Is 10–12 Reps Really "Old Science"? Here's What Women Over 45 Need to Know
"Apparently 10–12 reps is old science now."
That was the message one of my online clients sent me recently after seeing a fitness influencer on Instagram.
According to the post, every woman over 45 should be training using the "3–5 method":
3–5 exercises
3–5 repetitions
3–5 sets
3–5 minutes rest
As if there was suddenly one perfect way for every woman to train.
I'll admit... I sighed.
Not because lower-rep strength training is bad.
It absolutely has its place.
But because this is becoming increasingly common on social media. A small piece of evidence gets taken completely out of context and presented as the answer for everyone.
Unfortunately, our bodies don't work like that.
There isn't one "best" rep range.
One of the biggest myths in strength training is that muscle only grows within the famous 8–12 rep range.
Another growing myth is that everyone should now be doing 3–5 reps instead.
The truth?
Neither is correct.
Current research consistently shows that muscle growth can occur across a surprisingly broad range of rep ranges—roughly 5 to 30 repetitions—provided the sets are challenging enough and performed sufficiently close to failure.
That doesn't mean every rep range feels the same.
Or suits every exercise.
Or is equally practical.
But it does mean that your muscles don't magically stop responding because you're doing 10 reps instead of 5.
The real goal isn't a rep range.
It's mechanical tension.
This is probably the most important concept most people have never heard of.
When your muscles contract against resistance, they produce force.
The force experienced by the muscle fibres is called mechanical tension, and it's considered one of the primary drivers of muscle hypertrophy (muscle growth).
Think of mechanical tension as the message you're sending your body that says:
"These muscles need to become stronger because they're being challenged."
Your body responds by repairing and adapting those muscle fibres so they're better prepared next time.
Notice something important here...
Your muscles respond to tension.
Not to a specific number of repetitions.
But doesn't lifting heavier create more tension?
Yes... and no.
Heavier loads create high levels of mechanical tension almost immediately.
Moderate or lighter loads create increasing mechanical tension as fatigue builds and your body recruits more and more muscle fibres to keep the weight moving.
That's why both of these can build muscle:
6 challenging reps
15 challenging reps
Provided the effort is high enough.
The magic isn't in the rep number.
It's in challenging the muscle enough that it has a reason to adapt.
"Lift heavy" is one of the most misunderstood pieces of fitness advice.
You'll often hear people say:
"Women over 45 need to lift heavy."
I actually agree with the intention behind that advice.
I just don't love the wording.
Because what does "heavy" actually mean?
Heavy doesn't mean lifting the heaviest dumbbells in the gym.
It doesn't mean lifting what someone on Instagram is lifting.
It simply means using a weight that is challenging for you.
For one woman, that might be a 20 kg leg press.
For another, it might be 180 kg.
Both are lifting "heavy."
The goal is to finish a working set feeling like you only had a couple of good repetitions left in the tank - not that you could have happily done another ten.
Not every exercise should be trained the same way.
This is another reason blanket advice doesn't work.
Exercises are different.
Our bodies are different.
The demands of each movement are different.
Large compound exercises like:
Squats
Leg Press
Romanian Deadlifts
Lat Pulldowns
allow you to use heavier loads because multiple joints and large muscle groups are working together.
These exercises often work really well somewhere around the 5–12 rep range, depending on the movement, the goal and the individual.
Compare that with exercises like:
Cable glute kickbacks
Rear delt flyes
Lateral raises
These involve smaller muscles, longer lever arms and greater stability demands.
Trying to perform these for sets of five usually means technique breaks down long before the target muscle has done enough work.
For those exercises, somewhere around 12–20 repetitions often makes much more sense.
Same goal.
Different tool.
What about strength?
Strength and muscle size aren't exactly the same thing.
Lower rep ranges (around 1–5 reps) are excellent for improving maximal strength because they teach your nervous system to produce more force.
Moderate rep ranges often provide a practical balance between strength and muscle growth.
Higher rep ranges remain an excellent option for many isolation exercises while also being more comfortable on the joints for many people.
This is why good programs don't force every exercise into the same rep range.
They match the rep range to the exercise.
What about bone density?
This is particularly important for women during and after menopause.
Many people assume that only very heavy lifting improves bone density.
The reality is more nuanced.
Bones respond to progressive loading over time.
That means gradually exposing them to forces they aren't yet accustomed to.
You certainly don't have to perform every exercise for sets of three to achieve this.
A well-designed resistance training program that progressively challenges your muscles over months and years can support both muscle and bone health. Progressive overload, consistency and appropriate exercise selection are far more important than chasing one specific rep range.
So... what rep range should you use?
Here's the answer I give my own clients.
It depends.
On your experience.
Your goals.
The exercise you're performing.
Your injury history.
Your confidence.
Your equipment.
And, quite honestly...
What you enjoy.
Because the best training program is still the one you'll consistently follow.
Here's a simple guide I use in my own programming.
Goal Typical Rep Range My Thoughts
Maximal Strength 1-5 Excellent for building maximal strength on selected compound lifts.
Strength + Hypertrophy 5–8 A great option for many compound movements where heavier loading is appropriate..
Hypertrophy 6–12 A practical range that balances muscle growth, strength & progression for many exercises.
Hypertrophy 12–20 Particularly useful for isolation exercises where maintaining technique is easier than with
heavier loads.
Muscular Endurance 20+ Can absolutely build muscle if taken close enough to failure, but is generally more fatiguing
and less practical for most people.
Notice how these ranges overlap.
That's intentional.
There aren't rigid boundaries.
Here's what I want you to remember.
Don't chase rep ranges.
Chase good programming.
A well-designed strength program doesn't force every exercise into the same box.
It matches the rep range to the exercise, the person and the goal.
Instead of asking:
"What's the perfect rep range?"
Ask yourself:
Is my technique improving?
Am I progressively getting stronger?
Am I challenging my muscles?
Am I training consistently?
Am I enjoying the process enough to keep going?
If the answer is yes...
You're already focusing on the things that matter most.
Final thoughts
Social media loves certainty.
It loves black-and-white answers.
It loves declaring yesterday's science "outdated."
But the fundamentals of resistance training haven't suddenly changed.
Build strength.
Progress over time.
Train with intent.
Choose rep ranges that suit the exercise.
And most importantly...
Stay consistent.
Because that's what builds stronger muscles, stronger bones and a stronger, more capable body for decades to come.
Ready to stop second-guessing your training?
If you're tired of trying to work out which fitness advice is worth listening to, I'd love to help.
My 1:1 Online Coaching is completely personalised to you - your goals, your experience, your equipment and your lifestyle—so you never have to wonder if you're training the "right" way.
Or, if you're looking for a structured program you can follow at your own pace, StrongerYou is my 12-week progressive strength digital program designed specifically to help women build strength, confidence and muscle without feeling overwhelmed.
Information about both of these options are on this website.
If you'd like to know which option is right for you, get in touch - I'd love to help you get stronger.
Disclaimer: This blog provides health, fitness, and nutritional information and is designed for educational purposes only. You should not rely on this information as a substitute for, nor does it replace, professional medical advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional. Do not disregard, avoid, or delay obtaining medical or health-related advice from your health-care professional because of something you may have read on this site. The use of any information provided on this site is solely at your own risk.
