Five years of supervised training didn't slow the loss of smell in people over 70, but fitter people smelled better
A 10-year follow-up of Norway's Generation 100 trial found that sense of smell declined at the same pace whether older adults did interval training, steady training or followed general advice. Higher aerobic fitness still went with better scores.
Soma Labs3 min read
Our sense of smell tends to fade with age. Researchers have asked whether staying active could slow that decline, and observational studies suggested it might. A randomized trial now says it is more complicated.
The new results come from Generation 100, a large trial run by the Norwegian University of Science and Technology in Trondheim. They were published today in Frontiers in Physiology. The trial is registered as NCT01666340.
The setup
Generation 100 began in 2012 with 1,567 people aged 70 to 77 living in Trondheim. They were randomly assigned to one of three groups for five years. One group did high-intensity intervals twice a week: four 4-minute bouts at 85 to 95% of peak heart rate. One did 50 minutes of steady exercise twice a week at about 70% of peak heart rate. The control group was simply told to follow Norway's activity guidelines.
A subgroup of 106 volunteers also took a smell test before the trial and after 1, 3, 5 and 10 years. The test uses 16 pens, each with a different scent, and four answer choices per pen. The score is how many you name correctly. At the 10-year mark, the team tested 388 participants in total.
They also measured each person's peak oxygen uptake, a standard lab measure of aerobic fitness, at every visit.
What the trial found
Scores went down over the 10 years, as expected. But the decline was the same in all three groups. Neither kind of training slowed it compared with the control group, during the five years of training or five years after. The authors saw a small trend in favor of the training groups, but it wasn't statistically significant.
One reason may be that the groups ended up with similar fitness. The trial found no significant difference in peak oxygen uptake between them over time. In the smell subgroup, the control group even reported more minutes of exercise per week than the steady-training group at the 10-year visit.
Fitness itself told a different story. People whose peak oxygen uptake was above the Norwegian reference values at the start scored about 0.6 points higher on the 16-point test ten years later. At the 10-year visit, higher fitness went with higher scores at the same time point.
What to keep in mind
The smell results come from a volunteer subgroup, and 41.5% of the 106 were lost to follow-up over ten years. Those who dropped out tended to be less fit and to score lower at the start. The authors used statistical weighting to account for that, and the results held. The 10-year group was also healthier than the trial as a whole. The fitness findings are associations, so they can't show that fitness protects smell. Fitter people may differ in other ways.
Where Soma fits
The lesson we take from this is about what gets measured. Being assigned to a training program did not change the outcome. Actual fitness, measured carefully and repeatedly, did line up with it. We don't measure peak oxygen uptake. The Soma app, not yet available, will read what your phone and watch already store in Apple Health, so you can follow your own activity and heart data over years instead of guessing from what you meant to do.
Sources, as of November 6, 2026: Reitlo, Holmvik, Dyrvik, Wisløff, Stensvold and Håberg, Frontiers in Physiology, published under CC BY 4.0; trial registration NCT01666340. This post describes research and isn't medical advice.