Carbon Fiber Bones
Join Date: Apr 2007
Location: Adelaide, Australia
Bikes: '07 Scott Speedster S30
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Lower Threshold HR on TT Bike?
So I've recently built up a TT bike to help me be a bit more competitive in TTs next season. Yesterday was the first time I went out and did some proper training in the aero position - 2x20 intervals on a flat circuit. Weather was perfect, little wind and only about 27 celsius (80 fahrenheit), and I was coming off a fairly easy week of Base 2, with two easy days before the workout.
About 6 weeks ago, under almost identical conditions, I carried out a threshold heart rate test in the form of a 17km TT, as per Friel's instruction, and calculated my LTHR to be 179 bpm, which is consistent with my observations on many rides over the past 6 months. However, on the TT bike, I only averaged ~170 bpm for the 20 minutes, even though perceived exertion was at threshold levels.
So, my question is - does cycling in the aero position, when you're not used to it, result in a lowering of your threshold HR?
Also, I should note that I was faster on the TT bike over the course than I was on the road bike 6 weeks ago - 39.4km/h TT vs. 38.4km/h roadie.