Tl;dr If I know I’m getting dehydrated and I know I’m drinking at my bodies ability to absorb and I know I’m pacing within/under my bodies theoretical ability for the targeted duration… how do I further improve or limit the negative impacts resulting from a hydration related imbalance when I’m deep into my targeted event, but still have a long ways to go?
I’m fairly certain that after looking at all the possible elements that make up a “good day on the bike” that my biggest performance gap/opportunity for improvement is staying hydrated/hydration related.
I’ve done several sweat rate assessments and have identified that I can sweat anywhere from 40-70 oz per hour, depending on intensity and temp, and between 50-60 oz per hour around 65-70% of FTP at 70°f.
My ability to consume/absorb is around 35oz/hr and seemingly diminishes over time, so I almost always run at a modest hourly deficit and depending on duration this can cause significant and sometimes insurmountable challenges.
My target event is going to take me ~17 hours to finish, which even at a very modest intensity, puts me in the hurt pretty deep for perhaps as many as 7 hours based on my current conditioning, even while keeping a lid on intensity.
Fueling: I take in all my carbs in liquid form. Almost always tailwind (after trying several products), feeding via slurry out of a single bottle. The rest of my bottles are always plain water. I can consume up to 200-300 cal/hr or between 50-75g carb/hr without distress. I’ve mixed across all bottles before but struggled w/ being able to quench a thirst/dehydration since my sweat rate can vary so significantly (cramps, failure have always resulted) .
Effort: My ftp floats anywhere from 275-305 and puts my theoretical “all-day power” between 165w and 200w. Below is a recent example (fairly worse than average, but a good example none-the-less) however I can typically make it up to 9.5-10hrs (@~180w, ~130bpm) before coming completely, spectacularly unglued. What I’m attempting to illustrate here is the uncoupling of hr from effort, nothing more.
90°f, 160 miles, 11.2hrs 20° temp swing over ride duration.
Average power/hr: 126w & 129bpm.
Hour 6 started to come a bit undone, rested briefly.
Hour 9 effort became completely uncoupled from hr.
I’m almost 100% certain that (the collapse) is hydration related, despite fluid consumption at the highest rate my current ability to consume allows.
30 min splits:
- 109w / 113bpm -4
- 118w / 116bpm +2
- 142w / 121bpm +21
- 130w / 121bpm +11
- 157w / 130bpm +27
- 129w / 127bpm +2
- 154w / 121bpm +33
- 155w / 134bpm +21
- 135w / 135bpm 0**
- 140w / 135bpm +5
- 142w / 137bpm +5
- 101w / 125bpm -24**
- 109w / 124bpm -15
- 152w / 126bpm +26
- 119w / 134bpm -15
- 131w / 135bpm -4
- 167w / 151bpm +16
- 115w / 143bpm -28**
- 131w / 144bpm -13
- 62w / 120bpm -58
- 76w / 118bpm -42
- 89w / 127bpm -38
- 51w / 116bpm -65
So what do you think/recommendations? What’s my next move?
I will tell you that once hr uncoupling occurs, the odds of me quitting are pretty high. Whole body cramping is usually imminent, and my resolve pretty much evaporates. Mental picture: pre-decoupling eta = 2hrs, post-decoupling eta, 4-6 hrs, once I figure that I have 2-3x my time to destination, likelihood of giving up is very high. I realize that I need to work on my “mental strength/endurance mindset” but at the same time I’ve also accepted that willpower alone is sometimes not enough.