My opinion would be when you have a good base, and you are regularly running at least 30-40 miles per week, throw in a day of tempo or some intervals, hills or fartlek. So maybe when you are consistently running 30 or so miles a week for 5-6 months.<br><br>
Don't over-do, start off with just 'one key' workout a week, the rest, just do at a low HR, and steadily build your miles. If that works, then maybe add another day (once you have more base).
Don't over-do, start off with just 'one key' workout a week, the rest, just do at a low HR, and steadily build your miles. If that works, then maybe add another day (once you have more base).