Becoming the most decorated Winter Olympics athlete in history requires snow, fortitude, technique, squats, more squats, a team of dedicated physiologists, a stable body weight, running shoes, high-intensity intervals, about 940 annual hours of exercise — much of it conducted at a surprisingly light intensity — and a willingness to substantially shake up training when it is no longer working well.

Those are the findings of a new study published in Frontiers of Physiology that analyzed 17 years’ worth of records about the workout routines of the Norwegian cross-country ski racer Marit Bjorgen, who will turn 38 in March.

Ms. Bjorgen won five medals at the Pyeongchang Games, making her the most winning athlete there, for a career total of 15 medals, eight of them gold.

She also appears to have led a thoroughly examined life, keeping scrupulous, detailed diary entries about each of her workouts from the time she became a senior-level athlete at age 20.