A good runner needs to know when to quit. Just like other aspects of training, it requires as much discipline not to run as it does to run. If you do too much before a race, you won't do your best. Training hard for an event can leave you drained both physically and mentally.
The only way to get the maximum benefit from your training is to taper. Every runner who has trained for competition has wondered when to cut back, and how much total rest to allow before an event. Most runners have used a combination of guesswork, intuition, and experience to decide.
The problem with tapering your workouts is to balance the need for rest and recovery with the inevitable detraining effect. There is certainly no single answer. Variables include training intensity, volume, frequency, base level of fitness, and the given event. Different taper plans are needed for a 5K and a marathon.
In a review of the current literature, researchers from Spain concluded that slow progressive reductions are more effective than sudden reductions in improving athletic performance.
A study with swimmers from Australia showed that one week of reduced training was not long enough to maximize the benefits of tapering, but researchers weren't able to demonstrate an optimum tapering plan.
According to American Running Editorial Board Member Jack Daniels, Ph.D. in Daniels' Running Formula, (1998, Human Kinetics, Champaign, IL, $16.95, 287 pp.), the tapering phase is the time for sharpening the qualities needed for a successful race and can last six weeks. He warns that as mileage drops, the temptation is to increase speed but that is not what your body needs to perform it's best.
American Running Editorial Board Member Pete Pfitzinger, in his Road Racing for Serious Runners (with Scott Douglas, 1999, Human Kinetics, Champaign, IL, $16.95, 189 pp) gives a marathon training schedule that shows mileage decreasing from a peak at five weeks before the marathon to 40 percent of peak mileage the week before the race.
Tapering may still largely be a matter of guesswork and experience with each runner working it out for herself. The absolute bottom line to remember is that training intensely right up to the time of a race is a mistake. Optimize the performance your hard work and training can give you by tapering up to your race day