Why is the “brick session” a key pillar of pre-race preparation?

In triathlon you don't race three disciplines. You race the transitions between them. And the hardest one — bike to run — decides more races than any single workout.

A brick session is a workout in which you combine two disciplines immediately one after another — most often the bike, followed straight away by a run. The name comes from how your legs feel when you step off the bike: as if your muscles had turned to bricks.

What happens to the body in that moment

While you pedal, blood pools in the leg muscles in a cyclic, closed movement with minimal impact. The moment you stand up and start running, several systems have to reset at once: different muscle recruitment, different neural control of movement, a shift in blood distribution and the sudden arrival of impact forces that weren't there on the bike. For the first 5 to 15 minutes of the run the body is therefore “catching up” — heart rate is higher, pace is slower and your head keeps telling you it can't be done.

You can train the transition. You can't train away the panic — you switch that off through practice.

Why train it systematically

The good news: that slow start can be shortened dramatically. A body that knows the transition adapts faster — the nervous system “remembers” the switch and running economy off the bike improves. Even more important is the mind. Someone who has felt concrete legs twenty times in training won't panic when it comes in a race. They know it fades within a few minutes and hold their pace instead of letting fear slow them down.

How to include a brick session

You don't have to combine maximum volumes right away. The key is regularity and matching the workout to your race goal:

• Short sharp transition: after a longer ride, add 10–15 minutes of running at race pace. You teach the body to “switch on” the legs immediately.
• Long specific brick: a volume ride + a 30–45 minute run. You simulate the fatigue you'll carry into the run on race day.
• Rehearse the transition too: shoes, nutrition, the pace of the first minutes. In a race you don't work out what to do — you do it automatically.

The most common mistake? Riding the bike too hard and hoping the run somehow works out. The opposite is true: a smartly ridden bike leg is the best investment in a good run. A brick shows you exactly what bike pace your legs can still carry.