Running Volume vs Intensity

Within the past 6 weeks my run mileage has been building gradually, culminating in my first 50 mile run week since the end of May.  The graph below shows that the intensity I'm running at is steady, with an average heart rate of around 150 bpm and an average speed of around 8mph (7:30 min/mile pace).  The plan is to get out and log the miles, without worrying about specific workouts.  Just run.

*Average speed is lower on 19/12/10 due to snow and icy conditions*

Run Distance/Av. Speed/Heart Rate 13/12/10 - 19/12/10

(Click to Enlarge)

My approach to run training in the past two years has been very different.  From July 2008 - June 2009 I concentrated on frequency and volume, running 1600 miles over the 12 month period.  This averages out to roughly 30 miles/week.  During the winter I had a 3 month period of focussed running, with weekly long runs and regular 50+ mile weeks.  The intensity of every run was easy to moderate, with the majority at a steady pace.  I wasn't worrying about intervals or hill repeats, simply running day in and day out.  There was one particular week where I ran 12 times, doubling up on 5 days.  

Moving in to the 2010 season I changed things.  From July 2009 - June 2010 I reduced both the frequency and volume of running, but added in more intensity.  Over this 12 month period my volume was 1200 miles, which was a massive 25% reduction compared to the previous year, averaging only 23 miles/week.  I was running 4-5 times per week, but every session had some quality work.  I was doing everything I hadn't done last year, such as hill repeats, tempo runs and threshold intervals.  

Two different years, two different approaches.  The results: in 2009 I ran 3:33 at Ironman Austria and in 2010 I ran 3:26 at the same race (and a 3:27 in Hawaii).  That's a 3% improvement.  It doesn't sound like much, but over 26.2 miles, it makes a lot of difference.  So is reduced volume and higher intensity the way to go?  There are many variables in comparing results, such as weather conditions and race nutrition, so it can be difficult to draw conclusions.  I suspect the gains made this year were largely cumulative and a result of the past four years of consistent training, rather than solely down to the training done in the 12 months prior.  The take away - consistency is King.