has featured in a lot of press since it was published in August 2026 (e.g. Forbes, Women’s Health) and made an appearance in a GCN video this week too.
The conclusion proposes
“Collectively, these findings demonstrate that the exercise intensity is a major determinant of the human secretome and drives distinct proteomic and metabolomic responses and differences in predicted tissues of origin and target tissues. Integration with a large plasma proteome-phenome repository suggests that SIE acutely stimulates the release of protective proteins into the circulation to a greater extent than MIE. These data help explain how SIE, despite requiring only a fraction of the time of MIE, elicits robust metabolic signaling and whole-body benefits.”
Which, in layman’s terms, means that including a few 20 - 30 second sprints in your cycling once in a while is probably no bad thing.
That brings us nicely back to Coggan’s K.I.S.S. training tips
Yes, my last marathon training I did close to 100% maffetone… This time around I would do it different. If I can get to addequete volume levels for April 2027 I will do another marathon. This time around I will definitely include small amounts of intensity at the minimum… Try to get that pace up a bit.
Joe Friel makes it clear that from his perspective the aging athletes he coaches/knows that hold performance longer keep a bit of high intensity year round.
So inconsistent people like myself need to be more careful with intensity but if you are consistent and aging small amounts of intensity might be a good idea all year. Maffetone would say this could slow aerobic progress in some so hard to say the right approach.
Mark Allen gives some insight in when and how he added intensity to a Maffetone based training regime
Extract
“Over time, however, you will get the maximum benefit possible from doing just aerobic training. At that point, after several months of seeing you pace get faster at your maximum aerobic heart rate, you will begin to slow down. This is the sign that if you want to continue to improve on your speed, it is time to go back to the high end interval anaerobic training one or two days/week. So you will have to go back to the NO Pain, NO Gain credo once again. But this time, your body will be able to handle it. Keep at the intervals and you will see your pace improve once again for a period. But just like the aerobic training, there is a limit to the benefit you will receive from anaerobic/carbohydrate training. At that point, you will see your speed start to slow down again. And that is the signal that it is time to switch back to a strict diet of aerobic/fat burning training.
Keep your interval sessions to around 15-30 minutes of hard high heart rate effort total. This means that if you are going to the track to do intervals do about 5k worth of speed during the entire workout. Less than that and the physiological effect is not as great. More than that and you just can’t maintain a high enough effort during the workout to maximize our benefit. You want to push your interval making each one a higher level of intensity and effort than the previous one. If you reach a point where you cannot maintain your form any longer, back off the effort or even call it a day. That is all your body has to give.
This is what I did to keep improving for nearly 15 years as a triathlete.”