Dr. Julien Louis takes us through the training, pacing, and physiology of the father-son duo who set a new world record for combined time in the marathon. In 2019, Tommy (59 yrs) and Eoin Hughes (34 yrs) ran the Frankfurt Marathon in times of 2:31:30 and 2:27:52, respectively. Their combined marathon time was 4:59:22. Dr. Louis studied Tommy in a previous year and then studied the pair as they took on, and ultimately succeeded, in setting the new record. We discuss the father-son team and extract additional take-away messages for your training.