“We can mold the muscles, you see,” says Bruce Denton, the wizened 1970s guru in John L. Parker Jr.’s Once a Runner. “We can strengthen the mind, temper the spirit, make the heart a goddamn turbine. But then a strand of gristle goes pop and presto you’re a pedestrian.” It was true then and it’s still true now: tendons and ligaments are the athlete’s Achilles heel, crucial to movement but vulnerable to overuse and (unlike muscles) mostly inert in response to attempts to strengthen them.
Back in 2019, I wrote about a new-ish idea that was circulating among elite athletes and their trainers, the brainchild of UC Davis molecular biologist Keith Baar. Tendons and ligaments are mostly made of up collagen. Lab experiments with engineered ligaments suggested that the availability of certain key components of collagen, like the amino acid proline, could ramp up the repair and synthesis of new collagen in connective tissue. Collagen supplements have been around for a long time, but Baar had specific ideas about the type of exercise that tendons and ligaments respond to and the form of collagen that would be best…
