Weekly Blog

May 15

For many, April 26th might have seemed like any other day. For marathon fans, it was an epic performance - the kind that ushers in a whole new chapter in human achievement. On a near perfect day for racing in London last month, Sabastian Sawe from Kenya defended his 2025 course title, set a new world record and became the first person ever to officially break the 2 hour mark for the full marathon (26.2 miles) on a record-eligible course. To put some numbers to it, his average pace was an absolutely blistering 4 minutes and 33 seconds per mile (13.16 mph) for 1 hour, 59 minutes and 30 seconds - something most humans would struggle to do on a bike.

Experts suggest that the combination of perfect conditions, world-class physiology and the Evo 3 - an engineering marvel designed by Adidas as a "super-shoe" for this exact purpose - is what put him over the top (and perhaps explained why Ethiopia's Tigst Assefa, wearing the same shoes lowered her own world record to 2:15:41 in the women's race on the same day). However, another factor, mostly overlooked until recently, is buried in the details. It is a variable that holds great promise as we ready for the summer heat and muster the endurance required to "race" toward our limits.

"Durability" is a long-standing concept that has only recently been formally defined and studied for its power to predict athletic performance. As a concept it's essentially what we might expect: the ability of an athlete to resist performance losses as an event nears its later stages. However, until recently, there didn't seem to be much of a pattern. For marathoners, race predictions were traditionally based on three variables: the athlete's "engine" size (VO2Max), their "movement efficiency" (minimal wasted energy) and their "fuel economy" (ability to utilize fuel at the highest possible speed).  However, around 2021 as researchers tried to understand why the two-hour marathon remained elusive, they realized there was wide variation even among the best racers: some degraded significantly, while others seemed to improve as the day progressed. For example, Sawe ran his fastest two 5K (3.1 mile) segments beginning at mile 20, when most marathoners are "hitting the wall". The second half of his race was actually faster than the first half, known as "a negative split" - suggesting, much like we might describe a highly durable truck, that he was "overbuilt" for the task from his heart to his shoes. While most people aren't looking to break marathon records, this same physiological durability can be a major asset during the summer heat, when the workday can feel like it lasts 26.2 hours.

According to this 2025 article, training our bodies for greater resilience is possible. It requires emphasizing total exposure over time, consistency, controlled overload and microbursts at peak intensity. Let's break each of those down.

1. In some workplaces, long-term exposure is at times referred to as "old person strength": the idea that a person with many years of experience who may have only average strength in absolute measures, is remarkably strong while performing a given task because they are perfectly adapted to it, honed over many years of doing so. Athletes who have logged greater training volumes over long periods tend to have more durability. Runners from Kenya like Sawe for example are known to average +/-25 miles per day (100-150 miles per week) for years in preparation.

2. Training consistency is no surprise. Like adding layers of varnish coat by coat to protect a wood surface, or adding to a retirement account week by week to build a nest egg, showing up day in and day out to train builds the physiological reserves needed to perform under withering conditions.

3. Controlled overload can be likened to "game simulation". The idea is to create brief exposures to expected conditions to mimic what an athlete might face and allow the body to rise to the challenge. For at marathoner, this might involve harder efforts, at or even above the predicted race-pace near the end of a workout to mimic the fatiguing conditions of a race's later stages. In the Summer workplace, this might involve deliberate heat exposure at safe doses known to stimulate heat acclimation - 75-80 degrees for increasing time intervals - to prepare for long periods of truly hot days. To be clear, prolonged exposure to max intensity (e.g., over 90 degrees), especially without prior acclimation (as weather forecasts predict next week) is a bad idea. There is no shortcut for Durability. It cannot be rushed and acute over-exposure causes harm.

4. When training for durability, intensity deserves great respect. As shown in this 2026 review of studies on cyclists, high intensity efforts degraded durability more than lower intensity efforts, even when prolonged. While bursts of peak intensity help elite athletes build extra top-end capacity, it is critical to do so without delaying recovery timelines. Therefore, these efforts should be brief enough to stimulate but never exhaust. For an athlete this might include activities that train strength, power or explosiveness such as heavy resistance training or plyometrics. For consistent gym-goers and according to this study performing strength exercises at 5 sets of 4 reps with 2 minutes of rest between might be the sweet spot for soft-tissue durability. For those not currently going to the gym consistently, this might mean adding a short round of body weight exercises to the day's routine or trying to "power up" the hilly sections of an evening walk. For those closer to the sedentary end of the spectrum, stair-snacks, fast walking at lunch or taking the plunge into pickle ball can all make a difference.

For some regions of the country next week will be a preview. With any luck, it will serve as a reminder that the annual 100 day endurance race we call "Summer" is on the horizon. There's enough time to be ready if we start adding durability now. Let us know if you need a training plan.

Have a great weekend,

Mike E.