Triathlon Brick Sessions: Why Bother?

Whether or not you believe that triathlon brick sessions are a physiologically effective and beneficial method of training (there has been a fair amount of debate on this recently in the triathlon sphere), there is another angle to consider when deciding if you should add  a regular brick workout to your triathlon training schedule.

In many quarters the jury is out regarding the physiological value of incorporating regular brick sessions into your triathlon training schedule.

However, one area of benefit cannot be argued with; the fact is that brick sessions offer the uniquely specific opportunity to work on movement and technique based issues which occur at the start of the run.

Running Technique Quick Guide [FREE PDF]

As any triathlete will know, getting the legs running properly and efficiently off the bike can be a real challenge. This is particularly due to the lack of activation of the glute muscles as you begin to run. This glute inactivity due to the disadvantageous position they had been placed in during the bike section, and tightness in the hip-flexors which comes associated with extended time in the saddle. Running without engaged and strong glutes is very much a performance limiter as it prevents your ability to impart force into the ground as you extend the hip.

The physiological reason for this lack of glute activation is due to a neurological phenomenon called reciprocal inhibition (RI). The effects of RI can be seen across joints all over the body, where opposing muscle groups should work together to facilitate movement, but fail to do so when excess tightness or over-activity is held in one area.

In terms of RI at the hip: a normal reciprocal muscle action is for the hip flexors to relax and lengthen when we want to extend the hip, allowing the glutes to engage and work through to full extension, un-inhibited. However, when excess tightness is held in the hip flexors, available range into hip extension is limited, therefore limiting the ability of the glutes as a muscle group to engage and extend the hip. This is RI in action.

This RI often occurs on the bike, where we sit for an extended period in a hip flexed posture, allowing the hip flexors to get tight and over-active. Then, when we stand up to run, our range of hip extension is limited and we can’t engage our glutes properly. This can often take a significant time at the beginning of your run to normalise, costing you time as run efficiency is compromised.

It’s important to appreciate that the glutes function to create hip extension when running to power you down the road. When coming off the bike, the glutes are not doing that job well at all due to RI. The longer the ride, the greater the negative effect. With that in mind…

  • Use brick sessions as an opportunity to perfect and reinforce your running form, maintaining good posture and working to engage your glutes. As with all other skills, the skill of running off the bike can be developed, so that your body recognises the need to engage the correct muscle groups from the start.
  • Make sure that your bike fit is set up not simply to optimise your cycle efficiency, but also with a view to being able to run off the bike well, minimising hip flexor tightness.
  • Take time to fit regular hip flexor mobilising exercises into your program. I get my athletes to mobilise their hip flexors after every session on the bike and before/after every run session. This helps to reduce the chronic effects of RI.

I’m not saying that brick runs are the cure-all answer to running well off the bike. You need to develop active and strong glutes and learn to run with good technique first – then put these elements into specific context by practicing running well off the bike in a T2 specific situation.

What I am saying though, is that it’s largely irrelevant how important you feel brick runs are in terms of physiology, the fact is that you need to enable your body to learn the correct transition between two fundamentally different movement patterns. Becoming efficient at transitioning between the movement of cycling and that of running, and using the specific muscle groups in the right way is key to successful running performance coming out of T2.

Last updated on March 2nd, 2021.


  1. Just read the above article about brick sessions. I just wanted to know if you could explain what perfect bike setup is.

    1. That’s a difficult question, as it’s so specific to the individual and event. Also, I’m not a bike fitter! I have some great bike fit guys here in London that I encourage our coached triathletes to go and work with, @FreeSpeedLondon.

  2. James,

    I’d also add that because in distance running the availability of metabolic substrate (principally muscle glycogen and blood glucose) and the ability to regulate core body temperature are progressively more important determinants of success, that running in some state of glycogen depletion with a core temperature already elevated by preceding exercise can only improve efficiency in said post bike state.



    1. A.Jones. The Physiology of the World Record Holder for the Women’s Marathon. International Journal of Sports Science & Coaching Volume 1 · Number 2 · 2006

    1. Or alternatively you are completing your run training in a metabolically compromised state, and therefore not getting the most out of your training.

      Then again I am sure you were suggesting this as a complimentary session to your greater exercise program.

      Great article yet again James -thankyou

  3. So brick running sessions as well as exercises like single leg squats to work your glutes will help the transition from cycling to running smoother and more efficient? And also help running technique after the bike leg?