Sprinting is much better for health than marathons. Ever compare a sprinter’s body to one who does long-distance running?
HIIT is the ultimate. I do 40 sec mountain climbers with 20 sec rest until I reach 600 total mt climbers. I’m 66. Otherwise I walk 30 minutes most days at 4 mph. No injuries feel great! I used to run but it hurt my knees and Achilles.