The assumption is that this will be your first half marathon and that you have not yet currently run further than about 9 or 10 miles. You are regularly running three times a week, can do four runs some weeks, are comfortable running up to 7 or 8 miles on a weekly basis and have some ability to manage your running at different paces.
For you, ‘steady’ and half marathon pace are likely to be similar paces, and so your typical half marathon time is likely to be in the region of 115 to 135 minutes. Your priority is to build up and recover from the longer runs and therefore there is less initial focus on faster ‘interval’ type training as the balance between quicker improvement and an overuse injury is more likely to be unfavourable if you do too much too fast too soon.
There are weekly sessions of Threshold running, which is likely to be somewhere between your 5k/Parkrun and 10k race pace. Mileage calculations are on the notional basis that you will do about a 2 hour half marathon. This level of runner is more likely than the higher levels to make really substantial progress over 26 weeks so that T (Threshold) pace in week 24 may be significantly quicker than what T was in week 1.
The headlines for this half marathon training plan are:
- 3 or 4 runs per week, each week
- 26 week average = 23 miles per week
- Single week max = 29 miles
If you are over 40/45 years old you might think about replacing one steady run per week with aerobic cross training to keep the aerobic load high without the frequent impact of running.