Here’s your free but abridged version of this week’s “Run Long, Run Healthy” newsletter. Subscribe below to receive the complete, full-text edition with the newest and most authoritative scientific articles on training, nutrition, shoes, injury prevention, and motivation.
Super Shoes Or Super Placebo?
“Super shoes” like the Nike Vaporfly promise big gains—but do they really help everyone, or are we just buying the hype? A clever study tested whether the perceived benefits of super shoes could be explained by the placebo effect.
Researchers gave 24 female recreational runners two identical pairs of Nike Vaporfly Next% 2s. One pair was spray-painted black and described as a cheap knock-off. The other? Marketed as the same high-performance model worn by elites.
Each runner completed four treadmill sessions (6 minutes each at 10 km/h) wearing both “super” and “knock-off” versions. Researchers tracked oxygen use, biomechanics, and perception.
There were no differences in running economy, energy cost, or biomechanics between conditions. However, runners reported significantly greater comfort, enjoyment, and performance confidence with the “super” shoe. In fact, 87.5% of the participants preferred the super shoe—even though it was the same.
What this means for runners
Belief matters. A lot. If you think your shoes make you faster, you may feel better and run more confidently—even if there’s no mechanical difference. That’s the power of placebo.
RELATED ARTICLE: Are Super Shoes Worth The Hype, Or Are They Just A Hoax?
🦄 Boston Preview Show: Tips, Talking The Course, Who Will Win, and… Katelyn Is Running!
🎧 We break down the elite fields, reveal pro tips for conquering the course, and share behind-the-scenes details from our live coverage plans — plus, Katelyn Tocci opens up about her emotional return to Boston. Whether you’re racing, watching, or dreaming, this podcast has everything you need 💙.
Are You Overdoing Carbs On Your Long Runs?
Most endurance athletes know the drill: fuel early, fuel often. Current guidelines suggest up to 90g of carbs per hour during long events (and some athletes are pushing higher numbers). But your body may not be using all of that fuel efficiently, and overdoing it can lead to GI distress or sluggishness. A new study tested a smarter way to fuel based on the concept of personalized or individualized nutrition.
Researchers recruited 11 trained endurance athletes (VO₂peak ~59 mL/kg/min) for two separate 2.5-hour cycling sessions.
In one trial, athletes consumed a hefty 90g/hour of glucose (a common max recommendation). In the second trial, they were given a personalized dose, calculated based on how much of that 90g they had actually oxidized (used as energy) in trial 1.
Carbohydrate oxidation was tracked using 13C-labeled glucose (a technique that allows researchers to study how glucose moves through the body) and breath analysis, providing a precise measure of how much ingested glucose was actually being used.
Athletes oxidized the same amount of glucose (~0.9g/min or around 55g/hour) in both trials, even when consuming 28% less in the personalized condition (where they consumed an average of 65g/hour). There were no differences in blood glucose, lactate, or fat/carbohydrate oxidation rates between the trials. However, perceived exertion and stomach fullness were lower with personalized dosing, and oxidation efficiency—how much glucose was used compared to how much was consumed—jumped from 58% (with generic dosing) to 83% (with personalized dosing).
What this means for runners
If you’re blindly following 90g/hour fueling advice, you might be overloading your gut, increasing the risk of discomfort and underperformance, and wasting product and calories your body isn’t even using. This study shows that dialing in your carb intake—based on how much your body actually uses—can optimize performance and comfort. The problem? Personalized dosing currently requires specialized lab testing, so the best that most of us can do is trial-and-error.
RELATED ARTICLE: The Runner’s Guide To Carb Loading: Maximize Your Energy On Race Day
These Supplements Might Help You In The Heat
When it comes to battling the heat, hydration is key. Supplements—those are rarely included in the conversation. But if there’s a pill runner’s could pop that might have even the slightest benefit for hot-weather performance, it’s worth knowing about. A recent meta-analysis of 124 studies looked at how various dietary supplements influence core temperature and sweat rate in hot conditions. Some help. Others backfire.
Researchers analyzed the effects of 39 different supplements (from caffeine and creatine to taurine and polyphenols) on core body temperature and sweating rates. Participants were exposed to hot conditions while resting or exercising.
While most supplements didn’t do anything, a few stood out. Caffeine raised core temperature (a small but significant effect)—indicating a potentially negative effect on performance. Taurine (an amino acid commonly found in energy drinks) and oligonol (a polyphenol) lowered core temperature and increased sweating—suggesting heat-dissipating benefits. Most other supplements, including nitrate, BCAAs, creatine, and antioxidants, had no effect.
What this means for runners
In the heat, what you take matters. Some supplements boost cooling, others turn up the internal thermostat. Dose, timing, and other factors matter, so like all things, it will come down to figuring out what works (or what doesn’t) for you. Should you avoid caffeine before a hot run? Probably not, but just make sure not to overdo it.
RELATED ARTICLE: Summer Running Guide: 12 Top Tips To Beat The Heatner
SHORT STUFF You Don’t Want To Miss
HERE’S WHAT ELSE YOU WOULD HAVE RECEIVED this week if you were a subscriber to the complete, full-text edition of “Run Long, Run Healthy.”
- Do compression socks help or hurt your performance?
- How “healthy” food choices might contribute to low energy availability in runners.
- Sodium and potassium levels—can they predict ultramarathon times?
Thanks for reading. As always—Run Long, Run Healthy
~Brady~
