Exercise does increase collagen production, and the evidence for this spans tendons, skeletal muscle, bone, and even skin. Mechanical loading triggers cells in connective tissues to ramp up the genes responsible for making collagen, and chronic training leads to a sustained increase in collagen turnover. But the story is more layered than a simple “move more, make more collagen” message, because the type of collagen produced, the tissue in question, your hormonal environment, and what you eat around your workouts all shape the outcome.
What Happens in Tendons and Muscles
Tendons are where the exercise-collagen connection is most thoroughly studied, and the results are consistent: mechanical loading increases collagen synthesis. When tendon cells are stretched in a lab setting that mimics what happens during exercise, they produce significantly more type I collagen, the main structural protein that gives tendons their tensile strength.1PubMed Central. Enhanced collagen type I synthesis by human tenocytes subjected to periodic in vitro mechanical stimulation Cyclic tensile loading, the kind of force that tendons experience during running or lifting, has been shown to increase the expression of both type I and type III collagen along with tenascin-C, a glycoprotein involved in elasticity and stress resistance.2Journal of Sports Medicine. Tendon Cell Biology: Effect of Mechanical Loading
In living humans, the picture holds up. Blood flow, oxygen consumption, and collagen synthesis in tendon tissue all rise with mechanical loading, and gene activity for extracellular matrix proteins is enhanced after exercise. Chronic training leads to a sustained increase in collagen turnover and, depending on the collagen type, some degree of net new collagen.3PubMed Central. Metabolic activity and collagen turnover in human tendon in response to physical activity Inactivity, by contrast, markedly decreases collagen turnover, which helps explain why immobilized or sedentary tendons gradually become weaker and more injury-prone.
Skeletal muscle tells a similar story. The connective tissue sheaths that wrap around muscle fibers also increase their collagen production after exercise. The rate of collagen synthesis in muscle rises in a time-dependent way that roughly mirrors the increase in contractile protein synthesis, suggesting the structural scaffolding adapts alongside the muscle fibers themselves.4PubMed Central. Extracellular matrix adaptation of tendon and skeletal muscle to exercise With intense exercise, there is even evidence of microinjury to intramuscular connective tissue that triggers repair and remodeling, activating satellite cells and stimulating new collagen expression, particularly type I collagen in the connective tissue layers between muscle fiber bundles.
Eccentric Training Stands Out for Muscle
Not all exercise produces the same collagen response, and the distinction matters most in muscle. A rat study comparing concentric contractions (shortening under load, like the lifting phase of a bicep curl) and eccentric contractions (lengthening under load, like the lowering phase) found that while tendons responded to both types with increased collagen I and III expression, muscle tissue was far more sensitive to the specific type of force. Eccentric training produced a significantly greater collagen response in muscle than concentric training did.5PubMed Central. Expression of collagen and related growth factors in rat tendon and skeletal muscle in response to specific contraction types The enzyme lysyl oxidase, which is responsible for cross-linking collagen fibers into stronger networks, was upregulated up to 37-fold in tendon with training. That finding hints at an important distinction: exercise does not just make more collagen, it may also improve how that collagen is structurally organized.
For tendons, the type of contraction mattered less. All loading types triggered a robust collagen response, which aligns with what clinicians observe in rehabilitation: heavy slow resistance, eccentric protocols, and isometric holds all help tendons adapt. In muscle, though, the greater mechanical disruption caused by eccentric work appears to be a stronger trigger for connective tissue remodeling.
Bone Gets in on the Act
About 90% of the organic material in bone is type I collagen, so it would be surprising if exercise had no effect on bone collagen production. The evidence confirms it does. A marker called P1NP (a fragment released when new type I collagen is being assembled) rises during and after weight-bearing exercise.6PubMed. The role of exercise intensity in the bone metabolic response to an acute bout of weight-bearing exercise In a study of postmenopausal women with low bone mass, three months of weight-bearing and resistance training significantly increased both P1NP and the number of circulating bone-building cells, without a corresponding increase in markers of bone breakdown.7PubMed. Effects of a 3-month weight-bearing and resistance exercise training on circulating osteogenic cells and bone formation markers in postmenopausal women with low bone mass That ratio, more formation without more breakdown, is exactly what you want to see when the goal is building stronger bones.
The bone response appears to be driven more by the impact and load than by how hard you push your heart rate. Exercise intensity in the cardiovascular sense did not significantly affect bone formation markers in one study, which suggests that what matters for bone collagen is the magnitude and type of mechanical force rather than how winded you get.
Cartilage Is Trickier
Joint cartilage is a different beast. It has far fewer cells and almost no blood supply, so it relies on diffusion of nutrients from the surrounding joint fluid. The question of whether exercise helps or harms cartilage collagen has been debated for decades. In tissue-engineering experiments, dynamic compression of cartilage cells in hydrogel scaffolds increases both proteoglycan and collagen production compared with unloaded controls.8PubMed Central. Dynamic Mechanical Compression of Chondrocytes for Tissue Engineering: A Critical Review That is encouraging, but these are highly controlled lab conditions, not the complex loading environment of a human knee.
In living people, an exploratory trial comparing running, cycling, and rest found that the collagen picture in cartilage after exercise is nuanced. A marker of type II collagen degradation trended upward after cycling compared with running and resting, and the overall formation-to-degradation ratio tilted toward breakdown after cycling but not after running.9PubMed. Does moderate intensity impact exercise and non-impact exercise induce acute changes in collagen biochemical markers related to osteoarthritis? Running, which involves impact loading, did not shift that ratio adversely. This is a small exploratory study and not something to base sweeping conclusions on, but it aligns with a broader observation: moderate, regular impact loading appears to be well tolerated by healthy cartilage, while the cartilage response to non-impact exercise like cycling may work through different mechanisms.
Breakdown Is Part of the Process
An important caveat is that exercise does not simply add new collagen on top of old collagen. It accelerates collagen turnover, meaning both synthesis and breakdown increase. After a bout of resistance exercise, genes and enzymes involved in collagen degradation are powerfully upregulated in skeletal muscle. In one study, markers of collagen breakdown were elevated 72 hours after a resistance exercise session in both young and older adults.10American Journal of Physiology-Cell Physiology. Collagen remodeling increases after acute resistance exercise in healthy skeletal muscle irrespective of age No significant changes appeared at six hours, suggesting the remodeling response takes time to fully kick in.
This might sound alarming, but it is a normal and necessary part of tissue adaptation. Old, damaged collagen needs to be cleared out for fresh, properly organized collagen to take its place. The acute response to a single session looks destructive, but the long-term effect of habitual training is net constructive, with stronger, better-organized connective tissue as the outcome. Problems arise when the rate of damage outpaces the rate of repair, which is what happens with chronic overuse.
There is also an age dimension. The collagen-remodeling response to exercise is at least partly age-specific. A pilot study found that young men and older men showed different patterns of gene expression after a single resistance bout. Nine extracellular matrix genes changed only in the young group, while four changed only in the older group. For certain remodeling enzymes, the direction of change was opposite: a gene involved in collagen breakdown was upregulated roughly tenfold in young men but dropped to about one-fifth of baseline in older men.11PubMed. Age-specific response of skeletal muscle extracellular matrix to acute resistance exercise: A pilot study Aging is associated with denser, less flexible collagen deposition and reduced regenerative capacity in the muscle stem cell niche.12PubMed Central. Influence of exercise and aging on extracellular matrix composition in the skeletal muscle stem cell niche Exercise still promotes remodeling and stem cell accumulation even in older tissue, but the magnitude and character of the response are blunted.
What About Skin
Skin collagen is where the popular interest really lies, driven by the beauty and anti-aging market. The research here is thinner than in musculoskeletal tissues, but there is a genuinely interesting recent study. Researchers measured gene expression of skin-related extracellular matrix components in participants who completed either aerobic or resistance training programs. Both groups showed increased expression of genes encoding several collagen types, hyaluronan synthase (which makes the molecule responsible for skin hydration), and proteoglycans like decorin and versican. Aerobic training additionally increased expression of collagen types I, V, and XII, while resistance training boosted other proteoglycan-related genes.13PubMed Central. Resistance training rejuvenates aging skin by reducing circulating inflammatory factors and enhancing dermal extracellular matrices
How exercise would affect skin collagen when it is not the tissue being directly loaded is a fair question. The answer likely involves systemic signals: exercise changes circulating levels of growth factors, reduces chronic low-grade inflammation, and improves blood flow to the skin. The skin study measured gene expression in blood plasma, reflecting systemic changes that could drive dermal remodeling. Still, the evidence base here is small enough that anyone claiming exercise is a proven collagen treatment for skin is getting ahead of the science.
Estrogen Complicates the Picture
Hormonal status, particularly estrogen levels, has a complex and somewhat counterintuitive relationship with exercise-induced collagen synthesis. Estrogen generally improves muscle mass, strength, and the collagen content of connective tissues.14PubMed Central. Effect of Estrogen on Musculoskeletal Performance and Injury Risk Postmenopausal women using estrogen replacement therapy have higher baseline rates of tendon collagen turnover compared with non-users, and their tendons contain a greater proportion of smaller collagen fibrils, consistent with more active collagen remodeling.15PubMed. Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women
Here is the twist: while estrogen increases baseline collagen turnover at rest, the collagen response to exercise is negatively correlated with estradiol levels. In other words, higher estrogen is associated with a smaller exercise-induced bump in collagen synthesis. A study of young women found that those using high-estrogen oral contraceptives had a dramatically lower exercise-induced increase in tendon collagen synthesis compared with women not using hormonal contraceptives. The average increase in the collagen synthesis marker P1NP after exercise was roughly 24 ng/ml in the non-contraceptive group versus about 1.5 ng/ml in the oral contraceptive group.16PubMed Central. Ethinyl oestradiol administration in women suppresses synthesis of collagen in tendon in response to exercise The interpretation is that estrogen maintains higher baseline collagen activity, leaving less room for an exercise-triggered spike. For women on hormonal contraceptives or estrogen replacement, this does not mean exercise is useless for connective tissue health, but the acute collagen response to a single session may be blunted.
Gelatin, Vitamin C, and Timing
Nutrition can meaningfully amplify the collagen-synthesis response to exercise. The most-cited finding in this space comes from a study showing that subjects who consumed 15 grams of gelatin enriched with vitamin C one hour before exercise doubled their blood levels of a collagen synthesis marker compared with placebo.17The American Journal of Clinical Nutrition. Vitamin C–enriched gelatin supplementation before intermittent activity augments collagen synthesis A systematic review of collagen peptide supplementation confirmed this finding and added that the combination of collagen peptides and vitamin C consumed before exercise produced a significant increase in P1NP, the same bone- and tendon-collagen marker discussed earlier.18PubMed Central. The effects of collagen peptide supplementation on body composition, collagen synthesis, and recovery from joint injury and exercise: a systematic review
The proposed mechanism is straightforward. Gelatin and hydrolyzed collagen peptides provide the amino acids (glycine, proline, hydroxyproline) that serve as raw material for collagen assembly. Vitamin C is a required cofactor for the enzymes that stabilize collagen’s triple-helix structure, which is why scurvy, caused by severe vitamin C deficiency, leads to collagen breakdown and symptoms like bleeding gums and poor wound healing. By flooding the bloodstream with building blocks and cofactors shortly before exercise triggers the synthesis signal, you give the machinery what it needs when demand peaks. The practical takeaway is that timing matters: taking gelatin or collagen supplements with vitamin C about 30 to 60 minutes before a workout appears to enhance the effect beyond either exercise or supplementation alone.
When More Collagen Is the Wrong Answer
It is worth pausing on the assumption that more collagen is always better, because in some tissues it is not. In arteries, age-related collagen accumulation is a driver of arterial stiffness, one of the strongest predictors of cardiovascular disease. Aging arteries deposit excess collagen types I and III in their walls, partly driven by transforming growth factor-beta (TGF-β1), and this stiffens the vessels. In old mice, voluntary wheel running reduced arterial collagen I and III, lowered TGF-β1, and partially reversed the stiffening process.19PubMed Central. Arterial stiffening with ageing is associated with transforming growth factor-β1-related changes in adventitial collagen: reversal by aerobic exercise Exercise in this context was beneficial precisely because it reduced collagen deposition, not because it increased it.
In tendons, the type of collagen matters as much as the amount. Healthy tendons are dominated by type I collagen, which provides excellent tensile strength. When tendons sustain repeated microtrauma from overuse, they can heal by producing type III collagen instead, which is thinner, less organized, and weaker under load. Tenocytes from ruptured and tendinopathic Achilles tendons produce significantly more type III collagen than cells from healthy tendons.20PubMed. Tenocytes from ruptured and tendinopathic achilles tendons produce greater quantities of type III collagen than tenocytes from normal achilles tendons The accumulation of these weaker repair patches can eventually compromise the tendon’s ability to resist force and lead to rupture. The distinction between healthy collagen remodeling from appropriate exercise and pathological collagen accumulation from chronic overuse is real and clinically meaningful.
Collagen Quality and Cross-Linking
The strength of collagen tissue depends not just on how much collagen is there, but on how the fibers are linked together. Collagen molecules are woven into a lattice and stabilized by chemical cross-links that act like molecular rivets. Exercise appears to influence this cross-linking process in favorable ways. In a study on bone, exercise shifted the type of cross-links toward pyridinoline cross-links, which are associated with mature, mechanically strong tissue. When cross-linking was chemically inhibited in the same experiment, the bone became weaker, but adding exercise on top of that inhibition restored total mature cross-linking and mechanical properties back to the level of normal sedentary controls.21PubMed Central. Exercise increases pyridinoline cross-linking and counters the mechanical effects of concurrent lathyrogenic treatment
This gets at something often missed in discussions about collagen and exercise. Making more collagen is only part of the equation. How that collagen gets organized, cross-linked, and integrated into the existing matrix determines whether the tissue is actually stronger or just more fibrous. A tendon that produces abundant collagen but cross-links it poorly, or deposits it in a disorganized scar-like pattern, is not better off than a tendon with less total collagen arranged into tight, parallel fibers. Exercise appears to improve both sides of that equation, at least in the tissues where it has been carefully measured.
Exercise, Immune Cells, and Wound Healing
A less obvious route by which exercise supports collagen production runs through the immune system. Moderate-intensity exercise increases a particular class of immune cells called M2 macrophages, which are the “repair-mode” immune cells that help resolve inflammation and promote tissue rebuilding. In a mouse study, exercised animals showed higher levels of TGF-β1 derived from M2 macrophages, and this was associated with faster wound healing and better blood vessel formation at wound sites.22PubMed Central. Exercise-induced increase in M2 macrophages accelerates wound healing in young mice TGF-β1 is one of the most potent signals for collagen production by fibroblasts, so the exercise-immune-collagen pathway may partly explain why regular exercisers tend to heal from injuries faster than sedentary people, even accounting for other factors like circulation and body composition.
This systemic effect also helps explain the skin findings. You do not mechanically load your facial skin during a squat, yet the circulating inflammatory environment changes with habitual exercise in ways that could reach fibroblasts throughout the body. Whether that systemic signal is strong enough to produce visible changes in skin collagen density over months or years is still an open question, but the biological plausibility is there.