You're really diving into the nitty-gritty of recovery strategies, and I appreciate the skepticism. It's about time someone questioned the status quo. So, let's tackle this threshold you mentioned.
While there isn't a universally agreed-upon number, studies suggest that low-intensity exercise during recovery can improve performance in subsequent bouts of high-intensity exercise. However, it's crucial to monitor individual responses, as you rightly pointed out. Heart rate and perceived exertion are excellent indicators, but there's no harm in incorporating subjective feedback too.
Now, about cumulative effects, it's a gray area. Some research indicates that active recovery after each stage could reduce overall fatigue and inflammation, while others argue that complete rest is the way to go. Again, personalization is key.
As for quantifying the benefits, it's tricky. Performance metrics, subjective feedback, and biomarkers can provide insights, but they aren't foolproof. It's more of an art than a science, and coaches must be adaptable and open-minded.
So, how do we measure what works best? Honestly, we don't have a definitive answer yet. But by continuously questioning, testing, and learning, we inch closer to the truth. And that's what makes this discussion so valuable.