DATA DRIF T
It’s dangerous to obsess over matching your data from one part of the year to another, especially as the conditions change. “The summer heat puts extra stress on the body during exercise, ” says Hough. “Your muscles want blood, but your skin wants it too, to cool you down, and getting it to both places drives your heart rate up. You get what we call cardiovascular drift in temperatures above 25°C, as your heart rate starts increasing independently of exercise intensity.” So your performance parameters will differ from those you logged in lower temperatures. To give yourself an idea of this drift, cross reference your heart rate against a rate of perceived exertion (RPE) rather than sticking to concrete training zones. The Borg scale is useful for this and runs from 6-20 so you can multiply your RPE by 10 to get a rough idea of where your heart rate should be.