In an adult with an acute or chronic tendon injury (e.g., Achilles, patellar, rotator‑cuff), what is the evidence‑based protocol for type‑I hydrolyzed collagen supplementation—including dose, timing relative to exercise, duration, vitamin C co‑administration, and contraindications—when combined with a structured rehabilitation program?

Role of Collagen in Tendon Repair

Hydrolyzed collagen supplementation at 15–30 grams daily, combined with 50 mg vitamin C taken 30–60 minutes before exercise, should be used as an adjunct to eccentric strengthening exercises for 3–6 months in adults with acute or chronic tendinopathy.

Evidence-Based Supplementation Protocol

Dosing and Timing

• Administer 15–30 grams of hydrolyzed collagen peptides daily, with the higher dose (30 g) showing superior effects in middle-aged populations 1
• Take supplementation 30–60 minutes before exercise to maximize collagen synthesis during the mechanical loading window 2
• Co-administer 50 mg vitamin C with each collagen dose, as vitamin C is essential for hydroxylation of proline and lysine residues required for proper collagen synthesis 1, 3
• Continue supplementation for a minimum of 3 months, with optimal benefits observed at 6 months when combined with structured rehabilitation 2

Mechanism and Outcomes

• Collagen supplementation increases tendon cross-sectional area by approximately 6.8 mm² compared to 1.2 mm² with exercise alone after 12 weeks in middle-aged men 1
• Tendon stiffness and Young's modulus improve significantly more with collagen (+661 N/mm stiffness vs +247 N/mm with placebo) 1
• Pain reduction accelerates when collagen is added to exercise, with VISA-A scores improving by 12.6 points at 3 months versus 5.3 points with exercise alone 2
• Collagen supplementation augments cross-sectional area and tendon thickness while providing pain mitigation, though effects on microvascularity remain unclear 4

Integration with Rehabilitation

Primary Treatment Framework

• Relative rest remains the cornerstone, allowing continued activities that do not worsen pain while avoiding complete immobilization that causes muscle atrophy 5
• Eccentric strengthening exercises are mandatory and have proven efficacy in Achilles and patellar tendinopathies, with collagen supplementation enhancing these benefits 5, 2
• Apply cryotherapy for 10-minute periods through a wet towel for acute pain relief 5
• Most patients (80%) recover within 3–6 months with this combined approach 5, 6

Adjunctive Analgesics

• Topical NSAIDs are preferable to oral formulations for short-term pain relief, eliminating gastrointestinal hemorrhage risk while providing equivalent analgesia 5, 6
• NSAIDs do not alter long-term outcomes and should not be prioritized over mechanical loading and collagen supplementation 5
• Avoid corticosteroid injections into tendon substance, as they inhibit healing and reduce tensile strength despite providing acute pain relief 5, 7

Contraindications and Precautions

Critical Pitfalls to Avoid

• Never inject corticosteroids directly into tendon tissue—peritendinous injections carry unknown risks but intratendinous injections definitively predispose to spontaneous rupture 5
• Do not prescribe complete immobilization, as tensile loading stimulates collagen production and guides normal alignment of newly formed collagen fibers 5, 7
• Vitamin C deficiency undermines the entire protocol—without adequate vitamin C, procollagen synthesis decreases and hydroxylation of proline/lysine residues is impaired, hindering tendon repair 3

Patient Selection

• Collagen supplementation is appropriate for both acute and chronic tendinopathies affecting Achilles, patellar, and rotator cuff tendons 4, 2
• Middle-aged populations show robust responses to the 30-gram dosing protocol 1
• No adverse events have been reported in clinical trials of collagen supplementation for tendinopathy 2

Surgical Threshold

• Reserve surgical evaluation for patients who fail 3–6 months of well-managed conservative treatment including collagen supplementation, eccentric exercises, and appropriate load management 5, 6, 7
• Surgical techniques involve excision of abnormal tendinous tissue and longitudinal tenotomies to release scarring and fibrosis 6, 7

Mechanistic Rationale

• Tendon is composed of 60–85% type I collagen, making collagen peptide supplementation a logical therapeutic target 5
• Mechanical loading combined with collagen availability enhances collagen synthesis and promotes proper fiber alignment during the repair process 5, 1
• Vitamin C serves as an essential cofactor for collagen hydroxylation, without which the triple helix structure cannot form properly 3