The aerobic engine adapts. At a fixed Zone-2 effort, heart rate climbs slower over forty-five minutes. Six weeks of drift, retraced as a single line. This is what an adapting base looks like.
The class of person who reads this newsletter has already self-experimented. You've changed your training. You've added the supplement and dropped it. You've worn the patch, read the strip, and watched the curve. You've already decided that the answer to what is my body actually doing is too important to outsource to someone else's headline.
This essay isn't an argument for doing more of that. It's an argument for doing it on a protocol.
A protocol is not a regimen. A regimen is a list of things you do. A protocol is the standard you ran the list under, the dose, the duration, the sequence, the markers you read before and after, and the rule for when to stop. A regimen is what you do. A protocol is what you can hand to someone else and have them reproduce the result.
The protocol is the property. Not the molecule, not the gear, not the influencer's stack.
Every protocol that survives contact with real life has four parts: a baseline, a sequence, a markers list, and an exit. Most online "stacks" are missing two of the four, usually the baseline and the exit. Without a baseline, you can't tell whether the protocol worked. Without an exit criterion, you can't tell when to stop. Together, they're 60% of the work, and they're the parts you cannot copy from a screenshot.
A baseline is the panel of measurements you take before you change anything. It can be a blood draw, a body-comp scan, a Cooper test, a fourteen-day CGM trace, a sleep average, an HRV trend, or a one-rep-max test. The discipline is that the baseline is honest. You record it before the protocol starts, in the state you're actually in, not the state you wish you were in. Most attempts at self-experimentation fail at this step. People start the protocol the same week they decide to start it. The right move is to spend two weeks doing nothing different, recording what your body is actually doing, and only then making the change.
A sequence is the order in which you'll change inputs. The sequence is more important than the dose for almost everything. If you start training and start a GLP-1 the same week, you cannot tell whether the muscle loss is from the drug or the training error. The sequence is the variable you isolate.
A markers list is the panel you'll repeat at the end. If the markers list is the same as the baseline, you have a paired comparison. If you change what you measure mid-protocol, you have nothing.
An exit criterion is the rule for when to stop. Most protocols don't have one. People run them indefinitely. The exit can be a positive ("when I hit a marker, taper") or a negative ("if marker X moves the wrong direction by Y%, stop"). Either way, write it down before you start.
If you can't say why a thing should work in your body, you have no way to tell when it stops working. The molecule isn't the point. The mechanism is the point.
This sounds academic until you've watched a protocol go off the rails. A friend ran berberine for nine months on the assumption that it would do the same thing as metformin. The mechanism is similar, but berberine has a half-life problem the dose schedule has to respect, and an absorption problem the timing has to respect. He ran it like metformin. The fasting glucose moved the wrong way. The protocol wasn't wrong; the molecule's mechanism was different from the molecule he was modeling against.
Every protocol in this newsletter will tell you the mechanism, because the mechanism is what generalizes. It's also what tells you what the next protocol should look like when this one stops working. You can't iterate on a molecule you don't understand.
Most of the things on the canonical longevity list are correct in isolation and wrong in combination. They work in the right order at the right dose at the right phase. They don't work as a kitchen sink.
The current sin is the loaded morning stack, eight to fourteen capsules, an electrolyte, a peptide, a fasted training block, and a coffee. Each piece has an evidence base. Together they create a dosing schedule that the body's clearance systems weren't designed for, an absorption regime where everything competes for the same transporters, and a feedback loop where you can't tell what's helping and what's noise.
The fix is not to throw things out. The fix is to publish the sequence. We will tell you, for each protocol, what to take before, during, and after. What to take on training days vs rest days. What to drop during sleep enhancement. What to add during a build and remove during a cut. The sequence is the protocol.
One Feature, one Interview, one set of Numbers, one Log entry, one Glossary spotlight. Every month, the first Wednesday, at 0900 ET. The skeleton stays. The body underneath compounds.
The Feature is the lead essay or curriculum. The Interview is a conversation with a practitioner whose work informs how we sequence things. The Numbers are the math behind a single decision, the calculator, the curve, the data on which dose vs which outcome. The Log is what we're running on ourselves this month, with the markers and the early read. The Glossary spotlight is three terms we use repeatedly that deserve their own definition.
Issue 002 picks up the bookend protocol, what to measure on both ends of a twelve-week build, and the cheapest panel that actually tells the truth. Issue 003 is the GLP-1 protocol done right, the protein floor, the resistance floor, the walking quota, and the off-ramp. Issue 004 is the sleep architecture issue, three things that actually move deep sleep, and the four things people swear by that don't.
We're going to figure out what works on this list before we figure out what works for everyone else. Reply and tell us what you want next.
, Mitchell McClellan · Editor · SYSTEMM Holdings · 03 June 2026
Every other longevity intervention is a candle next to it. The cohort data are unusually clean: VO₂ max is the single physiological measurement most correlated with all-cause mortality across studies of working-age adults. A male in the bottom quintile of cardiorespiratory fitness has roughly five times the all-cause mortality of a male in the top quintile. No supplement, no sleep optimization, no lab marker moves the risk by anything near that magnitude.
The mechanism is dull and well-understood: cardiorespiratory fitness is a measure of the heart's ability to deliver oxygen and the mitochondria's ability to use it. A higher VO₂ max means a larger cardiac stroke volume, more capillary density at the muscle, higher mitochondrial volume, and better oxidative metabolism. These adaptations protect against cardiovascular disease, slow muscle loss, raise insulin sensitivity, and preserve cognitive function. None of this is news. The reason it gets ignored is that the protocol is hard work. You can't take a pill.
You need a measurement before you protocol. The cheapest valid field test is Kenneth Cooper's twelve-minute run: cover as much distance as you can in twelve minutes on a flat route or a track. The math is one line:
VO₂ max (ml/kg/min) ≈ (distance in meters − 504.9) / 44.73
A male covering 2,200 m in twelve minutes scores ≈ 38 ml/kg/min. A male covering 2,800 m scores ≈ 51. The formula is calibrated for adult males and is directionally correct across a wide range; for women, subtract roughly 5–7 ml/kg/min from the result. A treadmill test in a lab is more precise. The Cooper test is more honest about what you'll actually do.
Repeat the test every eight weeks. The slope of your own improvement is more useful than your absolute number.
The most validated protocol for moving VO₂ max in the literature is the Norwegian 4×4: a ten-minute warmup, then four cycles of four minutes at 90–95% of max heart rate alternating with three minutes of active recovery, then a five-minute cooldown. Total session: thirty-eight minutes, of which sixteen are at high intensity. Three sessions a week for twelve weeks moves a typical sedentary forty-something's VO₂ max by 6–8 ml/kg/min. The protocol is unpleasant. The signal is real. It is the cleanest intervention we publish.
The Zone 2 ballast, easy, conversational pace, sits underneath the Norwegian work. Two to three hours of Zone 2 per week, plus the three 4×4 sessions, plus one full rest day. Total weekly work: 4.5–5.5 hours. This is the floor. More volume helps, but not nearly as much as the intensity does.
A sedentary thirty-year-old male starts around 38. A sedentary forty-year-old around 34. A sedentary fifty-year-old around 30. A sedentary sixty-year-old around 26. Each decade loses roughly 10% of the baseline.
The twelve-week protocol returns most people two decades of decline. A fifty-year-old can pull a 30 to a 38 in twelve weeks, the same fitness level as a sedentary thirty-year-old. The reason this matters is that VO₂ max is path-dependent: the highest peak you ever reach in your twenties and thirties sets the slope of your decline through your fifties and sixties. Move the peak in your forties and you move the curve through the rest of your life.
We've built a VO₂ max calculator at getsystemm.com/calculators/vo2-max. Plug in your twelve-minute distance and your age. The calculator returns your VO₂ max, your age-percentile band, and the all-cause mortality reduction implied by a one-decile improvement. Use it as a baseline and again at week twelve.
Twelve weeks of Norwegian 4×4 plus Zone 2 ballast moves the marker. Then you've got two choices: deload for two weeks and re-baseline, or push the protocol another twelve. Most people benefit from one full cycle of stimulus and one cycle of consolidation per year. The mistake is running the protocol indefinitely. The body adapts; the stimulus has to keep getting harder, or it stops working.
We publish the next stage in Issue 005: the aerobic block periodization protocol for moving VO₂ max past the first 8-unit jump.
A few people in the world pair a terminal degree in exercise physiology with elite-level performance experience in the trenches. Pat Davidson is one of them. He holds a Ph.D in Exercise Physiology and a Master's in Strength and Conditioning. He has fought professionally in MMA, qualified twice for the World Strongman Championships, represented Team USA in Strongman at the Arnold Classic, and is now pursuing a career in bodybuilding with the goal of becoming an IFBB pro. He has written three books, co-hosts Strong Talk on Men's Health, and has educated thousands of personal trainers, rehab professionals, and competitive strength athletes. He sequences SYSTEMM's strength, conditioning, and recovery protocols. We caught up with him in late May, four weeks into a six-week cardiac-drift baseline.
, Edited for length and clarity
One week. One household. Track every distinct plant species consumed, herbs, spices, nuts, seeds, fruit, vegetables, grains, legumes. Repeat for four weeks.
The cleanest mechanism-first heuristic to come out of microbiome research in the last decade is one number: thirty distinct plant species per week. Tim Spector's lab at King's College ran the citizen-science cohort that produced the finding, looking at gut microbial diversity (alpha diversity, broadly: how many different species inhabit your gut, weighted by abundance) against dietary variety. The inflection point was thirty. Above it, alpha diversity meaningfully increased. Below, it plateaued.
Plant species, broadly defined: every distinct herb, spice, nut, seed, fruit, vegetable, grain, and legume counts as one. A cup of mixed greens with five named greens counts five. A trail mix with almonds, walnuts, raisins, and dark chocolate counts four. Cumin counts. Garlic counts. The threshold is variety, not volume.
Most diet research drowns in confounders, caloric intake, macro ratios, processing, satiety, social context. Plant species count is robust to most of them. It correlates with gut species count in a dose-response way across the cohort. It correlates with several downstream markers, short-chain fatty acid production, inflammatory markers, post-meal glucose response. And it doesn't require you to count calories, weigh anything, or eliminate any food group. It's additive.
The point of the count isn't to count forever. The point is to see the gap and close it.
| WEEK | TARGET | WHAT YOU'LL DO |
|---|---|---|
| 01 | Count what you already do | No changes. Log distinct plant species, Mon → Sun. Most people land 7–12. |
| 02 | Double it | Add one new herb, spice, or nut per meal. Use leftover produce. Buy a different grain. |
| 03 | Hit twenty | Add a "seven-plant" salad twice a week (any 5 greens + 2 others). Mix nuts. |
| 04 | Hit thirty | Three "seven-plant" meals + maintain the spice expansion. Track once. |
If you hit thirty in week four, the goal becomes maintenance, not increase. Most people stabilize around twenty-five to thirty-five once it's habitual. Below twenty for more than a month is a signal to reset.
Two things, fast. Bloating tends to decrease by week three for people who started high in animal protein and low in fiber. Bowel habits regularize. Cravings for highly palatable processed food drop, not because you removed anything, but because the substrate is more interesting.
What you won't notice by week four, and shouldn't try to: a body composition change, a marker shift on a panel, a sleep change. Diversity moves slow markers. The fast-feedback wins are gut comfort and the cravings shift. Everything else compounds across the year.
There's no exit on this one. You either count for a month and it's habitual, or you don't and the number drifts back. We'll publish a microbiome marker panel, what to actually measure on a stool test, and what to ignore, in Issue 007.
Issue 002 drops the first Wednesday of July. The bookend protocol, what to measure before and after a twelve-week build, and the cheapest panel that actually tells the truth. We publish the markers list. Until then, the archive.