Functional Reserve Capacity or FRC is the set energy amount you have available when you cycle beyond your critical power. It is like a battery that starts to run down when a certain level of intensity is reached. At the start of reaching the critical power, your battery is full then you reach past CP and you start draining that battery. The amount you have in that battery is set, but there are ways to increase its capacity as part of your cycling or triathlon training plans.
Understand your CP
This is something your cycle coach can help you with. Your critical power or CP is the highest effort you can maintain for a set period of time on the bike. Knowing where your CP levels are, helps you know what level of output you can maintain without burning out or pushing beyond it if it is not time to do so. The rate at which your FRC or the battery drains as you ride at an intensity above your CP depends on your capacity and how intense the effort is. You could deplete the battery quicker over a very short period of time, or you could ride a little less hard but be able to continue that intense effort for longer. But in each scenario, the size of your batter is the same and it will run out. You will reach a point when you are draining your FRC where you have nothing left and you have to stop or slow and recover.
Know your FRC value
Knowing your FRC value could be a part of personal triathlon training plans since when you know what it is you can then work on increasing it. Essentially you can train your body to have a bigger battery when you go past CP. Your FRC is measured in KJ and there are a number of options in how to get the value. There is software you can use that takes data from your workout, or there is also the CP3 test. Your cycle coach can help you choose how and get this important data. You should also get a better idea of what your recharge rates are so you know how long before you can dip into the battery again.
Improving your FRC
With your cycle coach, you can improve your FRC with what is essentially some interval training. It is tempting when doing such things to go hard straight out but remember those efforts are hard to reproduce at the next intense section, save the pushing to the extreme for the last few intervals but you should be pushing very close to the max before that. The intense intervals should last for between 30 to 120 seconds. It is important when you are at this point in your training that you use quality FRC specific sessions over quantity. It should be used in a conservative manner and integrated at the right stage. That is something the coach will better understand and help with. It is stressful on your body and it is easy to go too far.
