Mountain Biker here. I like it as it gives me more of a HIIT effect with my heart rate varying all over the place depending on the terrain. Typical ride below. I did see a cardiologist a couple of years ago just to make sure I was good to punish my heart like this in my 60s and he said to go for it and judge more by how I feel than worrying about the actual numbers. If I overdid it my body would tell me. At 65 hitting the below pace, when I come out of the woods I feel just fantastic!
