Bricks

If you've never heard the term before, a brick is likely to become one of the most useful sessions in your triathlon training.

It's also one of the few things you can't properly replace with more swimming, cycling or running on their own.

A brick teaches your body to do something that only happens in triathlon: switch from one discipline to another while already carrying fatigue.

What Is a Brick, Exactly?

A brick is a training session where you perform two triathlon disciplines back-to-back with little or no break between them.

The most common version is cycling straight into running, although swim-to-bike bricks can also be useful.

The name comes from the sensation itself: your legs can feel as though they've suddenly turned to bricks during those first few minutes of running after cycling.

That feeling isn't simply imagined.

Cycling and running use many of the same muscles, but with different movement patterns. You're also moving from a relatively supported, seated cycling position into an upright running posture.

The sudden change can make your legs feel heavy, awkward or uncoordinated while your body adjusts.

That's the "jelly legs" sensation almost every triathlete remembers from their first few bike-to-run sessions.

Why It Matters

Here's what makes bricks different from ordinary running: you can't completely reproduce the feeling of running off the bike by simply becoming a fitter runner.

The challenge isn't only running fitness. It's adapting to the sudden change in movement, posture and accumulated fatigue.

Skip brick training and the first time you experience that sensation may be halfway through your actual race.

Regular brick sessions help in three important ways:

• Physical adaptation. Your body becomes more accustomed to switching movement patterns, helping the transition feel more natural over time.
• Mental familiarity. When your legs feel strange on race day, you'll recognise the sensation instead of assuming something has gone wrong.
• Race-day rehearsal. You can practise changing shoes, grabbing nutrition and settling into your running rhythm while already carrying bike fatigue.

How to Do It — A Beginner Starting Point

You don't need to start with a long or intense session.

A sensible first brick could be:

• 20–30 minutes of relaxed, mostly flat cycling
• Immediately followed by 10–15 minutes of easy running

Keep the intensity low.

At this stage, the goal isn't to improve your maximum speed. It's to teach your body what the switch feels like.

Your first few minutes of running may feel surprisingly awkward. That's the point of the session.

How to Progress

Once the basic transition starts to feel familiar, you can gradually make your bricks more specific to your race.

• Start with one every 7–14 days. You don't need multiple brick sessions every week when you're starting out.
• Increase one variable at a time. Gradually make the run longer or introduce more race-specific intensity rather than increasing everything simultaneously.
• Build towards 20–30 minutes of running off the bike. As your race approaches, longer bike-to-run sessions can help you become increasingly comfortable running with tired legs.
• Make later sessions more race-specific. Closer to race day, your bricks can increasingly reflect the type of bike effort and running pace you'll actually use in competition.

You don't need to turn every brick into a race simulation.

Most of your training should still be straightforward, controlled work. The value comes from giving your body repeated exposure to the transition.

A Few Things Worth Knowing

• Fatigue is normal. Your legs may feel unusually heavy after a brick, especially when you're new to them. That is part of the adaptation process. Pain or excessive exhaustion, however, is a reason to stop and reassess the session.
• Practise your transition. Lay your equipment out as though you're in a real race. A brick is an opportunity to practise changing shoes, grabbing your race belt and getting yourself moving efficiently.
• Don't skip the warm-up. Even though the session may be relatively short, warming up properly before the bike portion still matters.
• Don't rush into full-distance bricks. Build a foundation of consistent swim, bike and run training first. Bricks are more demanding than their relatively short duration can make them appear.

The aim isn't to make every brick harder.

It's to make the transition increasingly familiar.

By race day, switching from the bike to the run shouldn't feel like a completely new experience.