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Today’s Health Upgrade
Can turning up the heat make you fitter?
Speak your way to a smarter brain
The power of the potato
Arnold’s Podcast
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On Our Radar
Can Heat Make You Fitter?
You’ve probably heard of cold plunges, but what if the real recovery and performance boost comes from turning up the temperature?
New research suggests that soaking in hot water after a workout may help improve endurance, lower your resting heart rate, and even increase your body’s oxygen-carrying capacity.
Researchers tested a concept called cross-adaptation, where one form of stress (such as heat) helps the body better handle a different stressor (like low oxygen).
The scientists had 20 healthy adults do interval cycling workouts. One group soaked in very hot water (42°C/108°F) for 40 to 50 minutes, five times per week.
After six weeks, the hot water group experienced more oxygen delivered to their muscles, a decrease in resting heart rate by seven beats per minute, and improved time to exhaustion.
It’s too early to suggest everyone needs to sit in the hot tub or sauna, but the study suggests heat exposure after exercise might teach your body to work more efficiently. You get better at cooling down, your cardiovascular system doesn’t have to work as hard, and your body adapts by producing more red blood cells to carry oxygen—all of which can enhance endurance and delay fatigue.
It’s like giving your body altitude training benefits, without going to the mountains. In other words, heat might be a hidden lever for performance, especially if you're looking to build stamina, recover faster, or push harder without feeling as fatigued. The next step is to determine if the results are replicated and how hot your body needs to be — and for how long — to experience the benefits.
Together With Babbel
Speak Your Way To A Smarter Brain
Just like you can transform your body with resistance, you can reshape your brain more than you think if you engage in the right activities.
Scientists found that mastering a second language increases grey matter density in your brain.
Researchers used brain imaging to compare grey matter density in adults who learned a second language. The scans revealed that bilingual individuals had increased grey matter density in the left inferior parietal cortex — a region of the brain involved in language, memory, and processing complex information.
But the real insight came when they looked closer: the extent of these changes wasn’t equal. Those who became highly proficient in their second language showed significantly greater grey matter density.
The researchers believe these structural differences reflect the brain’s ability to physically reorganize and strengthen itself in response to challenging, stimulating activities like learning a new language.
And it matters because enhancing grey matter may support better cognitive flexibility, memory, and even delay age-related cognitive decline.
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Foods Are Super
White Potatoes: The Satiety King
Think potatoes are the enemy of your waistline? Science says they might be your secret weapon instead.
White potatoes are among the most satisfying foods you can eat—scoring more than twice as filling as brown rice.
Most people think of potatoes as empty carbs, but the reality is they’ve been unfairly demonized. The original satiety index study compared 38 common foods and found that boiled white potatoes scored 323, making them the food with the highest satiety.
And it’s not just that you feel fuller; they also support your fat loss goals. Research found that people who consume low-energy-dense, high-satiety foods — including potatoes — experience greater satisfaction and are more likely to maintain long-term weight loss.
They might even be the ultimate leftover food. When you cook potatoes and then cool them (think potato salad or leftover roasted potatoes), some of their digestible starch turns into resistant starch — a fiber-like compound that resists digestion in your small intestine. Instead, it travels to your large intestine, where it feeds your beneficial gut bacteria. This fermentation process produces short-chain fatty acids, such as butyrate, which can help reduce inflammation, support gut health, and improve insulin sensitivity.
Instead of fearing potatoes, embrace them. They are a filling, nutrient-rich side that helps you stay satisfied, supports gut health, and can be easily incorporated into a weight-friendly diet.
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Publisher: Arnold Schwarzenegger
Editors-in-chief: Adam Bornstein and Daniel Ketchell
