A new study published today in the journal European Heart Journal says when it comes down to the anti-aging effects of exercise, cardio is queen. Endurance exercise–like running, swimming, or bicycling–and high-intensity interval training (HIIT) both slowed signs of aging compared to lifting weights–at least on the cellular level.
Here’s how the study went down: A team of German researchers divided 124 healthy but inactive adults between the ages of 30 and 60 into four groups. One group carried on with their non-existent exercise routines. The other three sweated it out for 45-minute sessions three times a week for 26 weeks.
The endurance training group walked or ran continuously. The HIIT group completed a warmup, four rounds alternating between faster and slower running, and a cool down. The resistance training group used eight different strength-training machines to complete a circuit of exercises including seated chest presses, lat pulldowns, and leg presses.
At the end of the study, people in both the endurance training and the HIIT groups had experienced anti-aging effects of their workouts, while the inactive and resistance training groups did not. Those turn-back-the-clock effects were measured at the cellular level, by examining white blood cells from blood taken before the start of the study and days after the final exercise session.
In those cells from runners and HIIT-ers, researchers noted two important changes: Their telomeres–the caps at the ends of chromosomes–lengthened, and telomerase–an enzyme involved in maintaining those caps–increased. These effects “are both important for cellular aging, regenerative capacity, and thus, healthy aging,” study author Ulrich Laufs, MD, of Leipzig University in Germany, said in a statement.
Telomeres naturally shrink over time, and as they do, cells die instead of continuing to divide. Cell death is bad news not just for wrinkles and gray hair, but for risk of age-related health concerns like heart disease, cognitive decline, and even early death.
So what was it about endurance and HIIT workouts that could stave off that shrinkage? The researchers hypothesize that those types of exercise affected levels of nitric oxide in the blood. Since nitric oxide increases blood flow and lowers blood pressure, it could in turn have affected the cell changes found in these two groups of participants.
This isn’t the first study to link exercise to telomere length. A team from Brigham Young University found that adults who jogged for 30 to 40 minutes five times a week had telomeres as long as those of people who were 9 years younger than them, for example. And HIIT workouts have been previously linked with additional anti-aging cellular changes. The new study, however, is thought to be the largest ever to directly compare the anti-aging effects on telomeres of different types of exercise.
However, according to an accompanying editorial published alongside the study, this research doesn’t necessarily mean one workout or the other is better for your physical fitness. “The authors reported that changes in telomere length were not associated with changes in cardiorespiratory fitness,” write the editorial authors, of Newcastle University in the UK. Further studies are needed, they say, to clearly understand the link between telomere length, telomerase activity, and disease prevention.
In the meantime, don’t go giving up your strength sessions. These results fall nicely in line with common exercise recommendations. “Our data support the European Society of Cardiology’s current guideline recommendations that resistance exercise should be complementary to endurance training rather than a substitute,” study co-author Christian Werner, MD, of Saarland University in Germany, said in a statement.
Same goes for recently updated exercise guidelines for Americans, which suggest getting 150 to 300 minutes of moderate intensity aerobic physical activity per week, as well as at least two sessions of muscle-strengthening activity.