The New York Times published a recent article, “Why Weight Lifting Is Good for Your Heart” (gift link), that caught my attention. Not because it was news to me but, rather, because a well-known doctor on Substack had blocked me after making essentially the same argument. I’d never quite figured out why.
It’s fine. I’ve been blocked by a few doctors (and fake people) on Substack for asking questions they didn’t like—usually about whether their columns were AI-generated. I believe doctors especially owe their readers clarity when the words under their bylines came from a machine.
But this wasn’t that. Reading that NYT article’s subheading about how strength training is “surprisingly good cardio” took me back to April, when Howard Luks, an orthopedic surgeon whose work I followed, published a lengthy Substack note claiming that weight training “doesn’t count as cardio.”
The two statements—one by a doctor who is not a sports cardiologist and one by a newspaper that interviewed a sports cardiologist and two exercise scientists—contradict one another. (Luks’s own note also opens with a claim that’s wrong and closes with one that’s right, which led to the exchange that precipitated our Substack breakup.)
In fact, neither is accurate.
How weight training can improve cardiorespiratory fitness
My personal experience, after close to five decades of strength training that now centers on high-intensity, HIIT-like workouts with weights, is that weight training can absolutely produce a cardio benefit. Not as much as, say, beach sprints or jumping rope, of course, but certainly more than “doesn’t count.” Especially given the way I’ve been working out the last several years, with supersets.
Related read: Supersets for strength, cardio & more fat burning
Supersets involve doing two or three different resistance exercises, usually with moderate loads, with minimal rest in between. They feel more like running with a weighted vest than lifting heavy to failure. Anyone who says supersets are incapable of producing a cardio benefit doesn’t, with all due respect, know what they’re talking about. That’s not just me talking; it’s the research.
A 2021 meta-analysis of 45 separate papers found that circuit-based resistance training “has been shown to be an effective method for improving body composition, cardiorespiratory fitness, and strength of the lower and upper limbs.”1 Such training, this analysis found, led participants to a 4.3% drop in fat mass, a 1.9% gain in muscle mass, and a 6.3% rise in VO2 max.
The American Heart Association, moreover, in a 2023 scientific statement on the subject, wrote: “In healthy older adults, [resistance training] improves muscle strength and power and results in increased mobility, physical function, and cardiorespiratory fitness” (Italics mine). So to say weight training doesn’t count as cardio is incorrect.
Disagreeing with a prolific Substack doctor
I shared that data point with Dr. Luks, who generates volumes of online longevity-related content that goes well beyond orthopedics, in a comment to his Substack note that asked whether he’d overstated the “doesn’t count as cardio” thesis. While strength training doesn’t replace cardio for heart health, I wrote in our 8-comment exchange, it surely provides a measurable cardio benefit—especially for people who don’t exercise much.
Wary of confronting a surgeon on a medical topic about which I had no clinical expertise, I had also asked a cardiologist on Substack to examine a post Dr. Luks had previously written on this subject, which includes a curious claim: “Lifting alone builds a heart designed for power, but not for endurance or longevity.”
A confounding argument, and then a block
I’m no expert, but there’s plenty of evidence showing lifting is a staple of longevity. The post itself, which seemed poorly argued and contradictory, later says as much. The headline credits aerobic training, not weight training, with building your heart. And in his April 2 note promoting the post, Dr. Luks says lifting “doesn’t count as cardio” but then closes by saying both kinds of training build a healthier heart.
Part of the confusion may be that at least the free portion of Dr. Luks’s article is AI generated, according to GPTZero. And so is his note, GPTZero also says. AI text analyzers are not always 100% accurate but they tend to not be 100% wrong. Five months earlier, in response to a question I’d asked for an article I was writing on doctors who use AI without telling readers, Dr. Luks had denied publishing AI-generated posts when I’d asked him about it.)
The cardiologist on Substack whom I’d asked for a reality check said, “The post is partially accurate but overstated. He is absolutely right that resistance and aerobic training produce different cardiac adaptations, but mischaracterizes resistance training as lacking cardiovascular benefit.”
Within a day or two, I was blocked and my comments from our exchange below his April 2 note were deleted, as happens when you get blocked. Slightly surprising but c’est la vie.
My point in relating this episode is about not automatically accepting arguments, even clinical ones from medical experts, that appear to contradict real-world experience or rely on half-baked AI analyses. And the importance of asking questions of self-proclaimed longevity-industry experts when their assertions don’t match the data.
Noblesse oblige.
How a New York Times article overstates the evidence
While Dr. Luks understates resistance training’s role in providing a cardiorespiratory benefit, the NYT’s article, from Oct. 9, goes beyond the evidence to assert that lifting weights is “surprisingly good cardio.”
Would that it were true. The study the article cites measured heart attacks and strokes, not aerobic fitness, and the rest of the evidence doesn’t support that claim.
The AHA statement I cited above calls lifting’s aerobic fitness gains “small to moderate,” adding that it “often has modest benefits.” The NYT article concedes that lifting does less for aerobic capacity in people who are already fit, and that they need to keep running, cycling or swimming.
“Surprisingly good cardio,” though, promises more than the evidence or the article delivers.
What did you think of this post? Let me know in a comment.
Ramos-Campo DJ, Andreu Caravaca L, Martínez-Rodríguez A, Rubio-Arias JÁ. Effects of Resistance Circuit-Based Training on Body Composition, Strength and Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis. Biology (Basel). 2021 Apr 28;10(5):377. doi: 10.3390/biology10050377. PMID: 33924785; PMCID: PMC8145598.
I'm a 90 year old woman who does modified weight lifting, hikes up steep trails, and does Pilates once a week and works with a trainer once a week. I think your article is fair and important. From my experience, a balanced regimen works best but what I do does not come from doctors--no matter how experienced--it comes from me knowing my body and my luck in finding great people with whom to work.
I think circuit training can be very strenuous and raise your heart rate considerably. It may be tough for individuals who are new to resistance training or have a low baseline level of cardiovascular fitness. I’ve done it intermittently over the years but prefer to separate my resistance program and cardio program. I’m an avid cyclist and that’s my go-to for cardio. My resistance program emphasizes upper body work with one day a week focused on the lower body due to all the riding I do regularly.