A short, high-intensity bike workout the day before your race can help increase muscle fuel stores available for the big event.
By and large, veteran triathletes train smarter than less experienced ones. They tend to do a better job of varying their workouts, training progressively over the course of a season and so forth. But, despite their experience and knowledge, training mistakes are common among the veteran ranks, too, and a few specific errors are peculiar to the veteran cohort—perpetrated far more often by competitors with a few seasons under their belts than by any newbie.
One example of a classic veteran training error is the use of very high-intensity intervals to sharpen up for a peak race during the final weeks of a training cycle. In a typical case of this kind, the athlete does nothing but slow stuff during the base phase of training, except perhaps in the pool, where he does whatever the rest of the masters group is doing.
In the mid-season he adds in some tempo, or threshold, workouts on the bike and run, and perhaps some longer intervals and/or hill work. Then, suddenly, in the peak phase of training, he starts running quarter-mile repeats on the track, churning out equally intense intervals on the bike and doing 25-yard sprint sets in the pool.
All of this super-high-intensity work is supposed to put the final edge on the athlete's readiness for an Olympic-distance triathlon, in which his average pace or speed in each discipline will be perhaps 20 percent slower than in these short training intervals.
If you think about it, sharpening up for an Olympic-distance triathlon with short intervals is sort of like sharpening for a 100-meter dash with 10-mile runs. It doesn't make a heck of a lot of sense. And yet it's a longstanding tradition in triathlon training, originally imported, I believe, from long-distance running, a sport in which even many of today's elite competitors still believe in the motto, First you build endurance, then you build speed.
Keeping on Track
The common rationale for emphasizing short, high-intensity intervals during the peak phase of training is that these workouts increase VO2 max, or the capacity of the muscles to consume oxygen during swimming, cycling and running. It's true that a boost in VO2 max almost always results in performance improvement.
It's also true that short, high-intensity intervals elevate VO2 max in many circumstances. However, in athletes who have already achieved a high level of fitness, this type of training has only a minimal effect on the muscles' capacity to consume oxygen. And if the athlete emphasizes short, high-intensity intervals earlier in the training cycle, as I recommend, repeating this emphasis in the peak phase will probably have no effect on VO2 max.
In fact, if you train properly throughout the training cycle, by including appropriate amounts of training at a broad range of intensities, your VO2 max will reach a temporary upper limit before you even get to the peak phase. No matter which type of training you emphasize in the peak phase, your aerobic capacity won't budge any higher. You'll have to wait until the next training cycle to see any further gains.
But there are other physiological variables, no less relevant to performance, which, with proper training, may continue to increase right up until race day. These variables include economy, or the energy cost of swimming, cycling or running at a given pace; metabolic efficiency, or the balance of fuels the muscles use and the relative contributions of aerobic and anaerobic metabolism while swimming, cycling or running at a given pace; and neuromuscular adaptations, such as increased ability to resist fatigue while swimming, cycling or running at a given pace due to increased ability to alter one's motor-unit recruitment patterns as preferred motor units become fatigued.
It is significant that I repeated the phrase "while swimming, cycling or running at a given pace" three times in the previous sentence. Each of the physiological adaptations I just cited is somewhat pace-specific, meaning that improvement at a slow pace will not fully translate into improvement at a fast pace, and vice versa. You will always see the greatest improvement in these performance-related physiological variables at the pace levels you emphasize most in your training.
Race-pace training is no exception. The greatest race pace-specific gains in economy, metabolic efficiency and neuromuscular fatigue resistance come from training at or near your goal race intensity.