If you’re one of the growing number of over-60s hitting the gym to keep your muscles strong – and if you’ve been at it a while, you’ll know how important that is for healthy ageing – here’s a curious bit of research that might make leg day just a little easier.

A new study published in Frontiers in Physiology has found that simply sniffing chocolate before and during a strength training session can help you push out more repetitions, without it feeling any harder.

The science of the sniff

Researchers, led by Dr Mohamed Nashrudin bin Naharudin from the University of Malaya’s Faculty of Sports and Exercise Science, wanted to understand how smell, appetite and exercise performance interact – an area that, surprisingly, hadn’t been closely studied before.

The study involved 23 moderately trained men who hadn’t eaten for at least 10 hours before performing leg extensions, a common resistance exercise. They were split into three groups, each exposed to a different scent before and during their sets: liquified dark chocolate (90 per cent cocoa), liquified milk chocolate (60 per cent cocoa), or plain water as a control.

The results were striking. Compared to the water control, sniffing the dark chocolate scent added around 18 extra repetitions to participants’ leg extension sets, while the milk chocolate scent added around nine. Crucially, participants didn’t report feeling like they were working any harder – the extra effort wasn’t accompanied by extra perceived exertion.

Why chocolate, and why does it work?

The dark and milk chocolate scents appeared to work through two different mechanisms. Sniffing dark chocolate reduced feelings of hunger and increased feelings of fullness, effectively tricking the body into an anticipatory sense of satisfaction, even without eating. Milk chocolate, meanwhile, didn’t change hunger levels at all – instead, it simply made the training experience more pleasant, which the researchers believe boosted performance through enjoyment rather than appetite suppression.

Dr Naharudin explains it as a kind of learned association: our brains connect certain smells with the foods we know well, and those associations can trigger real physiological and psychological responses, even when we haven’t actually eaten anything.

Could this work for foods beyond chocolate?

The researchers believe chocolate isn’t necessarily unique – it’s simply a food with an unusually strong, universal association with reward and satisfaction. They suspect other foods strongly linked to fullness could produce a similar effect, though this hasn’t been tested yet. The key seems to be genuine familiarity and appeal; a smell that isn’t pleasant to you personally is unlikely to produce the same benefit.

It’s worth noting the study is still a small, early piece of research – the sample was 23 younger men in their 20s, and the researchers themselves point out that no blood hormones or brain activity were measured to confirm exactly what’s happening physiologically. Larger and more diverse studies, including older adults, would help confirm whether the effect holds more broadly.

The takeaway for your next gym session

While it’s not exactly rigorous science just yet, there’s something appealing about a free, easy, zero-effort trick that might make strength training a little more manageable. If you’re someone who trains fasted, or simply finds certain gym sessions tougher than others, there’s no harm in packing a small bar of good quality dark chocolate in your gym bag – not necessarily to eat, but to give a sniff between sets.

At the very least, it’s a pleasant reminder that staying strong as we age doesn’t always have to feel like hard work.

This article discusses early-stage research findings and is general in nature, not medical or fitness advice. If you have questions about your own exercise or nutrition needs, it’s worth chatting to your GP or an accredited exercise physiologist.