Brick Training Guide: Why and How
The first time you try to run immediately after cycling, your legs will feel like they belong to someone else. Your quads will be heavy, your stride will feel awkward, and you’ll question whether you’ve somehow forgotten how to run. This disconcerting sensation is exactly why brick training exists.
What Is Brick Training?
A brick session involves training two disciplines back-to-back with minimal rest between them. The name supposedly comes from how your legs feel like bricks when you start running after cycling, though some say it stands for “bike-run-ick.”
Whilst you can combine any two triathlon disciplines, bike-to-run bricks form the foundation of triathlon-specific training. The swim-to-bike transition doesn’t create the same muscular adaptation challenges, and swim-to-run combinations are less practical for most athletes.
Why Brick Training Matters
On race day, you won’t have the luxury of resting between disciplines. Your body needs to adapt to the unique demands of running on fatigued legs with different muscles firing after an hour or more in the saddle.
The physiological changes are significant. During cycling, you’re using predominantly your quadriceps and hip flexors in a non-weight-bearing position. When you start running, you suddenly shift to full weight-bearing whilst demanding different muscle recruitment patterns and joint angles.
Your cardiovascular system also undergoes adjustment. Blood flow that was directed to your cycling muscles must redistribute to support your running gait. This transition creates temporary inefficiency that brick training helps minimise.
Beyond the physical adaptation, brick sessions build mental resilience. They teach you to push through discomfort and find your rhythm when everything feels wrong. This psychological toughness directly translates to better race performances.
How to Structure Brick Sessions
Start with short, manageable bricks. A 30-minute steady bike ride followed by a 10-minute easy run teaches your body the transition without overwhelming it. Quality matters far more than quantity in these early sessions.
As you adapt, gradually increase either the bike duration, the run duration, or the intensity—but never all three simultaneously. A well-structured progression might look like this:
- Weeks 1-2: 30-minute bike, 10-minute run, both at easy effort
- Weeks 3-4: 45-minute bike, 15-minute run, both at steady effort
- Weeks 5-6: 60-minute bike, 20-minute run, bike at tempo, run at easy effort
- Weeks 7-8: 60-minute bike, 20-minute run, bike at tempo, run at race pace
The transition between bike and run should be quick—imagine you’re in a race. Change shoes, grab water if needed, and start running within 60 seconds. This urgency reinforces the race-day experience and prevents your muscles from cooling down completely.
Frequency Recommendations
For sprint and Olympic distance racing, one brick session per week during your build phase is sufficient. If you’re training for a half or full Ironman, consider adding a second brick every other week during peak training.
Schedule your bricks on days when you’re relatively fresh—typically mid-week or on the weekend when you have time to recover afterwards. Avoid placing bricks immediately before or after your longest or hardest training sessions.
Remember that brick sessions are demanding. They create more fatigue than the same duration of bike and run done separately. Factor this into your overall training load and recovery planning.
Common Brick Training Mistakes
The most prevalent error is starting with bricks that are too long or too intense. Athletes often assume that if they can ride for two hours and run for an hour separately, they should combine similar durations in a brick. This leads to excessive fatigue, poor form, and increased injury risk.
Another mistake is neglecting the run portion. Some athletes focus so heavily on the bike that they arrive at the run completely depleted. Your brick isn’t about smashing the bike segment—it’s about learning to run well on tired legs.
Finally, many athletes skip brick training entirely until a few weeks before their race. The adaptations from brick training take time to develop. Start incorporating bricks at least eight to ten weeks before your target race.
Managing the Jelly Legs Sensation
Those first few minutes off the bike will always feel strange, but the sensation becomes less severe with regular brick training. Focus on quick leg turnover rather than stride length when you start running. Think of it as shaking out your legs to restore normal muscle firing patterns.
Keep your effort controlled for the first kilometre. You’ll naturally find your rhythm as your body adjusts. If you start too hard, you’ll pay for it later in the run.
Some athletes find it helpful to shift to an easier gear on the bike for the final few minutes, increasing their cadence to pre-activate their running muscles. Experiment to find what works for you.
Practical Training Tips
Set up your transition area at home or in your car exactly as you would on race day. Practice changing shoes quickly, grabbing nutrition, and starting your run. This rehearsal builds muscle memory for race day.
Use your brick sessions to test race nutrition strategies. Can you tolerate the energy gel you plan to use before the run? Does your hydration strategy work? Brick sessions provide the perfect opportunity to experiment without race-day consequences.
If you’re limited by time or fatigue, shorter, more frequent bricks often deliver better results than occasional marathon brick sessions. Even a 20-minute bike followed by a 5-minute run provides valuable adaptation stimulus.
Brick training transforms the chaotic experience of running off the bike into something manageable and predictable. Embrace the discomfort, trust the process, and watch as those heavy legs gradually learn to carry you smoothly through transition and onto a strong run split.
