Triathlon Swim Training: Pool Sessions and Open Water Tips

In a triathlon the swim comes first, but it is not the part you win. Its job is to get you to transition with fresh legs for the bike and run. Good swim training means holding a steady pace, saving energy and learning to find your way in open water. Here are the distances, how triathlon swimming differs from pool swimming, and three sample sessions for an Olympic triathlon in a 25 m pool.

Swim distances by race format

• Sprint: 750 m
• Olympic: 1500 m
• 70.3 (half Ironman): 1.9 km
• Ironman (full distance): 3.8 km

Some pool-based sprint races use shorter swims, such as 400 or 500 m. Always check your own race's rules: organisers can shorten the course, for example if the water is too cold.

How it differs from pool swimming

Steady pace. In the pool you often swim fast repeats with rest. In a race you swim a long way at a pace you can hold without going into oxygen debt. Start too hard and you pay for it on the bike.

Saving your legs. The bike and run are still to come. Many triathletes use a light, steady kick that keeps the body in line, and rely mostly on the arms. Coaches do not all agree on how much to cut it back, and swimmers whose legs sink still need a firmer kick.

Sighting. There is no line on the bottom in open water. You lift your eyes now and then to see the buoys and correct your course, without losing rhythm.

Swimming in a group. At the start and around the buoys you swim close to others, with bumps and choppy water. It is normal, and better if you have tried it before.

Wetsuit. It adds buoyancy and changes how your shoulders and breathing feel. If your race allows it, swim in the wetsuit a few times before race day. When it is permitted depends on water temperature and the race rules, so read the briefing.

No walls. No turns, no push-offs, no rests at the edge. After the start you swim continuously to transition.

Pool training in a 25 m pool for an Olympic triathlon

Three swim sessions a week suit many people; two are fine if the bike and run already take most of your time. First, a reference pace. If you know your CSS (critical swim speed), you have a pace per 100 m to tie your repeats to. If not, use a "comfortably hard" effort: a few words at the wall, not a full sentence.

These sessions assume you can already swim 1500 m without stopping, even slowly. They are suggestions, not numbers validated by studies: adjust them to your level.

Session 1: aerobic endurance (about 2100 m)

• 300 m easy freestyle
• 4 x 50 m (25 m drill, 25 m swim), 15 seconds rest
• 5 x 300 m at a steady, comfortable pace, 30 seconds rest
• 200 m easy, breathing every 3 strokes (or whatever feels natural)
• 100 m easy

Aim for the same pace on all five repeats. If the last one is much slower than the first, you started too hard.

Session 2: CSS pace (about 2000 m)

• 400 m easy
• 4 x 50 m building, each a bit faster, 15 seconds rest
• 6 x 200 m at CSS pace, 20 seconds rest
• 200 m easy with a pull buoy
• 100 m easy

As an alternative to the 200s, 10 x 100 m at CSS pace with 10 seconds rest. Short rests teach you to restart without being fully recovered, as in a race. Exact zones and rest times vary between coaches.

Session 3: sighting and technique (about 1800 m)

• 300 m easy
• 8 x 25 m technique drills (for example single-arm or fingertip drag), 15 seconds rest
• 6 x 100 m freestyle: about every 6 strokes lift your eyes forward for half a second, then lower your head and carry on. 20 seconds rest
• 4 x 50 m race-style start, then steady pace, 30 seconds rest
• 400 m continuous at a steady pace, without stopping at the wall if you can (at each end, a short push-off and go)
• 100 m easy

For pool sighting, pick a fixed point (a flag, a clock) and look at it. It is not the same as open water, but it trains your neck and rhythm.

Open water tips

• Look ahead every few strokes. Every 6 to 10 strokes is a common reference, adjusted to conditions: with chop or sun in your eyes you will look more often. Lift your eyes, not your whole head, and breathe on the next stroke.
• Practise starts. Do some repeats starting in a group, with contact and rough water.
• Swim with others. Never swim open water alone. Choose a supervised spot or go with a partner.
• Tow float and bright hat. They make you visible and give you something to hold if you need to stop.
• Check conditions. Weather, waves, currents and tides at the sea. If the water is rough or you do not know the place, wait.
• Do not jump or dive into unfamiliar water. The bottom can be shallower than expected and cold water can take your breath. Enter slowly and wait for your breathing to settle.
• If you have a health condition, check with a doctor before raising your training load.

Frequently asked questions

How many times a week should I swim? For an Olympic distance many people swim two or three times. Consistency matters more than the number of sessions. If two is what fits alongside bike and run, that is fine.

Do I need to kick? Yes, lightly: it keeps your body in line. Many triathletes kick less than a pool swimmer to save their legs. Coaches disagree, and if your legs sink you need a firmer kick.

Pool or open water? The pool is simpler and more controlled for building endurance and technique. A few open water outings before the race are still worth it for sighting, group swimming and the wetsuit. A good balance is mostly pool, plus some open water sessions done safely.

When do I start swimming in the wetsuit? A few times before the race, if you will wear one. If you never do, race day will feel different in your shoulders and breathing.

How much should I be able to swim for an Olympic? If you can swim 1500 m continuously at a steady pace without being wrecked, you have a good base. Your time depends on your level: build consistency first.

A plan that adapts

SwimSensei builds a swim plan from your level, the days you train and your pool length (25, 33 or 50 m), and adapts it every week. See how it works on the SwimSensei for swimmers page and join early access.