May 31, 2021, was a terrific day, right up until the moment I found myself at the bottom of the stairs with two ruptured quadriceps tendons.

I’m still not sure how, exactly, I landed in that spot.

I remember walking down the stairs, as I’ve done thousands of times without trauma. One leg gave way with a rupture and by the time I was at the bottom of the stairs, the other tendon had blown out, too. I remember looking down at the horizontal divots where those tendons used to connect my quad muscles to my kneecaps.

Somewhere in between those two moments, my body rearranged both my anatomy and my exercise priorities. After a lifetime of focusing on my muscles, it was time to think about the pieces holding them together.

My one consolation: I’m hardly the only fitness enthusiast to take my connective tissues for granted.

“We prescribe exercise to optimize skeletal muscle or to optimize cardiovascular improvements,” said Keith Baar, PhD, a professor of molecular exercise physiology at the University of California, Davis. “Very few people have ever said, ‘I wonder if that’s the right stimulus for tendons and ligaments?’ What we’re learning is that the ways we exercise are really not optimal for tendons and ligaments.”

Before we get into Baar’s training methods, let’s look at what those tissues are and how aging affects them.

What Holds Us Together

The human body has around 4000 tendons to connect more than 650 skeletal muscles to 206 bones.

The body also has some 900 ligaments connecting bone to bone to stabilize joints. Since tendons and ligaments are biologically similar, we’ll focus mostly on the former.

When a muscle contracts, the tendon stretches, pulling the bone from where it is to where you want it to be. That’s how you create movement.

That’s also how you create problems. Here’s how physical therapist Charlie Weingroff, DPT, explained it: “You have this mildly stiff thing, the muscle. It’s attached to this really stiff thing, the tendon. And that’s attached to this absolutely, immovably stiff thing, the bone. A mechanical engineer would say, ‘Oh s***, this building is going to collapse.’”

Weingroff, who’s also an athletic trainer and strength and conditioning coach, has spent the past quarter century dealing with the challenges of keeping connective tissues connected.

Tendons and ligaments are made of tough strands of collagen fibers which thicken in response to a stimulus like resistance training. But unlike muscles, which bulk up in response to that stimulus, tendons and ligaments will slim down a bit. “Collagen fibers actually get more tightly packed and lose a little fluid,” Baar said.

Having a little more collagen squeezed into a slightly smaller space increases the tissue’s stiffness, which improves its ability to transfer force from the muscle to the bone.

Efficient transfer depends on the collagen fibers remaining parallel to each other and directionally oriented with the line of force. That way, when the tendon stretches, all the fibers can contribute.

Alas, as many of us have learned, there are many ways to derail that relatively straightforward process.

What Tears Us Apart

Acute injuriesoccur when there’s a mismatch between the force of a muscle contraction and the tissue’s ability to stretch.

If the tendon is too stiff, the muscle takes the hit. Picture a sprinter trying to beat an opponent to the finish line. After matching the rival stride for stride, they take an extra-long step at the end, and instead of breaking the tape they tear a hamstring.

Conversely, if the tendon can’t match the force of the muscle, it gives way.

Think of a basketball player, someone who practices shooting for hours a day, who one day ruptures an Achilles tendon while driving to the net.

Chronic injuries, as you’d guess, are the result of accumulating more stress over time than the tendon can fully recover from. Whether that stress is caused by high loads or high repetitions, the effect can look similar: a tendon that isn’t stiff enough to effectively transfer load from the muscle to the bone.

Those chronically overworked and under-recovered tendons will eventually develop tendinopathies — areas of the tendon where the collagen is no longer directionally aligned.

In my case, the damaged areas were on the outsides of the tendons. For others, they might be closer to the middle, which researchers have compared to the hole in a doughnut. Now the tendon has both strong and weak parts.

“The tensional load doesn’t go through the injured part because it’s stretchy,” Baar said. “But it does go through the strong part on the outside. If we run, jump, do any of these dynamic moves, we’re giving a really good stimulus to those little strips of tissue. We’re not giving a good stimulus to the rest.”

But even if you manage to stay active without damaging your connective tissues, you’ll eventually have to navigate the challenges of aging.

How We Lose Our Direction

Unlike muscle, which decreases about 0.8% per year after age 30, tendons and ligaments may actually get a little larger over time — at least in terms of cross-sectional area.

That’s not because the fibers get bigger.

“We know collagen synthesis rates go down with age,” Baar said. You see it in hair, skin, or anywhere else collagen is a key component. In tendons specifically, Baar noted, “we see there’s a loss of elasticity in many people as they age.”

The tissues maintain their cross-sectional area, in part, because they accumulate molecules called AGEs — advanced glycation endproducts. And in part it’s because the collagen fibers are less tightly packed and they become more chaotically aligned rather than parallel to each other.

“If you don’t guide the tissue in the direction you want, it’ll remodel in a spontaneous direction,” Weingroff said. But that can happen at any age, Weingroff emphasized. “People who stay active and engage in all types of progressive loaded exercises can, at worst, retard these accepted age-related changes.”

That said, when it comes to tendons specifically, how you apply those loads makes all the difference.

‘Stress Relaxation’ and a Return to the Straight and Narrow

The biggest challenge, as we noted a moment ago, is that the stronger, healthier parts of the tendon will take on the load, bypassing the weaker, damaged parts. “We never will be able to fix that tissue unless we do something specific to get load going through that injured area,” Baar said.

That’s where stress relaxation comes in.

Baar uses the example of a wall sit, the second exercise in this slide show.

At some point, if you hold the position long enough, your quad muscles will start to shake. That’s a sign the strongest parts of the muscle-tendon complex are fatigued, which means the weaker tissues are forced to get off the sidelines and into the game.

Baar recommends specific isometric exercises for strengthening both upper- and lower-body tendons and ligaments.

Isometric exercises are essentially a movement with no movement: The muscle group is held in one position until near-failure. Time can vary depending on your fitness level and condition of your tendons and ligaments. Try anywhere from 10 seconds (heavier load) to 30 seconds (lighter load).

Quad and patellar tendons:

Isometric lunge: Perform a normal lunge but stop at the bottom when the legs are bent and hold for the allotted time. Rise to standing position.

Isometric squat: Squat until your thighs are parallel to the floor. Hold at the bottom of the squat for the allotted time. Rise to standing position.

Shoulders, chest, and elbows:

Modified pushup: Using the back of a chair, a wall, or other stable brace, perform a pushup but hold at the bottom of the movement. Push back up to starting position. Adjust angle for a bigger challenge or do them on the floor.

The best part: You don’t need a lot of weight to challenge the muscles/tendons this way. You’re looking for stimulus. Baar’s best-known experiment involved rock climbers, who are susceptible to chronic injuries in the tendons and ligaments of their fingers.

For his 2024 study, he compared several protocols for improving climbers’ grip strength:

• Submaximal hangs, using a fraction of the climbers’ body weight. They did 20 10-second hangs, with 20 seconds of rest in between.
• Maximal hangs, using more than their body weight. They did six 10-second hangs, with 2 minutes of rest in between.
• A combined protocol using both light and heavy hangs.

Those who trained with submaximal hangs improved their grip strength by 3%, as did those who trained with maximal hangs. Participants who used both protocols finished with a 6% increase in grip strength.

Weingroff prefers slow, heavy resistance training for tendon rehab.

“One of the immediate consequences of attempting to move a high load is you move really, really slow,” he explained. “It’s not that slow wins. It’s that heavy wins.”

That doesn’t mean the weight must be objectively heavy. It’s about challenge — the challenge needs to be the most your tendons/ligaments can handle at the moment. “As long as there’s no pain, you should feel confident that you’re not injuring/reinjuring the tissue,” Weingroff said.

Baar agrees about doing the exercises pain-free. On a scale of 1-10, he said, “we want to keep pain to zero, or 1-2 as a maximum.”

But his approach to loading diverges from Weingroff’s.

“The load amount isn’t the key thing,” he emphasized. “It’s how long you hold it.” Ideally, that would be 30 seconds with a lighter load and 10 seconds with a heavier one. “Over time you can build up.”

What to Feed Your Collagen

Protein makes up an estimated 42% of your body’s dry weight (and 15%-20% of your total weight). About 30% of that protein is collagen.

Unlike the protein in your muscles, which is regulated by the three branched-chain amino acids (leucine, isoleucine, and valine), collagen protein consists mostly of glycine and proline. Dairy proteins like whey are famously packed with BCAA but light on glycine.

Evidence doesn’t yet support the use of collagen supplements to stimulate protein synthesis in connective tissues. But there’s also no risk in taking them. You can also find abundant glycine in chicken and turkey skin, seafood, and legumes. Vitamin C, copper, and zinc also support healthy tendons and ligaments.

What Matters Most for the Tissues that Matter Most

Staying active is the most important thing you can do for your lifelong health and vitality. It’s also the most important thing you can do for your connective tissues.

“All we have to do is shift the training a little bit,” Baar said, “and suddenly we get much better adaptations, and much faster adaptations, to our tendons and ligaments.”

The key, he said, is optimizing load duration — 10-second isometric holds with heavier loads, 30-second holds with lighter resistance. Do that three times a week, either before your regular exercise sessions or separate from them.

These tissue-specific exercises are especially important if you have a history of tendon or ligament problems. The best predictor of future injury is a past injury, and because we can’t change the past, the best we can do is change what we do going forward.

Take it from someone who learned that lesson the hard way.

Barr and Weingroff reported having no relevant financial relationships. Disclosure information for study authors is available in the original study publication.