Improvement of Functional Ankle Properties Following Supplementation with Specific Collagen Peptides in Athletes with Chronic Ankle Instability

Dressler P, Gehring D, Zdzieblik D, Oesser S, Gollhofer A, König D · Journal of Sports Science & Medicine

The longest randomized collagen exposure with a ligament endpoint, and the arms did not start level. Randomisation left the collagen group substantially more impaired at baseline on all three questionnaires — Cumberland Ankle Instability Tool 15.5 against 20.8 (p=0.001), Foot and Ankle Ability Measure 81.6% against 90.3% for daily living and 60.5% against 76.2% for sport — and it finished at roughly where the placebo group began (20.8, 91.3%, 80.4%) while the placebo group, already near the ceiling, barely moved. On that comparison the treatment-by-time interactions are significant (p<0.001) and self-reported sprains during the three-month follow-up were fewer. Mechanical stability measured by ankle arthrometer did not differ: +0.08 N/mm on collagen against -0.77 N/mm on placebo.

Population

Amateur competitive athletes, mean age 27, with chronic ankle instability after at least one significant sprain

Intervention

5 g specific collagen peptides daily for 6 months alongside a thrice-weekly home loading programme, with a 3-month follow-up

Comparator

5 g maltodextrin, same loading programme

Limitations

The paper's own limitations section names the baseline imbalance first, notes that no counterbalancing was used in randomisation, and says it could be speculated that the lower starting score in the collagen group produced the larger improvement; the analysis was left unadjusted rather than moved to ANCOVA. At the end the collagen group's mean score still classified those athletes as unstable. The instrumented outcome was null while the questionnaire outcomes were positive, which is the pattern most vulnerable to expectation effects even under blinding, and the follow-up injury counts come from a shortened self-report questionnaire on small numbers. 60 were randomised and 50 analysed, 25 per arm. Part of the costs were paid by GELITA AG and the paper declares no conflicts; co-author Oesser is at the Collagen Research Institute, and the Freiburg group produced most of the positive collagen trials in this literature.