon requires separate zone targets for each discipline. Heart rate in the water runs 10 to 13 bpm lower than on land. Bike zones use FTP-based power if you have a power meter. Run zones set from a recent lactate threshold run test. Never apply the same bpm targets across all three sports.
Training zones tell you where to put your effort. In triathlon, one set of zones does not apply to all three sports. The physiology differs enough between swimming, cycling, and running that applying identical heart rate targets to all three will either under-stress you in the pool or blow up your race-day legs before you get to the run.
Why triathlon zones are different across disciplines
In swimming, cardiac output is lower and heart rate runs 10 to 13 bpm below equivalent effort on land due to the horizontal position, water pressure, and face immersion response. In cycling, you can sustain higher absolute watts than running at the same heart rate. In running, heat dissipation is less efficient and heart rate drifts upward at constant effort. All three require their own zone targets.
| Discipline | Zone 2 HR (relative to max) | Primary zone metric | Notes |
|---|---|---|---|
| Swimming | 47 to 57% of max HR | Pace + effort | HR monitors unreliable in water |
| Cycling | 60 to 70% of max HR | Power (55-75% FTP) | Power is more accurate than HR |
| Running | 60 to 70% of max HR | HR + pace | HR drifts up with duration |
How to set cycling zones
Use FTP-based power zones if you have a power meter. Set heart rate zones from your last 20-minute or ramp test if you do not. Power is the gold standard for cycling zone compliance because it is not affected by temperature, fatigue, or caffeine the way heart rate is.
Standard power zone definitions (Coggan/Allen model):
| Zone | Name | % of FTP | Use |
|---|---|---|---|
| Zone 1 | Active recovery | Under 55% | Easy spinning |
| Zone 2 | Endurance | 55-75% | Base building |
| Zone 3 | Tempo | 75-90% | Race-specific fitness |
| Zone 4 | Threshold | 90-105% | FTP development |
| Zone 5 | VO2max | 106-120% | Top-end capacity |
For most Ironman and 70.3 athletes, the bike leg is raced at 65 to 75 percent of FTP (Zone 2 to low Zone 3). The most common race mistake is spending the first hour of the bike at Zone 3 to 4, then paying for it on the run.
Use the FTP calculator to set your power zones and derive your Ironman bike target.
How to set running zones
Derive your run zones from a recent 10K race result or a 30-minute threshold test, not from your cycling or swimming results. A common error is using cycling heart rate zones for running. Running produces a higher heart rate than cycling at equivalent absolute work output because of the vertical displacement, greater muscle activation, and higher core temperature.
Standard run zone model based on lactate threshold heart rate (LTHR):
| Zone | % of LTHR | Feel |
|---|---|---|
| Zone 1 | Under 85% | Conversational, fully recovered |
| Zone 2 | 85-89% | Comfortable, could hold for hours |
| Zone 3 | 90-94% | Comfortably hard, can still talk |
| Zone 4 | 95-99% | Race pace, labored breathing |
| Zone 5 | 100%+ | Short intervals only |
The 80/20 split: 80 percent of run volume should be in Zone 1 to 2. 20 percent in Zone 3 to 5. Most age-group triathletes run too hard on easy days and too easy on hard days. Heart rate is the guardrail. See Zone 2 running for the full breakdown of pace benchmarks and weekly structure.
Use the heart rate zone calculator to find your Zone 2 ceiling in beats per minute from your max heart rate.
How to set swimming zones
Swimming zones are best tracked by pace per 100 meters and perceived effort, not heart rate. Water pressure on the chest, the horizontal position, and face immersion all suppress cardiac output relative to land exercise. Heart rate in water is typically 10 to 13 bpm lower than at equivalent effort on land. Most waterproof heart rate monitors are also unreliable during swimming.
Swimming zone targets by pace:
| Zone | Effort description | Pace (relative) |
|---|---|---|
| Zone 1 | Fully easy, full recovery between sets | CSS pace minus 15-20 seconds per 100m |
| Zone 2 | Steady, aerobic, sustainable | CSS pace minus 8-12 seconds per 100m |
| Zone 3 | Threshold sets, continuous effort | CSS pace minus 2-5 seconds per 100m |
| Zone 4 | CSS (critical swim speed) | CSS pace |
| Zone 5 | Sprints, short reps | Faster than CSS |
CSS (Critical Swim Speed) is the swim equivalent of lactate threshold. It is derived from a 400m and 200m time trial: CSS = (400m time minus 200m time) expressed as pace per 100m.
Zone 2 for triathlon base building
Zone 2 training builds the aerobic base that all three disciplines draw on at race pace. For most triathletes, 60 to 80 percent of weekly training volume should be in Zone 2 across all three sports. Zone 2 work develops mitochondrial density, fat oxidation, and cardiovascular efficiency without the recovery cost of harder sessions.
Weekly Zone 2 minimums for aerobic adaptation:
| Volume tier | Swim | Bike | Run |
|---|---|---|---|
| Maintenance | 2,000m | 2-3h | 45-60 min |
| Development | 3,000-4,000m | 4-6h | 60-90 min |
| Ironman prep | 5,000m+ | 8-12h | 90 min+ |
See Zone 2 cardio examples for how each discipline counts toward total weekly Zone 2 volume.
Zone 2 in the week before a race
Reduce volume but do not eliminate Zone 2 work in the final 10 to 14 days before an Ironman or 70.3. Keep one Zone 2 bike and one Zone 2 run per week in the final week, shortening each session by 40 to 50 percent. A complete week of rest before a long-course race leads to sluggishness and elevated heart rate on race morning. Short Zone 2 sessions maintain aerobic priming without adding fatigue.
Frequently asked questions
Are triathlon training zones the same as running zones?
No. Heart rate runs 10 to 13 bpm lower in swimming than at equivalent effort on land. Cycling zones are best set from FTP-based power, not heart rate, because heart rate on the bike lags behind power output by 30 to 60 seconds and is affected by hydration, temperature, and caffeine. Running zones are set from lactate threshold heart rate derived from a recent race or threshold test. Using the same bpm range for all three sports will either under-train you in the pool or send you over zone on the run.
How do I find my Zone 2 for cycling in triathlon?
Set your cycling Zone 2 from your FTP. Zone 2 on the bike corresponds to 55 to 75 percent of FTP. If you do not have a power meter, use heart rate: Zone 2 is 60 to 70 percent of your maximum heart rate on the bike. Do not derive your bike Zone 2 from your run heart rate zones because cycling max heart rate is typically 5 to 10 bpm lower than running max heart rate for most athletes. Run a separate 20-minute FTP test on the bike and a separate threshold test on the run to get accurate numbers for each discipline.
What heart rate should I target for an Ironman bike leg?
For a full Ironman, target 60 to 70 percent of your maximum cycling heart rate on the bike, or 65 to 75 percent of FTP if you use a power meter. This corresponds to Zone 2 to low Zone 3. Going above Zone 3 on the bike compromises your ability to run a strong marathon because glycogen burns faster at higher intensities. The run is where most Ironman athletes lose or gain time, so protecting the legs on the bike is more important than a fast bike split at the expense of the run.
How do I train my run fitness for triathlon without getting injured?
Triathlon run injuries most commonly come from running too fast on too-tired legs after heavy cycling volume. Build run volume gradually using the 10 percent rule for weekly mileage increases. Do most of your run volume in Zone 2, which allows more total mileage with less injury risk than running at pace. Brick workouts (bike immediately followed by a run) are essential for adapting to the discipline shift, but keep the run portion short and at Zone 2 pace until your legs consistently feel normal within 10 to 15 minutes of the brick transition.