The Cold Truth: Why Cold Plunges Could Be Killing Your Gains
Estimated read time: 3.26 minutes ย (just long enough for me to go from โI feel greatโ to โI might actually pukeโ during mile 1 of my marathon). ๐คฎ
Hey Performance Nerds! Jonah here. โ๐ค
Have you ever sprinted into a freezing tub after a hard run or lift thinking you were boosting recovery? I have cold, hard news.
New science shows cold plunges may be blunting your gainsโnot speeding them up.
Today weโre breaking down:
๐งฌ The surprising science behind cold plunges and muscle recovery
โ๏ธ When cold water could actually stall your progress
โ๏ธ Smart ways to recover that don't sabotage your adaptations
๐ Thank You, London
Hey teamโ I'm still buzzing from London's streets! Your messages, cheers, and high-fives carried me through every challenging mile in ways no carb gel ever could. Thank you from the bottom of my heart.
The clock told a different story than I trained for, but knowing this newsletter helped power your PRs is the medal I'm taking home.
Your support fueled my purpose, and I can't wait to keep giving it back as we chase our next start lines together. ๐
SiS is now the official sponsor of Marathon Science. Their performance productsโlike fueling bars, hydration mixes, and recovery supplementsโare trusted by pros and grounded in real sport science.
๐ง The Science: Cold Water Can Limit Muscle Recovery
Think cold plunges are recovery gold? Not so fast.
In a recent study, 12 active men did a heavy lifting session, then dunked one leg in cold water (8ยฐC) and the other in thermoneutral water (30ยฐC).
Hereโs what happened:
๐ฉธ Blood flow in the cold leg dropped by 70%
๐งฉ Muscle protein synthesis dropped by 30%
"Your muscle recovery is like pizza delivery. Cold plunging shuts down the roads. No pizza = no gains." โ Sciencey Jonah (2025)
Translation: Cold plunges shut down nutrient delivery and muscle rebuildingโat the cellular level.
๐ค "But I Feel Better After Cold Plunges..."
Cold might reduce sorenessโtemporarily.
But hereโs the catch: soreness relief โ real adaptation.
Itโs like popping ibuprofen for a sprained ankle. You might feel betterโฆ but your body hasnโt healed.
Cold plunging may make you feel fresh while slowing the adaptations you're training for.
And this isnโt just about strength gains:
Cold plunges can stall the endurance adaptations you're working so hard for:
They restrict amino acid deliveryโcrucial for building more mitochondria
They shut down PGC-1ฮฑ, the molecule that signals your cells to grow your aerobic engine
Yes, I judge you if you cold plunge after workouts. โ Augie (My Dog), Chief Recovery Officer ๐ถโ๏ธ๐ข
Translation: Youโre training for a Ferrari engineโbut cold plunges might be throwing it into neutral.
๐ ๏ธ How to Recover Smarter (and Still Use Cold if You Want To)
Hereโs how to recover without losing gains. Letโs make this practical.
โ When to Avoid Cold Plunges:
After strength training, long runs, or speed sessions
When you're chasing muscle or aerobic gains
โ When Cold Is OK:
After races or competitions with short recovery windowsโto reduce feelings of sorenessย
If you enjoy cold exposure, try it before workouts or wait a few hours after trainingย
๐ง What to Do Instead:
Prioritize nutrition: Fuel your post-session with carbs + protein (recovery shake + real meal), and meet your daily macro targets to support full recovery.
Keep moving: Gentle cycling or walking maintains blood flow and speeds up healing.
Train smart: Follow a progressive, well-structured plan to maximize adaptations.
Choose heat over ice: Try thermoneutral baths (~30ยฐC), warm showers, or sauna sessions to boost circulationโwithout blunting gains.
TL;DR: Cold plunges look cool on Instagram. But carbs, protein, and sleep? Way better for your quads. ๐ช
โ Practical Summary: Should You Cold Plunge After Running?
๐ฉธ Blood Flow Down: Cold plunges reduce blood supply by up to 70%
๐งฉ Muscle Repair Down: Protein synthesis drops 30%
โ Skip the Ice: Avoid after strength or endurance sessions
โ Do This Instead: Eat well, follow a periodized training plan, and sleep for better recovery
Are You a True Running Nerd? Prove it.. ๐ง
Welcome to the prove youโre a nerd section. Each week, I ask a question about a common running science myth.
Answer correctly, and youโll be entered into a weekly raffle to win a package of Jonahโs favorite supplements.
What primarily determines whether your body burns more fat or carbohydrates during a run, assuming everything else (like diet, duration, and fitness level) stays the same?
Last Weekโs Results: Cramp Myth Busters! โก๏ธ๐ฆต๐ง
Boom! Most of you kicked that old banana myth to the curb and locked in on the real reason marathon cramps strike. ๐ฅ
The correct answer? Muscular fatigue and altered neuromuscular control. Itโs less about your sodium stash and more about pushing tired muscles past their breaking pointโespecially when your pacing or strength work hasnโt kept up with your mileage. ๐ง ๐ก
Hereโs how the votes stacked up:
๐จ A. Losing too much salt from sweat ๐ง โ 121 votes
โฌ๏ธ B. Dehydration from not drinking enough water ๐ง โ 38 votes
๐ฉ C. Muscular fatigue and altered neuromuscular control โก๏ธ โ 281 votes โ
โฌ๏ธ D. Not eating enough bananas ๐ โ 4 votes
Moral of the story? Cramping is a training issue, not a potassium panic. Want fewer cramps? Build stronger, more fatigue-resistant legsโand save the bananas for your smoothie. ๐โโ๏ธ๐ช๐
Nerdy Finds of the Week ๐๐งโ๐ฌ
This section includes my favorite research, podcasts or books about running/lifting science.
Unpacking Creatine Monohydrate with Dr Darren Candow & Dr Dan Plews - PILLAR Podcast
๐ฌ Core Finding
โข Creatine isnโt just for strengthโit helps endurance athletes recover faster, stay cooler, and handle more training.
๐ Key Research Points
โข Daily 5 g cuts soreness by lowering inflammation and oxidative stress.
โข Boosts cell water: muscles + plasma hold up to 92% more fluid.
โข Body comp improves: +1โ2 kg lean mass, โ0.5โ1 kg fat.
โข Cramping risk drops with steady dosing (not loading).
โข Enhances repeat sprint, hill, and cross-training efforts.
๐ ๏ธ Practical Applications
โข ๐ฝ๏ธ Take 5 g creatine/day โ Reduce muscle damage and bounce back quicker.
โข โก No 20 g loading โ Avoid bloat and gain the same benefits in ~3 weeks.
โข ๐ก๏ธ Training in heat? โ Creatine pulls water into cells for cooling + heart support.
โข ๐ Race week? Pause 7โ10 days before weight-sensitive eventsโstores stay topped for ~4 weeks.
๐ฏ Bottom Line
โข Creatine helps you recover faster, train harder, and stay hydratedโespecially in the heat.
โข Dose low, stay consistent, and skip the loading phase for endurance-friendly benefits.
Donโt forget: You + Science = AWESOMENESS ๐
Yours in science,
Jonah
P.S. - We have a crew of 15,270+ nerds here who are running FAST using science.
Did you need running science advice or tips? ๐โโ๏ธ๐จ๐งช
Reply with your question, Augie and I (pictured below) will get back to you with science-backed tips!
Enjoy the newsletter? Please forward to a pal. It only takes 18 seconds. Making this one took 11.23 hours.
Please email me directly if youโre interested in references for this week!