Have you ever wondered if fellow runners who beat you at races are less at risk of cardiovascular disease than you because they are fitter? Even though we all train hard, some of us improve faster and become better runners. Are they going to live longer and healthier?
Both physical activity and fitness reduce your risk of cardiovascular disease, but they are not the same. Physical activity consists of all the voluntary movements that use energy and is therefore a behaviour, while physical fitness is a state of health and athletic abilities. Physical fitness includes aerobic fitness, allowing you to bring oxygenated blood and nutrients to the working muscles, and muscular strength.
Plenty of physical activity improves your fitness, but fitness is also determined by factors such as your age, sex and genetic profile. There is more and more evidence indeed that your genetic profile influences your trainability (the way you respond to exercise), and therefore the athletic abilities and physical fitness you can achieve. The question therefore becomes: if you have an unfavourable genetic profile and do not improve very much even though you are training hard, are you at an increased risk?
I have found only one study about this, and it suggests that as long as we train at the same intensity it does not make any difference. (If you have found more studies, please let me know.)
In 2013, Andrea Chomistec and her colleagues published their results after following 23,016 women for about 14.4 years. The women were part of the Women’s Genome Health Study, and had therefore given a blood sample for DNA analysis when entering the study. They then reported life style characteristics and medical history via questionnaires on a regular basis.
Based on the scientific literature, the researchers selected genetic variants likely to determine fitness, and scored these variants according to the degree they would improve fitness. Andrea Chomistec and her colleagues then compared the scores with the volume and intensity of physical activity and the medical history of the women. As always in studies about genetics, the statistics are complex. As you can now read the article for free, you can check them out for yourself.
Sure enough, the results showed that physical activity reduces the risk of cardiovascular disease, but this was independent of the genetic scores. An unfavourable genetic profile might therefore make it difficult for you to become an elite athlete, but training will reduce your risk just like everybody else’s. This is very good news indeed, because it would mean that reaching your maximal personal fitness matters more than your inborn talent.
Of course, there are a few problems with this study. First of all, it relies on questionnaires, and the researchers did not have any objective measurements of fitness, such as VO2max. People might over-or underestimate what they are doing, or simply forget, what makes questionnaires not that reliable. Furthermore, it is likely that there are more gene variants that influence trainability and physical fitness than that we know now. This is new science, and this study should be repeated when we have a better understanding if the genetic determinants of fitness. However, it is a large study with a long follow-up, and I think it is the best they could do with the knowledge and funding we have today.
All the participants were women of European ancestry, and we cannot automatically conclude that the results would be the same in other groups. We obviously need more research.
It makes thus sense to increase your physical fitness as much as possible for you, however talented you are. You can do so by training wisely. If you are in doubt how to do so, you should ask a qualified fitness professional for advice.