Marathon: how to improve on my finish time

Thuringen Ultra-2010

By now I've runned nine marathons on thirtheen months. Finish time on my first was 4h 37m 27s. Finish time on my last marathon-one week ago in Berlin-was 3h 44m 32s. Improvement in finish time is 53 min. That's excellent given that short range of time. I'm very satisfied with it.
However, I'm eager to continue with my development. In order to do that I need to summarize the evalutations from all my marathons and seek to establish week points that limits my performance as a marathon runner.

1. Marathons, completed:

.1 Stavanger Marathon-Norway, 29.8.09.
Finish time: 4h 37m 27s (1. Marathon)

.2 Oslo Marathon-Norway, 27.9.09.
Finish time: 4h 31m 10s (2. Marathon-New personal best!)

.3 Rome Marathon-Italy, 21.3.10.
Finish time: 4h 18m 50s (3. Marathon-New personal best!)

.4 Ålesund Marathon-Norway, 8.5.10.
Finish time: 3h 52m 9s (4. Marathon-New personal best!)
Placement: Overall winner, age group winner

.5 Copenhagen Marathon-Denmark, 23.5.10
Finish time: 3h 49m 14s (5. Marathon-New personal best!)

.6 Nordmarka Skogsmaraton-Norway, 12.6.10
(Forrest marathon)
Finish time: 4h 20m 23s (6. Marathon / First forrest marathon)

.7 Kongsvinger Skogsmaraton-Norway, 7th of August
(Forrest marathon)
Finish time: 4h 6m 26s (7. Marathon / Second forrest marathon)
Placement: Age-group winner, 4th overall.

.8 Stavanger Marathon-Norway, 28th of August
Finish time: 3h 46m 21s (8. Marathon-New personal best!)
Placement: Age-group winner, 4th overall.

.9 Berlin Marathon-Germany, 26th of Sep
Finish time: 3h 44m 32s (9. Marathon-New personal best!)
Placement: Age-group; 182 av 1.448 / Overall: 858 av 7.430

2. Experiences from finished marathon races:
The first marathon was like heading out in foreign territory. My longest run in advance had been 25 km. I was determined to finish, but I didn't know what kind of effort it would demand of me. Well. I had to walk large parts of the last 10km. My feet were pretty stiff. The limiter then was the ability of my feet to endure the distanse-lack of muscular endurance. One month later I ran my second marathon in Oslo. Not much of improvement, but I finished at a better time. In both races I needed to attend the toilette during the race-some 25-30 km out in the race.
The period leading up to the third marathon I had two sessions of running a week along with the same amount of sessions on the bike and strength-sessions. In addition I had a weekly session of swimming the frist quarter in 2010. I'm pretty certain that my emphasis on strength-training improved my core strength and made it possible to keep a higher, steady pace on my third marathon in Rome. The improvement in time is significant-13 minutes. A short visit at the toilette was needed this time as well.
After that I had a good transition period when travelling in Italy before starting my training in the second quarter. I then made the strategic decision to prioritize running the rest of the year to see how much I could improve on my running skills. It paid of well. After some weeks of building-focusing of quality-sessions-I finished at a new personal best in Ålesund. The improvement this time was very significant-26 minutes-finishing at 3h 52m 9s. At this race I remember feeling very fit. I'd planned on a slower pace, but quickly changed my mind and altered my moving pace. I felt almost surprised to finish at such a good finish time.
I'm certain that a rested body and mind after the stay in Italy, and 4-5 weeks of quality training made this possible. No need for a toilette visit this time.
In Copenhagen, two weeks later, I improved on my time with three more minutes. The reason? More quality work. In this race, as in the previous ones, I had made use of supply stations along the course as well as water from my drinking belt. No need for a toilette visit in Copenhagen either, but I was close by.
Positive split was 8,5 minutes.
The next two races are forrest-marathons and can only be compared with each other-not the other street-marathons. Anyhow, in Nordmarka skogsmarathon, I finished 8 minutes later than my targeted time. Positive split of 15 minutes. No toilette break.
After some ultra-races Kongsvinger skogsmarathon was due in August and I finished before my targeted time.
It was a tough race-hot and humid. No toilette break. Positive split of 6 minutes.
In both races I made use of supply stations in addition to water from my drinking belt. However, I think that the improvement of time in Kongsvinger-compared to Nordmarka(the races are pretty similar) is due to my focus on executing a predifined strategy. Three ultra-races had taught me some lessons on that matter.
In addition, to endure more pain as well.
At Stavanger marathon, in August-a week after an ultrarun-I managed to keep a steady pace right up to 33 km. By then I needed to made use of the supply station and lost 5 minutes. 5 km later I needed to attend natures call and lost additional 5 minutes. In spite of this I finished at new personal best. Positive split of 12 minutes. Again to decide on a strategy in advance paid off.
Finally in Berlin-a week after an demanding ultra-race on trails-I'd decided to run for a pace of 5min/km all the way through. The conditions weren't good for a record run with a lot of runners preventing me from keeping a steady pace and a lousy weather. Anyway, new PB. Toilette break after 24 km, and I needed to make use of supply stations after 30 km. Pains in my butt and some stiff hamstrings made the race difficult. My predetermined strategy helped me to keep focus during the race. Positive split of 11 min. I noticed pain in my lower back after the race and still feel some of it now-several days later.

3. Evaluation:
-Nutrition: 
I need to improve on that point. Now I'm not fully prepared at the start and I need to supply during the race in addition to what I bring along. Both points affects my finish time in a negative way. In later races I'll use my drinking belt, but load up with 6 bottles of energy drink and two bottles of Coca Cola. In addition I'll use energy gels to supply with energy during the race. I'll go for four-one every 45 min. In advance I will make sure that my glycogen storages are full. I will eat no solid food on race day before the race. I will establish a strict nutrition-regime before and throughout the race to follow.

-Technique: 
My core strength needs to be improved. The last races I have only been improving with minutes. I clearly feel that I'm capable of running at 5 min/km all the way, but that my core strength is a limiter. During the coming winter I'll be working serious on improving on that point.

-Mental part: 
I feel I'm getting better race by race on this point. Focus now is to accept that a good finish time demands more suffering-learn to endure even more pain. I'll be working on that during the coming winter in my ultra-long training runs(6h +), during the 6h race at the end of October this year and at my first 24h race at the end of November.

-Pace:
To get more steady is important. In marathon there is no such thing as a stop or a walking break during the race. I'm running all the time. Important to me during my training in the winter is to establish a more steady pace throughout all my running time. I'm going to use my ultra.long training runs to improve on that point.
I'm going to make an effort to get used to split times every 5km and work my way through every km checking on my pace.

-Preparing for race:
Next time my aim is to improve on my finish time I will have to make sure I am more rested. To race a week after an ultrarace is far from ideal. The way my competition programme looks now it seems like the fourth quarter next year will be a good time to establish a substancial improvement of PB.