A proper warm-up will significantly boost your race performance.
We work hard in the off-season, go to bed early and get up even earlier on weekends and weekdays alike. We even sacrifice our social lives in order to achieve levels of fitness we thought never possible. We train relentlessly, foregoing many of the pleasures our more "sane" friends enjoy.
We also go to great lengths to enjoy our personal obsession with our sport, and yet after all of that work, when we start to achieve a peak of fitness just in the nick of time, we often start to forgo many of the simple things that got us here to begin with. Warm-ups are often the first to go and, unfortunately for those who do not know any better, are often the practice that can make or break your performance in an event.
Whether it's a criterium, road race or time trial, the demands of your event will require specific energy systems to be ready to act when called upon during your race. Each event will require different contributions from different energy systems. If these energy systems are not activated and the clearance process initiated during your warm-up, they will not be ready to act when called upon in your race and your performance will suffer along with you in the process.
Shorter events often require a longer, more thorough, routine as the intensity is usually much higher and instantaneous. Longer events, conversely, often require a shorter but no less thorough warm-up.
Too many people, whether in a show of bravado or ignorance, blow off their warm-up thinking they will be able to warm into the race. If you are a Cat 1 with 15 years of racing in your legs, or a genetic phenomenon doing a local training race where the level of racing is beneath you, then this may be true. But if you're participating in a high-intensity event that matches your level of fitness and ability, then you had better be ready if you want to participate at any level--nevertheless excel.
Many also worry that they are going to blow up and not have anything left for the race if they go too hard in their warm-up. The level of work that you need and/or can tolerate is something that you can only find out in training, and we have seen far more instances of people being under rather than over warmed up.
As you train more, you'll find you are able to go harder later in your rides after doing your initial efforts, which prime your energy systems and activate the clearance process. This often comes as a surprise to those new to endurance training, but is a fact that cannot be denied. As you gain in fitness, you will find that it takes more time on the bike and more efforts to get a thorough warm-up and that you will not burn all your matches with a thorough routine.
This being said, it is also important to remember to drink during your warm-up so you do not enter your event in a state of dehydration. If calories are a concern, then be sure to drink a sports beverage containing electrolytes and carbohydrates during your effort. It is also highly suggested that you give yourself enough time to go to the bathroom, and take in a shot of gel so you do not enter your race hungry and depleted.
If you have several events in a weekend, or in a day, you still need to warm up again, contrary to popular thought. That being said, because your legs will be primed and more "open" from the previous efforts, you will not have to put in as many efforts or for as long. You will still want to stimulate these energy systems, but not overuse them, as caloric conservation and hydration is a concern at this point.
Stretch After, not Before
Additionally, many are observed performing static stretching prior to their event. As coaches, it always warms our hearts to see any athlete stretching, as it is often extremely difficult to get them to practice this lost art that is so beneficial when applied appropriately. However, according to Clark & Russell, static stretching has actually been shown to reduce the neuromuscular efficiency of the muscles being stretched--thus slowing muscle speed, reaction time and firing rate.