Dr. Stacy Sims Isn’t Anti-Zone 2: Seven Midlife Training Lessons
Updated: 2 days ago
The training advice aimed at midlife women contradicts itself. Some say lift heavy or don't bother. Others say stick to high reps. And plenty of people warn that cardio will cost you muscle. So a lot of women pick up their weights and second-guess the first set.
You don't have to pick a camp. On a recent episode of the Body Pod, Hailey and Dr. Stacy Sims, the exercise physiologist and author of ROAR and Next Level, answered the questions women ask most: zone 2, high intensity, rep ranges, jump training and protein. Their answers share one theme. There are very few absolutes, and the right approach depends on where you're starting from.
Discover the seven key lessons from that conversation, the research behind each one, and how each shows up inside the eight plans of the Power Happens collection.
1. Higher reps first, heavy later
One of the most common questions about strength programs built on Stacy's research sounds like this: if Stacy says to lift heavy with low reps, why does the beginner program start with higher reps? Lifting heavy is the destination; the early weeks are the road there.
Starting lighter does two jobs. "One, we don't want injury," Stacy says. "Two, we want people to learn how to move properly." The early phase answers practical questions. How deep is your squat? Where do you stall? Does your mobility need work? How strong is your core? Until those are sorted, heavy loads add risk without much benefit.
Lighter weeks still build muscle. "Your body responds to load and it doesn't matter if it's high or low load," Stacy explains; what changes is the type of adaptation. A 2017 meta-analysis of 21 studies by Brad Schoenfeld and colleagues found that when sets were taken to failure, light and heavy loads built muscle about equally, while heavy loads produced bigger gains in one-rep max strength. The lighter phase builds muscle and movement skill; the heavier phase is where maximal strength climbs. Even the best-known heavy lifting trial for postmenopausal women, LIFTMOR, spent its first month on bodyweight and low-load versions of each lift before any heavy sets.
Every rep range has a season
Each rep range earns a few weeks of your training year; none earns all 52 weeks. Higher reps build muscle, prepare tendons and ligaments for heavier work, help you rebuild after an injury, and give small stabilizing muscles the time under tension they need. Heavier, lower-rep sets drive maximal strength and send the nervous system the signal it needs to build bone. Moving between them on purpose is what periodization is. That's why she steers midlife women away from sets of 20 or more to failure as a default. Watch Stacy explain rep ranges in the full clip.
Inside Power Happens
Beginner 1.0 opens with higher rep ranges. Those early weeks prepare your tendons and ligaments and teach you to feel the muscle working before you add heavier loads. Over four 3-week programs, the methods advance and the loading builds at a pace your body can absorb. Hailey holds herself to the same rule: her annual foundation block has sets of 20 to 25 reps for three weeks. It's a tool to pick up and put back down.
2. Lift heavy, then back off and build again
Before menopause, estrogen plays a major role in building muscle and maintaining bone. As it declines, that signal fades, and the body needs a new one. Heavy, power-based lifting provides it by demanding a strong response from the nervous system. Stacy describes the goal as a "central nervous system response to actually take the place of estrogen to build the lean mass in the bone." By her definition, heavy means compound lifts like squats and deadlifts in sets of roughly six reps or fewer.
The LIFTMOR trial from Griffith University shows what that signal can do. Researchers trained 101 postmenopausal women, average age 65, all with osteopenia or osteoporosis, twice a week for eight months. After a month of technique work, the lifting group did deadlifts, back squats and overhead presses for 5 sets of 5 reps above 80 to 85% of their one-rep max, plus jumping chin-ups with drop landings. Their lumbar spine bone density rose 2.9%, while the low-intensity control group lost 1.2%. An exercise scientist and a physiotherapist supervised every session, and the researchers advised women with low bone mass not to attempt the protocol alone.
Heavy lifting is also a phase you cycle through rather than a place to live. Stacy doesn't want women to stay in "that high loading and lower rep range for the rest of their life."
Periodization handles this: build toward max strength, move into a recovery phase, then rebuild from a stronger starting point. That recovery phase is still training. Changing the stimulus keeps the nervous system learning, and it builds stress resilience. "First, we need to make sure your body's really resilient enough to take on those loads," Stacy says, and the planned back-offs are how that resilience keeps growing.
Inside Power Happens
You are never doing the same workout for twelve weeks. Every plan runs in short blocks, four 3-week programs in most plans and three 4-week programs in Express 2.0, and the method changes from one block to the next. Beginner 2.0 moves through trisets, antagonist and agonist supersets, and pyramids. Intermediate 1.0 is where max strength work begins, cycling between higher volume and heavier loads. Intermediate 2.0 adds descending max strength blocks, and Express 1.0 uses wave loading and the 5x5 method. The Advanced plans switch between full body days and an upper and lower split so the stimulus keeps changing.
3. What Dr.Stacy Sims says about Zone 2
Longevity advice now prescribes zone 2 for 45 to 90 minutes, four to five times a week. People often sum up the Stacy Sims zone 2 position as "no zone 2 ever," and she's quick to correct that: "I'm not anti-zone 2." Her point is about where the evidence comes from and how much time it asks for.
What women lose quickly with age are their fast-twitch fibers. So for health and longevity, Stacy recommends polarized training: true high-intensity work, proper strength training, and zone 2 as "soul food" for stress relief, recovery or a long walk with a friend. In her words, "it's not the bread and butter of what we do." Endurance athletes are the exception. Training for a marathon or a 100-mile race still calls for that base volume.
Inside Power Happens
Across Power Happens, heavy lifting does the main work, with conditioning days right beside it, and your soul-food session still fits around all of it.When you’re eating in a calorie deficit and aren't recovering well between sessions, a zone 2 walk or ride gives you something to look forward to instead of skipping the workout altogether. Further, you need a solid zone 2 base before safely adding intervals. Women new to zone 2 and hiit sessions need to build their zone 2 base first.
4. High intensity feeds your brain
The case for high-intensity work goes beyond fitness. When you push hard enough that your body can't keep up aerobically, your fast-twitch fibers produce lactate. Lactate has a bad reputation as a waste product, yet it's a valuable fuel. "The brain prefers lactate," Stacy explains, "so does the heart."
Research supports the brain's appetite for it. In a 2009 study in the Journal of Cerebral Blood Flow & Metabolism, researchers tracked lactate as it entered and left the brain. When blood lactate rose during hard cycling, the brain took up more of it and burned it for energy, with lactate covering up to 27% of the brain's energy use.
Stacy connects this to one of the most important sex differences in aging. Women are more affected by cognitive decline and Alzheimer's disease than men. Part of that is sociocultural, and Stacy points to a metabolic piece as well. Without regular lactate production, the brain leans harder on glucose, and she argues that brain cells then communicate less efficiently. High-intensity work keeps your fast-twitch fibers making lactate, and that’s part of looking after your brain into your 80s and 90s.
Inside Power Happens
This is why heavy lifting in Power Happens sits alongside sprint work. The strength sessions build muscle and bone, and the SIT and HIIT sessions give your fast-twitch fibers, and your brain, the intensity they need. Intermediate 1.0 offers an optional SIT finisher, Express 1.0 includes two SIT finishers each week, and Express 2.0 gives you a full SIT day and a HIIT day. Short, hard and done.
5. Phase everything in
None of this means jumping straight into sprints. For women new to exercise, or returning after a long break, Stacy's advice is refreshingly simple: start by moving. A brisk walk up a hill is already high intensity for a body that isn't used to it. Within a couple of weeks, that same hill flattens out.
From there, add intensity a little at a time. Take a detour up a flight of stairs on your 20- or 30-minute walk. Pick up the pace for a stretch. Try 30-second hill repeats at a walk, a power walk or a run. As you get fitter, work toward sprints, battle ropes and kettlebell swings. Stacy compares it directly to lifting: "We're not going to throw someone in the gym and have them do a 100 kilo deadlift."
The bigger goal is a positive start. Stacy points out that many kids love moving until a gym class forces them into something they hate, and they carry that attitude for years. For adults, 10 minutes of walking three times a week beats doing nothing, and removing small barriers makes a difference. In research she worked on at Stanford, cooling women down before exercise, taking away the discomfort of heat and sweat, helped them build enough fitness and confidence to join a class or a gym. Training with a friend helps too, because you'd never ask a friend who's just starting out to begin with 30-second sprints.
Inside Power Happens
Beginner 1.0 is built for exactly this woman, whether she's brand new to lifting or coming back after time away. Every plan in the series either runs 50 to 60 minutes (with a 30 to 40 minute alternate, so a short window never has to mean a skipped workout). Hailey’s goal for every woman who starts with training: stay injury-free, fall in love with strength training, and keep showing up for decades.
6. Jump to land hard for bone
Jump training is everywhere right now, and bone research backs it. Any jumping is good for bones, whether it's skipping rope or box jumps. When the goal is specifically to build bone density though, the way you land matters most.
Bone responds to force. A landing that sends roughly 2.5 to 4 times your body weight through your skeleton tells bone to get stronger, and several jump styles can get you there.
The low jump with a firm, flat landing is one of them: as Stacy explains, the body morphs with movement while the ground stays solid, so even a small jump creates a high ground reaction force and the multi-directional stress bone responds to. Bounds, drop jumps and jumps that change direction can clear that threshold too. Rotating through them keeps the stimulus changing and lets you build the load gradually.
Inside Power Happens
In Express 2.0, speed and power become the main training stimulus, bone density is one of the outcomes, and the methods come straight from athletic performance programming, slam ball included. It's the most demanding plan in the series, which is why it comes after you've built your strength foundation.
7. Protein is part of your training
A woman can look lean and still carry a high percentage of body fat, with too little muscle and bones that are less dense than they should be. Most people call this "skinny fat"; the clinical term is normal-weight obesity.
Stacy sees it most in women who were raised on the cardio-heavy advice of the 1980s and '90s. Training that’s mostly cardio keeps the body in a stressed, catabolic state, breaking down lean tissue. The fix has two parts: strength training, and enough protein.
Protein moves the needle more than most people expect. In a 12-week randomized trial published in the British Journal of Nutrition, 50 women with normal-weight obesity ate the same number of calories, with either 25% or 15% of those calories from protein. Neither group lost weight, yet the higher-protein group gained about 1.5 kg (3.3 pounds) more lean mass and improved fat mass, body fat percentage and waist size.
Midlife pushes protein needs higher.. Stacy notes that the official Recommended Dietary Allowance (RDA) is the minimum needed to avoid malnutrition, which is far below what an active woman needs to build or keep muscle. By her account, women start to develop anabolic resistance, a blunted muscle-building response to protein and exercise, from around age 40, compared with the mid-50s for men. Her recommendation for active midlife women is to work toward roughly 0.75 - 1 gram of protein per pound of body weight.
She adds a bonus: when women eat enough protein, cravings for sugar and carbohydrates often settle, because the body is finally getting the amino acids it has been asking for.
Stacy's favorite shortcut is a protein coffee: stir protein powder into cold milk, add coffee and chill it overnight for an iced latte with around 30 grams of protein. Another is splitting breakfast around training, so you fuel the session and still get your protein without feeling overfull.
Inside Power Happens
Hailey tells women to step-load their protein. If 120 grams feels impossible at first, and 100 feels doable, start at 100., That counts, and you build from there. Beginner 1.0, Intermediate 1.0 and Advanced 1.0 all come with nutrition guidelines and access to Q&A replays with Dr. Stacy Sims, so you have support on the food aspects of your training while you build strength in the gym.
Training for life
Very few absolutes found in these lessons, and one consistent pattern. Keep zone 2 as soul food, and give more of your week to short, hard intervals and heavy lifting. Phase into intensity and load gradually. Cycle between building and backing off. Land your jumps with purpose, and fuel all of it with enough protein.
This is how you're still lifting your own suitcase into the overhead bin at 85.
REFERENCES:
Hailey and Dr. Stacy Sims, the Body Pod (video embedded above): YouTube
Nuzzo JL. Sex differences in skeletal muscle fiber types: a meta-analysis. Clinical Anatomy, 2023;37(1):81-91. Abstract
van Hall G, et al. Blood lactate is an important energy source for the human brain. Journal of Cerebral Blood Flow & Metabolism, 2009;29:1121-1129. Abstract
Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis. Journal of Strength and Conditioning Research, 2017;31(12):3508-3523. PubMed
Watson SL, et al. High-intensity resistance and impact training improves bone mineral density and physical function in postmenopausal women with osteopenia and osteoporosis: the LIFTMOR randomized controlled trial. Journal of Bone and Mineral Research, 2018;33(2):211-220. Journal
Clissold T. The quantification and development of an osteogenic jump-landing programme and its chronic effects on bone health in premenopausal women. Auckland University of Technology, 2021. Repository
Dr. Stacy Sims, Jump to improve your bone health (OSTEO-GAINS). drstacysims.com
The effect of 12 weeks of euenergetic high-protein diet in regulating appetite and body composition of women with normal-weight obesity: a randomised controlled trial. British Journal of Nutrition. Journal
Tonal, Losing weight after menopause (Stacy Sims on lifting heavy). Tonal
