Gymgoers put a lot of stock in “science-based” fitness influencers, often changing their training based on their guru’s latest post. In many cases, however, an influencer’s hottest takes hinge on a single piece of research—and that’s shaky ground.
In a new large-scale study published in Sports Medicine, 29 research teams tried to replicate 25 exercise science papers printed in leading journals between 2016 and 2021.
They went to great lengths to match the original studies—recruiting participants with the same characteristics and using the same sample sizes, equipment, and procedures. They even asked the original authors for guidance when important details were missing or unclear (though few replied).
Only 28% of the studies held up, and in 88% of those, the effects were far smaller than originally reported—about 75% smaller on average. The rest failed outright or were too muddled to interpret confidently.
In other words, fewer than one in three exercise studies have reproducible results—and the minority that can be replicated usually overstated the findings.
How did this happen?
Most sports science studies involve just a handful of participants, which makes it easy to get results that look impressive but are really just statistical flukes.
What’s more, they often track changes so small that everyday factors can skew the results. For instance, if someone shows up to a lab tired, stressed, or just off their game, they’ll probably underperform during testing—but their numbers still end up in the final analysis.
It’s also hard for scientists to push a field forward by replicating and building on each other’s work when methods vary so much between labs. Even when they try, crucial details (the exact training program, the equipment used, how effects were measured, etc.) are often missing from the original paper.
And because researchers rarely share their raw data, others can’t easily verify the numbers, re-analyze the results, or catch errors, which makes it harder to confirm whether the findings are reliable.
Not all exercise science is junk, of course.
But this is a pointed reminder that single, flashy studies—especially those that contradict decades of prior research—shouldn’t be taken as holy writ. Reliable conclusions come when you consider the weight of all the evidence, which is why systematic reviews and meta-analyses matter far more than lone experiments.
So, the next time you hear a hot new “science says” claim, check the source. If it’s based on a single study, it’s probably not worth rearranging your regimen.
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