I've been a fairly serious age-group athlete since 1984. My strength and favorite part of triathlon has always been the bike. I've had a few breakthroughs over the years; one being the season after my first full winter of cycling - indoors and out depending on weather. I recall having a little breakthrough when I first started using deep race wheels. One would think after all these years of training and competing, at 55 years old, my fastest performances would be behind me.
The summer season of 2012, I had two races with bike speed averages faster than I've ever gone before. One at the Indy Triathlon and a few weeks later had another in Chicago (26 miles in 59 min).
The difference this year? Cyclocross last winter.
Cyclocross is the perfect activity to keep motivated and bike fit over the winter. And as it turns out, triathlon training is absolutely awesome base training for cyclocross racing. And together, they make a well rounded fitness program.
Triathlon fitness is all about "threshold" effort and therefore threshold training. At the end of the tri season when a triathlete has maxed his/her threshold, it's time to switch to anaerobic and VO2 Max intervals for cyclocross season. When cyclocross season wraps up in December, you roll back to base training for triathlon season - except this time, the level of fitness going into base is much, much higher than ever before.
It's good for the body to be pushed in new ways. Cyclocross racing puts a higher level of stress on the muscle and cardio system than does even the shortest sprint triathlon, increasing total fitness and anti-aging effect.