I own 3 acres in the country, I have a lot of outside yard work, and building repairs to attend to. Before I started taking these amino acids, after a day of work, my muscles would be sore, and I would have to rest a few days before continuing. but, taking these, I don't get as tired, and the next day, I don't feel any muscle pain at all. the recovery is excellent. This is the only protein supplement I take.