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Muscle density: why you should focus on strength, not size, of your muscles

Updated: Mar 25

Chloe Gray for Workouts, Stylist Magazine

Muscle density is the little-discussed concept that can help you train better and live longer.

If you think that lifting weights gives you bigger and stronger muscles, you’d be right. If you think that they’re the same thing, you’d be wrong. Strength and size may be correlated, but they aren’t mutually exclusive.

So rather than focusing on how big your muscles are, instead we should focus on muscle density. This term refers to the strength versus size ratio, explains personal trainer Nancy Best: “Muscle density is associated with how strong your muscles are for their volume, which relates to the size of the muscle,” says Nancy Best.

Essentially, it’s about packing your muscle tissue with strong fibres, rather than just making the tissue itself bigger.

WHY IS MUSCLE DENSITY IMPORTANT? “While building muscle mass is important for overall metabolic health, generally speaking, people with greater muscle density can lift more weight than those of the same size who have lower muscle density,” explains Best. A 2021 paper published in JAMDA, found that density was more strongly associated with good physical performance than muscle size.

But it’s not only about improving your training. A 2009 study from the Journal of American Geriatrics found that weak strength, poor function and low muscle density was associated with an increased risk of hospitalisation in adults aged 70-80. Notably, their muscle size and lean mass measurements made no difference to their risk of injury – proving that rather than focus on building muscles you can see, we need to focus on what they’re made of.

HOW DO YOU BUILD MUSCLE DENSITY? “Most people following a good strength training programme will see an improvement in their muscle density without needing to get caught up in the detail,” says Best.

However, if you want to fine-tune your workouts in the weights room, consider opting for lower-rep, high-weight training over hypertrophy. Building strength usually comes from working in a one to five rep range, where your final rep is close to failure while building big muscles comes from slightly higher rep ranges of around eight to 12.

While there’s no real test for density – other than a professional CT scan – you’ll know you’re on the right track if you focus on how strong you feel – and how able you are to lift and improve with your training.

“The key takeaway is that just because you can see muscles, it doesn’t mean they’re strong. In fact, it’s more important that people are lifting heavy even if they don’t have the aesthetics you’d assume come with that. Density isn’t something you can measure from looking at someone,” reminds Best.

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