Strength Training For Women: Setting the Record Straight

There are a lot of misconceptions about strength training for women. This article clearly lays out what the research says about male vs. female strength and muscle growth, and the inferences we can draw from those findings.
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There are a lot of misconceptions about strength training for women, and there are a lot of reasons for those misconceptions.  Women are less likely to be represented in exercise research, women are less likely to take part in strength training or compete in strength sports, and there are still a lot of societal biases against women lifting (heavy) weights.

With that in mind, there are two general camps when it comes to strength training for women:

  1. The first camp says women and men are very different, respond to training very differently, and therefore women should ignore general strength training advice and only focus on advice specifically marketed as being “for women.”  This camp is divided into two sub-camps.
    1. Some people claim that men will respond way better to training and that women’s results will be quite meager in comparison.  This is a pretty standard “bro” position.
    2. Other people argue that bad things will happen to women if they lift heavy.  They’ll either get hurt or get “too bulky,” so lifting heavy weights should be left to the men.  This is a pretty standard position in a lot of women’s fitness magazines.
  2. As a semi-reactionary response to the first camp, a second camp contends that men and women are basically the same, respond to training in basically the same ways, and that training programs or expected training outcomes shouldn’t be at all influenced by sex.

Both groups, incidentally, tend to be heavy on narrative and light on research.  What I want to do in this article is present the research comparing and contrasting male and female strength training.  My goals with this article are to:

  1. Inform people (women specifically, but also coaches of both sexes) about the similarities and differences between men and women when it comes to strength training responses since there’s so much misinformation on the topic.
  2. Encourage more women to lift weights.  Lifting is beneficial for damn near everyone, but for women especially, lifting weights can improve self-esteem and self-efficacy and can help dramatically with decreasing osteoporosis risk later in life.

With that out of the way, this article is going to start with a review of the research comparing strength and muscle growth in men and women.  After that, I’ll focus just on the research using participants with prior training experience, and then I’ll review the inferences we can draw from sex differences in strength sports.  At the end, I’ll discuss some other sex differences and female-specific considerations beyond rates of strength gains and muscle growth.

What you're getting yourself into:

5000 words, 17-35 minute read time

Key points:

1) While men start with more muscle mass and strength, relative strength gains actually tend to be larger in women, at least in the short term. This is especially true for younger women and upper body strength gains.

2) Long-term, relative rates of muscle growth and strength gains are probably roughly equal for men and women, though women may make slightly larger gains, relative to their starting point, across their entire training career.

3) Women are not just "little men."  While relative muscle and strength gains may be similar, there are key differences between men and women that impact training and recovery.

Comparison of strength gains and muscle growth

Men are, in the vast majority of cases, both stronger and more muscular than women.  They also gain both strength and muscle mass at a higher absolute rate.  That much is obvious.  However, relative rates of muscle growth and strength gains are, I think, the more interesting comparison since we largely tend to compare our progress to our own starting points.  If a man gets 10% stronger in response to training, can a woman also expect to get 10% stronger after training, or should she instead expect to gain strength at a faster or slower relative rate?

Most of the time, there are meta-analyses to answer questions like this.  A meta-analysis is essentially a “study of studies,” pooling the results from many different (smaller) research projects to make some sort of comparison.  Meta-analyses are useful because individual studies may have skewed results, and a single study can’t possibly hope to answer every facet of a general research question like “how do relative gains in strength and muscle mass differ between men and women?” (What if they used different exercises?  What if they used different training programs? What if they manipulated diet differently? What if they used people in a different age range? What if the study lasted twice as long? etc.)

Strangely, however, I couldn’t find a meta-analysis comparing strength gains and muscle growth in men and women.  I say “strangely” because there are meta-analyses covering damn near every facet of strength training under the sun.  Typically, once there are around a dozen studies on a given topic, someone’s going to do a meta-analysis. However, there have been 70+ studies comparing strength gains and muscle growth in men and women over the past 44 years, and no meta-analyses.

So…I did one.  If you’re interested in the technical notes, you can find them here.  In the results below, a positive number in a comparison means larger gains for women, while a negative number means larger gains for men.

Studies included in the analysis

Author Title
Abe Time course for strength and muscle thickness changes following upper and lower body resistance training in men and women.
Ahtiainen Heterogeneity in resistance training-induced muscle strength and mass responses in men and women of different ages
Alway Effects of resistance training on elbow flexors of highly competitive bodybuilders.
Arnarson Insulin-like growth factor-1 and resistance exercise in community dwelling old adults
Bamman Gender Differences in Resistance-Training-Induced Myofiber Hypertrophy Among Older Adults
Bellew The Initial Effects of Low-Volume Strength Training on Balance in Untrained Older Men and Women
Bemben Dose–response effect of 40 weeks of resistance training on bone mineral density in older adults
Beneka Resistance training effects on muscular strength of elderly are related to intensity and gender
Capodaglio Muscle function and functional ability improves more in community-dwelling older women with a mixed-strength training programme
Carlsson The effects of strength training versus ski-ergometer training on double-poling capacity of elite junior cross-country skiers
Charbonneau ACE Genotype and the Muscle Hypertrophic and Strength Responses to Strength Training
Colliander Responses to eccentric and concentric resistance training in females and males.
Cureton Muscle Hypertrophy in men and women
Da Boit Sex differences in the response to resistance exercise training in older people
Daniels The effect of two years training on aerobic power and muscle strength in male and female cadets
Delmonico Effects of moderate-velocity strength training on peak muscle power and movement velocity: do women respond differently than men?
Delmonico Alpha-Actinin-3 (ACTN3) R577X Polymorphism Influences Knee Extensor Peak Power Response to Strength Training in Older Men and Women
Dias Impact of an eight-week weight training program on the muscular strength of men and women
Donges Effects of resistance or aerobic exercise training on total and regional body composition in sedentary overweight middle-aged adults
Dorgo Comparison of Lower Body Specific Resistance Training on the Hamstring to Quadriceps Strength Ratios in Men and Women
Fernandez-Gonzalo Muscle damage responses and adaptations to eccentric-overload resistance exercise in men and women
Garthe Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes.
Geirsdottir Gender, Success, and Drop-Out during a Resistance Exercise Program in Community Dwelling Old Adults
Gentil Comparison of upper body strength gains between men and women after 10 weeks of resistance training
Guadalupe-Grau Strength training combined with plyometric jumps in adults: sex differences in fat-bone axis adaptations
Gudlaugsson The effects of 6 months’ multimodal training on functional performance, strength, endurance, and body mass index of older individuals. Are the benefits of training similar among women and men?
Häkkinen Serum hormones and strength development during strength training in middle-aged and elderly males and females.
Häkkinen Neuromuscular adaptations during bilateral versus unilateral strength training in middle-aged and elderly men and women.
Häkkinen Changes in agonist-antagonist EMG, muscle CSA, and force during strength training in middle-aged and older people.
Häkkinen Basal concentrations and acute responses of serum hormones and strength development during heavy resistance training in middle-aged and elderly men and women.
Häkkinen Changes in electromyographic activity, muscle fibre and force production characteristics during heavy resistance/power strength training in middle-aged and older men and women.
Häkkinen Effects of Heavy Resistance/Power Training on Maximal Strength, Muscle Morphology, and Hormonal Response Patterns in 60-75-Year-Old Men and Women
Hand Influence of promoter region variants of insulin-like growth factor pathway genes on the strength-training response of muscle phenotypes in older adults
Holviala Effects of prolonged and maintenance strength training on force production, walking, and balance in aging women and men
Hostler The Effectiveness of 0.5-lb Increments in Progressive Resistance Exercise
Hubal Variability in muscle size and strength gain after unilateral resistance training
Hulya Factors affecting the benefits of a six-month supervised exercise program on community-dwelling older adults: interactions among age, gender, and participation
Hunter Resistance training and intra-abdominal adipose tissue in older men and women
Hurlbut Does age, sex, or ACE genotype affect glucose and insulin responses to strength training?
Ivey Effects of age, gender, and myostatin genotype on the hypertrophic response to heavy resistance strength training.
Ivey Effects of strength training and detraining on muscle quality: age and gender comparisons.
Jozsi Changes in power with resistance training in older and younger men and women
Kell The influence of periodized resistance training on strength changes in men and women.
Kosek Efficacy of 3 days/wk resistance training on myofiber hypertrophy and myogenic mechanisms in young vs. older adults
Lemmer Effect of strength training on resting metabolic rate and physical activity: age and gender comparisons.
Lemmer Age and sex differentially affect regional changes in one repetition maximum strength.
Lemmer Age and gender responses to strength training and detraining.
Lexell Heavy-resistance training in older Scandinavian men and women: short- and long-term effects on arm and leg muscles.
Liu Skeletal muscle gene expression in response to resistance exercise: sex specific regulation
Maddalozzo High Intensity Resistance Training: Effects on Bone in Older Men and Women
Martel Age and sex affect human muscle fibre adaptations to heavy-resistance strength training.
Martin Ginis Mind over muscle?: Sex differences in the relationship between body image change and subjective and objective physical changes following a 12-week strength-training program
McCartney Long-term Resistance Training in the Elderly: Effects on Dynamic Strength, Exercise Capacity, Muscle, and Bone
McCartney A longitudinal trial of weight training in the elderly: continued improvements in year 2
Melnyk Effects of strength training and detraining on regional muscle in young and older men and women.
O’Hagan Response to resistance training in young women and men.
O’Hagan Comparative effectiveness of accommodating and weight resistance training modes
Peterson Progression of volume load and muscular adaptation during resistance exercise.
Raue Transcriptome signature of resistance exercise adaptations: mixed muscle and fiber type specific profiles in young and old adults.
Reichman Steroid sulfatase gene variation and DHEA responsiveness to resistance exercise in MERET
Ribeiro Effect of 16 Weeks of Resistance Training on Fatigue Resistance in Men and Women
Ribeiro Analysis of the training load during a hypertrophy-type resistance training programme in men and women
Ribeiro Hypertrophy-type Resistance Training Improves Phase Angle in Young Adult Men and Women
Roth Muscle size responses to strength training in young and older men and women
Rutherford The role of learning and coordination in strength training
Salvador Effect of eight weeks of strength training on fatigue resistance in men and women
Schmidt The effect of high-intensity circuit training on physical fitness
Sherk Effects of Resistance Training Duration on Muscular Strength Retention 6-Month Post-training in Older Men and Women
Spurway The effect of strength training on the apparent inhibition of eccentric force production in voluntarily activated human quadriceps
Staron Skeletal muscle adaptations during early phase of heavy-resistance training in men and women.
Stock Sex comparisons of strength and coactivation following ten weeks of deadlift training.
Tracy A More Efficient Magnetic Resonance Imaging–Based Strategy for Measuring Quadriceps Muscle Volume
Tracy Muscle quality. II. Effects Of strength training in 65- to 75-yr-old men and women.
Walts Do Sex or Race Differences Influence Strength Training Effects on Muscle or Fat?
Washburn One set resistance training: effect on body composition in overweight young adults
Weiss Effects of heavy-resistance triceps surae muscle training on strength and muscularity of men and women.
Williamson Reduction in hybrid single muscle fiber proportions with resistance training in humans
Wilmore Alterations in strength, body composition and anthropometric measurements consequent to a 10-week weight training program.

Findings

strength training for women summary of findings
Positive values mean larger relative gains for women, while negative values mean larger relative gains for men. Diamonds = Effect size 95% CI. Black = not significant. Red = significant difference. The white region represents trivial effects, light blue is small effects, darker blue is medium effects, and darkest blue is large effects.

Overall strength gains

There were 63 comparisons of strength gains, encompassing 3,332 subjects.  In these studies, men got 29.41% stronger, on average, while women got 37.42% stronger.  The average difference was 8.01%, with a 95% confidence interval from 4.59-11.43%. This was a significant difference (p<0.0001) and would be considered a small effect (d=0.34; 95% CI: 0.19-0.48).  On average, strength increased about 27% faster in women.

Strength gains in young (<35 years old) people

There were 32 comparisons of strength gains in young people, encompassing 1,745 subjects.  In these studies, men got 30.87% stronger, on average, while women got 45.71% stronger. The average difference was 14.84%, with a 95% confidence interval from 10.26-19.42%.  This was a significant difference (p<0.0001) and would be considered a medium effect (d=0.56; 95% CI: 0.39-0.74).  On average, strength increased about 48% faster in young women.

strength training for women - weekly strength gains in young people

Strength gains in older people

There were 31 comparisons of strength gains in older people, encompassing 1,587 subjects.  In these studies, men got 27.80% stronger, on average, while women got 28.30% stronger. The average difference was 0.50%, with a 95% confidence interval from -3.11-4.11%.  This was not a significant difference (p=0.79).

Upper body strength gains

There were 27 comparisons of upper body strength gains, encompassing 1,599 subjects.  In these studies, men got 34.92% stronger, on average, while women got 47.51% stronger.  The average difference was 12.59%, with a 95% confidence interval from 6.45-18.73%. This was a significant difference (p=0.0002) and would be considered a medium effect (d=0.66; 95% CI: 0.34-0.98).  On average, upper body strength increased about 36% faster in women.

Lower body strength gains

There were 53 comparisons of lower body strength gains, encompassing 2,287 subjects.  In these studies, men got 28.47% stronger, on average, while women got 30.64% stronger.  The average difference was 2.17%, with a 95% confidence interval from -0.92-5.26%. This was nearly a significant difference (p=0.087), but probably isn’t practically relevant and would be considered a trivial effect (d=0.08; 95% CI: -0.03-0.19).

Strength gains in studies lasting 20+ weeks

There were 20 comparisons of strength gains in studies lasting 20+ weeks, encompassing 927 subjects.  In these studies, men got 28.91% stronger, on average, while women got 29.91% stronger. The average difference was 1.00%, with a 95% confidence interval from -5.04-7.03%.  This was not a significant difference (p=0.75).

Indirect measures of muscle growth

There were 28 comparisons of indirect measures of muscle growth (i.e. lean body mass), encompassing 1,607 subjects.  In these studies, men increased measures of lean mass by 2.03%, on average, while women increased measures of lean mass by 1.92%.  The average difference was -0.11%, with a 95% confidence interval from -0.40-0.19%. This was not a significant difference (p=0.47).

Direct measures of muscle growth

There were 25 comparisons of direct measures of muscle growth, encompassing 1,664 subjects.  In these studies, men’s muscles grew 13.21%, on average, while women’s grew 12.24%. The average difference was -0.97%, with a 95% confidence interval from -3.02-1.08%.  This was not a significant difference (p=0.36).

strength training for women - weekly increases in muscle

It wasn’t worth splitting apart the young and older subjects to do formal subgroup analyses for hypertrophy outcomes (I like having at least 20 studies to pool), but just looking at simple averages, it seems that men and women gain muscle at a similar rate regardless of age.  In the studies on young participants (N=8), the men increased muscle size by 13.1%, while the women increased muscle size by 14.1%. Similarly, in the studies on older participants (N=17), the men increased muscle size by 11.9%, while the women increased muscle size by 11.8%. Both of these differences are clearly trivial.

Limitations

The main limitation of this analysis was that most of these studies were performed on untrained participants.  In fact, only 5 of these studies were done on trained subjects. There aren’t enough studies on trained subjects to meta-analyze, but we can examine them individually below.

Another limitation is that, in studies on untrained subjects, we can’t necessarily assume that their backgrounds are identical prior to the start of a study.  In other words, it’s possible that the “untrained” men in these studies had previously undertaken more activities outside the gym that required high levels of muscular exertion than the “untrained” women.  If that were the case, you’d expect women to have faster initial relative strength gains simply from catching up with the male baseline.

That’s why I included the analysis of studies lasting 20+ weeks, to specifically look at studies where that sort of effect wouldn’t influence the results as much.  That’s also why I separated upper body and lower body strength gains, as I’d expect this type of effect would be more prevalent for upper body strength than lower body strength.  In support of the hypothesis that “untrained” women may be more untrained than “untrained” men – especially when it comes to upper body strength – women gained strength faster than men in shorter studies but not longer studies, and in measures of upper body strength but not lower body strength.

Trained subjects

Here are the main results from the five studies on trained subjects:

strength training for women - trained subjects chart

As such, we basically have no good research telling us about rates of muscle growth in trained men and women.  My hunch is that relative rates of muscle growth will continue to be similar, but we’ll have to wait on further research to say for sure.As you can see, only one of these studies (Alway et al.) reported a direct measure of hypertrophy, and only one (Garthe et al.) reported an indirect measure of hypertrophy.  Alway et al. is hampered by a very small sample, while Garthe et al. has a couple other confounding factors – 1) the main purpose of the study was to compare different rates of weight loss, so while the groups with differing rates of weight loss had similar numbers of men and women, it’s possible that group allocation affected results and 2) the study included athletes from many different sporting backgrounds, so while all of them did have prior training experience, it’s possible that the women were somewhat less trained than the men.

However, it’s clear from these studies that relative rates of strength gains seem to be somewhat higher in trained women than trained men.  One study reported no significant differences, while the other four reported at least one significant difference in favor of women, and none in favor of men.

With that being said, it’s certainly possible that there were differences in real-world training status that are basically impossible for a study to account for.  For example, if the men tended to train like hardcore powerlifters or bodybuilders, and the women tended to do the sort of lighter, higher-rep “toning” workouts that are often recommended to women, it would make sense that the women would gain strength faster.  In other words, “research tends to indicate that trained women still gain strength quicker than trained men, but I’m concerned those studies are hampered by methodological limitations, so I’ll continue to assume the null (similar relative rates of strength gains) until research on a more representative population is conducted” is also a very defensible position.

To go a little deeper, we can look at powerlifting meet results to see how the gap between men and women shifts when comparing less competitive lifters to more competitive lifters.  As mentioned in a previous article, women lift about 67% as much as men in the squat, 56% in the bench, and 71% in the deadlift, on average (using allometric scaling to correct for differences in body mass).  However, those gaps are larger when looking at less successful lifters (those in the 10th percentile of relative strength) and smaller when looking at more successful lifters (those in the 90th percentile of relative strength).  A 5th percentile woman has about 62% as much relative strength as a 5th percentile man in the squat, 53% in the bench, and 67% in the deadlift. On the other hand, a 95th percentile woman has about 71% as much relative strength as a 95th percentile man in the squat, 60% in the bench, and 75% in the deadlift.  An analysis of weightlifting results in CrossFitters had similar findings (though they didn’t correct for differences in body mass):  larger sex gaps in snatch and clean & jerk performance in lower-level lifters and smaller gaps in higher-level lifters.

allometrically scaled strength in men and women
Notice how the relative gap is smaller in lifters at higher strength percentiles.

The narrowing of the gap as competitiveness increases suggests that women may truly continue gaining strength at a slightly faster relative rate across their training careers.  Similarly, a 2014 study of elite athletes in a variety of sports found that the women had about 85% as much lean body mass as men; before training, women tend to have ~60-70% as much lean body mass as men, suggesting that women may actually gain relatively more muscle than men long-term (though, for all of these comparisons, you can’t assume causation from cross-sectional analyses).  

So, just to wrap up this section, here are the big takeaways:

  1. Relative rates of muscle growth in men and women are virtually identical.
  2. Relative rates of strength gains are at least equal between sexes, though possibly faster in women.
    1. Especially during the first few months of training, relative rates of upper body strength gains are probably considerably higher in women than in men.
    2. Long-term, relative rates of strength gains may be slightly higher in women.  However, if a difference exists, it’s likely very small.

Strength Training for Women – Discussion

I’m sure there are some people in a state of mild disbelief as this point.  After all, men have more testosterone, and testosterone is anabolic; therefore, men should be at a huge advantage when it comes to building muscle and gaining strength, right?  An implication of this analysis is that, assuming a given woman and a given man start with similar amounts of muscle mass and strength, they’d be likely to gain the same amount of muscle and strength if they both started lifting.  That just doesn’t sit right with some people.

However, the role of testosterone may be overstated.  My friend James Kreiger recently published a super thorough analysis (note: paywall, but totally worth it) on all things testosterone and muscle growth, including analyses of cross-sectional research on people with different testosterone levels, studies comparing men and women, studies where people are given exogenous testosterone, and even studies where people were put on drugs to totally suppress testosterone production.  The main takeaway was that testosterone levels can dramatically affect the amount of muscle you start with, but they don’t really impact relative rates of muscle growth.

To quote James, “Variations in your blood levels of testosterone impact your ‘base’ level of muscle, but have minimal impact on your relative (%) gains.  Thus, having higher testosterone levels means having a higher base level of muscle.  While the relative gains will be mostly similar, the absolute gains will be higher due to the higher baseline.”  

That’s very much in line with this analysis: Men start off with more muscle and more strength,  largely due to higher testosterone levels, and absolute muscle and strength gains are larger because they started with a higher baseline.  However, relative muscle gains are identical between sexes, and relative strength gains are likely similar long-term.

Also note, testosterone isn’t the only relevant sex difference here.  There are sex differences in gene expression, sex differences in other anabolic hormones like IGF-1 (which may play a bigger role in women than men), and, obviously, sex differences in estrogen (which, contrary to popular belief, exerts anabolic effects in muscle tissue).  Testosterone is only one piece of a much larger picture that only gets more confusing and convoluted the more you look at it.  At the end of the day, it’s best to just remember the messiness of physiology and understand that outcomes (similar relative muscle growth and strength gains, supported by heaps of research) trump mechanisms (differences in testosterone levels) every time.

Other Female-Specific Considerations

If you’ll harken back to the beginning of this article, you’ll recall the two camps I mentioned:  1) people who claim that the process and outcomes of strength training for men and women are really dissimilar, and 2) people who claim that the process and outcomes of strength training for men and women are basically identical.  As I’m sure you’ve figured out by now, I think that the people in the second camp are closer to the truth than the people in the first camp. However, I think they miss the mark to some degree as well, since there are sex differences that extend beyond average results.

For starters, women tend to be less acutely fatigable than men, meaning they can generally do more reps per set at a given percentage of 1RM, do more sets with a fixed number of reps at a given percentage of 1RM, or both.  There are several factors underpinning this difference, but the two most important seem to be a) women tend to have a higher proportion of type I muscle fibers, which are more fatigue-resistant and b) women tend to have less muscle mass, so they don’t occlude blood vessels quite as quickly when lifting, meaning they can more efficiently deliver oxygen and clear metabolic waste products from their muscles.  (However, I’ll note that this isn’t a unanimous finding).

Second, women may recover from training a bit faster than men (one, two, three).  When I’ve mentioned this in the past, the counterargument I typically hear is that women don’t create as much force, so of course their muscles won’t sustain as much damage, and will therefore recover faster.  However, that doesn’t make much sense when you think about it. For starters, I’m not aware of any evidence showing that people who are stronger or more muscular at baseline experience more muscle damage, more soreness, or larger/longer performance decrements than people who are weaker or less muscular, all else being equal.  More importantly, what each of your muscle fibers “feel” is the tension on that specific fiber; the contractile force of the entire muscle shouldn’t matter, as long as each fiber is being recruited to a similar degree and experiencing a similar amount of tension. I think the more likely explanation is that estrogen may exert a protective effect on muscle, limiting damage and potentially accelerating repair.

Third, men and women may respond differently to low-load training.  At this point, there’s a tremendous amount of evidence showing that low-load training (i.e. sets of 20+ reps) can build muscle just as effectively as heavier training (though just because you can build muscle effectively with low-load training, that doesn’t mean you should).  However, only one of the studies comparing high-load and low-load training was done with women.  It found that women training with higher loads (6-10RM loads) gained way more muscle than women training with lower loads (20-30RM loads).  This stands in stark contrast to similar studies performed on men, suggesting that women may respond to normal, heavy-ish training the same way men do (mostly doing sets of 5-15 reps), but may not respond as well to low-load training.

Finally, women also have to deal with the menstrual cycle (women taking hormonal contraceptives can probably ignore this paragraph).  There’s some evidence that women’s response to training varies based on menstrual cycle phase.  For starters, it takes women longer to recover from training during the luteal phase (last half) of the menstrual cycle.  Building on that, several studies (one, two, three) show that concentrating your training during the follicular phase (first half of the cycle) can lead to larger strength gains and more muscle growth than concentrating your training during the luteal phase or evenly dispersing it across the entire month.  On a more practical level, it’s probably not wise to use an extreme program like the ones used in those studies (for example, training 3-5 times per week during the follicular phase, and only once per week during the luteal phase), but it’s possible that you can increase your progress in the gym while minimizing overtraining risk by adding an extra workout or two per week during the follicular phase.  For example, if you normally train three times per week, every week, you could probably keep training three times per week during the luteal phase, but increase your frequency to four or five times per week during the follicular phase. This would help you take advantage of faster recovery rates and reap the benefits of the larger strength gains and enhanced muscle growth that occur during the follicular phase.

Faster strength recovery during the follicular phase of the menstrual cycle. From Markofski et al., 2014.

Closing Words

I hope you can take something away from this article.  If you’re a woman, I hope it was illuminating and empowering.  If you train women, I hope it was informative. Men and women are more alike than different when it comes to training responses, but similar doesn’t mean identical.  Women are not just smaller versions of men, though they should expect the same relative rate of progress a man would.

If you got something out of this article, I’d really appreciate it if you’d share it with your friends, your gym buddies, and anyone else who you think might benefit.  Since women are so underrepresented in strength training research, I find that this is a topic with so much misinformation swirling around.  I hope this article can serve as a small beacon of sanity.

Addendum, July 2018: Strength Training for Women

A new study investigated male and female strength gains and hypertrophy after strength training, and I found another obscure older study that I missed in my initial sweep.

A recent study by McMahon et al. had men and women train their quads for eight weeks.  Physiological cross-sectional area increased by about 23% for men and 30% for women, and knee extension torque increased by about 14% for men and 22% for women.  These differences were not significant.

A 1985 study by Hunter had men and women do full-body training either three or four times per week for seven weeks.  Lean body mass increased by less than a kilo in all four groups, and bench press strength increased significantly more in the group training four times per week than the group training three times per week.  The male subjects increased their bench press by 11.87% and 16.69% in the groups training three and four times per week, respectively, while the female subjects increased their bench press by 19.54% and 33.33%.  Strength gains were not significantly different between the sexes.

The results of these two studies are in line with the findings of this meta-analysis.

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125 thoughts on “Strength Training For Women: Setting the Record Straight”

    1. “The main takeaway was that testosterone levels can dramatically affect the amount of muscle you start with, but they don’t really impact relative rates of muscle growth.”

      Did you take into account weight gain on anabolic steroids? What if you gain 40 pounds from steroid use. Sure “you don’t increase relative rates of muscle growth”, but clearly you increased muscle growth beyond what you “start with”.

  1. Hi Greg,
    I am a 47 year old woman that has been athletic all my life. I love to tinker with my own training – my training goals are somewhat contradictory – faster 1/2 marathon times and stronger lifts. I just discovered your content a few months ago (MASS subscriber as well) and have found it extremely helpful in trying to create plans that achieve both without over training. But I really appreciate the attention and info for female athletes – this article in particular. There is much more work to be done by the research community – but anything that continues to educate women about the value of resistance training is a needed step to a healthier community

  2. Very interesting topics I just turned 50 and use to go to the gym regular, but I have not been there I a few months and really want to get back in there I want muscle mass when I was going before I some gain ,but I wonder if I have lost any strength. Thank you

  3. Off topic question,

    Does weight training only boost testosterone in the short term, or does it also have a positive effect on testosterone long term?

  4. Johanna Anderson

    I appreciate such a thorough synthesis on this topic. As a systematic reviewer, my main concern would be a lack of systematic assessment of risk of bias in the individual studies. I see you did a funnel plot to see any bias by study size, but there are so many other things involved in study quality (study design, selection of participants, statistical adjustment for potential con founders, etc). I would be interested to see how many of these studies were fair or better quality (there are several well accepted quality rating tools available for various study designs). I would also be interested to see a sensitivity analysis to see if the pooled results differ when high risk of bias studies are eliminated, for example. Thanks for an interesting read.

    1. PEDro is the scoring scale I’m most familiar with, but I’m not sure how applicable it is to these trials. Random allocation, concealed allocation, blinded subjects, baseline comparability, blinded therapists, and blinded assessors just aren’t going to be possible. That’s most than half the scale out the window before even starting. Would you recommend just scoring them on a heavily modified scale?

      1. Johanna Anderson

        I’ll admit I have not looked at any of the individual studies to see what kind of study designs you were dealing with. PEDro is designed for RCTs, and I’m guessing you didn’t have all RCTs, so I agree it wouldn’t be the best tool to use. The Cochrane Collaboration has a tool for non-randomized studies. It’s pretty in-depth but could be simplified. I would most be concerned about tracking potential bias in selection of participants into the intervention/control groups, differences beteeen groups at baseline, adjustment for any differences at baseline, measurements of intervention adherence, and handling of missing data.

        1. Johanna, I agree with you on the general importance of checking SRs and MAs for these points. But have you thought how these biases would represent themselves specifically *in this very topic*? You sound as if this was an SR on a drug or surgical procedure with a clear risk and direction and means of accomplishing a biased result . Greg subtlely pointed out that this topic is a lot different.

          1. Tbh, I think bias assessment is a bit different here vs. topics where the hypothesis is that there are differences between two things (you generally wouldn’t state a hypothesis in a meta-analysis, but there’s generally one there implicitly). The primary bias in research is publication bias – you slice and dice data to get significant findings, and significant findings are way more likely to get published than non-significant findings. So, if there’s high risk of bias and significant differences, you should probably assume the actual mean effect is smaller than the one you came up with.

            In this case, most of the comparisons were nonsignificant, so if there are more unpublished null results floating around out there, they’d just reinforce the main finding here (and, in point of fact, there were; I also came across about a dozen studies stating that there were no significant differences between men and women in either strength or hypertrophy, but they didn’t report enough number or have figures to actually make a quantitative comparison). And for the significant differences, I don’t mind too much if they’re potentially overestimates because a) I’m very confident they’re true differences (I calculated how large of a true null would be needed to get below the significance threshold – it would take a study with anywhere from 3,000-11,000 subjects, depending on the comparison) and I’m not too hung up on the actual magnitude and b) I think the differences are probably only applicable for short-term training responses anyways (no differences in studies lasting 20+ weeks) so a misestimation of magnitude for short-term differences wouldn’t impact long-term implications to any real degree anyways.

  5. Although you’ve mentioned relative gains, some may understand this as they’ll get as big as a man. This might reinforce the fear in woman that they will end up looking like a bulky man if they strength train.

    1. How can one express that this is not the case any more clearly than explaining relative gains, different baselines and even addressing the implications of the results (the very fear of getting as big vs not getting any muscularity) at great lengths like Greg did? Hey, this is strongerbyscience, the home of strong-nerds, not the clientele for a …dumb-sized pink message sticker or fitness catchphrase in a glossy lifestyle magazine. I expect the audience of this blog of having above average interest in and knowledge about the topic and reading comprehension (only their written English becomes bumpy at times as a non-native speaker like me…). I fully trust the overwhelming majority to understand the article the right way and even educate others about it.

  6. Greg,
    Do you know if isometric holds where you’re resisting the eccentric for periods of 30secs to 1 minute be an alright way to build some muscle?

  7. Hey Greg,
    I just want to let you know that this article is absolute gold. You’re the real MVP for conducting a meta-analysis on this topic, especially when it’s so hard to find much research out there. More importantly, you’ve paved a way to explain more fully why strength training is so great for women to women and the benefits of it in comparison to men. Research is not only assuring and affirming, but it’s convincing for people who dabble with the idea of something, so thank you! Anyways, very well done and please keep doing what you’re doing!

  8. Great work, Greg.

    I often find that many women tend to ‘psyche themselves out’ from really pushing hard in the gym from the misconception that they can’t really make great gains, so might as well just “tone” or hit the cardio deck. This should clear that up.

    I also like that you mentioned the menstrual cycle differences. Many women and coaches aren’t aware of this (although intuitively they should have been), but it does make a difference. I did a write up on this a few months back, and a big key I see here as well is the impact on appetite (more research on this) and perceived exertion (more anecdotal). Useful for dieting phases to work that in as well. Or for a little recomp

  9. Hello there!
    I’m pretty sad you didn’t include my last paper 🙁 just kidding, I leave you the link here If you haven’t seen it!
    https://www.researchgate.net/publication/322701638_The_load-velocity_profile_differs_more_between_men_and_women_than_between_individuals_with_different_strength_levels

    Hope you found it intersenting, there is another one coming comparing gender differences in different set configurations!

    Kind regards!

    Alejandro Torrejon.

    1. Hey Alejandro! Yep, I’ve read it. I ALMOST picked it for MASS a couple months ago, actually, and it’s included in the lit review for my thesis project (we’re using load/velocity profiles to track fatigue recovery in men and women). Tell me if I’m crazy, but it seems like the effect sizes were just large because the variability was so low. Looking at figure 1, it doesn’t seem like the differences are really all that large or meaningful.

      1. Yes, I totally agree with you. The most interesting part is the comparission fof “strongs” and “weaks”. I have to say that the subjetcts, men and women, didn’t differ much more in strenght. That was a pilot study for whats coming, where, spoiling you :P, women tend ton lower velocity decrements. Im working now with powerlifter, so the results would be more “realistic/practical”.

        It’s very interesting your topic, I had been thinking to use VBT to track fatigue too, evenmore know with the cheaper and abaliable technology out there. Waiting to see whats coming!

        Thank you for answer!

        1. Thanks, Alejandro! I’m looking forward to reading it. I’ll start piloting next week, so I should have some preliminary info on how well it works for tracking fatigue/recovery soon.

  10. Strength training is an area that is geared predominantly toward men. As a woman interested in strength training, I really appreciate that this article address the differences between men and women and helps me to understand what I can do to get the most out of my strength training. I love that there was a study done about strength gains specifically in women, it’s so interesting that women’s strength increased 27% faster than men’s.

  11. I have always encouraged my women clients to lift weights. This is a fantastic break down and thank you for all of the information. I will be pointing all of my female clients here for more information on the subject.

  12. Thank you for a very informative article. As a young woman starting to dip my feet in strength training, it’s great to see articles like this.

  13. Hi, I was just wondering:

    1) Do you have any articles related to program design for women for hypertrophy? Would love to read this.

    2) Do you have any articles that answer how many sets should be taken to failure (or close to it) per exercise for maximum hypertrophy? I think the terms here would be straight sets vs pyramid, etc. I’ve always naturally done a pyramiding-style where every set acts almost as a warm up to my one real working set, as to produce maximum output for that one true working set. In other words, instead of traditional pyramiding 90×10, 95×8, 100×6 it will be more like 90×5, 95×3, 100×6. And I will never repeat a set I’ve taken to failure (never do straight sets). Anyway, I’ve never seen a definitive answer as to which is better and have been surprised that straight sets seem to be the standard recommendation.

    Thanks. Love the site.

    1. 1) Nope. It wouldn’t be that dissimilar to hypertrophy training for men, though, with the exception of potentially higher volume, and potentially varying frequency throughout the month to account for changes in recoverability with the menstrual cycle (if you’re not on hormonal contraceptives).

      2) I think how often you go to failure should primarily depend on a) how frequently you train a muscle/exercise and b) how much fatigue/soreness an exercise causes. If you’re just doing an exercise/training a muscle once per week, you can probably go to failure a bunch and be just fine. If you’re training the same muscle again 48 hours later, it probably wouldn’t be a good idea to go to failure very often. If you’re doing an exercise that causes a lot of soreness and fatigue (like DLs), you probably shouldn’t go to failure very often. If you’re doing an exercise (like biceps curls) that doesn’t cause much soreness/fatigue, you can probably go to failure more often.

  14. Greg,
    Thanks so much for this article. Is your thesis research going to include post-menopausal subjects? I ask as much of the research on women and strength training is focused on the role of estrogen. I don’t think post-menopausal women are “little men” but haven’t such much research on the topic. More insight and research would be very welcome.

    Angela

    PS: I first came to your site for your squat treatise/extravaganza, recommended by GMB Fitness. The exact words:
    “For a ridiculously detailed exposition on the barbell squat see Greg Nuckols’s treatise here; it’s the best piece I’ve read on the barbell squat – it’s brilliant).” They’re right!

    1. I may include post-menopausal women at some point, but I won’t for my thesis. The basic reason is that I want to use trained subjects (since I’m mainly interested in fatigue and recovery, that’s a more homogenous population. With untrained folks, you get some people who are in great shape who just don’t lift weights, and some people who are total couch potatoes. Those differences make a huge difference in fatigue and recovery, independent of sex), and I’d have a hell of a time trying to find enough post-menopausal, trained subjects in Chapel Hill (which isn’t a huge city) who were willing to participate. There is actually quite a bit of research on post-menopausal women, though. This pubmed query should include a lot of it: https://www.ncbi.nlm.nih.gov/pubmed?term=((resistance%20train*)%20OR%20strength%20train*)%20AND%20((menopaus*)%20OR%20postmenopaus*)

  15. Hi Greg grt review.

    However isnt the following a contradiction:

    -estrogen seems to be a protective facor inducing quiker recovery
    -during the luteal phase, estrogen levels are high & strength decrements are high i.e. women tend to workout less than in the follicular phase

    Btw check out prof Baars research about tendon stiffness & estrogen!

    1. It’s not necessarily a contradiction. It’s just that estrogen isn’t the only factor in play. Specifically, progesterone is also higher during the luteal phase, and it’s thought to counteract some of the effects of estrogen in muscle.

      I know all about Dr. Baar’s work! I wrote an article about the menstrual cycle a couple years ago, and the section on injury risk was largely based on his stuff.

  16. Thank you for covering women for a change! As an older women I am always looking for information on both groups. I have found that I do better with higher reps simply because heavier weights end up causing me injuries. I think it may be because we start so much weaker (especially me!) that we are more likely to have imbalances if we miss a muscle. Does that make sense? I also get into situations often where I can do one weight many times but can’t really do a higher weight at all. (ie 10# 16 times but 12# not at all with decent form.) So I am now using weight gloves to achieve in between weights. I usually use weights I can lift 12-15 times to (or almost to) failure, doing 3 sets total but in rotation so I have some time to recover. Is that a reasonable approach?

    1. Yep, I think that’s a reasonable approach. And it makes sense that it could be hard making a jump from 10 pounds to 12 pounds. On one hand, it’s just two pounds. On the other hand, that’s a 20% load increase! Proportionally, it would be the same as someone increasing their working weight for squats from 500lbs to 600lbs overnight. That would be brutal!

  17. Felipe Saldarriaga

    Wow! So much useful information in a single article… I’m blown away in the most positive of ways! Kudos amd keep it up, for all of your reader’s sakes! 🙂

  18. English isn’t my native language so i am trying my best to understand. I will try to make this question as simple as i can in order to get a direct response and hopefully understand it.

    1) Is the average man physically stronger than the average women? (given the testosterone, more muscle etc etc)
    2) now if we have let’s say 100 men and a women of the same height,weight,age even muscle mass if possible that had never exercised and give them the same training or the best possible given their gender. Will the average man still have more raw and psychical power of that of the average woman or not?

    thanks in advance

  19. 1) Absolute is weight on the bar/scale. Relative is on a percentage basis over one’s starting point.

    2) It’s not a limit, if that’s what you’re asking. That was just the average based on a sample of elite athletes.

    1. If I’m remembering the paper correctly, it was just total muscle mass. It didn’t adjust for weight, but sports select for similar body types, so that at least partially equates for weight.

  20. No. If body mass represents, say, 80% of 1RM for a female and 50% for a male (just using random but probably fairly representative numbers), the male will still be able to do more reps simply due to differences in strength. Using my wife and I as an example, I can do way more push-ups than her because she benches a shade over bodyweight, and I bench something closer to double bodyweight, so our bodyweights represent different percentages of our maximal capacity to produce force. But on the flip side, she can do way more reps with 50% of her 1RM on bench press than I can. That’s pretty typical.

    1. It’s a combination of factors. Smaller muscles mean you don’t occlue blood flow quite as easily *during* contractions, but greater perfusion generally (via greater resistance exercise induced vasodilation) helps with “work capacity” (ability to recover between sets and complete more high quality work in a training session) independent of muscle size.

      1. I understand correctly that here in the article and in the article they describe the relative muscular endurance? And the fact that women have higher relative muscle endurance?

          1. Understood, thank you, otherwise in scientific circles they do not divide into two types of muscular endurance, and it turns out that there are no matches in terms of the physical capabilities of men and women, knowing the statistics in the army and various sports disciplines.

          2. “otherwise in scientific circles they do not divide into two types of muscular endurance”

            That’s not true at all. If anything, the inverse is true – there are far more “types” of muscular endurance that are recognized and researched. Reps to failure with an absolute load, reps to failure with a particular relative load, time to task failure holding an isometric contraction at a given percentage of MVC, rate of torque decline during maximal-force isometric contractions, rate of torque decline during maximal-force isokinetic contractions at a given angular velocity, fatigue index during multi-set efforts, intermittent submaximal isometric time to task failure, etc. I’m sure I’m forgetting some. Muscular endurance is a multifaceted phenomenon, and lots of different methods can be used to probe the concept in different ways, but they are all discrete to some degree. However, measures of relative endurance are used FAR more often in a research context, because they do a better job of capturing a discrete physical phenomenon (just muscular endurance), rather than being influenced by another physical measure (absolute strength).

            Just to illustrate, by virtually any measure, I have pretty bad strength endurance. However, I’ve squatted a set of 4 reps with 700 pounds. >99% of lifters never squat 700, so I could claim that I have greater strength endurance than >99% of lifters because I can squat more reps at 700 pounds than they can. Most people would recognize that such a claim is fairly specious, because the set of 4 at 700 has WAY more to do with strength than with any specific physical capacity related to endurance. That same issue is present any time someone’s basing a claim about strength endurance on measures of “absolute endurance.” Since your measure is influenced by strength to (arguably) a greater extent than endurance per se, it’s more just a measure of general performance than endurance specifically.

          3. I divide the comments into several parts because large comments can not be published on your resource.

            “That’s not true at all. ” —— Yes, but it would be easier if these types were divided into absolute and relative endurance. Similarly with the force(after all, it is divided). This is extremely confusing for the media and other people who are not familiar with scientific analysis. I understand that endurance can be measured in different ways. Moreover, if we are not talking about muscle endurance, then there is one of the most important indicators of endurance, namely aerobic power. Just for example, you can often find the statement that women have higher endurance(they don’t even make a clarification that this applies to muscles). But even with relative muscle endurance(which is still slightly higher in women), it does not apply to all muscle groups, and the results are more or less consistent only in isometric exercises. In dynamic exercises, the results of comparisons are more confusing and gloomy(I think you also said this in your meta-analysis).

            “Muscular endurance is a multifaceted phenomenon, and lots of different methods can be used to probe the concept in different ways, but they are all discrete to some degree.” —- I can agree that muscular endurance, like any other, is too multifaceted a concept and it is widely used even beyond physical capabilities. Even more often, endurance is replaced by the word stability.

          4. “However, measures of relative endurance are used FAR more often in a research context, because they do a better job of capturing a discrete physical phenomenon (just muscular endurance), rather than being influenced by another physical measure (absolute strength).” —— I understand this, but it doesn’t really make sense when we’re just comparing two people. Is it possible to say that a person with a height of 160 cm and a weight of 60 kg, who has a large relative strength, is stronger than a person of 200 cm and a weight of 100 kg? Of course, this does not make sense when comparing two people. It is obvious that a person with a height of 200 cm will be much stronger, but a person with a shorter height simply has a higher relative strength. Endurance correlates with strength(both absolute and relative, which is higher in men on average). Therefore, it makes sense to divide, by analogy with muscle strength, into two categories and muscle endurance. In the first case, absolute endurance is obtained(which, as I understood from your answers to Aleachandro and me, is higher in men), in the second, relative muscle endurance (where women have a slight advantage, depending on the muscle group and type of exercise, i.e. there is not a universal result here).

          5. “>99% of lifters never squat 700, so I could claim that I have greater strength endurance than >99% of lifters because I can squat more reps at 700 pounds than they can” —— Well, I would not use the term strength endurance. It is somewhat incomplete. Absolute and relative endurance are still more adequate terms. For example, in the army, first of all, absolute endurance is measured, i.e. the ability to carry a load with a certain weight for some time (for example, 100 feet). Here, of course, those who are physically stronger will have more absolute endurance. I understand that you are passionate about powerlifting, but I’m talking more about the broader application of terms. Further, I don’t understand why you can’t be said to have high muscular endurance. Endurance is directly and positively correlated with muscle strength. The more muscles and, accordingly, strength, the higher the endurance, this is obvious. You may not have the highest relative endurance(and strength) to some extent, but in absolute terms, more importantly, you have high strength and endurance. There are no contradictions here. Perhaps only we differ in the use of terms, but you have a high endurance.

            “Most people would recognize that such a claim is fairly specious, because the set of 4 at 700 has WAY more to do with strength than with any specific physical capacity related to endurance” —- To the force is of great importance when we are talking about a single

          6. “Most people would recognize that such a claim is fairly specious, because the set of 4 at 700 has WAY more to do with strength than with any specific physical capacity related to endurance” —- To the force is of great importance when we are talking about a single repetition of the 700-foot climb. It speaks of strength. When you lift 4 in a place once, this is already talking about endurance, because you do 4 in a place once. And since you claim that a very small number of people are capable of this, then these people should be envied. You have high strength and muscular endurance. I don’t see any contradictions here. After all, as I have already said, strength is associated with endurance and vice versa.(well, if we are talking about muscle enduranc

          7. But after all, muscle endurance develops through an increase in strength. Total performance = muscle strength + muscle endurance(it can be calculated both in absolute terms and in relative terms, it does not make sense). Therefore, again, I think, by analogy with muscle strength, it makes sense to divide both muscle endurance and endurance in general. After all, there is cardio tolerance (which consists primarily of respiratory function, aerobic power, etc., which is higher in men, and this is one of the reasons why men usually(of course there are exceptions) run better at any distance, even at the longest ultramarathon of 3100 miles.

          8. There is muscle endurance, which is divided into two types(and which is already less consistent because it differs even from the muscle group and the type of exercise itself). And anyway, I am conducting a diologue with you regarding non-strength endurance(this term seems to me somewhat incomplete and extremely generalizing, what is not right to do). Strength endurance is a simple ability to create strength for a certain period of time. This is too simple and inaccurate a term. Because the creation of strength can be expressed in different quantities, and then your statement that women have higher strength endurance becomes incorrect. After all, men can pull themselves up, do push-ups longer than women (i.e. create this type of strength). For this reason, I like a higher level of detail in the terminology. But I am grateful to you for your experience. I also read your articles of 12 years about endurance and I completely agree with them.

    2. You can then ask the following questions.

      1) can men do more repetitions of 80-100% 1PM than women?

      2) Can women do more repetitions than men with a lower weight of 50% 1PM or less?

        1. Sorry, I meant 100% 1RM and not PM. That is, a greater number of repetitions with the maximum weight. You have stated somewhere in the comments that men, for example, will be better at push-ups with body weight(i.e., I understood 100%RM).

        2. Just then can you please explain to me in which cases a man can do more repetitions, and in which cases a woman can. I don’t really understand, because I thought that at 100% 1RM a man would be able to do more repetitions. Well, or close to 100%.

  21. Hey Greg, very informative article!

    So taking into account that women may recover from mostly anaerobic activities faster (sprinting and weightlifting), should the same apply to almost aerobic dominant activities (long distance running on the treadmill for example)?

    1. Assuming same relative intensity (% of HRR, subjective RPE, intensity relative to LT, etc.) is the same, I think recovery from aerobic stuff is pretty similar between sexes, primarily because the mechanisms of fatigue are different.

      1. Thanks for the answer Greg. One last question, the question is about this paragraph.

        “women tend to have less muscle mass, so they don’t occlude blood vessels quite as quickly when lifting, meaning they can more efficiently deliver oxygen and clear metabolic waste products from their muscles.”

        So are you saying the second factor is men have larger muscles that demand more blood, so their hearts have to work harder?

        Is that what you are saying? I am pretty sure I am wrong in what I am interpreting.

        1. Not exactly. Blood flow through peripheral veins (first) and arteries (later) can be cut off when muscles forcefully contract, and it generally happens earlier for people with larger muscles.

  22. Wow great article.
    I would like to ask a question but I don’t know if this is in your field of expertise.

    The question revolves around the RPE and ETL scales, and the subject of this article. Is this in your field of study?

  23. Men: none, on average, if you’re asking specifically in relation to percentages of 1RM.

    Women: Depending on the exercise, loads below 50-80% of 1RM

    At 100% of 1RM, everyone’s only able to do one rep

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