Brick Sessions

A brick session is a training workout where you complete two disciplines back to back with no meaningful rest between them - almost always a bike ride followed immediately by a run. The name comes from how your legs feel in the first ten minutes of that run.

It is the single most race-specific session in triathlon, and the one self-coached athletes most often skip. Here is what a brick session does, how to structure one properly, and how often you actually need them.

Why brick sessions matter

Riding hard and running well are two different skills. Doing them consecutively is a third skill entirely, and it has to be trained.

When you come off the bike, blood is concentrated in the muscles you have been using for the cycling movement pattern. Your running muscles are being asked to work at race pace on legs that feel wooden and unresponsive. Your cadence drops, your form deteriorates and your perceived effort is far higher than the pace would normally suggest.

Athletes who never practise this arrive at T2 on race day and experience it for the first time under pressure. They either panic and run too hard, or they slow dramatically and never recover the rhythm. Athletes who train bricks regularly know exactly what those first ten minutes feel like, know it passes, and pace through it.

How to structure a brick session

The critical detail is the transition itself. The run has to start within a few minutes of the bike finishing. Riding, showering, eating and running an hour later is two sessions, not a brick, and it delivers almost none of the adaptation.

Beginner brick

40 to 60 minutes steady on the bike, followed immediately by a 10 to 15 minute easy run. The aim here is purely familiarity - you are learning what the sensation feels like, not chasing fitness. Keep the run genuinely easy.

Sprint and Olympic brick

60 to 75 minutes on the bike with the final 15 minutes lifted to race effort, then a 20 to 25 minute run with the first 10 minutes at target race pace. This teaches you to hold pace when the legs are least willing.

70.3 brick

2.5 to 3 hours on the bike at half-distance race power, then a 30 to 40 minute run building into race pace. This is also your primary opportunity to rehearse fuelling, because gut tolerance is trained, not innate.

Ironman brick

4 to 5 hours on the bike at Ironman effort, then a 30 to 45 minute run held deliberately controlled. The purpose is durability and nutrition rehearsal, not speed. Running fast off a five-hour ride teaches you nothing useful and costs you a week of recovery.

How often should you do brick sessions?

Less often than most athletes assume. Bricks carry a high recovery cost, and doing them weekly year-round tends to produce chronic fatigue rather than race readiness.

In the base phase, once every two or three weeks is plenty, kept short and easy. In the specific phase leading into your race, weekly is appropriate, building in duration and race-pace content. In the final two weeks, one short sharp brick keeps the neuromuscular pattern fresh without adding fatigue.

A reasonable guide is that bricks should make up no more than around 10 to 15 per cent of your total training. They are a sharpening tool, not a foundation.

Common brick session mistakes

Running too hard. The instinct is to prove you can run fast off the bike. What you actually need to practise is holding your target race pace under fatigue, which is usually considerably slower than your standalone pace.

Taking too long in transition. Five minutes changing shoes and checking your phone removes the entire training stimulus. Have your running kit laid out and move straight through.

Doing them too often. Bricks are demanding. Two quality bricks a month in the right phase beats four mediocre ones that leave you flat for everything else.

Neglecting fuelling. Long bricks are your rehearsal for race-day nutrition. Practise the exact products, quantities and timing you intend to use.

Ignoring cadence. Deliberately running the first kilometre at a slightly higher cadence than feels natural helps override the heavy-legged pattern and shortens the adjustment period.

Frequently asked questions

What is a brick session in triathlon?

A workout combining two disciplines back to back with minimal rest, most commonly a bike ride followed immediately by a run. It trains your body to handle the physiological shift between disciplines that occurs in a race.

Why is it called a brick?

It describes how your legs feel running off the bike - heavy and unresponsive, as though made of brick. Some coaches also use it as an acronym for bike-run-int-continuous-kilometres, but the sensation explanation is the one every triathlete recognises.

How long should a brick session be?

It depends on your race distance. Beginners can start with a 40 minute ride and a 10 minute run. Ironman athletes may ride four hours and run 45 minutes. The run does not need to be long - the first 10 to 15 minutes deliver most of the adaptation.

Can you do a swim to bike brick?

Yes, and it is underused. Swim-bike bricks are valuable for open water racing, where you exit the water with an elevated heart rate and reduced coordination. They are simply harder to organise logistically, which is why most athletes focus on bike-run.

Should beginners do brick sessions?

Yes, but keep them short and easy. A first-time sprint triathlete benefits enormously from simply knowing what running off the bike feels like before race day. Familiarity is the goal, not intensity.

How soon before a race should I stop doing bricks?

Keep one short, controlled brick in the final ten days. It maintains the movement pattern without adding fatigue. Avoid long or hard bricks inside the last week.

Getting bricks into your plan properly

The difficulty with brick sessions is not knowing what they are. It is knowing how many to do, when to introduce them, how hard to run, and how to fit them around the rest of your week without accumulating fatigue you cannot clear.

That is a periodisation question, and it is exactly the sort of thing a coach handles. If you would like your training built around your actual race and your actual available hours, book a free consultation and we will talk it through.

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