Endurance Innovation is now on Patreon [https://www.patreon.com/enduranceinnovation]! Have a peek at our page and show us some love. * 2:00 meet life-long runner and retired professor of engineering Hans van Dijk * 5:00 meet (also a) lifelong runner and engineer Ron van Megen * 9:00 where does all that work that we do as runners go? * Overcoming running resistance (influenced by running efficiency) * Overcoming aerodynamic drag * Overcoming changes in elevation * 11:30 running efficiency / energy cost of running (ECOR) * Potentially large interindividual differences: up to 20%! * Minimized through training * 13:15 aerodynamic drag * Average runner CdA is 0.24 in free air and 0.20 while drafting * Eliud Kipchoge was down to 0.16 during his Breaking 2 attempt * 18:15 changes in elevation * Running efficiency improves when running uphill and worsens when running downhill * 20:30 factors that influence running efficiency / ECOR * Global, multi-year training load: more training tends to reduce ECOR * Experiment with: cadene, arm carriage, shoes, etc., to find minimal ECOR * Reduce weight  * 31:30 factors that affect aerodynamic drag * Runner speed * Drafting * 34:00 Hans and Ron's models of run performance * 39:00 using the stryd power meter to calculate running efficiency Learn more about Hans and Ron and browse their books at their website [https://hetgeheimvanhardlopen.nl/en/].