Brick Workouts for Triathletes

A brick is a bike session immediately followed by a run, with the transition kept to under five minutes. The name supposedly comes from how your legs feel coming off the bike: heavy, hollow, and refusing to turn over at a normal cadence. That sensation is not a quirk to be tolerated. It is the entire reason brick workouts exist, and skipping them is the single most common reason recreational triathletes blow up in the back half of the run.

This guide covers what bricks actually train, how to structure them by race distance, how to fuel them, and how Movement Rebels programs the whole thing as one continuous session rather than two siloed workouts.

What a Brick Actually Trains

The bike-to-run transition is a neuromuscular problem before it is a cardiovascular one. After 60+ minutes on the bike, your quads have been firing in a closed-chain, seated, ~85-95 rpm pattern. Switch to running and you ask the same muscles to do something completely different: open-chain, weight-bearing, 170-180 spm, with high eccentric load through the calf and hamstring. Your nervous system needs a few minutes to reorganize the firing pattern, and untrained, that reorganization can take 10-20 minutes. In a race, that is the difference between a 4:30/km opening kilometer and a 6:00/km death march.

Bricks compress that adaptation window. Done weekly, the brick run feels normal inside 3-5 minutes. Done sporadically or never, you cross the dismount line on race day with legs that will not cooperate for the first 5K.

Beyond neuromuscular adaptation, bricks teach four things the bike and run alone cannot: pacing discipline (cycling at threshold and then trying to run controlled is humbling), in-race fueling logistics (whether you can absorb 60-90g carbs/hr while running with bike fuel still in the gut), gear transitions (helmet, shoes, race belt, glasses), and the mental anchor of knowing exactly how the legs will feel when the run starts.

Brick Distances by Race

Brick volume scales to your race distance, not to how fit you feel. Overdoing brick volume is one of the fastest paths to a hamstring or calf injury because the run is loading already-fatigued tissue.

Sprint (750m / 20K / 5K): Bike 30-45 min at race effort, run 10-15 min off the bike. The point is intensity, not duration. Run the first 5 minutes at race pace, not "feel it out" pace.

Olympic (1.5K / 40K / 10K): Bike 60-75 min, run 20-30 min off the bike. One longer brick (90/45) every other week to rehearse the back-half feel.

70.3 (1.9K / 90K / 21.1K): Bike 2-3 hours, run 30-60 min off. Build to one big brick (3hr / 75 min) 4-5 weeks out from race day. This is the workout that tells you whether your pacing plan will survive.

Ironman (3.8K / 180K / 42.2K): Bike 4-5 hours, run 30-45 min off. The run portion stays short because the cumulative load is already enormous. The famous "30/30" Ironman brick (3 hours bike + 30 min run, twice in a week) is more useful than one giant 5-hour session for most recreational athletes.

The dial you adjust most is bike intensity. Race-pace bike with an easy run teaches one thing. Easy bike with a tempo run teaches something completely different. Both have a place, and your weekly plan should rotate them.

Intensity Patterns That Work

There are four brick formats worth knowing, and Movement Rebels rotates them based on where you are in the training block and what your readiness signal looks like that morning.

Race-rehearsal brick. Bike at goal race watts/HR, run at goal race pace. The point is to make race day boring. Run during a peak block, 4-6 weeks before race day.

Over-under brick. Bike at threshold for the last 20 minutes, then run easy. Trains the worst-case scenario where you have spent too much energy on the bike (because someone surged, because the wind was wrong, because you got excited) and still have to run a controlled split.

Strength-endurance brick. Hilly bike with low cadence (55-65 rpm) work, then a flat steady run. Targets the slow-twitch capacity in the quads and is brutal in the best way. Pair this format with the strength logger in Movement Rebels so the coach knows your last heavy squat session was 48 hours out, not yesterday.

Mini-brick "transition" brick. 3-4 short bike-to-run swaps (15 min bike / 5 min run, repeated) inside one session. Pure neuromuscular work, low total volume, useful in the final two weeks before a race when you cannot afford fatigue.

Fueling the Brick Block

Bricks are where most age-groupers learn that their fueling plan does not actually work. Carbs absorbed while cycling (gut is relatively undisturbed, blood flow is favorable) feel completely different from carbs absorbed while running (jostling, splanchnic blood flow drops, and that gel you took at 45 min on the bike is about to make itself known at 5 min into the run).

For sessions over 90 minutes, target 60-90g carbs/hr split across the bike and run blocks, with the heavier end loaded earlier on the bike. The Rebel Fuel macro estimate inside Movement Rebels calculates the carb-per-hour target for the specific brick on your calendar that day, based on duration, intensity zone, and your bodyweight. The snap meal feature handles pre-session fueling: photograph your oatmeal at 5:30 AM, log it, and the coach sees the actual carb load you went into the bike with rather than a guessed average.

Hydration ladders the same way. Tracked in Rebel Fuel, the coach can flag if you went into a hot 70.3 brick with 800ml of fluid total the day before. That is a real correction the AI coach will make in the next morning brief, not a generic "stay hydrated" reminder.

Recovery and the Day After

The brick run is high eccentric load on legs that are already glycogen-depleted. Recovery is where adaptation happens. Movement Rebels handles this in three places.

The morning brief reads your overnight HRV from Garmin (or Apple Health on iOS, which is where WHOOP, Oura, Polar, and COROS data lands) and adjusts the next day. If your readiness drops more than expected, the coach swaps a planned threshold run for an easy spin and queues NSDR in the recovery tools tab. The biohack history view shows whether you actually did it, or whether you skipped it three weeks running.

For sleep debt that builds across a peak block, the breathwork timer and a structured wind-down ladder are inside the same app. You do not leave Movement Rebels to find a recovery tool.

How Movement Rebels Handles This

Bricks are programmed as one continuous session on your calendar with the bike block, the transition, and the run block all sequenced. The Garmin push sends the structured workout to your watch so the bike intervals beep correctly and the run autostarts on the dismount. Strava write-back posts a single rich activity description back to your feed, so your training partners see what you actually did.

The AI coach reads your last four weeks of training, your race date, your bodyweight, and your Rebel Fuel log to set the brick volume and intensity for the upcoming week. If you missed a session, the plan rebalances automatically rather than asking you to drag it around manually.

One app instead of five: planning, the workout file on the watch, the activity post-write, the fueling math, the recovery tools, and the coach chat that ties it all together.