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For those building base since November, the end is near. After eight weeks of strict low intensity, cutting loose some efforts in higher zones is near orgasmic. But, proceed with caution. Too much intensity too soon will bring on form like gangbusters, which can lead to some great performances in late February and March, but will leave you sputtering just when the season is getting to full swing. The faster you ascend to form, the more fleeting and unpredictable the peak. That's why a transition period after base is required.
I recommend a week of active rest after base is done. The last week of base can be hard, with the hours peaking usually in the high twenties, demanding long rides on the weekends and perhaps some night riding during the week for those with regular work schedules. A casual week is needed. Funny thing is, after base, many riders are busting at the seams to dump the HR restrictions and rip some hard efforts. Bust a move. You deserve it. A couple of hard efforts to get the carbon off the plugs isn't going to hurt anything. You can go recreate with vigor. Don't even take your HR monitor with you. Go run, skate ski, or whatever you wish to get your lactic fix. Enjoy it in this rest week, because the next three weeks are going to be somewhat less footloose and fancy free.
The next block is to take you gently from low intensity to high intensity. 'Gently' isn't an adjective generally used to describe the basic nature of elite cyclists. Don't shake the champagne if you want it to last through the meal. The perfect recipe for this block is leg-speed and on-the-bike strength work. These two drills are somewhat polar physiologically and will stretch neuromuscular systems and allow you to gradually grow into intensity. In doing these drills, your HR will flirt with lactate threshold, but be careful not to sustain threshold for anything over three minutes. There will be no structured threshold during this block, but you may dance all around it. The drills are fun, and provide a variety that was not there during base, so you should arrive home satisfied after these rides.
Here's a sample of a workout during this block. If you don't have a watch with a countdown alarm, get one. They come in handy for many training drills. Set it for a five minute countdown and repeat. Start the alarm and begin with 5 minutes of a comfortable cadence at zone 2. When the alarm beeps, switch gears to super-low resistance and take the cadence up to 120 or higher. If you can't spin 120 below threshold, tone it down (and start working on your pedaling efficiency). When the bell tolls again, go BCR and take the cadence to sub 50, and work up a good burn in the prime movers. Do some in the saddle and out of the saddle. That's five at normal recovery cadence, five at low resistance/high cadence, and five at high resistance/low cadence. Repeat this for two hours and you will have earned your oats for the day. Do this workout three days a week. You can vary the interval length as well. You can focus on strength one day, and leg-speed the next. There are infinite options. Make it interesting and fun. Fill in the gaps with recovery rides, and a passive day.
The rapture is coming, but it will be another month. Be patient. This is a fun phase, but you still have to control yourself. By the end of this block, your need to go on fast, dicey group rides will come to an exquisite crescendo. Bide your time. Let those without a plan go ballistic. You must hold back. Bottle the fury. When transition is over, you can uncork, knowing that you are on track for a predictable and long-lasting peak window in prime-time.