What exactly is a brick workout?

A brick workout is a bike session followed immediately by a run. In triathlon training, it teaches your legs to switch from cycling's seated, circular motion to running's load-bearing stride. Short bricks of 40 to 60 minutes on the bike plus 15 to 20 minutes of running are enough for most Ironman athletes.

How often should Ironman athletes do brick workouts?

Most age-groupers benefit from one longer brick every 10 to 14 days, plus a short 10-minute transition run after one other midweek ride. Daily bricks add fatigue without extra benefit.

Do brick workouts need to be long to work?

No. A short brick of 40 to 60 minutes on the bike followed by 15 to 20 minutes of running is enough to practise the bike-run transition. The final bike effort should be at race pace.

Can brick workouts replace run volume for Ironman training?

No. Run durability comes mainly from consistent running. Bricks translate that run fitness onto tired legs, but they should replace one bike-run split, not your key run sessions.

Are long bricks still useful for Ironman athletes?

They can be. A long brick of two hours or more on the bike plus 35 minutes of running is useful in the final 9 weeks before a race, but it should not be a weekly default. Treat longer sessions as endurance work and shorter sessions as skill practice.

What should I set up before a brick workout?

Set up a transition area with running shoes, socks, a hat, a race belt, and a small bottle of fluid before you start the bike. That removes delays and mimics race-day transition.

Brick Workouts for Ironman Running: Why They Work

Q: What is the biggest mistake athletes make in a brick workout?

Running the first kilometre too hard. The first 5 minutes should be 15 to 20 seconds per kilometre slower than goal Ironman pace so the body can settle into a rhythm.

cyclist riding bicycle on road — Photo by Pablo Ulloa on Unsplash

Every Ironman athlete has felt it: the first kilometre of the marathon after 180km on the bike feels like someone replaced your legs with wet cement. The fitness is there. The run form is not. Brick workouts address that exact disconnect, and they are becoming a bigger part of how age-groupers and pros approach Ironman running.

A brick is simply a bike session followed immediately by a run. The term comes from the heavy-legged sensation when you first switch disciplines, though coaches debate the exact origin. No special equipment is needed. You ride, you change, you run, and you pay attention to what happens in the first ten minutes.

Why Ironman Running Does Not Feel Like Normal Running

Running after a long ride is not simply running while tired. It is running after hours of seated, non-weight-bearing pedalling. That changes which muscles are ready to fire. Your quads and hip flexors have been working nonstop. Your calf complex and achilles tendons have been mostly along for the ride, and the glute medius has been quiet. When your foot hits the ground, the stabilisers are sluggish.

That is why so many triathletes describe the first 3km to 5km of an Ironman marathon as a shuffle. The stride shortens and the pelvis tips forward. That small collapse in posture leaves the arms working harder to compensate. Coaches now treat the first ten minutes of the run after a bike as a specific skill. The goal is not to be fast. The goal is to be in control.

Research in triathlon run economy has repeatedly found that athletes run slower at the same effort after cycling than when they run fresh, with the biggest drop in the first minutes. The numbers vary from study to study, but the direction is consistent. A short brick lets you rehearse that drop without the full physical cost of a long ride.

That framing is a shift. Older training advice treated the long brick as an endurance session. Many coaches now describe short bricks as neuromuscular practice. TrainingPeaks describes the run off the bike as a chance to teach the legs to fire in a new movement pattern while under fatigue.

The New Way Long-Course Coaches Use Bricks

The heavy stack of a five-hour ride plus a 90-minute run still exists, but it is no longer the default. The newer pattern is shorter and more frequent, with each brick built around one race cue. A typical Ironman-focussed session is a 90-minute bike with the final 30 minutes at goal race power, then a 25-minute run. The first 5 minutes of the run are deliberately easy. The final 20 sit at Ironman goal run pace.

That session will not build much aerobic fitness. It gives you repeated exposure to the exact feeling of race day. When an athlete panics in the first mile of a triathlon run, the pace often drops because the stride tightens, not because the engine has failed. A brick teaches the brain that the tightness fades if you stay relaxed and let the rhythm settle.

Some pros have moved toward rolling bricks, especially for hilly Ironman courses. A rolling brick might be 4 sets of 20 minutes on the bike at race effort, each followed by a 3-minute run. This is useful when the goal is to practice repeated surges, but it costs more muscular fatigue per hour. It belongs in a specific block where recovery is protected, not as a weekly staple for a beginner.

The trend toward shorter bricks has also been helped by power meters becoming standard on training bikes. Ten years ago, many age-groupers did not know what goal race power felt like. Now they can ride the final 20 minutes of a brick at a precise wattage and then measure the run pace that follows. That feedback loop makes a 90-minute brick more useful than a 4-hour ride where the last 30 minutes are a guess.

A Progression That Fits Into a Working Week

A useful brick does not have to eat an entire Saturday. The minimum effective dose for most age-group triathletes is a 40- to 60-minute bike followed by a 15- to 20-minute run. The key detail is that the final bike portion must resemble the effort you plan to hold on race day. A soft spin into transition will not create the heavier legs you need to practice with.

One progression for an Ironman-focussed athlete:

Weeks 1 to 3: ride 60 minutes, with the last 20 minutes at goal bike power, then run 15 minutes. Run the first 5 minutes at easy pace and the last 10 at goal run pace.
Weeks 4 to 6: ride 90 minutes, with the last 30 minutes at goal bike power, then run 25 minutes. Settle into goal run pace for the middle 15 minutes.
Weeks 7 to 9: ride 2 hours, with the last 45 minutes at goal bike power, then run 35 minutes, holding goal run pace for the final 20 minutes.
Every 7 to 10 days, add a short 10-minute transition run after a standard midweek ride just to keep the bike-to-run switch familiar.

These sessions replace one bike-run split in your week. They should not be added on top of your existing volume. If you do a long brick on Saturday and a hard long run on Sunday, the recovery debt erodes the quality of the next week. Long-course training is settled by consistency, not by the single biggest weekend you survive.

Set up your transition area before you start. Shoes, socks, a hat, a race number belt, and a small bottle of water should be waiting exactly as they would be in transition. That removes the ten-minute break during which your legs tighten up and your mind talks you out of the run. Even a short delay changes the session.

Triathlete coaching guidance highlights a common mistake: running the first kilometre too hard to get it over with. In training that habit often carries into a race. Your first 5 minutes in a brick should be 15 to 20 seconds per kilometre slower than goal run pace. The run then settles into a rhythm you can hold without gasping for air.

What the Sport Science Does and Does Not Show

There is no single magic brick protocol, and any coach who claims one is selling certainty the research does not provide. Most studies on triathlon running use bike bouts of 20km to 40km, followed by a 5km run. That is a far cry from Ironman distance. The findings still point in one direction: prior cycling changes run economy and cadence while sharply raising perceived effort, with the largest disruption in the first ten minutes.

A short brick gives you a controlled laboratory for those first ten minutes. What the research does not say is that you need a weekly five-hour-plus brick for months. That is a coaching decision, not a scientific necessity. Many age-groupers benefit from one longer brick every 10 to 14 days, with a shorter transition run after one other bike session. Run durability still comes from running volume. The brick translates that run fitness onto a tired pair of legs.

The 80/20 Endurance approach draws a useful line: if the brick is under 90 minutes total, treat it as a skill session; if it is longer, treat it as an endurance session. That distinction helps prevent the common mistake of turning every brick into a sufferfest.

The One Small Change

If you currently do nothing, start with this: after your next long ride, put on running shoes and run 10 minutes. Not 30, not 60. Ten minutes. The first three minutes will feel wooden and disjointed. That feeling is the cue. Your brain learns that the heaviness fades and the stride opens up. The pace stops feeling forced.

In an Ironman run, that knowledge is the difference between a calm first 5km and a panicked shuffle that costs ten minutes by the half-marathon mark. Brick workouts do not replace bike volume or run volume. They make the volume you already tolerate show up at the right time, in the right movement pattern, with the right expectation.