If you're running a marathon this spring, you're about to enter the most critical – and difficult – four weeks of training, when 1) your weekly mileage is at its peak; 2) your motivation may be flagging; and 3) you're most likely to get sidelined
inspired the trend in 1954 with epic sessions like 10 x 200 metres followed by 50 x 400 metres – a combined 13.67 miles of speedwork. Ambitious runners the world over have aspired to that imposing standard ever since, in a quest for that elusive PB
