I think people are reading too much into this trial. I don’t think the results suggest that rapamycin is detrimental at all. For short term exercise gain it may be detrimental, and if that’s all you care about then you might want to stay away from it. But the trial couldn’t possible answer whether it has beneficial effects on aging in humans.
Effects on aging would take much longer to show up and wouldn’t show up as changes in exercise performance in the short term. It’s entirely possible that muscle strength and size gains are somewhat reduced in the short term, while over the long run, rapamycin would have protective effects on muscle quality, which would leads to improvements that won’t be detected until someone has taken it for many years, if not decades.
Note that calorie restriction reduces muscle mass for obvious reasons, but when done over the long run it actually prevents sarcopenia and improves muscle quality in rodents. It’s a case of a shorter term sacrifice (in strength and mass) for long term benefits.
The fact that rapamycin slightly blunted gains from exercise might actually be considered somewhat of a confirmation that it’s effectively doing what we want it to do, which is inhibit mTOR.
Btw I recall seeing evidence that blocking mTOR only blocks some of the muscle gain stimulation because some of it is independent of mTOR inhibition. Anecdotally, rapamycin doesn’t appear to have much of an effect on the ability to gain muscle, so the effect is at best small in most people. It’s possible of course that it is more significant in older more frail people.
My hope is that this study doesn’t give rapamycin a negative publicity. People must realize that this study does in no way indicate that rapamycin doesn’t work for slowing down aging. To detect the effects of rapamycin on aging requires much longer trials, and so far we only have animal studies to go by in that regard.
