The efficacy of eccentric exercise in the treatment of Achilles tendinopathy: a systematic review and meta-analysis

Background​ Achilles tendinopathy(AT) is a prevalent degenerative disorder affecting athletes and individuals of the general population, with significant socioeconomic impacts. While eccentric exercise(EE) has emerged as a promising intervention, its comparative efficacy against other conservative treatments remains inconclusive due to limitations in previous meta-analyses. This study aimed to comprehensively evaluate EE’s efficacy by incorporating both clinical symptoms and ultrasonographic structural outcomes. Method​ Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA) guidelines, we analyzed 21 randomized controlled trials(RCTs)(n = 994) from major databases up to September 2025. Studies comparing EE with other conservative treatments(exercise/physical/injection therapies) were included. Primary outcomes included pain(Visual Analogue Scale, VAS/numerical rating scale, NRS), function(Victorian Institute of Sport Assessment-Achilles, VISA-A), and ultrasonography parameters. Risk of bias was assessed using Cochrane criteria, and random-effects models calculated effect sizes(Standardized Mean Differences, SMDs with 95% CIs). Result​ EE demonstrated superior pain reduction compared to physical modalities(VAS: SMD=-0.54; NRS: SMD=-0.29) but showed comparable effects to other exercise therapies. Ultrasonography revealed significant improvements in tendon structure, with increased anteroposterior(AP) thickness(SMD = 0.41) and reduced vascularity. Functional outcomes (VISA-A) indicated smaller improvements in the EE group versus controls, with extremely high heterogeneity(I²=86.1%), precluding definitive conclusions. Discussion​ The findings establish EE’s dual benefits: symptom relief and structural improvement. Its superiority over physical therapies likely stems from enhanced neuromuscular control and potential tendon remodeling. The equivalent efficacy to other exercises suggests mechanical loading intensity as the key therapeutic driver. High heterogeneity in functional outcomes underscores the need for standardized protocols and AT subtype-specific approaches. Conclusion​ This meta-analysis confirms EE can serve as a first-line treatment option for AT within load-based exercise programs, particularly when structural improvement is desired. However, it is not an independent gold standard superior to other forms of exercise. While equally effective as other exercises for pain relief, EE offers unique advantages in tendon remodeling. Future research should address protocol standardization and subtype stratification to optimize clinical outcomes.