Many women reach their 40s and notice that maintaining their weight suddenly feels harder. The first thought is usually, “My metabolism must be slowing down.” While changing hormones can certainly play a part, they aren’t the whole story.
One of the biggest reasons your metabolism changes as you age is something most people have never been told about: muscle power.
Your body is made up of different types of muscle fibres. The fast-twitch fibres are responsible for quick, explosive movements like jumping, sprinting, catching yourself if you trip, or lifting something heavy with ease. They’re also some of the most metabolically active tissue in your body, meaning they require a significant amount of energy to maintain.
The problem? If you don’t use them, you lose them.
From around the age of 40, these powerful muscle fibres begin to decline more rapidly. When they become inactive, your resting metabolic rate naturally decreases because your body simply doesn’t need as much energy anymore. It isn’t just that you’re getting older. Your body is adapting to what you ask of it.
This is why many women spend hours walking or doing steady cardio but still feel like their body isn’t responding the way it used to. Traditional cardio is excellent for heart health, but it doesn’t challenge the fast-twitch fibres enough to keep them strong and active. Even slow, controlled strength training has its place, but if you never ask your muscles to move with speed, your body gradually forgets how.
Aging Isn’t Just About Getting Weaker
Think about the difference between a child and an older adult.
Children run, jump, skip, change direction in an instant, and seem to bounce effortlessly through life. Many older adults, however, walk more cautiously, move more slowly, and often avoid quick movements altogether.
That “bounce” isn’t just youthful energy. It’s muscle power.
Research shows that we lose muscle power at twice the rate that we lose muscle strength. In other words, even if you still feel reasonably strong, your ability to move quickly may already be declining.
The encouraging news? Your body is incredibly adaptable. When you regularly train for power, your muscles and nervous system respond. You can improve speed, coordination, balance, and confidence at almost any age.
Why Power Training Matters
Training for power can help you:
- Keep your metabolism working more efficiently.
- Preserve the fast-twitch muscle fibres that naturally decline with age.
- Improve balance and reduce the risk of falls.
- Build confidence in everyday movement.
- Stay active, capable, and independent for longer.
- Feel stronger, faster, and more energised.
Power training isn’t about exercising harder. It’s about moving with intent. It’s the speed of the movement that makes the difference.
What Does Power Training Look Like?
You don’t need to become an athlete or spend hours in the gym.
Simple exercises performed explosively, while maintaining good technique, are enough to challenge those fast-twitch fibres.
Some examples include:
- Kettlebell swings
- TRX jump squats
- Jumping lunges
- Box jumps
- Seated jump squats
- Medicine ball slams
- Fast step-ups
- Short, powerful intervals on the rowing or SkiErg machines
These movements teach your muscles and nervous system to stay responsive, springy, and athletic.
At MissFit, you’ll find these principles woven throughout many of our sessions. HIIT and PowerMet classes combine strength with explosive movement to keep your muscles challenged. Our Aerobic Erg sessions include short power intervals on rowing and SkiErg machines, while Mobility classes help improve movement quality so your body can generate power safely and efficiently.
Don’t Accept “Slowing Down” as Inevitable
Growing older doesn’t automatically mean becoming slower.
It means becoming more intentional about how you train.
If you want to support your metabolism, maintain your independence, and continue doing the things you love for decades to come, strength alone isn’t enough. Your body also needs to move with speed.
Every jump, every kettlebell swing, every powerful push is a reminder to your muscles that they still have a job to do.
And the more often you remind them, the more your body rewards you.
At MissFit, we believe every woman deserves to feel strong, capable, and confident at every stage of life. Because healthy aging isn’t about simply adding years to your life. It’s about adding life to your years.