The Mushy Middle

In defiance of Thursday's heat (mercury hit 39 celcius), I still managed a good training day with a 16km morning run followed by a 61km ride and then an easy swim. In the afternoon I did another 6km run and 500m bay swim. However Friday morning's swim didn't go as well. We arrived very late meaning I missed the warmup which resulted in me hurting my back in the first set (butterfly). I struggled on for a while, but without without the warmup and probably a little fatigue from Thursday I never got into the session and ended up hopping out after only 1.8km - very disappointing.

The Saturday Brick session with the Triathlon Club was always going to be the key session for the week. With this in mind I eased off my efforts in the preceding days - only ran 6.9 on Tuesday and cut back Thursday's planned 18km to 16km. This caution seemed to pay off, as although I felt a little stiff, it was probably the best I've felt in a few weeks thanks to a lot of stretching and foam roller sessions.

The Brick session was a 100km Ride followed by a 10km Run. We rode to Mt Martha with 30 minute efforts (race pace) followed by 10 minutes of recovery, repeating for the whole ride. Well at least that was the plan, I ended up riding the whole way back at race pace until the last 5km when my legs finally gave up. I'm not worried about not staying strong for the entire ride. It is still early in my preparation and I have plenty of time to build up my endurance.

At the beginning of the run my legs understandably felt quite heavy. I used the first kilometre as warmup, running at 5 min pace and the legs quickly loosened up. In between a 1km warmup and 1km cooldown, the plan was to run at 4m30s pace (per km) which I believe is a good Half Ironman pace (about a 1h35m Half Marathon). The problem is I rarely run at this pace, so I have no feeling or natural rhythm for this speed. As a result I found myself either running too fast or too slow. Most of the time I was too fast and even though it felt very comfortable at the time, my heart rate would slowly creep up. Around 155bpm is roughly the heart rate I will am aiming for, but by the 6km mark it was 165bpm. Once the heart rate is up it is very difficult to get it back down unless you slow down significantly, so I decided to drop into cooldown mode and make it a 7km run instead.

Most of my run training falls into 2 categories - Slow or Fast. The majority of my runs are slow (around 5m20s pace) with occasional recovery runs that are even slower. When I do speed sessions (I've only done 5 this season) I run the efforts between 3m30s and 3m40s pace. The slow pace running builds aerobic endurance and allows you to build run mileage with reduced chance of injury and better recovery between sessions. Whereas the fast running builds speed and improves your body's ability to manage oxygen debt, but takes more recovery and is more susceptible to injury. In between these two speeds is often referred to as the Mushy Middle. This middle speed pace is too fast to improve your aerobic threshold (because you are not running aerobically) and too slow to get speed improvements. So the Mushy Middle tires you out quicker than slow running, contains more risk of injury, requires more recovery time, limits your ability to build mileage and provides less training benefit.

The exception to my fast or slow run training pace is when I do brick sessions (bike & run). The run off the bike will usually be done at race pace. My early season brick sessions were targetted at the Sprint distance, so fast running (sub 4 min pace). Last season I was targetting Ironman pace, so slow running. Now is the first time in 2 years that I am targetting Half Ironman pace (4m30s pace), so this speed has become unnatural to me.

I've only completed 2 Half Ironman's and both times struggled at the end of the run leg. I believe the key to solving this problem is more run mileage and more brick sessions to practice run pace. Next time I'll set a HR alert at 160bpm which will hopefully help me discover a good rhythm around 4m30s pace.