Ok, so its hot as balls in Texas right now (probably other places too, but I'm being selfish today). I've been training in the heat all summer: long runs at lunch, FTP and Long Tempo rides in the afternoons. I really don't pay much heed to the temperature. I kinda run by heart rate, RPE, and pace---and just adjust for the situation. The bike has been mostly unaffected, there has been enough cooling from moving through the air...that I rarely feel the heat.
...Until yesterday...
Yesterday the heat index crossed into the 10x range, it was 101F and 33%rh. So, the heat index was in the 105F range. It was also my threshold bike day. I knew it was "hot", but I didn't look up a heat index before I headed out. I did shift my start time by about 30 minutes, as a nod to the heat, but no other considerations before heading out. The results were not what I expected.
The prescription was 2x20 @95% IF. The first 20 went as expected until about the last 5 minutes, where my RPE really began to climb---more like I was working at 105%. After 3 minutes rest, the second 20 minutes was as you might expect: pretty much picking up where I left off with an abnormally high RPE. I seriously considered bailing at the 10m, 15m, and 18m marks. So, it was a bit of a sufferfest.
I do these every Tuesday. Last week it was 2x20 @ 90%IF. My remarks at the time were that it seems really easy, more like a tempo workout. I could have held the power "indefinately". Ath the end if the first 20, I did 30s at 115%. At the end of the second 20, I spend the last 3 minutes at 110% IF, because I was feeling frisky, and I wante to see how that felt. Last week the temperature was 85F / 50%rh, for a heat index of 90F.
So, now I'm looking at the data for the two rides. Specifically, my HR response to the step changes in power.
My VI was <1.01 (1 watt difference between NP & AP) for both intervals on both rides.
ETA: I do not have HR displayed on my 920xt during these intervals. I have power, cadence, speed, and interval time-remaining. I could switch screens, but I never do. So, HR is only viewed in post-analysis. I just ride the power, and note the RPE.
Note that last week my HR stabilized within 120s of start. Yesterday, besides starting 6bpm highter, it continued climbing through the 10-12m mark, and reached a terminus 15-18 bpm up.
The other interesting observation was during the 3m rest interval. 10-July my HR stabilized at 131bpm within 45s. 17-July HR fell linearly (like ruler-straight) at 8bpm / minute...just reaching 137bpm at the start of the second interval. In both cases, the second interval shoes a much more rapid return to steady-state with a terminal HR 1-2bpm higher than #1.
So, my questions:
1. Is my theory that this is heat induced, correct? Ie, my body just couldn't move the heat out quickly enough so HR continued to elevate, and stayed high in recovery?
2. Besides the immediate risks of heat related illnesses, are there training stress / fatigue effects from such events (I'm assuming so, since my legs feel like shit today)? Assuming so, what are they? Can they be mitigated (other than the obviuous---don't do that)?
3. What is the impact on training effects of either training at prescribed, or reducing the power-target to a more appropriate RPE?
I'm already working to rejig my schedule to avoid doing these (and other critical workouts) in the heat in the future.
ETA2: My training leading into these two events was nearly identical. Arguably, I was "more rested" going into yesterday, than last week. My bike TSB was +1 for both weeks, run TSB was -12 for both weeks. I'm in a swim/run block at the moment, so I'm just "holding serve" on the bike.
...Until yesterday...
Yesterday the heat index crossed into the 10x range, it was 101F and 33%rh. So, the heat index was in the 105F range. It was also my threshold bike day. I knew it was "hot", but I didn't look up a heat index before I headed out. I did shift my start time by about 30 minutes, as a nod to the heat, but no other considerations before heading out. The results were not what I expected.
The prescription was 2x20 @95% IF. The first 20 went as expected until about the last 5 minutes, where my RPE really began to climb---more like I was working at 105%. After 3 minutes rest, the second 20 minutes was as you might expect: pretty much picking up where I left off with an abnormally high RPE. I seriously considered bailing at the 10m, 15m, and 18m marks. So, it was a bit of a sufferfest.
I do these every Tuesday. Last week it was 2x20 @ 90%IF. My remarks at the time were that it seems really easy, more like a tempo workout. I could have held the power "indefinately". Ath the end if the first 20, I did 30s at 115%. At the end of the second 20, I spend the last 3 minutes at 110% IF, because I was feeling frisky, and I wante to see how that felt. Last week the temperature was 85F / 50%rh, for a heat index of 90F.
So, now I'm looking at the data for the two rides. Specifically, my HR response to the step changes in power.
| Code |
Time 10-July 17-July IF
WU 128 134 60%
T0 127 135 90/95%
2m 146 152 90/95%
4m 147 155 90/95%
6m 145 157 90/95%
8m 146 157 90/95%
10m 145 160 90/95%
12m 144 162 90/95%
14m 144 162 90/95%
16m 146 163 90/95%
18m 147 163 90/95%
20m 145 163 90/95%
My VI was <1.01 (1 watt difference between NP & AP) for both intervals on both rides.
ETA: I do not have HR displayed on my 920xt during these intervals. I have power, cadence, speed, and interval time-remaining. I could switch screens, but I never do. So, HR is only viewed in post-analysis. I just ride the power, and note the RPE.
Note that last week my HR stabilized within 120s of start. Yesterday, besides starting 6bpm highter, it continued climbing through the 10-12m mark, and reached a terminus 15-18 bpm up.
The other interesting observation was during the 3m rest interval. 10-July my HR stabilized at 131bpm within 45s. 17-July HR fell linearly (like ruler-straight) at 8bpm / minute...just reaching 137bpm at the start of the second interval. In both cases, the second interval shoes a much more rapid return to steady-state with a terminal HR 1-2bpm higher than #1.
So, my questions:
1. Is my theory that this is heat induced, correct? Ie, my body just couldn't move the heat out quickly enough so HR continued to elevate, and stayed high in recovery?
2. Besides the immediate risks of heat related illnesses, are there training stress / fatigue effects from such events (I'm assuming so, since my legs feel like shit today)? Assuming so, what are they? Can they be mitigated (other than the obviuous---don't do that)?
3. What is the impact on training effects of either training at prescribed, or reducing the power-target to a more appropriate RPE?
I'm already working to rejig my schedule to avoid doing these (and other critical workouts) in the heat in the future.
ETA2: My training leading into these two events was nearly identical. Arguably, I was "more rested" going into yesterday, than last week. My bike TSB was +1 for both weeks, run TSB was -12 for both weeks. I'm in a swim/run block at the moment, so I'm just "holding serve" on the bike.
Last edited by:
Tom_hampton: Jul 18, 18 8:58
