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How Women and Men Really Build Muscle. What the Latest Science Says About Strength Training and Sex Differences

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Building muscle is the product of consistent effort, good nutrition and your body’s natural responsiveness. A major 2025 meta-analysis led by Refalo and colleagues has taken a fresh look at how men and women compare in this process, using a Bayesian* approach to uncover not just if there are sex differences in muscle growth, but how much they matter in real-world training.


As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies at bottom of page.

 

Muscle Growth: Absolute vs Relative Gains


The most striking finding? While men tend to gain more muscle in raw terms (due to starting with more), the relative increase from baseline is nearly identical for both sexes. On average, men’s muscle growth outpaced women’s by just 0.69% - a negligible difference when viewed through the lens of proportional change.


This means if two people start resistance training - one male, one female - they can expect a similar rate of improvement relative to their starting size. The takeaway? Muscle hypertrophy potential isn’t locked to your sex; it’s shaped far more by how you train, how often and how consistently.

 

Where and What Grows: Body Region and Fibre Type Matter


Absolute muscle growth in the upper body slightly favoured men more than in the lower body, likely reflecting greater baseline muscle mass in men’s upper bodies. Yet, when measured as a percentage increase, both sexes gained similarly across all regions.


At the microscopic level, men showed more growth in Type I muscle fibres (linked to endurance) but growth in fast-twitch Type II fibres - important for strength and explosive movement - was virtually the same. This suggests women are just as capable of building strength, especially with exercises that challenge these fibres.

 

You Don’t Need Heavy Weights to Start


One of the best takeaways from this research is that results don’t depend on how you train, but that you train. Resistance training doesn't have to mean barbell squats and gym memberships. Calisthenics - bodyweight exercises like push-ups, squats, lunges, planks and wall sits - are highly effective for building strength, improving coordination and enhancing muscular endurance. Even better, they require no equipment and can be modified for beginners.


Resistance bands, too, offer a joint-friendly and adaptable way to progress in strength. Bands provide variable resistance that challenges muscles differently from weights and are ideal for people returning from injury, new to exercise, or looking for at-home options. They also make warm-ups, mobility work and focused activation drills easier to perform.


By combining these two methods - calisthenics and bands - you can build a structured, full-body training routine that suits your space, schedule, and fitness level. It's a flexible, low-cost and highly effective route to getting stronger.

 

Training Background: No Need to Train Differently


Whether you’ve never touched a dumbbell or you’ve been training for years, the data show similar hypertrophy responses across all experience levels. Men and women do not need drastically different training plans - what matters more is your consistency, progression and enjoyment.


You can build an effective programme with minimal gear. A mix of resistance bands, bodyweight moves, and optional weights can be more than enough to stimulate growth and build confidence. Focus on the basics, and let your body adapt naturally over time.

 

Beyond Biology: A Recent Review Adds to the Conversation


While the Refalo study focused on how muscles grow in measurable ways, Nuzzo’s 2023 review provides the social and psychological context that helps explain why men and women often approach strength training differently in practice - even when the biological capacity for progress is similar.


Women tend to prefer structured, supportive environments, such as group classes, supervised training or programmes with clear instructions. Men are more likely to train alone, seek competitive challenges and focus on upper-body training. These tendencies aren’t random - they are shaped by social norms, evolutionary psychology and personal motivations.


For example, women often cite improved appearance, muscle "toning" and body weight management as key drivers. Men are typically motivated by competition, muscle size and strength performance. Knowing this can help you pick a training style that aligns with your natural preferences and keeps you coming back.


Crucially, women often face more psychological barriers to entry - such as gym intimidation or concerns about “bulking up”. But research shows these fears are misplaced. Resistance training doesn't automatically lead to bulky physiques. Instead, it fosters tone, posture, confidence and functional strength - on your terms.

 

What Else You Should Know


As with most areas of health and fitness, muscle growth is more nuanced than it first appears. Here are a few additional insights from the research that can help you personalise your approach and boost your confidence, no matter your starting point:


1. Muscle Growth Is Not All About Hormones. Yes, testosterone plays a role in muscle size - but it's not the only player. The study found that men and women have similar muscle protein synthesis responses to training, and that other factors - like mechanical tension and training volume - are just as important. That means both sexes can effectively build muscle through consistent, well-structured workouts.


2. Muscle Quality Matters as Much as Quantity. Muscle isn’t just about size - it’s about function. Women may have smaller muscles on average, but their fibre type profile often supports better endurance and fatigue resistance. This means high-rep, moderate-load training can be especially effective.


3. Resistance Training Experience Doesn’t Change the Rules. Whether you're new to lifting or have been training for years, the rate of muscle growth is similar between sexes. What changes is the starting point, not the potential. And the beauty of resistance training? You can begin at any age or ability level and still make meaningful gains.


4. Band Workouts and Bodyweight Training Are Legit. The research doesn’t favour barbells over bands or machines over push-ups - it simply tracks what creates consistent challenge and overload. Progression is key. If your resistance band workout gets harder each week, it’s working. If you’re adding reps, improving form or trying tougher variations in calisthenics, you’re building strength.


5. Your Why Is Personal, But the Science Has Your Back. Whether you want more definition, greater resilience, or improved metabolic health, resistance training is one of the most powerful tools you can use. And now we know: men and women both have the capacity to benefit - equally and impressively - when training is consistent and purposeful.

 

Final Thoughts


This latest research confirms what many strength coaches have observed: women are just as capable of building muscle as men, especially when measuring progress as a percentage of starting size. Whether you’re pushing a barbell or doing push-ups in your living room, your body will respond to resistance and grow stronger over time.


The key is to start. Whether with weights, bands, or bodyweight, consistent resistance training boosts physical confidence, supports long-term health and empowers you to feel capable in your own body.


Strength doesn’t belong to any one gender. It belongs to anyone willing to show up, challenge themselves, and stay consistent. With calisthenics and resistance bands, getting started is easier than ever. No excuses, no gym required - just you, your body and the will to grow.


Changing health for the better it about progress, not perfection, and even small changes can make a meaningful difference over time. For most people, improving health is about finding motivation and prioritising self-care - with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle and circumstances, The Whole Health Practice is here to help.


Whether your interest is healthspan and longevity, to beat chronic illness or to enhance your mental health and well-being, our consultations and programs deliver results that are tailored to your needs.

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Alastair


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*A Bayesian approach is a statistical method that updates the probability of a hypothesis as more evidence becomes available, combining prior beliefs with new data to make more nuanced, probabilistic conclusions.

 
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Related Studies


Refalo MC, Nuckols G, Galpin AJ, Gallagher IJ, Hamilton DL, Fyfe JJ. Sex differences in absolute and relative changes in muscle size following resistance training in healthy adults: a systematic review with Bayesian meta-analysis. PeerJ. 2025 Feb 25;13:e19042. doi: 10.7717/peerj.19042. PMID: 40028215; PMCID: PMC11869894.



Other

Huiberts RO, Wüst RCI, van der Zwaard S. Concurrent Strength and Endurance Training: A Systematic Review and Meta-Analysis on the Impact of Sex and Training Status. Sports Med. 2024 Feb;54(2):485-503. doi: 10.1007/s40279-023-01943-9. Epub 2023 Oct 17. PMID: 37847373; PMCID: PMC10933151.


Hawley SE, Bell ZW, Huang Y, Gibbs JC, Churchward-Venne TA. Evaluation of sex-based differences in resistance exercise training-induced changes in muscle mass, strength, and physical performance in healthy older (≥60 y) adults: A systematic review and meta-analysis. Ageing Res Rev. 2023 Nov;91:102023. doi: 10.1016/j.arr.2023.102023. Epub 2023 Jul 27. PMID: 37507092.


Jones MD, Wewege MA, Hackett DA, Keogh JWL, Hagstrom AD. Sex Differences in Adaptations in Muscle Strength and Size Following Resistance Training in Older Adults: A Systematic Review and Meta-analysis. Sports Med. 2021 Mar;51(3):503-517. doi: 10.1007/s40279-020-01388-4. PMID: 33332016.





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