Why more repetitions make you last longer, but heavier weights make you stronger
Originally published on https://yogaforms.substack.com Aug 21, 2025
If you’ve ever wondered why doing more reps in the gym helps your endurance, but doesn’t necessarily make you stronger, you’re not alone. It can feel a little backwards at first: shouldn’t doing more of something mean you’re getting stronger? Not quite.
Endurance vs. Strength: What’s the Difference?
Think of your muscles like different engines. Some are built for long-distance travel (endurance), and others are built for power and speed (strength). When you do lots of reps, like 15, 20, or even more per set, you’re mostly training your muscles to keep going, not necessarily to lift more weight. That’s great for building muscular endurance.
Let’s say you’re doing bodyweight squats. If you manage 3 sets of 25: first well done! You’re amazing! Your legs are definitely going to burn. You’re teaching them to work longer without tiring out. But eventually, if you keep using only bodyweight, your legs will stop getting stronger. They’ll just get better at doing that specific movement for longer periods.
Why Lifting Heavier Is Important
Now, if your goal is to get stronger, for instance to deadlift more, or press a heavier dumbbell overhead, you’ve got to challenge your muscles in a different way. That means increasing the weight and cutting back on the repetitions. Instead of 20 squats with just your body, you might want to hold dumbbells and do 5 slow, deep reps. And you’ll notice it is a totally different experience.
Heavier weight forces your muscles to recruit the big, powerful muscle fibers: the ones built for short bursts of strength. That’s how you build real power. You can’t trick your body into getting stronger with just light weight and lots of reps. It just doesn’t work like that.
But What If You Can’t Go Heavy?
Not everyone has access to heavy weights or wants to go super heavy, especially if you’re working around an injury or just starting out. That’s where slow reps come in.
Instead of lifting heavier, you can make the same movement harder by slowing it way down. In my Slow Strengthening, getting into a squat takes about 15 seconds and another 15 seconds to push back up! Even without added weight, our muscles are on fire by the end of a set of 4. That’s because we’re increasing what’s called “time under tension,” and our muscles have to work harder the whole time. It’s another way to build strength without needing a ton of equipment, and it is a great way to stimulate bone cells.
So, What Should You Do?
It all comes down to your goals. If you want better endurance, let’s say, you’re a runner or just want to be more active without getting tired, then high-rep sets with light to moderate weight are perfect. But if your goal is to get stronger (both in your muscles and bones), then you’ve got to either lift heavier or slow things way down to really challenge your muscles.
At the end of the day, doing more reps will help you go longer but going heavier or slower will help you go stronger. It all depends on what you want to achieve. And don’t be afraid to mix it up!
If you’d like to join (one of) my strengthening classes (whether it is a Fitness or a Yoga class), here are the options:
Monday: 8.30 to 9 am UK time: Strengthening Exercises with Weights (option to do them on a chair). This is a fitness class with weights.
Tuesday: 7 to 7.30 am UK time: Strengthening Yoga. This is a Yoga class (no weights), in which we focus on strengthening various parts of the body. Some weeks, we’ll focus on the legs. Others on the core, the glutes, the back, the arms or the whole body!
Thursday 7 to 7.30 am UK time: Slow Strengthening. This is a class based on the Mindful Strengthening To Failure Approach where we use weights or bodyweight and move super slowly.
Check https://tamingthewalrus.com/timetable/ for details.
At the end of the day, what really matters is that you incorporate strengthening into your weekly routine.