Key Lesson: Hydrate well for 24hrs before a hot ride

This week I had three sets of tempo intervals to complete and then two endurance-miles sessions to complete. Friday afternoon when I went out, I was not well hydrated and the heat (of the air, not from the road) was 95F. I finished the intervals but you can see in the first chart here that they were a stress on the system. The regression of heart rate to power is 0.21bbm/W and the 150bpm power is 119W. In the second chart, from the following day, I hydrated much better for the pre-ceding 18hrs and even though I’d been stressed the day before, the regression co-efficient is 0.15bpm/W and the 150bpm power is 195W.

Poor hydration means harder work per Watt

Better hydration led to better cardiac efficiency