I've assumed for a very long time that the purpose of telomeres was to prevent cancer mutations from killing a complex organism, since the resulting growth woul

I've assumed for a very long time that the purpose of telomeres was to prevent cancer mutations from killing a complex organism, since the resulting growth would be limited to X generations where X is the number of telomeres on the mutated strand of DNA, and then die without those cells being able to divide again. So while I believe the study will likely hold up; I do wonder why exercise adds telomeres. One answer is that exercise reduces cancer risk (it will get you to bed on time, mostly) so the body optimistically adds teleomeres. Alternatively, and perhaps more likely, exercise may trigger more cell division (for purposes of repair, all exercise causes some damage, to collagen if nothing else) so the extra telomeres are added as compensation in order to return to status quo cap on allowed cell divisions; maintaining the preventative but not actually extending it.