I did some search on Maffetone Method and bumped into his website. There are several interesting articles, and I got interested in his method of calculating max heart rate. Instead of the traditional 220 minus half the age he uses 180 minus age minus some number depending on your fitness level, Full article is at this link: Maffetone MaxHR formula The number obtained is considerably lower than that derived by using conventional equation. According to Maffetone training at low intensity is more beneficial than pushing yourself every time you train. I guess read the article and make your own opinion about it.
Maffetone method seems to be quite popular among runners, and there are lots of testimonials where running slower during training resulted in faster race times. Are long sets with 16 kg bells similar to long slow runs? Who knows, I guess.