Prolonged and intense endurance training like cycling increases your protein requirements for two reasons. Firstly, you need more to compensate for the increased breakdown of protein during training. When muscle glycogen stores become low (around 60-90 minutes of endurance training) certain amino acids known as branched chain amino acids which make up a substantial proportion of muscle protein (see box below) can be used for energy.
Secondly, and perhaps more importantly for cyclists, protein is vital for the repair and recovery of muscle tissue after a ride. It’s in this post-recovery phase that you may need to rethink what you’re eating. Not only should you be rebuilding your fuel stores immediately after a ride, but you also need to repair damaged muscle ﬁbres as soon as possible.
Eat the wrong foods after training and you’ll end up exhausted with sore, aching legs. If you eat right then your body will get stronger, ﬁtter and recover faster.
Protein-rich foods have additional beneﬁts too – they are involved in producing neurotransmitters, chemical messengers in the brain keeping you alert, focused and energised. They also slow down the release rate of glucose into the bloodstream, helping stabilise blood sugar between rides, and containing energising nutrients such as B vitamins, iron and zinc.
Source: Bike Radar