For the last 12 weeks I've had two goals when running: improve my technique and increase my volume. The reason for this has been pretty simple. After evaluating my performances last season, it was easy to see that technique and endurance were serious limiters on the run. To address this, improving these two aspects of training has taken precedent over everything else.
In the past 12 weeks I've covered just over 550 miles, averaging 45+ miles/week. Taking Extreme Endurance has helped reduce the muscle soreness from high volume running. Within this time period, my aerobic pace has improved by over 1:00 minute/mile. I'm now completing my runs at an average pace of <7:15 minutes/mile. Running aerobically, you'd expect aerobic performance to improve, but that's not all. Following a recent recovery week, I ran a hilly 9.5km TT test loop which I've been using for the past 4 years. Surprisingly, I set a new PB by over 30 seconds! As I mentioned before, this was with absolutely NO intensity sessions, just concentrating on technique and staying aerobic in training.
If you feel that you've hit a bit of a plateau in your running, it's well worth looking at your volume. As with everything, there is a point of diminishing returns, but most age-groupers don't get close to it. Understandably, many people are time constrained and can't increase their run volume. In these cases, including intensity is key. It's important to remember that the 25 mile/week runner should not be following the same programme as the 50+ mile/week runner.
Tempo and threshold run sessions certainly have their place, I just don't believe that at this stage they will yield the best return on investment for me and my goals. In the past I have not put in the required miles to excel on the Ironman run, but that's what I'm working towards this year. When I reduce my run volume in the lead up to April I'll include some intensity sessions. Ironman South Africa is now just 11 weeks away, and as with every race, the end result will be determined by the run. You'd be a brave (and foolish!) man to guess the run split in a race, but I'm very confident of improving on last year's times.