Training stress. Resistance training is sympathetic dominant stress. As is high intensity cardio. Your stress cup fills way to fast.
Zone 1-2 is a parasympathetic stress. You can tolerate much more total stress if you have two flavors
Also zone 3 is not a good training zone for most. Stay out of it for most of your training Either drive cardiovascular/mitochondrial adaptation with zone 2, or go full send with a safe (don’t tear a hammy) in zone 4/5 for its adaptations.
Zone 1-2 is a parasympathetic stress. You can tolerate much more total stress if you have two flavors
Also zone 3 is not a good training zone for most. Stay out of it for most of your training Either drive cardiovascular/mitochondrial adaptation with zone 2, or go full send with a safe (don’t tear a hammy) in zone 4/5 for its adaptations.