Tapering training is critical for reaching the starting line in peak fitness and with maximal energy reserves. The challenge during the last several weeks leading up to the marathon is to find the best balance between continued training to get into the best possible racing shape and resting to eliminate the fatigue of training.
Put simply, tapering corrects the accumulated wear and tear of training. More specifically, it appears that tapering leads to improvements in running economy (how much oxygen you need to run at a given pace) and muscle strength.
The scientific evidence indicates that the key to effective tapering is to substantially reduce mileage while maintaining the intensity of training. Reducing the amount that is ran reduces accumulated fatigue to improve marathon performance, while interspersing efforts that have been done throughout the buildup, including VO2max intervals and strides, maintains the adaptations that runners worked hard to gain over the past several months. (During tapering, runners should do shorter sessions at those paces, so while maintaining the intensity of training, the quantity of higher-intensity training is still being reduced.) A tune-up race 2 weeks before the marathon is also a key session for advancing fitness (and, ideally, providing psychological reinforcement).
How much your overall mileage is reduced depends on the current training volume, past experience (know thyself), and overall health. In general, older runners tend to require slightly more time to taper than younger runners. Our guidelines for cutting back mileage, based on research, discussions with elite marathoners and coaches, and personal experience, are as follows:
- Third week premarathon: Reduce mileage by 20 to 25 percent.
- Second week premarathon: Reduce mileage by 40 percent.
- Marathon week (6 days before race): Reduce mileage by 60 percent.
For example, a marathoner whose training peaks at 70 miles (113 km) per week would reduce her mileage by 20 to 25 percent (to 52 to 56 mi; 84 to 90 km) in the third week before the race, by 40 percent (to 42 mi; 68 km) the following week, and by 60 percent (to 28 mi; 45 km) during race week. For race week, the 60 percent mileage reduction is for the 6 days leading up to the marathon.
Three weeks before a marathon is arguably the most important time for a successful taper. This is the week that many marathoners do too much because the marathon still seems a long way off. If a marathoner works too hard during this week, however, they may find themselves feeling flat with 2 weeks to go and struggling to rest up as quickly as possible for the race. It's much better physiologically and psychologically to allow the body to start to freshen up during this week. This allows for a much more relaxed state of mind, feeling that marathon preparation is on track rather than stressing that all efforts are going to be wasted.
This is an excerpt from Advanced Marathoning.