If you've been training more or less correctly, the last few weeks of a specific training program should be the race preparation phase, also called the peak phase. During this period of training you will complete a fair bit of training at your specific race effort levels. There should still be a significant amount of base/endurance, strength maintenenace, and some level of threshold or V02 max type efforts. However, those are no longer the focus of your weekly training.
Race prep for an Ironman or long distance is much different than a sprint triathlon. The volume is higher and the intensity is lower. More time and energy has to be devoted to nutrition and hydration practice than a sprint race. This holds true through the spectrum of racing.
The goal with race prep workouts are to spend a fair amount of time at race level effort. This helps the athlete in a number of ways. Dialing in pace/power/HR; managing fatigue and discomfort; dialing in nutrition and hydration requirements; discovering upper limits on fitness; and reducing race day variables and race anxiety.
Athletes need to know the very narrow range of their maximal sustainable effort level for the race in order to achieve top results. This is not something to guess about and race day prep workouts determine this.
An Ironman race prep workout could be something like a 30 minute swim - 4 hour ride - 1 hour run, all completed at goal race effort.
A sprint triathlon prep workout could be a 30 minute easy ride - 30 minute hard ride - 20 minute hard run with the hard portions at goal race effort.
Power and HR targets will vary among individual athletes due to their specific training and ability. Generally speaking, Ironman would be +/- 70% of functional threshold power (FTP) or +/- 85% of lactate threshold (LT) heart rate, and sprint races would be +/- 90-95% of FTP or just a bit below LT HR. Half Ironman and international distance events fall somewhere on the curve between the two.
With proper nutrition and hydration, faster athletes can hold a higher percent of LT/FTP as they will finish sooner. A goal is to finish just before becoming fatigued.
Individually speaking, as the duration increases the effort level needs to decrease in order to manage and minimize fatigue. So a 'fit' 4-hour 70.3 athlete will have a different FTP/LT target than a fit 6-hour 70.3 athlete.
These ranges and targets should be well established in training before entering the race prep phase. The goal with your race prep workouts is to have a really, really good idea of what works for you.
It's OK if you discover that 70% FTP for 112 miles leaves you a little too gassed for the run! Better to figure that out now and dial the bike effort back then wind up walking/stumbling through the last 10 miles of your Ironman. The same goes for sprint races. Super fit athletes can ride at or even over FTP for a 10-15 mile bike leg. You may not be able to and still run within your ability.
Don't guess. Discover. Prepare.
That is how you PR.
Marty Gaal, CSCS, is a USA Triathlon coach who lives in the Triangle area of North Carolina. Marty has been coaching endurance athletes since 2002. You can read more about OSB coaching services at www.osbmultisport.com.