I feel when i used to run on the track i used to hit the same splits i'm hitting now but they used to be at a higher heart rate at around 187ish. Now these same splits are hit at 173ish and i can't run any faster. It's so strange. I used to warm up by cycling on a bike at high gear for 10-15 minutes and do dynamic hamstribg stretches pre-pandemic. I stopped doing that. Could that explain why i can't run faster and can't get a higher heart rate?