Collagen for Tendons — Does It Really Work?

This Week’s Research Highlight

Your muscles might feel the burn after a tough workout, but your tendons are the silent workhorses of every move you make.

They don't scream in protest the same way sore muscles do, but they take a beating nevertheless. Every explosive movement loads the tendons with forces many times your body weight. And their ability to handle that stress can make the difference between powerful, fluid movement and frustrating aches and injuries.

But here’s the problem: Tendons age. Just like the rest of the body.

Once you hit your 40s, tendon quality starts to decline — collagen fibers weaken, elasticity fades, and structural disorganization sets in. The effects are subtle at first, but over time, they show up in slower recovery, reduced power transmission, and a higher risk of nagging injuries. Movement becomes less efficient, less explosive — and if tendons aren’t trained properly, setbacks take longer to recover from.

So what can we do about it?

Hydrolyzed collagen has been gaining traction as a tool for tendon health.

But it’s often misunderstood. You might think that taking collagen is sort of like patching a pothole — eat collagen, replace collagen. It's actually a little more complicated than that. Instead, hydrolyzed collagen acts as a signal, prompting the body to ramp up its own collagen production.

When tendons and ligaments are subjected to mechanical stress, they naturally break down, releasing specific collagen-derived peptides (like Pro-Hyp and Hyp-Gly) into the bloodstream. These serve as a cue for the body to repair and rebuild.

Consuming hydrolyzed collagen appears to mimic this process, flooding the bloodstream with the same signaling peptides that appear after tissue breakdown. In effect, it tricks the body into prioritizing connective tissue repair.

But there’s another key factor: Collagen synthesis doesn’t happen randomly — it’s directed by mechanical stress. The body directs repair to tissues that experience load and strain. In other words, collagen supplementation alone isn’t enough; it needs to be combined with resistance training.

A study published last year put this phenomenon to the test by giving young men 30 grams of hydrolyzed collagen before strength training. Sure enough, the researchers found that the supplement acutely boosted markers of collagen synthesis in response to exercise.

So, this sounds promising, but that study left two key questions unanswered:

• Do these short term biochemical changes translate to long-term structural improvements in tendons?

• Does this work in middle-aged adults, whose tendons are ostensibly less responsive to training and nutritional support?

That’s exactly what researchers aimed to find out in this new study, which focused on whether collagen supplementation could enhance tendon remodeling in middle-aged men over a 12-week resistance training program.

What did they find? Well, it seems that aging tendons do still have the ability to adapt — and with the right stimulus, those adaptations can be dramatically enhanced.

Let’s break it down.

Inside the Study

Researchers conducted a double-blind, randomized controlled trial — the gold standard for scientific research. They recruited twenty recreationally active men (ages 40-60; average age 47) who were not engaged in regular strength training.

Participants were randomly assigned to one of two groups:

• Collagen group: Consumed 30g of hydrolyzed collagen + 50mg of vitamin C immediately after training.

• Placebo group: Consumed a calorie-matched maltodextrin supplement + 50mg of vitamin C immediately after training.

Both groups completed a 12-week progressive resistance training program, training twice per week with lower-body exercises like barbell back squats, Romanian deadlifts, and trap-bar deadlifts. The program followed progressive overload principles, with weight increasing over time to drive adaptation.

To ensure consistency, all training sessions were supervised, and supplement adherence was monitored.

Measuring Tendon Adaptations

Tracking changes in tendons isn’t as straightforward as measuring, say, muscle growth. Unlike muscle, tendon adaptations happen internally and subtly, requiring specialized imaging techniques to detect.

You could measure collagen synthesis directly via tendon biopsies — but let’s be honest, that wouldn’t be much fun for the participants. Instead, the researchers relied on non-invasive imaging methods to examine three different dimensions of tendon adaptation:

Did the tendon grow?

To measure changes in tendon size, researchers used ultrasound to assess patellar tendon cross-sectional area (CSA) at multiple points along the tendon. An increase in CSA indicates tendon hypertrophy, meaning the tendon physically grew — potentially increasing its ability to handle mechanical stress.

Did the tendon tissue itself improve?

Size alone doesn’t tell the full story. Young’s modulus measures the intrinsic material quality of the tendon, independent of its dimensions. This calculation standardizes stiffness based on tendon structure, revealing whether collagen fibers became denser, more organized, and structurally stronger — essentially, whether the tendon itself became more resilient.

How well does the tendon resist stretching under load?

Tendon stiffness represents both size and material quality in a single functional measurement. Using ultrasound and isometric contractions, researchers assessed how much the tendon deforms when force is applied.

By assessing both structural and material changes, researchers could determine whether collagen supplementation influenced tendon remodeling beyond the expected effects of resistance training alone.

So what did they find?

Similar Gains in Muscle Size and Performance

After 12 weeks of resistance training, both the collagen and placebo groups saw similar improvements in muscle size, strength, and performance. Quadriceps muscle thickness increased, knee extension strength improved, and participants jumped higher and moved more explosively.

In other words, collagen supplementation did not enhance muscle growth or strength beyond what training alone provided.

But when it came to tendon adaptations, the story was completely different.

Collagen Led to Greater Tendon Growth

The patellar tendon, which connects the quadriceps to the shin, grew significantly more in the collagen group than in the placebo group.

• Collagen group: Tendon cross-sectional area increased by +6.8 mm² — a substantial change!

• Placebo group: Tendon size barely changed, increasing by just +1.2 mm².

But what’s even more interesting is where this growth occurred. Tendon hypertrophy wasn’t uniform — it was concentrated at the attachment points.

• Proximal region (near the kneecap): Increased by +6.6 mm²

• Distal region (closer to the shin bone): Increased by +6.0 mm²

• Mid-portion of the tendon: Largely unchanged

This growth pattern is not random. The attachment sites experience the greatest mechanical stress during movement, making them the most responsive to training. In the placebo group, these regions barely changed, suggesting that collagen supplementation amplified the tendon’s ability to remodel itself in response to exercise.

Collagen Improved Tendon Quality

While CSA tells us how much the tendon grew, it doesn’t reveal how strong or resilient that new tissue is. That’s where Young’s modulus comes in — it measures the intrinsic stiffness of the tendon material itself, independent of size.

Young’s modulus is measured in gigapascals (GPa), a unit that describes how much force a material can withstand before it deforms. For context, rubber has a Young’s modulus of around 0.01 GPa, while bone is closer to 15-20 GPa. Tendons fall somewhere in between, acting as both flexible and load-bearing structures.

• Collagen group: Young’s modulus increased significantly by +0.21 GPa.

• Placebo group: A much smaller increase of +0.09 GPa was observed.

Collagen supplementation didn’t just make the tendon bigger — it made it structurally stronger.

Collagen Led to Nearly Three Times Greater Improvement in Tendon Stiffness

Tendon stiffness is the most functionally relevant measurement because it reflects the combined outcome of both structural growth (cross sectional area) and material improvements (Young’s modulus). A stiffer tendon transfers force more efficiently from muscle to bone, reducing energy loss and improving movement efficiency and power output.

Tendon stiffness is measured in newtons per millimeter (N/mm) — basically, how much force is required to stretch the tendon a given distance. A higher number means the tendon is more resistant to deformation under load, allowing for quicker, more powerful force transmission.

• Collagen group: Dramatic 56% increase in stiffness (+661 N/mm)

• Placebo group: Modest 19% increase (+247 N/mm).

This means that after three months of training, the tendons in the collagen group required far more force to stretch the same distance as before, making them more resilient and efficient at transmitting force.

Why This Matters

One of the big questions driving this study was: Do middle-aged tendons still have the ability to adapt when provided with the right stimulus?

The results offer a clear answer: Yes.

Collagen supplementation enhanced the tendon’s remodeling response to resistance training — leading to greater structural growth, improved material properties, and superior stiffness adaptations. In effect, these changes appear to restore some of the strength and organization seen in younger tissue.

This has several key real-world implications:

Greater tendon growth at key stress points.

The fact that hypertrophy was concentrated at the attachment sites is significant. These regions bear the most mechanical stress and are common sites of overuse injuries like tendinopathy. Strengthening them may improve load-bearing capacity and reduce injury risk over time.

Stronger tendon tissue, not just bigger tendons.

A larger tendon isn’t necessarily a better tendon. What matters is internal structure — how well the collagen fibers are aligned, connected, and densely packed. Improvements in Young’s modulus suggest that collagen supplementation didn’t just increase tendon size; it improved the quality of the tissue itself, making it more resilient and efficient at transmitting force.

Increased stiffness = More explosive power

Tendon stiffness is directly tied to performance. A stiffer tendon transfers force more efficiently from muscle to bone, reducing energy loss and improving the rate of force development — a key factor in sprinting, jumping, and quick directional changes. In fact, great sprinters tend to have stiffer tendons, which store and release more elastic energy with each stride, propelling them forward with greater power. The fact that the collagen group saw nearly triple the gains in stiffness suggests a tangible performance advantage, not just improved tissue health.

Putting It Into Practice

This study shows that even aging tendons can still adapt — but only with the right combination of mechanical stress and nutritional support. Here’s how you can apply these findings yourself:

1. Prioritize strength training that loads the tendons.

Tendons don’t adapt to casual movement — they respond to consistent mechanical loading. The training program in this study focused on progressive lower-body resistance exercises like squats and deadlifts, which directly load the patellar tendon.

Of course, you don’t have to do those specific exercises. But in general, incorporating compound movements that challenge the tendons under load — and gradually increasing that load over time — may help stimulate tendon remodeling.

2. Use timing to your advantage.

The participants consumed 30g of hydrolyzed collagen immediately after training along with 50mg of vitamin C — an important cofactor for collagen synthesis.

While we still haven’t determined the optimal timing, available evidence suggests that consuming collagen in close proximity to exercise, either before or after, may enhance tendon adaptations.

3. Stay consistent and patient.

Unlike muscle, tendons adapt more slowly to training. Improvements in tendon size, structure, and stiffness don’t happen overnight, so steady, progressive training over months is key.

That also means avoiding excessive jumps in training volume or intensity — since tendons lag behind muscles in their ability to adapt, pushing too hard too quickly may increase injury risk rather than build resilience.

Summary: A double-blind, randomized controlled trial investigated whether collagen supplementation could enhance tendon adaptations in middle-aged men undergoing resistance training. Over 12 weeks, participants who took 30g of hydrolyzed collagen post-workout experienced greater increases in tendon size, improved tendon material quality, and nearly three times greater gains in stiffness compared to a placebo group.

Random Trivia & Weird News

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After seven years of bureaucratic gridlock stalled plans for a new dam in the Czech Republic, eight beavers quietly took matters into their own paws — building a perfectly functional dam where humans had failed.

No permits. No invoices. Just twigs, mud, and a deeply engrained sense of purpose.

Experts estimate the rodents saved the government $1.2 million, and helped restore wetland habitat in the process.

As Jaroslav Obermajer, an official at the Czech Nature and Landscape Protection Agency, put it: "Beavers always know best.”

When bureaucracy fails, beavers prevail.

Podcasts We Loved This Week

• Tommy Wood & Josh Turknett: How to recover from loss of smell and boost cognitive function. Via Better Brain Fitness.

• Anissa Armet: Can we restore the gut microbiome through dietary changes? Via Sigma Nutrition Radio.

Products We Like

Vital Proteins Collagen Peptides with Hyaluronic Acid and Vitamin C

If you’re considering collagen supplementation, this is a solid, hassle-free option. Vital Proteins Collagen Peptides dissolves effortlessly in hot or cold liquids (no weird clumps), has a neutral taste, and comes preloaded with vitamin C — which is key for collagen synthesis.

It’s also independently tested for heavy metals and contaminants, so you can feel confident about what you’re putting in your body.

humanOS Catalog Feature of the Week

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Wishing you the best,