jimatbeyond wrote:
I trained for about five years before my first Ironman.
In the ten months prior to the race, I was training at least 15 hours every week. There were two bike focused weeks where I rode for more than 25 hours each.
You may have done that, but it's absolutely unnecessary and for many people it's utterly unrealistic and perhaps undesirable to commit that amount of time.
I did my first IM on a typical volume of about 8hrs/wk for about 7 months peaking at about 12-13hrs/wk for a couple of weeks. I was doing around 7-8hrs for the first couple of months, rising briefly to a peak of about 12-13hrs with a couple of months to go. Then, due to unavoidable and unforeseen work issues, I was forced to reduce my training volume hugely in the last 2 months. I never planned to do huge training volume, but I did intend to average about 9-10hrs per week over the 7 months and peak around 13-14hrs. The interruption to training in the last 8 weeks or so was a huge problem. I was down to something like 5-6hrs a week for a few weeks IIRC. I was also a little overweight and lost about 20-25mins on the run due to a stupid nutrition error (I had some salt capsules in my pocket for the run but forgot to take any. I was going well until about ~25km then suddenly got huge pain in my arms, back and sides which forced me to walk most of the time from around the 27km mark. My legs and core, the muscles actually doing the work, were fine but when i ran it the virbration was excrutiating. I didn't know what was wrong, then realised it might be salt, took a couple of capsules and after another 15mins I was feeling much better and back running slowly from about the 35km mark. From that point on I was recovering and picking up speed all the way to the finish). I finished in just over 13hrs, which I was a bit disappointed with but without the run issue I think about 12:40 was definitely realistic. Had I been able to stick with my planned training volume and not the silly 5-6hrs in the months before the race something in the vicinity of 12:15 was realistic. That's not fast. But it's nowhere near worrying about the cutoff either.
Me: History: 5 years casual cycling and sporadic running with a few sprint duathlons and adventure races mixed in. I probably averaged about 4hrs/wk for the first 2-3 years and more like 5-8hrs/wk for year 3, 4 and fifth year up until start of IM prep about 7 months out. 1 year out from 1st IM I did an Olympic distance race and a couple of months later a 70.3. Enjoyed them and signed up for an IM the following season.
IM specific Preparation: 7 months averaging ~8hrs and a long reduction to 5-6hrs/wk where the peak volume should have been. Peaked at around 12-13hrs for a couple of weeks about two months out from the race.
jimatbeyond: History: 5 years training. Volume unknown
IM specific Preparation: 10 months with all weeks at minimum of 15hrs. Peak couple of weeks were 25hrs+.
There's quite a difference between those two approaches, and there's a huge middle ground that I reckon is perfectly reasonable for most people.
I was well able to complete my first IM on the low volume and horribly compromised training described even if my time wasn't fantastic. A plan to build from 70.3 to IM in 4 months based around 10-12hr weekly volume seems pretty reasonable to me, providing the 70.3 went well and was not excessively slow. I'd be a bit concerned given the OP took 6:45 for the 70.3 and had been hoping for 6:00. That's a big difference and starting from 6:45, an IM in 4 months looks considerably tougher. I'd want to be confident I knew whether the 6hrs was just hugely optimistic or if there were specific causes for the difference. If there were specific causes, they'll surely be far more significant in the context of an IM.