Picture a medieval torture rack for Smurfs. The device, called a uniaxial tensile tester, is about the size of a shoebox. With long tweezers, a doctoral researcher at the UC Davis Functional Molecular Biology Lab plucks a freshly grown, two-weekold anterior cruciate ligament, or ACL, from an incubator and clamps the ends to anchors on the tensile tester. A USB cable then hooks it to a laptop, allowing the researcher to tweak how hard and fast the tendon gets yanked, and for how long—hours, sometimes days.
While the thought may be horrifying to anyone who’s experienced the searing pain of snapping an ACL—it connects your femur and tibia, and is prone to blow out if you play basketball, football, soccer, or ski—thousands of ACLs, cultivated from samples donated by knee-surgery patients, have been torn, twisted, and pulverized with this miniature device. The man behind the mayhem is the lab’s director, Keith Baar, Ph.D., a renowned scientist in the emerging field of molecular exercise physiology. Baar is leading a team of researchers attempting to fathom the complex relationship between your muscles and the connective tissue that holds them together.
Your connective tissue consists of tendons, ligaments, and what’s known as the “extracellular matrix,” a scaffold-like network of fibers that permeates muscle. Scientists have long known that lifting heavy weights produces bigger, stronger muscles—it activates genes and proteins that instruct cells to build more muscle fibers. During that exercise, it was always thought, your connective tissue was limited to a simple mechanical function: transfer force from muscles to bones, or for ligaments, bones to bones. (Picture train couplings between railcars.)
But recent discoveries are revealing that connective tissue does a whole lot more. As it turns out, it plays a crucial role in muscle building, a process called hypertrophy. On top of that, it appears that your connective tissue can be improved with specific exercises and nutrient supplements to profoundly impact athletic performance and strength, and prevent injuries.
“The reality is, if you want to be strong, you need to have not only big muscles, but also really good connective tissue,” says Baar. And any exercise routine that overlooks it, he warns, would be like a workout that only targets, say, the left half of your body.