Tapering your mileage before a long distance race is all about conserving energy and ensuring race readiness. Long distance running, particularly training for a marathon, brings heavy fatigue with it. Shorter races, such as the 10k or even the half marathon (if you are a seasoned runner) may not require a taper, but the marathon absolutely will. If you are new to running, you will want to incorporate a taper into your half marathon preparation as well.
So how do you know when to begin tapering mileage before a race? Ideally, you should start 3 to 4 weeks prior to race day. This is the optimal window to retain fitness and allow your body to rest before the big event. Tapering any sooner than 4 weeks may cause your body to lose some of the fitness achievement you have retained, so it is not recommended. If you begin your taper at 4 weeks, it is best to do a slow taper so that you retain fitness while giving your body the break it needs to conquer the race mileage.
A marathon training program typically consists of 16 weeks. At the start of those training weeks, you typically build mileage every 4th running day. Typical training programs include at least 4 days of running with 2 days of cross training and 1 off day. At least 2 runs should be tempo runs, while 1 day is reserved for speed work. The other day is for the long run, which is to build mileage. Typically, mileage is increased at a rate of 10% increase, although some runners increase higher amounts than this earlier on if they have a strong running base. Each week, the mileage increases on the long run by about 2 or 3 miles. Many programs peak at the 18 – 24 mile range. Some programs advocate running the full marathon distance while others recommend keeping mileage lower. This is up to the individual runner and his or her goals. However, tapering should be fairly uniform across the board. Tapering should decrease approximately 10% per week of the mileage up until race day.
The last phase of training should be about energy conservation. If you attempt to run longer distances just before the race you run the risk of injury, burn out or a less than ideal performance. The taper allows you the chance to mentally prepare for the distance, while running long runs that you have already conquered. Many first time marathoners get very nervous about accomplishing the distance on race day when they haven’t achieved it in training. The truth is, the energy of the race will carry you a lot further than you have been able to make it on your training runs so far. Practicing successful distances is far more important than pushing mileage until the last minute.
This is also a time to rest, stretch and perhaps get a massage prior to the race to ensure than muscles are prepared and ready to push through the mileage on race day. Hydration, nutrition and sleep are very important during this phase (as they are throughout the entire training program) so that the body can recover from training and prepare for racing.