I do a lot of running as well and have observed the same effects. After anaerobic sprints or a race of up to 10k, sleep HRV drops / HR is higher and running HR:pace is elevated for up to a week. However, usually this is then followed by some improvement in all of these metrics compared to the baseline before the hard workout. Anaerobic exercise builds/maintains especially fast-twitch muscles, and higher muscle mass has positive influence on many health markers; as we get older we slowly lose muscle mass, but the losses are predominantly fast-twitch muscles [1]. So I believe anaerobic workouts are very important, despite causing quite some stress temporarily. Totally agree they require a lot of recovery inbetween.
Unrelated, out of curiosity, when you say 80% of your training: is it in mileage/time? Or some effort metric like TRIMP, calories, avg. HR, or so? Or something else?
Unrelated, out of curiosity, when you say 80% of your training: is it in mileage/time? Or some effort metric like TRIMP, calories, avg. HR, or so? Or something else?
1. https://pubmed.ncbi.nlm.nih.gov/7493202/