I got a great question from a 45-year-old lifter. He trains full body 5–7 days per week, keeps moving between exercises, and rarely sits around.

RDLs. Bench. Leg extensions. Rear delts. Walk to the next station, recover, smash another set.

His heart rate stays elevated for most of the 45-minute session, so he asked: does this count as cardio?

Sort of.

Cue the angry meathead noises.

Your heart rate is not a cardio detector

Lifting absolutely has cardiovascular benefits. Blood pressure, insulin sensitivity, vascular function, even VO2peak can improve.

Here's where it gets weirder than the usual talking point. A meta-analysis in healthy older adults found resistance training bumped VO2peak by roughly 1.9 mL/kg/min — but only in programs running under 24 weeks. Past that mark, the improvement vanished (Smart et al., 2022). So lifting can move the aerobic needle, and then it apparently stops moving it.

Still, your heart is doing more than sitting there eating Cheetos while you curl.

But an elevated heart rate does NOT automatically mean you're creating the same adaptations as dedicated aerobic training.

Welcome to the cardiovascular hydraulic fight club

During a hard set of RDLs, you've got a metric crap-ton of muscle contracting and squeezing blood vessels. Pressure goes up, blood flow gets interrupted, and then the set ends and blood comes screaming back into the muscle like somebody opened the Hoover Dam.

Dedicated aerobic training creates a different problem. Now large amounts of muscle are repeatedly contracting at relatively low force while demanding oxygen continuously. Cardiac output stays elevated, muscle keeps extracting oxygen, and your mitochondrial machinery has to keep cranking out ATP instead of hiding behind the squat rack hoping nobody notices it.

THAT is the stimulus we're after when building the aerobic engine.

Lifting pokes that system. Dedicated cardio grabs it by the collar and drags it into the parking lot.

What about Metcons?

They can absolutely help. The problem is assuming that making lifting suck harder automatically makes it great aerobic training.

A 2025 meta-analysis of metabolic resistance training in trained athletes found VO2max moved in the right direction, but the effect didn't reach statistical significance (Tongwu & Chuanwei, 2025). Meanwhile, head-to-head comparisons in middle-aged and older adults favored aerobic training over resistance training for VO2max/peak (An et al., 2024).

Turns out training the aerobic system is a pretty good way to improve the aerobic system. Exercise physiology strikes again.

The clue buried in his question

He said breathing DOESN'T limit his lifting. Perfect. I want your RDL set ending because your posterior chain is cooked — not because your lungs filed a workplace grievance while your hamstrings still had five reps left.

So don't turn good strength training into shitty cardio. Keep the lifting. Add cardio separately.

What I'd do

You don't need six hours of Zone 2 and a Tour de France cosplay kit. Start small. Add some dedicated aerobic work after lifting or on separate days, then measure something.

I like a maximal 2K Concept2 row. Important nerd note: a 2K does NOT directly measure VO2max — you need gas-exchange testing for that. But it is cheap, repeatable, horrifyingly objective, and gives you a useful benchmark.

Test. Train. Retest.

Now you've got data instead of staring at your Garmin during rear-delt flies trying to read your mitochondrial horoscope.

Want the full nerd chute on aerobic development, VO2max, testing, and how to do cardio without murdering your lifting?

https://miketnelson.com/flexible-meathead-cardio

Your lifting is already helping your cardiovascular system. Just don't expect one tool to do every damn job in the garage.

Much love and bigger aerobic engines,

Dr. Mike.

PS — If your current cardio program is "I walk from the bench to the cable stack," the full article walks through where to start and how to know it's working. Then get back to lifting heavy crap like a civilized hoooooman.

https://miketnelson.com/flexible-meathead-cardio

Nerd Fuel

An, J., Su, Z., & Meng, S. (2024). Effect of aerobic training versus resistance training for improving cardiorespiratory fitness and body composition in middle-aged to older adults: A systematic review and meta-analysis of randomized controlled trials. Archives of Gerontology and Geriatrics, 126, 105530.

Smart, T. F. F., Doleman, B., Hatt, J., Paul, M., Toft, S., Lund, J. N., & Phillips, B. E. (2022). The role of resistance exercise training for improving cardiorespiratory fitness in healthy older adults: A systematic review and meta-analysis. Age and Ageing, 51(6), afac143.

Tongwu, Y., & Chuanwei, D. (2025). The effectiveness of metabolic resistance training versus traditional cardio on athletic performance: A systematic review and meta-analysis. Frontiers in Physiology, 16, 1551645.

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Mike T Nelson CISSN, CSCS, MSME, PhD
Associate Professor, Carrick Institute
Owner, Extreme Human Performance, LLC
Editorial Board Member, STRONG Fitness Mag

Mike T Nelson is a PhD and not a physician or registered dietitian. The contents of this email should not be taken as medical advice. It is not intended to diagnose, treat, cure, or prevent any health problem - nor is it intended to replace the advice of a physician. Always consult your physician or qualified health professional on any matters regarding your health.

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