Watermelon Cuts Next-Day Muscle Soreness

G'day mate!

We were anchored off Cala Gonone on the Sardinian coast. Mates jumping off the boat, and a skipper who spoke zero English but nailed the brief with a fruit platter mid-afternoon.

I'd been having the best peaches of my life all week. But it was the watermelon that made me think.

I've eaten it at ultra aid stations for years, grabbed it mid-effort without thinking twice, and always put it down to the cold and the refreshing hit. Sitting there in the heat, I asked myself something I'd never properly sat with. Is that all it is, or is our body responding to something inside it?

There's something in it.

In this week’s newsletter (4 min read):
🍉 What citrulline is, and why it matters for nitric oxide
🔬 The performance and recovery data on soreness and fatigue
✅ The part of the watermelon with the most citrulline that everyone bins

If you have a mate who eats watermelon by the kilo and has no idea why it works, send them THIS link.

What Citrulline Actually Does

Watermelon is about 92% water. The other 8% is where it gets interesting.

The pink flesh carries an amino acid called L-citrulline. Your body makes its own, and what you eat tops that up.

Citrulline converts to arginine, and arginine is what your body uses to make nitric oxide. Nitric oxide widens your blood vessels, so more blood, oxygen and fuel reach working muscle, and the by-products clear faster. It's the same end point beetroot works toward, reached by a different road.

There's a quirk worth knowing. Eating arginine directly doesn't work as well, because your gut breaks a lot of it down before it reaches your bloodstream. Citrulline skips that step, converts in the kidneys, and raises arginine more reliably than arginine itself does. That's why it's the version that ends up in pre-workouts.

And the white rind carries more citrulline than the flesh, by roughly half again in some analyses. Almost everyone bins it. It's less sweet and a bit bitter, but if you're blending, leave it in.

Less Soreness, Less Fatigue

• Lower soreness the next day. A 2013 study in the Journal of Agricultural and Food Chemistry gave athletes natural watermelon juice before exercise and found significantly less muscle soreness 24 hours later.

• Less fatigue at intensity. Citrulline trials consistently show reduced perceived exertion and better time to exhaustion.

Now the honest part. A decent serve gives you around a gram of citrulline, and supplement trials use three to six. So if you're chasing a dosed pre-workout effect, watermelon on its own isn't it.

That's not the reason to eat it. The reason is everything that turns up alongside the citrulline.

Lycopene, Potassium and Hydration

Watermelon is also one of the richest food sources of lycopene, the carotenoid behind the red colour. It's a potent antioxidant with real anti-inflammatory data. Unlike tomatoes, which generally need cooking to free their lycopene up, watermelon lycopene is readily absorbed straight from the fresh fruit.

The potassium matters if you're training in heat. You lose it in sweat, and it's involved in muscle contraction and fluid balance. It won't replace a proper electrolyte plan on a long session, but afterwards it does real work on replenishment.

One storage tip most people get backwards: keep whole watermelons on the bench, not in the fridge. Uncut melons stored at room temperature keep making lycopene, up to 40% more than chilled ones. Once you cut it, then it goes in the fridge.

What One Serve Actually Gives You

Roughly 500g of watermelon, four or five decent wedges, gives you:

• About 450ml of fluid, close to a full bottle

• Around 38g of fast carbohydrate, the same ballpark as two gels

• Roughly 550mg of potassium, an electrolyte you sweat out

• About a gram of citrulline, plus lycopene, for 150 calories

That combination is the point. On a hot day you're chasing fluid, carbs and potassium anyway, usually from three different products. Watermelon covers most of it in one thing you eat with your hands.

The other bit nobody mentions: heat kills your appetite. Come off a long session in 30 degrees and a chicken bowl is the last thing you want, but cold watermelon goes down easy. The best recovery food is the one you'll actually eat. That's why it's on every ultra aid station table, and it explains why I kept reaching for it without knowing the mechanism.

What to Actually Do

• 500g in the hour after a hot session. Fluid, carbs and potassium in one go.

• Pair it with protein and salt. It isn't a complete recovery meal on its own. Feta, yoghurt or leftover chicken covers the gap.

• Blend the rind in if you're juicing. That's where the citrulline concentrates.

• Store it whole on the bench, not in the fridge. Uncut melons keep making lycopene at room temperature, up to 40% more than chilled ones. Refrigerate after cutting.

• In heat, count it as part of your hydration, not the whole plan. It won't cover your sodium.

Final thoughts

The skipper didn't bring out that platter because he'd read the citrulline literature. He brought it out because that's what you eat on a boat in Sardinia in summer. The wisdom around whole foods usually runs well ahead of the science.

Watermelon isn't a supplement and I wouldn't sell it as one. It's fluid, carbs, potassium and a bit of citrulline in a form you'll actually finish in the heat. In August, that beats most things in a tub.

Quick Notes

🗽As amazing as the honeymoon in Italy was, I’m glad to be back in NYC for a bit, with Ironman training fully underway.

🚴 If you haven’t seen the new YouTube video yet, watch it HERE.

#EatGoodFeelGood

— DC