Heart-rate training
Heart-rate training for swimmers: a coach's guide
Most swim training is prescribed by pace and interval. That tells you how fast a swimmer went, but not how hard it was for them. Two athletes can hit the same send-off and be in completely different places physiologically. Heart rate is how you see that difference, and it’s how you make sure each swimmer is training in the zone you intended.
This is the pillar guide. It links out to the specifics: how the signal is captured, what each zone means, and how to run it for a whole squad.
Why heart rate, not just pace
Pace is an output; heart rate is a window into the effort behind it. When a swimmer holds threshold pace but their heart rate is climbing set after set, they’re fatiguing, and the set is no longer doing what the plan said. Reading heart rate live lets you adjust in the moment instead of finding out at the next meet.
Setting zones from threshold pace
The cleanest anchor for a swimmer’s zones is their Critical Swim Speed, their threshold pace. You can calculate it in two minutes from a 400 and a 200 time trial using our CSS calculator in apxswim, which also outputs a starting set of zones. From there, heart rate gives you the physiological check: the pace defines the target, the heart rate confirms the effort.
The five working zones
- Recovery: easy, conversational; flushes fatigue between hard work.
- Aerobic / endurance: the bread-and-butter base; sustainable for long sets.
- Threshold (CSS): right at the edge of sustainable; builds the engine.
- VO₂ / race pace: hard, repeatable efforts near race intensity.
- Speed: short, maximal; not about heart rate so much as output.
Capturing it for a whole team
The practical problem is that monitoring one swimmer is easy; monitoring twenty at once is where most setups fall apart. How the signal is transmitted matters a lot here; see ANT+ vs Bluetooth for swim heart rate for why a connectionless broadcast lets one receiver read the whole squad without pairing or dropped connections.
In apxswim, each swimmer’s zones live on their athlete card, live heart rate comes in over ANT+ for the whole group at once, and you can see at a glance who’s hitting the target intensity and who’s just going through the motions.