Last week I touched on using HR to dictate effort and pace on the run so that you can execute your intended game plan during the race. A big part of executing a good run plan is executing a smart bike plan. A strong bike will build a solid run. One vital tool that will help you with the bike is using a power-meter.
I first started training with power when I bought a used set of Garmin Vector 2 pedals on Ebay for a steal of a deal. Pedal based power meters work by measuring the force on the pedal (applied by the rider) using strain gauges, subsequently converting the staring gauge measurement to Power (Watts) using the angular velocity of the pedal. Power meters are not cheap, so if you are a beginner (like me), I recommend looking for used equipment whenever you can.
Using a power meter will allow you to bike within your known capability zones and save your legs for a strong run finish. When I raced my first half IronMan last year (2017 Bayshore 70.4), my strategy was to simply average 18mph on the bike using a simple speedo/odo-meter system. This device does not take into account wind resistance, gradients, and overall fatigue as the bike progresses. I ended up getting off the bike after 56miles with heavy legs and suffered on the 13.1 miles. I had simply exceeded my known capability.
Fast forward to the 2018 Bayshore 70.4 triathlon where I used primarily power output to pace my bike leg. I had done an FTP test (see the T-13 week update) just 3 weeks prior and was sitting right around 235W for a 1-hour window of effort. I then used my 75-80% capability window for the half-IM distance to arrive at a target window of 176-188W throughout the 56-mile course. My power and speed distribution during the half is shown below.
While the power output will show a variance of +/- 20W on average relatively easily, it is a useful tool to gauge your perceived effort. I got off the bike feeling fresh and even ended up beating my old bike course time by 25 minutes (due to a much better prep effort this year). This played a big role in my running time, beating my old run course time by 16 minutes.
I spent most of my bike in power-zone 2 (145-195W), right where I needed to be (see below). As mentioned before, my normalized power output was right at the 80% mark (188W). Normalized Power is an estimate of the power that you could have maintained for the same physiological output if power had been perfectly constant. The Pw.Hr and EF are both measures of aerobic endurance, and are way over my head at this point to cover here, but you can find out all about it here.
This week marked the start of building higher volume in training, including a 75mile bike yesterday and 16mile run today. Next weekend I will be planning on completing a 100mile bike and 18 mile run, with further increases on the bike and run taking place for T-5 through T-3 weeks. Training numbers for this week are below.
