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Today’s Health Upgrade
Number you won’t forget
When good nutrition intentions take a surprising turn
Weekly wisdom
How early struggles can lead to more success
Health
Number You Won’t Forget: 6 Minutes
Want to Improve Neuroplasticity? Fire up your heart rate.
Brain health advice is not a competition. More sleep. Manage your stress. Eat your vegetables. None of that is wrong, and they should all be priorities.
But, if you talk to biohackers, they might tell you to prioritize everything from fasting to probiotics. However, the real king of better cognition is something much more basic.
Researchers found that 6 minutes of high-intensity exercise produced a 4- to 5-fold greater increase in a key brain-protective protein than 90 minutes of light activity.
Researchers put physically active adults through three separate conditions: a 20-hour fast, 90 minutes of easy cycling, and 6 minutes of hard intervals (six 1-minute efforts with recovery between each). They measured circulating levels of BDNF — a protein that supports neuroplasticity and neuron survival — before and after each condition.
Light cycling raised BDNF modestly. Fasting did not move the needle. And the hard intervals pushed BDNF levels the most, and it wasn’t close. Researchers believe circulating levels reflect brain activity, but cognitive outcomes weren't tested here.
Intense exercise drives a sharp spike in blood lactate, which researchers believe signals the brain to ramp up BDNF production. Fasting did raise ketones — another brain fuel — significantly, but ketones didn't produce the same response. Intensity, not fuel availability, appears to be the driver.
If you want to give your brain a short- and long-term boost, you don't need to spend a long time in the gym. But you do need to push hard, to the point that holding a conversation might feel incredibly challenging. Don’t worry about comparing your intensity to someone else. Scale it to where you are right now, and build from there.
Just six minutes. Go get a pump.
Together With Function
Can A Healthy Habit Go Too Far?
A recent blood test helped me realize that even good behaviors can sometimes lead to unintended bad outcomes. Over the last few years, I started eating more fish, which helped improve my LDL and triglyceride levels.
Unknowingly, the addition of more fish had an unintended consequence. During a recent blood test, my mercury levels came back surprisingly elevated — not dangerously, but enough to require a change in my diet.
Fish are an excellent source of protein, healthy fats, and other key nutrients. And it’s linked to reduced risk of cardiovascular disease. But quantity and quality are important. Eat too much of certain kinds, and you could unknowingly increase levels of a toxic compound: mercury.
In a 2021 systematic review and meta-analysis of 14 studies across more than 34,000 participants in 17 countries, researchers found that elevated mercury exposure was associated with a 68% higher relative risk of cardiovascular disease mortality. In other studies, mercury has been linked to elevated risk of cardiovascular disease and neurological damage.
The issue isn’t going cold turkey. It’s recognizing that methylmercury, the form found in fish, has a half-life of about 40-90 days in the body.
Fish at the top of the food chain — including shark, swordfish, king mackerel, and bigeye tuna— carry higher concentrations of mercury due to bioaccumulation from their regular food sources. Smaller fish like sardines, anchovies, and Atlantic mackerel sit near the bottom of that chain and carry a fraction of the load.
When I traced it back in my own diet, the culprit wasn't anything exotic. It was likely tuna, usually from sushi, which I eat each week.
The fix isn't cutting fish. It's swapping species. Consider eating wild salmon, sardines, anchovies, herring, and trout as good sources of omega-3 fatty acids with a dramatically lower mercury burden. If you eat moderate-mercury fish like albacore or mahi-mahi, keeping it to about one serving per week (per FDA/EPA guidance) can help with your body’s natural clearance time. Third-party-tested fish oil or algal oil can also provide a source of omega-3s with less risk of accumulation.
The good news is that dietary methylmercury responds to behavior change. Because mercury is cleared from the body over weeks to months, avoiding high‑mercury fish can lead to measurable declines in blood levels over time. No detox protocol required.
The only reason I caught my high mercury levels was because I tested for them.
My regular annual exam didn't include mercury testing. I felt fine. No symptoms.
Function was the difference. Members get access to 160+ lab tests, including heavy metals that most routine physicals skip. Every member receives detailed Clinician Notes interpreting results in context, so you can learn what each number means and potential next steps.
Many people test and find their numbers look good. That's worth knowing, too. But sometimes you may catch something you were unknowingly doing to yourself, something simple and fixable.
If you’re like us, you don’t want to schedule a doctor visit every time you want to know if your health habits are translating into meaningful changes. And Function makes it easier to keep an eye on what matters, understand where you can improve, and work with your physician when needed.
Pump Club readers get a $25 credit toward their first year of Function membership, automatically applied at checkout. No code needed.
Don’t just assume you’re healthy because you feel healthy. Keep an eye on your blood, because awareness matters.
Mindset
Weekly Wisdom
You stepped on the scale Monday morning, and the number was higher than last week. Maybe you missed all your workouts. Maybe you ate in ways you said you wouldn't because the stress of everything just landed all at once. Or maybe, you just had terrible sleep, ate a little more sodium and drank a little less water, and had yet to go to the bathroom.
Whatever the reason, you're standing in your bathroom doing the math about what kind of person that makes you.
And it’s not worth figuring out that calculation.
There's a move the mind makes where it takes a single data point — like one day on the scale — and builds a verdict out of it. I weighed more, so I'm backsliding. I skipped the gym, so I'm lazy. I had a rough week, so this is who I am now.
This is where the quote should help you navigate the days of judgment.
The weather rolls in, and we forget we're the sky.
Pema Chödrön wasn't writing about fitness when she said this. But she might as well have been. What she understood is that we are not our conditions. We're the thing that holds them. The temporary passing through the permanent.
A bad weigh-in is weather. A stressful week is weather. A season where everything fell apart? Still weather. It moves through. The sky doesn't stop being the sky just because a storm shows up.
The problem isn't that we feel those things. Feeling them is honest.
The problem is obsessing over them. Deciding that what's happening right now is evidence of something fixed about who we are.
That's when a missed Monday becomes a failed month. That's when one rough patch becomes a story about your limits.
Arnold has talked about this: the difference between being knocked down and being knocked out. Everyone gets knocked down. What separates people isn't whether the storm comes. It's whether they remember the storm isn't them.
Turn Wisdom Into Action
The next time something goes sideways — the workout skipped, the food choice regretted, the stressful spiral — write down exactly what happened. Just the facts. Not the verdict.
"I didn't sleep well and skipped the gym on Tuesday."
Not: "I'm someone who always quits."
Facts are weather. Verdicts are identity. The work is learning to tell them apart.
You're allowed to note the storm. You're not allowed to become it. Because the sky doesn't hold grudges against the weather. It just keeps being sky.
Better Questions, Better Solutions
Why Struggling First Makes You Learn (And Succeed) Faster
Old question: "Am I ready to start?"
New question: "What will starting teach me?"
Most people treat mistakes as something to minimize: a sign you jumped in too soon, moved too fast, skipped a step.
A more logical approach is “learn it right, then do it.” Watch the tutorial. Study the form. Understand the program completely before starting. The instinct makes sense. Why fumble through something when you could learn it right the first time?
But that instinct might be costing you.
Research suggests that struggling before you're taught isn't a detour; it's the more direct path to lasting skill.
A meta-analysis of 53 studies involving more than 12,000 participants found that people who attempted a problem before receiving instruction learned more deeply than those who were taught first and then practiced. Not a little more. Researchers found that the approach could be nearly twice as efficient as standard instruction, and that when people failed productively during the initial attempt, outcomes were up to three times better than in traditional learning.
The researchers call it "Productive Failure."
The mechanism is counterintuitive: when you attempt something without knowing the answer, you activate your existing knowledge, expose what's missing, and create mental gaps that instruction can actually fill.
You're not just learning what to do. You're learning why it matters, and that understanding transfers. The people who struggled first didn't fall behind on basic execution. They got better at applying what they learned in new situations.
While it’s common to “wait until you’re ready,” when you struggle, your brain maps what it doesn't know. Instruction lands differently — more completely — when you've already experienced exactly where it would have helped most.
For anyone building a fitness habit, coming back after a layoff, or chasing any new or big goal, this reframes everything. The first awkward attempt isn't wasted time. It's neurological groundwork.
The next time you're learning something new, don’t wait. Take action. Attempt it before you feel completely ready. Do it imperfectly. Notice what you learn and what questions you have. Then seek the instruction. You'll absorb it differently because your brain now has a specific gap it wants filled, not just information arriving with nowhere to land.
The goal isn't to make random mistakes. It's to make your mistakes; the ones that tell you exactly what you need to learn next. And then take the step to get help, fill the gaps, and improve.
Failure or frustration isn’t wasted effort. It’s how your brain gets ready to win.
And that’s it for this week. Thanks for being a part of the positive corner of the internet. Remember, you have endless opportunities to get better every day. Don’t overthink, do something, and repeat. Have a fantastic weekend!
-Arnold, Adam, and Daniel
Better Today
Take any of these tips from today’s email and put them into action:
1. 6 Minutes of Hard Exercise Raises a Key Brain-Protective Protein 4–5x More Than 90 Minutes of Easy Cardio
Six minutes of hard interval exercise — six 1-minute efforts at high intensity — increased BDNF, a protein critical to neuroplasticity and neuron survival, by 4 to 5 times more than 90 minutes of easy cycling in the same group of physically active adults. The mechanism appears to be blood lactate: intense effort drives a sharp lactate spike that researchers believe signals the brain to ramp up BDNF production — a trigger that 90 minutes of easy pedaling couldn't match and that a 20-hour fast (which raised ketones significantly, but not BDNF) couldn't replicate either. The research points to one variable above all others: intensity, not duration, and six hard minutes is enough to move the needle.
2. You Might Be Eating Too Much Fish. The Wrong Kinds Can Elevate Mercury Without Any Symptoms
A 2021 meta-analysis of 14 studies covering more than 34,000 people across 17 countries found that elevated mercury exposure was associated with a 68% higher relative risk of cardiovascular disease mortality — a risk that accumulates silently through routine fish consumption, with no symptoms until a blood test catches it. Methylmercury, the form found in fish, has a half-life of 40 to 90 days in the body, meaning it builds gradually through high-accumulation species like shark, swordfish, king mackerel, and bigeye tuna. Swapping to low-mercury options — wild salmon, sardines, anchovies, herring, and trout — delivers the same omega-3 benefits without the risk of accumulation, and because methylmercury clears behaviorally rather than through any detox protocol, reducing intake measurably lowers blood levels over weeks to months.
3. You Are Not Your Worst Week: The Mental Framework for Staying On Track
Scale weight fluctuates for reasons that have nothing to do with progress — sodium intake, hydration, sleep quality, and bathroom timing can swing the number by several pounds in a single morning. Arnold has described the core distinction directly: getting knocked down is a condition, not a verdict, and the difference between people who move through setbacks and people who get swallowed by them is whether they can separate what happened from what it means. The practical move is simple: write down what actually occurred as fact ("skipped the gym Tuesday, poor sleep"), not as identity ("I always quit"), and treat temporary conditions as exactly that.
4. A 53-Study Meta-Analysis Found That Struggling Before Instruction Produces Up to 3x Better Learning Outcomes Than Standard Teaching
A meta-analysis involving more than 12,000 participants found that attempting a problem before receiving any instruction produced learning that was nearly twice as efficient as traditional teach-then-practice methods. When learners failed productively on that first attempt, outcomes were up to three times better than those under standard instruction. The mechanism, which researchers named "Productive Failure," works because struggling without the answer forces the brain to activate existing knowledge, expose specific gaps, and create the exact receptivity that makes instruction land completely when it arrives. You're not just learning what to do; you're learning why it matters, in the precise place you need it most. For anyone starting a new training program, returning after time off, or tackling any unfamiliar goal, the implication is clear: the first imperfect attempt isn't wasted time — it's the neurological groundwork that makes everything that comes after it stick faster.
The Positive Corner of The Internet
About Arnold’s Pump Club Editorial Standards
We do things a bit differently here, starting with transparency.
The Content: All APC emails are researched, written, and fact-checked by the APC editors (see bottom of the email), with written contributions from Arnold (noted with “Arnold’s Corner”). Links take you to original studies (not second-hand sources).
Does AI play a role? Not for the primary content, but it is used in two ways. The main items are original content written by the APC team. The summaries at the end are AI-generated based on the human-written content above. We also use an AI tool to review our interpretations of the research and ensure scientific accuracy. We don’t assume AI is right, but we use technology to hold ourselves accountable.
Yes, we have partners (all clearly noted). Why? Because it allows us to keep the APC emails free. We first test products, and then reach out to potential partners who offer ways to help you improve every day. The bar is set high, and to date, we have turned down millions in ad deals. (Example: we will not partner with any non-certified supplements or those without evidence in human trials). If we won’t buy the product, we won’t recommend it to you. And if there’s no evidence it works, then there’s no place for it here.
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Publisher: Arnold Schwarzenegger
Editors-in-chief: Adam Bornstein and Daniel Ketchell
