at 3K to 5K race pace will work your cardiovascular system to its limit, which will help increase the stroke volume of your heart and improve your muscles' ability to use oxygen to produce energy aerobically," explains Karen Hancock, coach
, what you ate, the weather and even your general mood before, during and after each run," adds Wood. "It'll help you identify patterns and the cause and effect of good and bad runs." And training logs don't have a ‘use by' date. "I have all my training
