How & Why Women Should Strength Train & Do Less "Cardio"

Dr. Stacy Sims and Dr. Andrew Huberman break down why women should prioritize heavy resistance training over moderate-intensity cardio, how training needs change across different life stages, and why "polarized training" — combining very high intensity with very low intensity while avoiding the middle — is the key to longevity, body composition, and brain health for women.

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1. The Baseline: Resistance Training Is Non-Negotiable 💪

Dr. Andrew Huberman opens by expressing how delighted he is that the culture around women and resistance training has shifted so dramatically. He recalls taking his sister to the gym when they were in high school and she was practically the only woman there. Times have changed, and now there's a strong push for both men and women to lift weights.

Huberman lays out his general belief:

"I'm a big believer in people, everybody, getting ideally two or three resistance training sessions in per week and two, maybe three cardiovascular training sessions per week. That would be ideal."

But the conversation quickly pivots to the real question: what should women specifically be doing, and how does that change with age? Huberman asks Dr. Stacy Sims — an exercise physiologist and nutrition scientist specializing in female-specific training — to break it down across age brackets: women 30 and younger, 31 to 40, 41 to 60, and 61 and beyond.

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2. Training Recommendations by Age Group 📋

Women in Their 20s to 30s

Dr. Sims emphasizes that for younger women, the first priority is learning how to move well. Whether someone is 20 or 60, she phases them in the same way — start with mastering complex movements before loading them up with weight.

Once foundational movement patterns are solid, she recommends three to four resistance training sessions per week. These don't need to be marathon gym sessions. If a younger woman is training to failure (which Sims recommends for this age group to build strength and hypertrophy), sessions might run about 45 to 60 minutes.

On top of that, she suggests adding sprint interval training at the end of one of those sessions, or fitting in at most two HIIT sessions on separate days — especially if training for a specific endurance goal like a marathon or triathlon.

"Ideally we look at three to four resistance training with really good movement when we're in the younger set, with two high intensities."

Women in Their 30s

As women enter their 30s, Sims says the focus should shift from just "going through a circuit" to being more intentional and strategic about resistance training. This means:

• Focusing on compound movements (squats, deadlifts, chin-ups, rows, overhead presses, bench presses)
• Doing heavier work
• Periodizing training in roughly six-week blocks that build on each other

"We want that base foundation so when we get to be 40 plus we can actually go and do our power-based training."

The Critical Distinction: Younger vs. Older

Huberman and Sims land on a powerful and surprisingly simple distinction:

"The key when you're younger is working to failure. The key when you're older is working heavy."

For younger women, training to failure drives lean mass growth alongside strength. For older women, because it becomes so much harder to put on lean mass, the emphasis shifts purely to the strength component. This matters enormously for longevity because heavy strength training stimulates the central nervous system, which feeds forward into:

• Better proprioception (awareness of body position in space)
• Attenuation of cognitive decline
• More neural growth patterns and neural pathways

Sims highlights that there's fascinating research on strength and power-based training for older women, particularly regarding sex differences in conditions like dementia and Alzheimer's. There's even interesting literature suggesting that unilateral movements (training one limb at a time) may be especially beneficial as people age.

"There's some really interesting research looking at strength training in that power-based stuff when we're getting into our older ages because we get more neural growth patterns and more neural pathways."

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3. Resistance Training Splits: What Works Best? 🏋️‍♀️

Huberman asks a practical question: should women train the same muscle groups three to four times per week, or use some kind of split routine (upper body/lower body)?

Sims's answer is refreshingly flexible — it depends on the individual's schedule:

• Short on time? Do a split routine (upper/lower on different days).
• Can allocate an hour to an hour and a half? Total body sessions with adequate rest work great.

The key isn't the specific split; it's the quality and intensity of the work being done.

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4. How Men and Women Age Differently: The Perimenopause Factor ⚠️

This is where the conversation takes a crucial turn. Dr. Sims explains a fundamental difference in how men and women age:

"Men age more in a linear fashion, whereas women we have a definitive point in our late 40s, early 50s where all of a sudden things go to where it's that perimenopausal state."

She describes getting countless emails and DMs every day from women saying:

"I'm 46 or I'm 47, I'm putting on body fat, I don't know what's going on, I can't sleep."

When she tells them it's perimenopause, many respond with "What is that?" — highlighting a massive gap in awareness.

During perimenopause, the body undergoes enormous changes: declining sex hormones, more anovulatory cycles (meaning little to no progesterone), and erratic estradiol levels that flatline. Because every system in the body is affected by these hormonal shifts, the consequences are wide-ranging:

• Increased soft tissue injuries
• Frozen shoulder and plantar fasciitis — two hallmark conditions of perimenopause
• Changes in body composition

Sims stresses that this mid-40s to early-50s window is a definitive aging point for women, and this is exactly why she pushes so hard for women to get into heavy lifting and polarized training before perimenopause hits:

"I really tried to get women to get into the heavy lifting and get into the patterns of polarizing their training... so that when they get into that one point in time of that perimenopause, their body is already conditioned for the stress that's coming."

For men, these kinds of changes — soft tissue injuries, body composition shifts — tend to happen in their late 50s to early 60s, giving them a wider bandwidth to prepare. For women, the timeline is more compressed and more predictable, making early action even more critical.

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5. The Cardio Problem: Why Moderate Intensity Is the Enemy 🚫🚴‍♀️

Huberman observes that most women, unless they know better, default to cardiovascular exercise over resistance training. So if a woman in her late 30s to 50s is already doing her resistance training, what about cardio? Should she be careful about how much she does, and what kind?

Dr. Sims doesn't hold back. She's famously critical of popular fitness programs that target this exact demographic:

"I am notorious for slamming things like Orangetheory and F45 because they market specifically to that age group of women and it's not appropriate because it's not true high-intensity work."

She tackles the widespread belief that cardio helps with fat loss and body composition:

"Women who are really trying to maximize body composition change and longevity... unfortunately default to cardio because they think, 'Oh, that's going to help change my body composition, it's going to help me lose body fat.' It doesn't."

Huberman asks about Soul Cycle and similar spinning classes — all that sweating, all those "calories burned" metrics flashing on screen. Sims explains the core problem: these classes put women squarely in moderate intensity. Women leave feeling absolutely smashed, which feels like it must be working. But here's what's actually happening physiologically:

"It's putting you in a state of intensity that drives cortisol up, but it's not a strong enough stress to invoke the post-exercise growth hormone and testosterone responses that we want to dampen that cortisol."

This is the origin of the common (but misleading) advice that women in their 40s and beyond "shouldn't do high-intensity work." Sims corrects this:

"Actually, they shouldn't do moderate intensity. They need to avoid that."

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6. Polarized Training: The Real Solution ⚡

So what should women do? Polarize. This means training at the extremes — very high intensity and very low intensity — while deliberately avoiding the moderate zone in between.

What "True High Intensity" Looks Like

Sims defines it precisely:

• HIIT: 1 to 4 minutes at 80% or more of maximum effort
• Sprint interval training: full gas for 30 seconds or less
• Done only a couple of times per week — not every day — because adequate recovery is essential to actually hit those intensities

"Those are the intensities that are going to give you those post-exercise hormonal responses to drop cortisol."

A Practical Example

Sims shares what she has many women do in practice:

1. A 20-minute heavy lower body session
2. Then hop on the assault bike and go as hard as possible for 30 seconds
3. Recover as long as needed
4. Repeat for another 30-second all-out effort

"Most people go, 'Oh, I can do four or five of those.' After two, they're completely gassed because it's that hard of work."

That's the point — if it doesn't feel almost impossible after just a few rounds, it's probably not intense enough.

What About Zone Two and Long, Easy Cardio?

Sims acknowledges the appeal of long, easy efforts. She herself loves riding her gravel bike on weekends for long periods, even though she admits:

"Which is not optimal for me, my age, that kind of stuff, for all the things that I want to see improvements in. But mentally it's great."

Zone two — the kind of effort where you can maintain a low-level conversation — is fine for mental health and enjoying nature. But for optimal health and well-being, it shouldn't be the focus:

"For optimal health and well-being, we don't want to do that. We want to look at resistance training as a bedrock and true high-intensity work to help with body composition change, metabolic control, insulin sensitivity, brain health, and dropping that cortisol."

The Full Polarized Picture

Huberman summarizes to make sure he's got it right: polarized training means three or four days of high-intensity resistance training (45 to 75 minutes per session) combined with walking or very easy movement for recovery — and avoiding those middle-ground classes that leave you drenched in sweat but don't actually drive the adaptations you need.

Sims confirms, adding one final clarification:

"You have very, very low intensity for recovery and super, super high intensity for metabolic and cardiovascular changes. That's what we're after."

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Wrapping Up 🎯

The core message from Dr. Stacy Sims is both simple and transformative: women need to lift heavy, train at truly high intensities for short bursts, and stop spending hours in moderate-intensity cardio that drives cortisol without delivering the hormonal benefits they need. This becomes even more critical as women approach perimenopause — a dramatic inflection point that men simply don't experience in the same way. Polarized training isn't just a performance strategy; it's a longevity strategy that protects the brain, builds resilience against age-related decline, and prepares the body for the hormonal storm ahead. The bottom line: resistance training is the bedrock, true high intensity is the catalyst, and everything in between is where women should spend the least amount of time.