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It’s understandably frustrating when you put in more effort at the gym than your friends, only to see similar results. New research suggests that’s not in your head: there are certain genetic variants linked to being more fit, and they’re also associated with a lower risk of developing a range of diseases.
It’s important to say this upfront: the findings don’t suggest that you should give up on exercise if you suspect you’re not genetically predisposed to being fit. But they do imply that some people may be better set up for success in the fitness department than others, which could explain how someone can run a 5K with no preparation while you need to train consistently.
What’s the takeaway? A study author and cardiologist explain.
Meet the experts: Eleonora Fornara, RD, lead study author, dietitian, and PhD researcher at the University Ramon Llull, Blanquerna School of Health Sciences and Cheng-Han Chen, MD, interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, California.
What Did the Study Find?
For the study, which was published in Medicine & Science in Sports & Exercise, researchers screened multiple long-term study databases for 712 health-related phenotypes. Phenotypes refer to observable characteristics of an organism, such as blood pressure or height.
After analysing the data, researchers identified 34 associations between genetically predicted aerobic fitness and different health outcomes. People with certain genes showed a range of health benefits that may give them an advantage, including a lower risk of stroke, higher heart rate variability, lower blood pressure and a reduced risk of asthma. They were also more likely to have spent more years in education than those without these genes – something that has previously linked to better health outcomes.
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The researchers found that genes associated with ‘being fitter’ may be linked to a lower risk of developing around 30 diseases.
‘We know from decades of observational research that physically fit people tend to be healthier,’ says Eleonora Fornara, RD. ‘Most prior studies couldn't rule out the possibility that healthier people simply exercise more, rather than exercise making them healthier.’
But Fornara and her colleagues wanted to look more closely at the genes that predispose people to fitness. ‘Because our genes are assigned at birth – before any disease develops – this method lets us make much stronger causal inferences than traditional observational studies,’ she explains. Their research provides stronger evidence of a potential causal link between being fit and a lower risk of disease and related risk factors.
What Does ‘Fit’ Mean?
This study focused on cardiorespiratory fitness, which is the body’s ability to respond effectively to physical effort.
‘This reflects how well the heart, lungs and muscles work together during sustained exercise,’ Fornara says. ‘We didn't study a specific sport or exercise type, but rather the underlying biological capacity to be physically fit.’
In general, fitness isn’t determined solely by your genes, says Cheng-Han Chen, MD. ‘Genes probably play a role, but they’re only part of the picture,’ he says. ‘You can have genes associated with fitness but, if you don’t exercise and make use of that potential, you may not be fit.’
Can You be Active but ‘Unfit’?
Yes. ‘Physical activity (what you do) and physical fitness (how your body responds) are related but not identical,’ Fornara says. ‘Two people can follow the same exercise routine and end up with very different fitness levels, partly due to genetics.’
However, she stresses that activity remains essential. ‘Being active still brings broad health benefits – even for those who don’t see large gains in cardiorespiratory measures,’ she says.
How Important Is it to Have the Genes for Fitness?
It’s easy to read this and think there’s no point in putting in the effort at the gym. But that’s not the takeaway, according to Chen. ‘We are not at the point where we can say, “If you have these genes, you will have better health outcomes,”’ he says. ‘What the researchers are saying is that these genes are associated with better markers of health, such as heart rate variability.’
Fornara agrees. ‘You don’t need to be genetically gifted,’ she says. ‘Cardiorespiratory fitness is a modifiable factor that improves with regular aerobic exercise. Anything you do to improve your fitness – running, cycling, swimming or brisk walking – moves you in the right direction, regardless of your genetic starting point.’
Overall, Chen stresses the importance of staying active. ‘Physical inactivity is associated with cardiovascular disease,’ he says. ‘Whether you have favourable genetics or not doesn’t change that.’
Carina Hsieh, MPH, is the deputy features editor of Women’s Health. She has more than a decade’s worth of experience working in media and has covered everything from beauty, fashion, travel, lifestyle, pets, to health.
She began her career as an intern in the fashion closet at Cosmopolitan where she worked her way up to Senior Sex & Relationships Editor. While covering women’s health there, she discovered her passion for health service journalism and took a break to get her Masters in Public Health. Post-grad school, she worked as a freelance writer and as The Daily Beast’s first Beauty, Health, and Wellness Reporter.
Carina is an alum of the Fashion Institute of Technology and the Yale School of Public Health. She and her French Bulldog, Bao Bao, split their time between Brooklyn and Connecticut. She enjoys reformer Pilates, (slow) running, and smelling the fancy toiletries in boutique fitness class locker rooms.
