Brick Workouts Explained: When, Why, and How Many You Actually Need
by The Next Race
The name comes from how your legs feel the first time you try one.
A brick workout is simple in concept: you cycle, then immediately run. No rest, no sitting down, no changing into your lucky socks. You rack the bike, switch shoes, and go. The run that follows — especially in the first kilometre — feels genuinely strange. Heavy. Unresponsive. Like your legs have been replaced with something denser and less cooperative.
That sensation is the whole point.
Why your legs feel like bricks
When you cycle, your body recruits muscle fibres in a pattern specific to cycling. The glutes and quads do most of the work. Blood pools in those muscles. Your cardiovascular system calibrates to the seated, lower-impact demand of pedalling.
Running asks for something different. The muscle recruitment pattern shifts. Your calves and hip flexors take on a bigger role. Your cardiovascular system needs to recalibrate for the higher-impact, upright demand of running. The awkwardness you feel is that transition happening in real time — and it takes approximately one kilometre for your body to sort itself out.
Here's what matters: that transition gets shorter with repetition. Athletes who do bricks regularly feel normal after 500 metres. Athletes who don't do bricks often feel off for the first two or three kilometres of the run leg, which at Olympic distance is a meaningful chunk of the whole race.
There is no substitute. You can be an excellent cyclist and an excellent runner in isolation and still find the first kilometre off the bike deeply uncomfortable if you haven't trained for it.
When to introduce them
Not week one.
The first two to three weeks of any training cycle should establish basic fitness across all three disciplines separately. Adding the physical and psychological complexity of bricks before you've built a consistent routine is a recipe for burnout.
Weeks three or four is the right window for most athletes. Start with a short version: 45 minutes on the bike followed by a 15-minute run. The bike shouldn't be race intensity — tempo pace, working but not gasping. The run should be easy pace. The goal is neuromuscular adaptation, not cardiovascular punishment.
From there, bricks scale naturally with your training phase. During base, do one every fortnight. During the build phase, do one per week. In the race-specific phase, do one or two per week — one shorter and sharper, one longer and race-paced.
The three types that actually matter
The transition brick is what most people do: a full bike session followed by a run. This is your bread and butter.
The race-simulation brick goes longer and tries to replicate race conditions as closely as possible. You ride your race distance at roughly race effort, then run 5–6km at race pace. You don't do this every week. You do it two or three times in the final four weeks before your race, and it does more for your confidence than almost any other session.
The short and sharp brick is underused. Twenty minutes on the bike at threshold intensity, immediately followed by a 10-minute run at faster-than-race pace. It's hard. It teaches your legs to run fast when tired, which is exactly the demand of the final kilometre of a triathlon run.
How many do you actually need
For a sprint triathlon: 6–8 over the whole training cycle.
For an Olympic: 10–14.
For a 70.3: 14–20, with increasing specificity as the race approaches.
These numbers assume you're training consistently across all three disciplines. If you're behind on bike fitness, bricks become less important — there's no point in practising the transition if the bike leg is the problem.
The mistake athletes make
They make every brick a suffer-fest. They go hard on the bike, feeling like they should maximise every session, and then die on the run. They come away with the wrong lesson — that running off the bike is just awful and always will be — when what they've actually learned is that going too hard on the bike makes the run awful.
The brick should end with you thinking: that was uncomfortable, but manageable. If you end every brick session completely destroyed, dial the bike effort back. The adaptation you're after is neuromuscular, not cardiovascular. You're teaching your legs a skill, not punishing them into fitness.
One practical note
Set up your transition before you start. Shoes already loosened, laces already elastic if you use them, run hat already out. Walk through it in your head before you clip in. The habit of a fast, calm transition starts in training, not on race day.
The brick is the session most triathletes dread and most wish they'd done more of. Start them earlier than feels necessary, keep them more controlled than feels productive, and do them more consistently than feels required.
You will thank yourself at kilometre one of the run.