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Over the years, it has become apparent to me that cyclists are human after all. Though extraordinary in every way, cyclists are subject to the same laws of physics as every other physical entities in the universe. Ever notice how the moon cycles from new to full and wanes back to a sliver, all in about a month? It's no coincidence that most creatures on our planet also have cycles that adhere to a similar chronology. There is a divine pattern to a cyclist's progression, one that goes hand in hand with universal physical law. If they want to ride to stardom, cyclists must obey those universal laws.
When the body undergoes a stress, there is a set period where the body absorbs that stress, evaluates it, and then decides to make the needed modifications allowing it to adapt to that stress. I call this period the adaptation cycle: the time it takes for the body to take a stress and manifest a positive physical gain. For most living things (including we humans), three weeks is the average period it takes to make a physical change for the better. Universal physical laws dictate the chronology -- not the rider, nor the coach. The three week number was not determined by convenience. It's the result of physical forces that repeat themselves in extremely predictable patterns throughout the universe, from the largest galaxy down to the tiniest subatomic particle. Fibonacci, da Vinci, Newton, Einstein, Crawford -- the greatest minds of all time have been in touch with the overwhelming physical patterns that govern our progress.
As an example, let's look at the period it takes for a cyclist to make a positive adaptation to altitude. An athlete comes to 7000 ft from sea level and begins training. Each day that goes by finds the athlete a bit more depleted, with blood levels typically falling each day for around ten days. This is the absorption cycle, when the body is absorbing and calculating the stress, and deciding if an adaptation is necessary. At this point, most athletes will begin to pull out of the seeming downward cycle, due primarily to an endocrine erythropoetic response (the body starts making red blood cells). Each day after this, the cyclist's training effect will grow until it peaks, usually at around 21 days. After peak blood levels have been achieved, the body will revert to homeostasis (the basal blood level), unless a similar upgrade in oxygen depletion is exercised to maintain peak levels. In short, if you go to altitude to acclimate and get stronger, you need to allow for three weeks to get the effect you desire.
In many aspects of fitness, the positive gains can be accumulative with each cycle. In some, like blood levels, there are limits to the gains that can be made. It is necessary to keep the stress constant throughout the cycle. For example, if power gains are desired, then power must be the consistent theme of the cycle. Stick to the theme and keep the stress in the power mode, and you can expect to make great gains on the power side. Same with threshold, leg speed, strength, endurance. Two cycles of these elements will pay good dividends and create a balanced cyclist.
Don't make the error of trying to force an adaptation to happen faster. It can be done, but the result is unpredictable and often disastrous. This three week plan is simple to follow and extremely effective, allowing for continuous progression, and preventing burnout and fatigue. It is still necessary to periodize on the macro level, but the best guideline once the season starts is to always take the fourth week easy, even if you have to race the weekend. It will keep you on track, and going good through the season.
The reason the three week pattern is not always apparent is because it is an optimal number, not a real number. Optimal doesn't happen in nature. We can' t force the three week pattern to work, it must be planned and achieved with care. Nature tends to be reactive, and to achieve greatness in cycling, we must be proactive. Three weeks is enough time anticipate the reaction to training stress, and keep a positive training response from slowing down due to lack of inertia. A month is not a random time period; it is the period of growth and renewal for optimal perpetual progression. Work for three, rest for one. It is your cosmic destiny.