Collagen Peptides for Athletes: The Evidence
Peptides in Sports Medicine
15-16 wk to see tendon changes
Multiple randomized controlled trials show that collagen peptide supplementation combined with resistance training increases patellar tendon cross-sectional area and stiffness over 14-16 weeks.
Jerger et al., 2023; Balshaw et al., 2023
Jerger et al., 2023; Balshaw et al., 2023
View as imageCollagen peptides are the most widely used peptide supplement in sports nutrition, and unlike most performance supplements, they have a growing body of randomized controlled trial data supporting specific claims. The evidence divides into two distinct categories: tendon and ligament remodeling (structural changes measurable on ultrasound) and joint pain reduction (subjective but consistent across trials). A 2025 randomized controlled trial added a third: increased muscle-tendon stiffness and explosive strength in sedentary males after 16 weeks of supplementation.[1] For the broader landscape of peptides used in athletic contexts, see the pillar article on peptides in sports medicine.
The evidence is real but limited. Most trials are funded by collagen supplement manufacturers. Sample sizes are modest. And the effects, while statistically significant, are small enough that individual athletes may not notice them. This article examines what the controlled data actually shows, where the evidence is strongest, and where it falls short.
Key Takeaways
- A 16-week RCT found collagen peptide supplementation increased muscle-tendon stiffness and explosive strength in 50 young males compared to placebo (Miyamoto et al., 2025)
- 14 weeks of collagen peptides (5g/day) plus high-load resistance training increased patellar tendon cross-sectional area compared to resistance training alone (Jerger et al., 2023)
- 15 weeks of collagen peptides with lower body resistance training showed tendon remodeling effects detectable on ultrasound (Balshaw et al., 2023)
- A systematic review found collagen supplementation reduced activity-related knee joint discomfort in young physically active adults by 38-43% versus placebo (Zdzieblik et al., 2021)
- Collagen peptides combined with calf-strengthening exercises improved Achilles tendinopathy outcomes more than exercise alone in a controlled trial (Praet et al., 2019)
- Replacing whey protein with collagen peptides did not improve muscle damage markers or recovery after eccentric exercise (Robberechts et al., 2024)
How collagen peptides reach tendons and joints
Collagen peptides (also called collagen hydrolysate) are produced by enzymatic hydrolysis of animal collagen (typically bovine, porcine, or marine sources) into fragments of 2-20 amino acids. After oral ingestion, these fragments are absorbed in the small intestine. Some are further broken down to individual amino acids (glycine, proline, hydroxyproline), while others are absorbed as intact dipeptides and tripeptides, particularly hydroxyproline-containing peptides like Pro-Hyp and Hyp-Gly.
The intact peptides are the biologically interesting part. Pro-Hyp accumulates in blood at measurable concentrations after oral collagen intake and has been detected in joint and skin tissue. In cell culture, Pro-Hyp stimulates fibroblasts (the cells that produce collagen in tendons, ligaments, and cartilage) to increase collagen synthesis. The hypothesis is that orally consumed collagen peptides deliver bioactive fragments to connective tissues where they signal fibroblasts to produce new collagen.
This mechanism is plausible but not proven in living humans. The cell culture evidence is strong. The blood level data confirms absorption. The tissue accumulation data exists for skin but is limited for tendons. The clinical trials measure downstream outcomes (tendon thickness, joint pain) without directly measuring collagen incorporation.
The tendon evidence: structural changes from supplements
Three randomized controlled trials have measured tendon structural changes with collagen peptide supplementation using ultrasound imaging. This is the strongest category of evidence because structural changes are objective, measurable outcomes.
Jerger et al. (2023) randomized healthy adults to 5 grams of specific collagen peptides or placebo daily for 14 weeks, with both groups performing high-load resistance training targeting the patellar tendon.[2] The collagen group showed increased patellar tendon cross-sectional area compared to the placebo group, indicating that collagen supplementation enhanced the tendon's structural adaptation to training.
Balshaw et al. (2023) tested specific bioactive collagen peptides over 15 weeks of lower body resistance training.[3] Tendon remodeling was detectable on ultrasound, with changes in tendon mechanical properties that were not seen in the training-only group.
Miyamoto et al. (2025) conducted the most recent and comprehensive trial: 50 healthy young males were randomized to collagen peptides or placebo for 16 weeks.[1] The collagen group showed increased muscle-tendon stiffness and improved explosive strength (rate of force development). This is the first RCT to link collagen supplementation to a functional performance outcome (explosive strength) rather than just a structural measurement.
Bischof et al. (2023) examined recovery-related biomechanical characteristics of tendons during 12 weeks of concurrent training (combining endurance and resistance exercise).[4] Specific collagen peptides influenced tendon recovery properties, though the differences from placebo were modest.
These trials share a consistent pattern: collagen peptides enhance tendon adaptation to mechanical loading. Without training, the effect would likely be minimal. The supplement appears to amplify the tendon's natural remodeling response to exercise rather than acting independently.
The joint pain evidence: consistent but subjective
Joint pain reduction is the most commercially promoted claim for collagen supplements, and the evidence is more abundant but methodologically weaker than the tendon structural data.
Zdzieblik et al. (2021) tested specific bioactive collagen peptides in young physically active adults with exercise-induced knee discomfort in a double-blind, placebo-controlled trial.[5] The collagen group reported 38-43% greater reduction in knee pain scores compared to placebo over 12 weeks. The effect was statistically significant and clinically meaningful by standard pain assessment thresholds.
Schulze et al. (2024) extended this to joint discomfort in the lower extremity during daily activities, finding that specific bioactive collagen peptides reduced pain scores in physically active individuals.[6]
Park et al. (2025) tested low-molecular-weight collagen peptides specifically in knee osteoarthritis patients (a clinical population rather than athletes) in a randomized, double-blind, placebo-controlled trial.[7] The collagen group showed improvements in pain and function scores, adding clinical-grade evidence to the athletic joint pain data.
The limitation of all joint pain studies is their reliance on subjective outcome measures (pain questionnaires, visual analog scales). Placebo effects are substantial in pain research, and while these trials used double-blinding, the biological mechanism for pain reduction is not well characterized. It may involve anti-inflammatory effects, cartilage protection, or simply improved connective tissue hydration. Joint imaging data (MRI of cartilage thickness or quality) in response to collagen supplementation in athletes is lacking.
The Achilles tendinopathy trial: clinical rehabilitation
Praet et al. (2019) conducted the most clinically relevant trial for injured athletes.[8] Patients with Achilles tendinopathy were randomized to specific collagen peptide supplementation plus a calf-strengthening exercise protocol or exercise alone. The collagen group showed greater improvements in Achilles tendon function and pain scores, and returned to sport faster than the exercise-only group.
This trial is significant because it tested collagen peptides in a rehabilitative context rather than a preventive or performance context. For athletes recovering from tendon injuries, the combination of mechanical loading (rehabilitation exercises) with collagen peptide supplementation appears to accelerate recovery. The study is also relevant to the broader question of whether the BPC-157 preclinical tendon data could eventually be complemented by collagen peptide evidence in clinical practice.
Where collagen peptides do not help
Not all collagen peptide claims hold up. Two areas where the evidence is negative or absent are worth noting.
Muscle damage and exercise recovery. Robberechts et al. (2024) tested whether partly substituting whey protein with collagen peptides would improve muscle damage markers or recovery after eccentric exercise.[9] It did not. Muscle damage indices (creatine kinase levels, muscle soreness, strength recovery) were not different between whey-only and whey-plus-collagen groups. This finding separates collagen's tendon/joint effects from any claim about muscle recovery or muscle protein synthesis.
Muscle hypertrophy as a standalone. Collagen peptides are an incomplete protein source. They lack tryptophan entirely and have low leucine content, meaning they are poor stimulators of muscle protein synthesis compared to whey, casein, or other complete proteins. The Miyamoto 2025 trial showed explosive strength gains, but these likely resulted from improved tendon stiffness (enabling better force transmission) rather than increased muscle mass.
Dosing and timing: what the trials use
Across the positive trials, several patterns emerge:
Dose: 5-15 grams daily. Most tendon remodeling trials used 5 grams of specific bioactive collagen peptides. Joint pain trials have used 5-15 grams. The Miyamoto 2025 trial used a standard collagen peptide dose without specifying a proprietary formulation.
Timing: 30-60 minutes before exercise. This timing is based on the Shaw et al. (2017) finding (published in the American Journal of Clinical Nutrition) that collagen peptides taken with vitamin C one hour before exercise maximized collagen synthesis rates in engineered ligament constructs. Most subsequent trials have adopted this pre-exercise timing.
Vitamin C: Often co-administered (50-500 mg). Vitamin C is required for the enzymatic hydroxylation of proline and lysine during collagen synthesis. Whether co-supplementation is necessary for in vivo effects has not been tested in an isolated comparison.
Duration: 12-16 weeks minimum for structural tendon changes. Joint pain improvements may appear as early as 4-8 weeks. The Czajka et al. (2018) study on skin collagen showed improvements at 12 weeks.[10]
Limitations across the evidence base
Several concerns apply to the collagen peptide literature as a whole.
Industry funding. Many trials are funded by companies that manufacture specific collagen peptide products (GELITA, Nitta Gelatin). While the trials are generally well-designed (randomized, double-blind, placebo-controlled), funding source creates a publication bias concern. Negative results from industry-funded trials may be less likely to be published.
"Specific bioactive collagen peptides." Multiple trials specify that their results apply to particular collagen peptide formulations with defined molecular weight profiles and peptide compositions. Whether generic collagen hydrolysate from different sources produces equivalent effects is unclear. This makes direct consumer guidance difficult: the collagen powder on a store shelf may not match the formulation tested in trials.
Small sample sizes. Most trials enroll 30-60 participants. This provides adequate statistical power for large effect sizes but may miss smaller effects or be susceptible to sampling variability. The Miyamoto 2025 trial (n=50) and the systematic reviews provide more robust estimates.
No long-term data. The longest trials run 16 weeks. Whether tendon structural changes persist after supplementation stops, whether years of collagen supplementation provides cumulative benefit, or whether there are any long-term safety concerns remain unknown.
The systematic review by Khatri et al. (2021) assessed the entire evidence base for collagen peptides on body composition, collagen synthesis, and exercise recovery.[11] Their conclusion: collagen supplementation shows promise for connective tissue health and joint pain but evidence quality remains moderate, with most outcomes supported by only a small number of trials.
For athletes considering collagen peptides alongside other recovery strategies, the articles on BPC-157 and athletes and TB-500 and athletic recovery cover peptides that operate through fundamentally different mechanisms.
The Bottom Line
Collagen peptide supplementation has the strongest evidence of any sports nutrition peptide for tendon remodeling and joint pain reduction. Three RCTs demonstrate that 5-15 grams daily combined with resistance training increases patellar tendon cross-sectional area and stiffness over 14-16 weeks. Joint pain studies consistently show 38-43% greater improvement versus placebo. A 2025 trial linked collagen supplementation to improved explosive strength. Collagen peptides do not improve muscle damage recovery or muscle protein synthesis. Most positive trials use specific bioactive collagen peptide formulations with industry funding, and equivalence with generic products is unproven. The evidence supports collagen peptides as a legitimate sports nutrition supplement for connective tissue support, with the caveat that effects are modest and best realized when combined with targeted exercise.