Elite runner trusts watch data

Jacob Kiplimo is one of the fastest road runners alive, and he says a wristwatch helps decide when he should push and when he should back off before the 2026 London Marathon on April 26. Samsung said on April 10 that the Ugandan uses Samsung Health data from a Galaxy Watch8 to shape both training and recovery. (samsungmobilepress.com) That sounds less strange once you remember what marathon training actually is: not one giant workout, but dozens of small decisions about pace, sleep, and rest made over weeks. A bad call on Tuesday can ruin a race on Sunday, so runners look for signals that show whether the body is absorbing work or just getting worn down. (samsungmobilepress.com) One of those signals is heart rate variability, which is the tiny change in time between one heartbeat and the next. Think of it like a car engine at idle: a body that is recovered usually shows more natural variation, while a body under stress often looks flatter and more strained. (samsungmobilepress.com) Another signal is training load, which is just a running total of how much stress recent workouts have put on the body. Instead of trusting mood alone, an athlete can compare today’s fatigue with data from the last several days and decide whether the right move is intervals, an easy run, or no run at all. (samsungmobilepress.com) Kiplimo told Samsung he checks running analysis data that includes heart rate, pace, and asymmetry. Asymmetry is the left-right balance in how you run, and a change there can hint that one side is taking more load than the other. (samsungmobilepress.com) The reason his routines get attention is simple: Kiplimo already owns one of the biggest records in distance running. World Athletics says he ran 56:42 for the half marathon in Barcelona on February 16, 2025, taking 48 seconds off the previous world record and becoming the first man under 57 minutes for the distance. (worldathletics.org) He then lowered that mark again to 57:20 in Lisbon on March 8, 2026, according to World Athletics. That means the watch story is not about a recreational jogger buying gadgets, but about an athlete using daily measurements while operating at world-record speed. (worldathletics.org) The marathon is also a different beast from the half marathon, because it doubles the distance from 21.1 kilometers to 42.195 kilometers. Small recovery mistakes that might be survivable in shorter races can become expensive late in a marathon, when glycogen runs low and pace starts to slip by seconds per mile. (worldathletics.org) London is a serious test for that approach because the field is loaded. World Athletics says defending champion Sabastian Sawe, Olympic champion Tamirat Tola, Joshua Cheptegei, Yomif Kejelcha, and Kiplimo are all entered for the men’s race on April 26, 2026. (worldathletics.org) For everyone else, the useful part is not the brand name or the celebrity runner. It is the basic idea that sleep data, heart rate variability, and training load can act like a dashboard, because even elite runners do not rely on feel alone when the cost of one hard day is losing weeks of training. (samsungmobilepress.com)