Of course, some days there's nothing doing and everybody just sits around and the horses yawn. But the hounds started a coyote the last time I was out, and we didn't have a check for 30 minutes. We were strung out all over the countryside, and my horse was blowing so hard that she was shaking. I was ready to toss my guts. That's aerobic.
I'd agree to a random sampling of resting pulse, so long as you include the round-the-block riders with the bells and baskets on the handlebars (the equivalent of your average equestrian). The range of people who say they're equestrians includes folks whose experience consists of sitting on Ol' Dobbin, and unlike a bike you don't have to keep moving to keep Dobbin from falling down. As I said, you probably get more exercise in a rocking chair. Or, alternatively, we can compare resting pulse of combined training competitors - I'll even concede to Tadpole or Pre-Novice - with road bikers.
In fairness, before you take that bet, I was baiting you. Marathoners, tri-athletes and road cyclists have the lowest resting heart rates of any athletes. Years back, they tested NBA pros, and NFL pros against amatuer cat cyclists. There was no comparison when it came cardiovascular fitness. Some of the cat cyclists were 30% over the best V02 Max of the best of the rest. It wasn't even a contest.
Your description of your coyote induced ride sounded taxing for sure, but it's certainly nowhere near running 26 smiles, doing even a half tri, or biking 100 miles.