The Complete Guide to Brick Training: Why Running After Cycling Is Always So Painful—A Coach Breaks Down the Transition Curse

Coach’s Opening: That Downhill Legged With Cement

Almost every athlete I’ve coached has the same expression on their face for the first 400 meters after hopping off the bike, changing into running shoes, and heading out on the run during their first brick session—it’s not fatigue, it’s the bewilderment of “how can this be happening.”

One of my athletes, Xiao Lin, had a cycling FTP of 240 watts and could run a 42-minute 10K on his own—a solid combination on paper. But the first time he came to me, he complained that every time he raced a 51.5 (standard Olympic distance) triathlon, his final 10K run was 8 to 10 minutes slower than his standalone training runs. He asked me, “Coach, is my running base just too weak?”

My answer stunned him: “It’s not that you’re weak—it’s that you’ve never taught your body how to start running after cycling 40 kilometers.”

That’s what we’re here to talk about today—brick training. The name sounds tough, and honestly, that feeling when you jump off the bike and start running really does feel like your legs have been filled with cement. This isn’t a willpower issue; it’s a solid, physiological phenomenon. Once we break down the mechanisms behind it, you’ll understand: the pain of transition can be trained, tamed, and even turned into a weapon to overtake your competitors.

In this article, I’ll walk you through it the way I coach my athletes—from the scientific foundation to specific workouts, then how many bricks to do before race day, how to fix common mistakes, and finally, a ready-to-follow action checklist for athletes at different levels.

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1. Why Is Running After Cycling So Painful? Three Physiological Truths

Many people think “brick legs” are just psychological, but they have a very clear physiological origin. I usually break it down into three parts for my athletes.

1. Blood Flow Redistribution: Your Body Hasn’t Switched Modes Yet

When cycling, you’re seated, your upper body is relatively forward-leaning, and your heart pumps blood toward the quadriceps and glutes in a steady rhythm. The moment you jump off the bike, stand upright, and start running, your body has to process a cascade of changes instantly.

According to sports science data, when transitioning from a seated position to upright running, the pattern of venous return changes, heart rate typically spikes immediately by about 10 to 15 bpm, stroke volume needs to readjust, and your breathing rhythm has to switch gears. Your autonomic nervous system is still stuck in “cycling mode” for a while, blood is still pooled in the muscles you were just hammering, and the blood flow distribution running requires isn’t quite the same as cycling. That mismatch for a few minutes is one reason you feel breathless, heavy-legged, and like your heart rate is through the roof.

2. Muscle Recruitment and Joint Angles: Completely Different Movement Patterns

This is the part many people overlook, but it’s actually the biggest factor.

The hip flexion angle used in cycling and running differs enormously. Based on exercise physiology data, hip flexion during cycling is roughly 75 to 110 degrees, with the quadriceps in a relatively shortened state, repeatedly performing concentric contractions. Running, on the other hand, involves hip flexion of only about 10 to 50 degrees, requiring the quads to lengthen and absorb eccentric load upon landing.

In other words, you’ve just spent an hour training your muscles to contract “the cycling way,” and now you need them to instantly switch to “the running way.” The recruitment order and firing rhythm of your neuromuscular system all have to be rearranged. This “delay in switching motor memory” is the core reason your stride feels clunky and your step length won’t open up. I often use this analogy with athletes: it’s like speaking English continuously for an hour and then being asked to switch to fluent Japanese on the spot—your brain knows to switch, but your mouth needs a few sentences to smooth out. Your legs are the same; they need a short “warm-up” to switch from cycling language back to running language.

Research also indicates that this transition-induced running “sluggishness” is most pronounced in the first 2 to 10 minutes after cycling, during which your running economy drops, stride length shortens, and the oxygen uptake state of your muscles is still rebalancing.

3. Glycogen Depletion and Metabolic Waste: You Start the Run Carrying Debt

The third piece is fuel—and it’s the most lethal the longer the distance gets.

When you start running, you’re essentially setting off with metabolic debt. After cycling, muscle glycogen has been partially depleted, especially in the Type I slow-twitch fibers responsible for endurance. Sports science data clearly states that in Olympic-distance, middle-distance, or long-distance triathlons, leg muscles are more or less in a glycogen-depleted state after 40, 80, or 180 kilometers of high-intensity cycling.

The long-distance scenario is even more critical—data shows that after three to five hours of riding, muscle glycogen is heavily depleted and fat oxidation rates rise, making the subsequent run a lesson in “maintaining pace on mixed fuel”—which is exactly the real-world scenario of the Ironman marathon leg.

So you’ll find a brutal truth: no matter how well you train your standalone running, it can never fully replicate the state of “starting the run with fatigue and glycogen depletion.” That’s why brick training is irreplaceable.

This also explains a confusion many beginner triathletes have: “I can easily hit a certain pace in standalone runs, so why am I gasping at the same pace on race day?” The answer is right here—in a race, you’re never running on “fresh legs,” but on “legs that have already ridden a while, burned some fuel, and haven’t switched their movement pattern back yet.” These are two completely different abilities. And brick is the only thing that can stitch these two together.

Coach’s Summary: Blood flow hasn’t switched, muscle movement patterns haven’t switched, and fuel has already been partially burned—these three things happening simultaneously create those cement legs. Once you understand this, you’ll stop blaming yourself for “being bad at running” and start specifically training “transition ability” as an independent skill.

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2. What Does Brick Training Actually Develop?

Since the pain has a physiological root, the value of brick training is clear—it targets each of the three areas above and creates adaptations.

• Neuromuscular Adaptation: By repeatedly practicing “run immediately after ride,” your nervous system learns to switch recruitment patterns faster, and that clunky first 10 minutes gradually shortens. This is the fastest, most obvious improvement.
• Cardiovascular Adaptation: Your body learns to redistribute blood flow more smoothly, the heart rate spike diminishes, and you don’t feel like you’re about to explode the moment you start running.
• Metabolic Adaptation: Long bricks train your body to deliver energy steadily and improve fat oxidation efficiency even with partially depleted glycogen, holding your pace.
• Psychological Adaptation: This is often underestimated. When you’ve “gotten used to” that cement-leg feeling in training, it won’t panic you on race day—you’ll know “this is normal, just get through the first 10 minutes.”

Sports science data also mentions that brick training improves running biomechanics and coordination, thereby enhancing running economy, especially in the first 2 to 10 minutes after transition—precisely the most painful, most collapse-prone stretch.

A Commonly Misunderstood Concept: Brick Isn’t About “Getting More Tired,” It’s About “Getting More Specific”

I often have to correct a misconception: athletes think the value of brick lies in “accumulating more training volume in a single day.” Wrong. If you just want volume, you could ride two hours in the morning and run one hour in the evening—the total is identical, but your body barely learns anything about transition.

The truly rare, irreplaceable value of brick lies in that “seamless connection” interface—you start running in that “specific physiological state” where muscles are still warm, blood flow is still in cycling mode, and glycogen has already been partially burned. You can’t manufacture this state in any standalone workout; only brick can give it to you. So I often tell athletes: “Brick is a ‘transition lesson,’ not a ‘volume lesson.’” You need to train that connection with focus and quality, not treat it as a way to pile on mileage.

Once you understand this, you’ll see why one high-quality brick per week beats three tired, half-hearted long sessions.

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3. Brick Workout Design: From Beginner to Advanced

This is the part athletes want most. I divide bricks into three major types, each with a different goal—don’t mix them up.

Comparison Table of Three Brick Types

Type	Primary Goal	Bike Segment	Run Segment	Suitable For	Recommended Frequency
Transition Brick	Train neural switching, get used to cement legs	30–60 min moderate intensity	10–20 min light-fast run	All levels, first choice for beginners	Once per week
Intensity Brick	Train race pace, fatigue-resistant running	Includes intervals or race intensity	Target pace or slightly faster	Intermediate and above with a base	Once every 1–2 weeks
Long Brick	Train long-distance glycogen management and psychology	Long aerobic ride	Medium-long steady run	Half/full ironman preparation	Once every 2–3 weeks

Specific Example Workouts for Each Type

Below are examples I’ve actually prescribed to athletes at different levels—you can reference them directly. Intensity is marked with RPE (Rate of Perceived Exertion, 1–10) and heart rate zones, so even those without a power meter can execute them.

Workout Name	Suitable For	Bike Segment	Transition	Run Segment	Total Duration
Beginner Entry Brick	Beginner finish goal	40 min RPE 5–6, HR Zone 2	Aim for under 90 seconds	10 min RPE 6, light-fast is fine	About 55 min
51.5 Pace Brick	Standard distance, aiming for a PR	Main set 3×8 min race intensity (RPE 7–8) with 3 min rest between	Quick shoe change	15 min: first 5 min find cadence, last 10 min build to target pace	About 75 min
Mini Continuous Brick	Advanced, train neural switching	15 min ride + 5 min run × 3 cycles	Quick switch each round	See left	About 60 min
70.3 Endurance Brick	Half ironman preparation	2.5–3 hr Zone 2 aerobic, last 20 min at race intensity	Under 90 seconds	40–60 min steady run, pace close to race target	About 4 hr
Full-Distance Simulation Brick	Full ironman preparation (once 4–6 weeks before race)	4–5 hr long ride	Quick transition	60–90 min including nutrition rehearsal	5.5–6.5 hr

Key principles I make clear to athletes when prescribing workouts:

• Beginners start with “short bike + short run”—the point isn’t fatigue, it’s getting the body to remember the switch. Ride 40 minutes, run 10 minutes, once a week, and you’ll quickly feel that clunkiness shorten.
• Intensity bricks must have a clear pace target, not just “run whatever after the ride.” This workout is for calibrating “your true pace ability under fatigue.”
• Long bricks are for glycogen management and nutrition—intensity doesn’t need to be high; the key is sufficient duration, and you must rehearse the exact nutrition you’ll use on race day during the workout—this is crucial, and I’ll emphasize it again in the common mistakes section.
• Mini continuous bricks (bike-run-bike-run alternation) are especially effective for shortening neural switching time, and many elite athletes love them, but they’re tough—beginners should stay away for now.

An 8-Week Progressive Example (Using an Intermediate Standard-Distance Athlete)

Looking at workouts alone can be confusing, so let me lay out the skeleton of Xiao Lin’s 8-week plan to show you how bricks “progressively stack.” Intensity is always built on an aerobic base first, then specific intensity is gradually added.

Week	Week’s Main Brick Workout	Focus
Weeks 1–2	Ride 40 min Zone 2 + run 10 min light-fast	Pure adaptation, get the body to remember the switch; establish the transition routine
Weeks 3–4	Ride 50 min (including 2×10 min Tempo) + run 15 min	Add cycling tempo segments, run still aiming for smoothness
Weeks 5–6	Mini continuous brick: 15 min ride + 5 min run × 3	Dense neural switching training, shorten the clunky phase
Week 7	51.5 pace brick (race intensity simulation)	Calibrate true pace under fatigue
Week 8	Pre-race wake-up brick: ride 20 min + run 5 min	Taper, only wake up, don’t create fatigue

You’ll see a clear logic: volume before quality, adaptation before intensity, taper before race day. Each week builds a little on the previous one, rather than hitting hard from the start. That’s why I keep emphasizing: brick isn’t about training harder—it’s about progressing with rhythm.

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4. Pre-Race Brick Frequency: When to Do It and How Many Times

This is where athletes make the most mistakes—it’s not about doing more. Bricks place a heavy load on the body (after all, you’re accumulating both cycling and running fatigue at once), and overdoing it digs a hole for yourself.

Brick Frequency Recommendations by Race Distance

Race Distance	Recommended Brick Frequency	Last Long Brick Before Race	Taper Handling
Beginner / Sprint (e.g., 400m swim + 20km bike + 5km run)	1 short brick per week	7–10 days before race	In the final week, switch to a very short “wake-up brick”
51.5 Standard Triathlon	1 per week, alternating intensity and transition types	10–14 days before race	Keep 1 short, fast brick during taper
70.3 Half Ironman	1 every 1–2 weeks, including 1–2 long bricks	About 3 weeks before race	Start shortening 2 weeks out, keep frequency but lower intensity
226 Full Ironman	1 long brick every 2–3 weeks	4–6 weeks before race (last big brick)	No long bricks after 3 weeks out, only short wake-ups

Core principles:

• The longer the distance, the farther the last long brick should be from race day. For a full ironman, the key long brick should be scheduled 4 to 6 weeks out; afterward, your body needs enough time to recover and supercompensate. Forcing one closer to race day only means showing up fatigued.
• Taper doesn’t mean zero bricks—it means “shorten, reduce volume, keep frequency.” I usually schedule a very short wake-up brick in the final week (e.g., ride 20 minutes, run 5 minutes) to remind the nervous system “you’ll need to switch soon,” not to create fatigue.
• Don’t do any brick within 3 days of race day. At that point, just do light activity and let your body arrive fully recovered.

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5. Local Taiwan Race Application: Using IRONMAN 70.3 Kenting as an Example

Rather than abstract principles, let me give you a real scenario. One of Taiwan’s most representative long-distance triathlons is IRONMAN 70.3 Kenting.

According to official race information, the event consists of a 1.9 km swim + 90 km bike + 21.1 km run. The bike course follows the southern Taiwan coastline, passes through Pingtung’s local scenery, and loops back near Kenting National Park for two laps; the run course is an out-and-back along the South Bay coastline, described officially as “flat and fast.”

Sounds beautiful, right? But I need to warn athletes about two things:

First, Taiwan’s climate is a silent killer. This race takes place in early November, and even in early winter, the midday sun and humidity in southern Taiwan are still formidable. After riding 90 kilometers with depleted glycogen, starting a run that’s “flat but sun-baked to dehydration” amplifies those brick legs several times over. So when I coach athletes preparing for Kenting, I deliberately schedule long bricks around midday, during the hottest part of the day, so the body adapts to the triple threat of “fatigue + heat + dehydration.” Taiwanese athletes have a unique environmental advantage—we don’t need to go looking for it; our summers are the best heat-acclimatization training ground there is.

Second, nutrition must be rehearsed until it’s second nature in training. Taiwan’s aid stations commonly have sports drinks, cola, bananas, and salt candies, but whether your gut can absorb them under high intensity, heat, and fatigue is something only training can tell you. This ties into the next section on common mistakes.

If you’re still in the beginner stage, Taiwan has plenty of environments suitable for brick training: riverside bike paths (like the Xindian River and Dahan River paths in Greater Taipei) are perfect—flat roads, light traffic, and you can plan a safe brick route of “ride a stretch, stop to change shoes, run a stretch” without traffic lights breaking your rhythm.

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6. Common Mistakes and Fixes: All the Pitfalls a Coach Has Stepped In

This section covers the mistakes I’ve repeatedly seen in 15 years of coaching. Avoid these, and you’re already ahead of half the field.

Mistake 1: Transition Too Slow, Turning Brick Into “Rest Then Run”

Many people get off the bike slowly, drink water slowly, change shoes slowly, and dawdle for 5 minutes before starting to run—this defeats the purpose entirely, because your body has already “rested and switched.”

Fix: The goal is to start running within 90 seconds of finishing the ride. Set out your running shoes, cap, and race number in advance, simulating the T2 transition area. Transition speed itself is a skill that needs practice.

Mistake 2: Riding Too Conservatively, or Making the Run the Focus but Being Too Wrecked to Run

Some people do the opposite—they ride way too hard, then completely fall apart on the run, failing to train “fatigue resistance at pace.”

Fix: Be clear about the goal of the session. If it’s an intensity brick, the bike segment should simulate race intensity, but don’t surge so hard that the run is a total loss. Learning to save a little leg for the run during the bike segment is itself a race strategy.

Mistake 3: Starting the Run With Too Slow a Cadence, Forcing Long Strides

Those legs won’t open up right off the bike, and many people instinctively try to “stride big and forceful,” which makes it clunkier and increases injury risk.

Fix: For the first 2 to 3 minutes of the run, deliberately use a high cadence with short strides (imagine quick, small steps), letting the nervous system find the running rhythm again, then gradually open up the stride once your legs “come alive.” This trick works almost immediately for every athlete I’ve coached.

Mistake 4: Using Nutrition for the First Time Only on Race Day

This is the most painful pitfall. I’ve seen athletes use an untested energy gel in a race, and their gut revolted on the run, costing them a toilet stop and their placing.

Fix: Every piece of nutrition you’ll use in the race must be rehearsed in long brick training. You need to know how much your gut can absorb under fatigue and heat, which brands cause discomfort, and how often to refuel. Taiwan’s food culture is convenient, but race-specific items like energy gels and salt tablets absolutely must be tested in training first.

Mistake 5: Frequency Too High, Treating Brick as a Daily Routine

Bricks are high-load; doing them daily accumulates fatigue and increases injury risk, and you won’t get quality out of them anyway.

Fix: Go back to the frequency table above. Quality over quantity—one high-quality brick per week beats three tired, half-hearted ones.

Mistake 6: Only Training in Cool Hours While Racing at Noon

This is one Taiwanese athletes especially overlook. Many people always train bricks in the early morning or evening to “run comfortably,” then hit midday heat on race day and collapse. Most Taiwanese triathlons (especially southern ones) have the run segment hitting the hottest part of the day, and combined with post-ride dehydration, those brick legs get amplified twofold by the heat.

Fix: Schedule at least a few bricks at a time close to race time and race temperature before race day, building heat adaptation and sweating efficiency. This isn’t self-punishment—it’s turning Taiwan’s humid heat into a training asset. Also, be sure to rehearse your hydration and electrolyte replacement rhythm.

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7. Action Recommendations for Athletes at Different Levels

Finally, let’s distill everything above into a checklist you can “start tomorrow.”

If You’re a Beginner Triathlete (Goal: Finish)

• 1 entry brick per week: ride 40 min Zone 2 + run 10 min light-fast.
• The focus isn’t speed; it’s getting the body to remember “riding is followed by running.”
• Practice quick transitions: set out your running shoes, start running within 90 seconds of finishing the ride.
• Start the run with high cadence and short strides; don’t rush into long strides.
• Find a safe, uninterrupted route like a riverside bike path.

If You’re an Intermediate Standard-Distance Athlete (Goal: PR)

• 1 brick per week, alternating transition and intensity types.
• Intensity bricks must have a clear target running pace—train “true pace under fatigue.”
• Start incorporating mini continuous bricks (bike-run alternation) to accelerate neural switching.
• Do your last quality brick 10–14 days before race day, then taper.

If You’re Preparing for 70.3 or Full Distance (Goal: Finish or Hit a Target)

• 1 long brick every 2–3 weeks, focusing on glycogen management and nutrition rehearsal.
• Schedule the key long brick for a full ironman 4–6 weeks out, then leave ample recovery time.
• Deliberately train in hot hours for heat adaptation (a natural advantage for Taiwanese athletes).
• Test every single piece of race-day nutrition in long bricks until it’s second nature.
• During taper, keep only very short wake-up bricks; no bricks within 3 days of race day.

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8. The 8 Brick Questions Athletes Ask Me Most (FAQ)

These are the questions athletes have worn out in our LINE group chats over the years—here they are, all in one place.

Q1: Do I have to run immediately after riding? Can I take a sip of water or use the bathroom in between?

A sip of water and quick transition actions are fine; the key is don’t let the pause exceed 1 to 2 minutes. Once you rest too long and your blood flow and heart rate “settle,” it’s no longer a brick—it’s two separate sessions. Transition technique itself needs practice, so I recommend treating actions like drinking and shoe placement as part of your T2 transition routine to rehearse.

Q2: Can I do bricks on an indoor trainer (rollers/direct-drive)?

Absolutely, and it’s super practical for Taiwan’s summer afternoon thunderstorms or poor air quality days. Ride the trainer, then change shoes and head out the door, or continue on a treadmill—both work. The trainer’s advantage is precise intensity control; the downside is missing outdoor wind resistance and posture variation, so in the weeks before race day, you should still schedule a few outdoor bricks to let your body adapt to real conditions.

Q3: Can I only do bricks and skip standalone running?

No. Brick is a “specific transition session,” but your running “base ability” (speed, aerobic engine, strength) still needs to be built through standalone running sessions. Treat brick as part of your running training, not all of it. A typical weekly structure is: several standalone swim/bike/run sessions + one brick—that’s complete.

Q4: Is a “reverse brick” (run then bike) necessary?

For the vast majority of athletes racing in the swim-bike-run order, prioritize “bike then run.” A reverse brick (run then bike) is useful for certain special training purposes, but it’s not essential. Put your limited training energy into the order you’ll actually face in competition.

Q5: I’m especially sore the day after a brick—is that normal?

Normal. A brick accumulates both cycling and running fatigue, and that “running under fatigue” segment carries greater eccentric load, so soreness is expected. That’s also why frequency can’t be too high. If soreness lasts more than 3 days or affects daily life, it means the intensity or volume of that session was too much—pull it back next time.

Q6: Can I train without a power meter or heart rate strap?

Yes. Using RPE (Rate of Perceived Exertion, 1–10) is more than enough. For transition bricks, aim for RPE 5–6 on the bike; for intensity bricks, 7–8. The human perception of “effort” is actually quite reliable—don’t skip training just because you lack equipment.

Q7: What should I eat before and after a brick?

It depends on the session length. Short transition bricks don’t need special fueling; but long bricks absolutely must rehearse race nutrition during the session—that’s one of their greatest values. Within 30 to 60 minutes after finishing, take in carbs plus protein to help replenish glycogen and repair. Taiwan’s convenient food options make this easy—an onigiri with unsweetened soy milk, or a bowl of braised pork rice with a tea egg, are both solid recovery meals.

Q8: I’m a pure runner/cyclist crossing into triathlon—will brick be harder for me?

Usually, pure cyclists transitioning to triathlon feel brick legs especially acutely (because you’re not used to running under fatigue); pure runners often burn too much leg power on the bike segment first. Both types need bricks, but be more conservative in the starting phase—begin with the shortest transition type and let your body gradually get to know this new connection state.

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Conclusion: Train the Pain Into Your Weapon

Back to Xiao Lin at the start. I set him up with an 8-week, once-a-week brick plan, progressing from transition type to intensity type. In week 9, he raced a standard-distance triathlon, and his run segment was less than 3 minutes slower than his standalone training runs—a dramatic improvement from the original 8 to 10 minutes behind. He texted me: “Coach, those cement legs are still there, but this time I knew they’d pass, so I didn’t panic.”

That’s the essence of brick training. Those cement legs will never completely disappear—they’re a physiological certainty: blood flow needs to redistribute, muscle movement patterns need to switch, and fuel has already been partially burned. But through training, you can shorten that pain, hold your pace even within it, and keep your mind from being crushed by it.

When your competitors are falling apart in the transition area, floundering in the first 2 kilometers of the run, you’ve trained yourself to smoothly settle into rhythm and overtake them. Transition ability has always been the most underestimated—yet most race-defining—skill in triathlon.

Next time you finish a ride and jump off the bike, remember—it’s not that you’re not strong enough; it’s your body talking to you. And now, you know how to answer it.

If I had to close with one sentence for you reading this: Triathlon isn’t the sum of three separate sports—it’s the art of the connection. Whoever handles the seams between swim-to-bike and bike-to-run more smoothly is the one who moves steadily forward while others collapse. And brick is the most direct, most honest tool you have for honing that art. Go train—those cement legs are waiting to be tamed by you.

This article is educational content and cannot replace individual assessment by a physician, physical therapist, or nutritionist.

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References

• USA Triathlon — How to Use Brick Workouts in Triathlon Training: https://www.usatriathlon.org/articles/training-tips/how-to-use-brick-workouts-in-triathlon-training
• Sports Performance Bulletin — Triathlon training: improving the bike-run transition during competition: https://www.sportsperformancebulletin.com/training/techniques/triathlon-training-improving-the-bike-run-transition-during-competition
• PMC — Discovering the sluggishness of triathlon running (attractor method, bike-run transition): https://pmc.ncbi.nlm.nih.gov/articles/PMC9802668/
• PMC — Effects of Cycling on Subsequent Running Performance, Stride Length, and Muscle Oxygen Saturation in Triathletes: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572577/
• IRONMAN 70.3 Kenting Taiwan (race distance and course information): https://www.k226.com/events/eventitem.aspx?id=1864

Related Reading

• Brick Training for Triathlon: Designing Leg Adaptation Workouts for Running Immediately After Cycling
• The Physiology of Brick Training: Why Your Legs Feel Like Lead After Getting Off the Bike
• The Science of Brick Training: Why Running After Cycling Feels Like Stepping on Cotton
• Brick Training: Why Your Legs Won’t Obey After Getting Off the Bike? Breaking Down the Physiological Impact of the Bike-to-Run Transition and Training Methods