Getting your taper right is a significant factor in achieving a good performance. Too much running in the last week will leave you tired, rather than recovered, and not fully reaping the benefits of your training. But some running is needed to keep your legs ticking over and stop you feeling flat on race day. Just how much will be partly dependent on how much running you normally do. A general rule is to run approximately one third of your usual volume but, of course, the type and amount you do on each particular day of the last week is important.
Tapering is a very individual thing, and different tapers work for different runners. Even many top elite athletes like to take one or two days off before a marathon. Experience and looking back at previous pleasing performances will help you find the taper strategy that works best for you. The following is a guide for a runner who usually trains most days of the week.
Presuming your marathon is on a Sunday it's good to do your last longish run (9-12 miles, at most) the Sunday before, having done a session with some pace within the two previous days. On the Monday, try a short, easy run of around 5 miles, or rest. On Tuesday or Wednesday, do some easy running and a mini interval session to keep your muscles firing, running the intervals a little quicker than race pace. Try 6 x 75 secs or 4-5 x 2 mins, with 90 seconds’ recovery between efforts. On Thursday, try a short run of 3-4 miles. On Friday, rest or do a short run of 2-3 miles with perhaps 3-4 very easy strides. Saturday should be a short run of 2-3 miles, or rest.