Strength Training Won't Raise Your VO2max. That's the Whole Point.

A cyclist I've been trading messages with for the better part of a year sent me a screenshot in early March. He'd just come off a six-month strength block — two sessions a week, heavy squats and trap-bar deadlifts, the whole Rønnestad protocol he'd read about on some endurance forum. Before he started, his VO2max test had come back at 58.4 ml/kg/min. After six months, he went back to the same lab, same treadmill, same technician, same morning protocol. The new number was 58.6. Within the test's own noise. He attached the screenshot with one line: "Six months for 0.2. I think this strength stuff is a scam."

I get some version of this message about four times a year. The numbers vary — somebody's threshold didn't move, somebody's pVO2max held flat, somebody's 20-minute power test gained 4 watts and they're not sure if that's real. The story underneath is always the same. A cyclist starts lifting, expects the engine to get bigger, runs the test that measures engine size, and reads the unchanged number as a verdict on the training.

It isn't a verdict. It's the mechanism doing exactly what it does. The unchanged VO2max isn't the thing that failed. It's the thing the research has been telling us for fifteen years not to expect to move, and the reason the rest of the chart matters at all.

The Bad News That Wasn't

The meta-analysis people are quoting is Llanos-Lagos, Ramirez-Campillo, and Sáez de Villarreal, published in the European Journal of Applied Physiology in 2025. It pulled together 17 studies covering 262 trained cyclists doing heavy strength training alongside their normal endurance work, and ran the effect-size math on every physiological variable the studies had tracked.

The headline most people latched onto was the VO2max number. Effect size −0.04. P-value 0.77. In plain English: strength training did not budge VO2max in any direction that's distinguishable from noise. The authors were careful with their wording — they did not say strength training "doesn't help cyclists." They said it doesn't help VO2max. Those are different sentences. The internet read the first one.

The same paper, two columns over, reported the variables that did move. Cycling economy — the watts you produce per liter of oxygen consumed — improved with an effect size of +0.353 (p = 0.012). Time-trial performance moved by +0.463 (p = 0.016). Anaerobic and sprint power moved by +0.560 (p = 0.024), the largest effect of any variable in the analysis. Lactate threshold sat next to VO2max in the noise pile, also not moving. pVO2max — the power output at VO2max — also didn't budge.

If you read that table top to bottom and treat each row as equally weighted news, the picture is confusing. Some things moved, some didn't, the certainty rating is low, draw your own conclusions. If you read it through the equation that actually governs cycling performance, the table tells a single clean story.

The Equation Nobody Reads Carefully

Power, on the bike, is roughly oxygen consumption multiplied by how efficiently that oxygen gets turned into pedaling force. Sports scientists write it as:

Sustainable power ≈ VO2max × fractional utilization × gross efficiency

VO2max is how much oxygen your system can deliver and use per minute at flat-out effort. Fractional utilization is what percentage of that ceiling you can hold for a sustained period — basically your lactate threshold expressed as a fraction of max. Gross efficiency, or cycling economy, is how many watts come out the cranks per unit of oxygen burned.

Three terms. Multiply them together, and you get something close to your sustainable power output on the road.

Now look at what the strength-training meta-analysis actually showed. VO2max: didn't move. Lactate threshold (and by close extension, fractional utilization): didn't move. Cycling economy: moved with a clean, statistically significant effect. Time-trial performance, which is power output integrated over a long enough window to be a fair test of sustainable wattage: also moved.

There is only one term in the equation that changed. The performance change shows up downstream of it.

This is what people miss when they look at the unchanged VO2max number and call the training a failure. The mechanism by which strength training improves cycling performance is not a bigger oxygen-delivery ceiling. It's a more efficient use of the ceiling you already have. If VO2max had moved, that would mean strength training was somehow growing the cardiovascular system, and there's no plausible biology for that — the cardiovascular adaptations come from the bike work, and they were already saturated in these trained subjects. Strength training pulls a different lever. It improves how much road speed you extract from each milliliter of oxygen your heart and lungs deliver.

A cyclist who finishes a strength block with the same VO2max and a higher time-trial power has not failed to get faster. They have gotten faster through the only door that was open to them, which is the door labeled economy.

What Actually Changes Under the Hood

The mechanistic literature on this is, by sports-science standards, embarrassingly clear. When you do six-rep sets of heavy back squats twice a week for three months, four things change in your legs and nervous system, and none of them are "more mitochondria."

Tendon stiffness goes up. Bohm and colleagues (2024) showed this directly in well-trained triathletes — heavy lifting remodels the collagen matrix of the patellar tendon, makes it stiffer, lets force transmit from muscle to bone with less wasted energy on each pedal stroke. A stiffer tendon is a better lever. The same metabolic cost moves more wheel.

Neural drive goes up. Aagaard and Andersen's 2010 review, which is still the cleanest summary of this stuff, documented something like a 15% improvement in rate of force development after fourteen weeks of heavy lifting. Translation: the top of every pedal stroke gets sharper. The muscle reaches peak force faster, finishes the stroke earlier, and spends less time fighting itself.

The slow-twitch fibers themselves get stronger. This one is counterintuitive — most people associate "strength training" with fast-twitch fibers, but the more useful adaptation for endurance cyclists is in the type I fibers. After a heavy block, those slow fibers can produce the same submaximal force at a lower percentage of their maximum capacity. Which means they fatigue later. Which means the fast-twitch IIA fibers get recruited later in a long effort, which means you can hold tempo for longer before the wheels come off. Vikmoen and colleagues (2016) documented exactly this in female cyclists: fractional utilization of VO2max rose from 78.9% to 82.2% over a strength block.

And the fiber population itself shifts. Type IIX fibers — the explosive, glycolytic, fatigue-prone ones — convert toward type IIA, which are still fast but much more endurance-capable. The cyclist comes out of the block with a leg that's better at every wattage demand from tempo to sprint, with no extra mitochondrial density and no extra oxygen-delivery capacity.

None of this shows up on a VO2max test. All of it shows up on a stopwatch.

This was one of the realizations that shaped how Dorsi talks about training response — most users want the metric to move, but the most important adaptations don't move the metric they're watching. They move the metric two steps downstream, and the user has to be told where to look.

Reframing the Test

There's a particular kind of cyclist — and I've been this cyclist — who books a VO2max test before starting a strength block and another one six months later, expecting the second number to validate the first six months of squats. The expectation is wrong from the moment it's set.

The right test for a strength block, if you're going to test anything, is a 20-minute power effort or a real time-trial on a familiar course. That's where economy gains show up. If your TT power at the same heart rate is 4% higher than it was in October, and your VO2max is unchanged, those two findings are not in tension. They are the two sides of the same coin: the engine is the same size, and you've gotten better at using it. The combined story is you got faster — which is presumably why you started lifting in the first place.

The reason this gets misread, I think, is that VO2max has become the prestige number in endurance culture. It gets quoted in podcast bios. It's the metric Strava-adjacent fitness Twitter argues about. It feels like the engine-size readout, the headline number, the one that "actually" tells you how fit you are. And so when it doesn't move, the cyclist concludes nothing important moved.

But VO2max being unchanged is not bad news. It is, in this specific context, the cleanest possible evidence that the strength training did its job through the right channel. If your VO2max had gone up after a strength block, you would have a different problem on your hands: you'd be looking at the data wondering whether the gain came from the lifting, from a confounded change in your cycling load, from a measurement artifact, or from something else entirely. The unchanged VO2max means the lifting did not contaminate the metric it isn't supposed to touch. Whatever else moved, moved because of the strength work and not because of some hidden cardiovascular shift.

This is the part that, once you see it, you can't unsee. The cyclist who comes out of a strength block with the same VO2max and a measurably faster TT has produced a textbook result. Not a disappointing one.

What to Tell the Cyclist with the Screenshot

I wrote back to my friend with the 58.4 → 58.6 result more or less the following. The VO2max test was the wrong test for the training you did. Your strength training was never going to move that number, and the meta-analysis you didn't read explicitly says so — effect size negative 0.04 in 262 cyclists across 17 studies, which is statistical language for "this lever was never connected to that dial." If you want to know whether the six months were worth it, retest your 20-minute power. Retest your sprint. Look at how long you can hold tempo on a climb you know well before your legs go. Those are the dials the strength work was wired to. The fact that VO2max didn't move is the system behaving correctly.

He went out the next weekend and did a 20-minute test on a flat road he uses for repeat efforts. The number was up 11 watts at the same heart rate. He sent me another screenshot. The message that came with it just said: "Okay."

Six months of squats. Eleven watts at the same cost. Same engine, better lever.

A metric that doesn't change is often the cleanest evidence the mechanism worked. You just have to be looking at the right one to read it that way.