Cold plunge before a workout doubled fat burning, Holmer says
The study put the cold before the session instead of after it, and the contrast version kept working into easy riding.
Brady Holmer has flagged a study that flips the usual cold plunge timing. Instead of testing an ice bath as recovery after a session, researchers asked what cold water, or alternating cold and sauna, does before and during exercise.
The numbers are striking. Five minutes after 10 minutes in 50F water, fat oxidation (how much of your energy is coming from fat rather than carbohydrate) was nearly twice as high as the control condition, Holmer says. That spike did not last. By 20 minutes it had faded.
Contrast held on longer
The contrast protocol, alternating cold and sauna, was the more interesting arm. Holmer says fat oxidation stayed elevated into easy cycling, and heart rate ran roughly 9 to 13 beats per minute lower at the same workloads. Same work, lower heart rate, more fat being used.
The catch is in the next line. Perceived effort did not change. The riders did not report the easy cycling feeling any easier, even with heart rate sitting lower.
What it actually means
This is a physiology finding, not a training recommendation. Holmer is explicit that nobody has shown this turns into a better session, and nothing in the study says a pre-run plunge makes you faster or fitter. A one-off shift in fuel mix during easy riding is not the same thing as a training adaptation.
It is also worth keeping the context straight. The lower heart rate at the same workload sounds like a win, but cold exposure changes how blood moves around the body, and the effort reading did not budge. Reading a lower heart rate as a free fitness gain is the easy mistake here.
Holmer has been consistent about separating what a study measured from what a runner should change. This one fits that pattern. The effect is real in the data, the window is short, and the part runners actually care about, whether the workout goes better, is untested.
Interesting physiology. Whether it translates into a better workout is still an open question though.
Contrast had a more persistent effect. Fat oxidation stayed elevated into easy cycling
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