Abstract
Introduction & Purpose
Tendinopathy is a disabling and painful condition, with a prevalence of up to 45% in specific sports like running, basketball, and volleyball (Nutarelli et al., 2023). Mechanical overuse of the tendon due to repetitive strain beyond physiological limits, results in a degenerated and weakened tendon (Radovanović et al., 2022). Eccentric training (ECC), has been the gold standard of treatment in tendinopathies for the last 30 years. However, alternative protocols like Heavy-Slow Resistance Training (HSRT) have attracted the interest of researchers since eccentric training can be mechanically demanding and painful (Sayana and Maffulli, 2007). This scoping review aims to synthesize the available evidence on the effects of chronic eccentric training and HSRT on structural, morphological, and clinical outcomes in patients with patellar and Achilles tendinopathy.
Methods
An electronic search was conducted in three databases (PubMed, Scopus, and Web of Science). In total, 7176 studies were identified. Articles were screened based on sample age (18-50 years old), intervention type, and duration (> 8 weeks). Tendon thickness, stiffness, cross-sectional area, neovascularization and Young’s modulus, along with pain, muscle strength, and the Victorian Institute of Sports Assessment (VISA) questionnaire were assessed. To estimate changes due to the different interventions, percentages of changes between pre and post values were calculated for each study. Percentage changes were weighted based on sample size of each study. Pooled mean percentages were classified into different magnitudes, ranging from trivial to very large, based on those suggested by Behm et al., 2016.
Results
After a thorough screening process, 16 studies were included in the review. Both interventions showed beneficial results on clinical and functional outcomes, increasing muscle strength and VISA questionnaire score in both tendons, and decreasing pain. HSRT yielded superior results when compared to ECC by reducing (pathologic) tendon thickness (-2.1%, n=8 vs 1.3%, n=5) and neovascularization (-23.2%, n=6 vs -11.7%, n=5), while ECC training showed greater increases in tendon stiffness (7.1%, n=6 vs 0.3%, n=3) (Fig.1).
Discussion
Tendon-specific responses were observed, with an increase in stiffness in individuals with Achilles tendinopathy, and a decrease in those with patellar tendinopathy. While these differences may reflect underlying anatomical and physiological characteristics as well as tendon-specific functions (Finni, 2001; Biewener and Roberts, 2000), the heterogeneity of measurement methods limits direct comparisons (Khair et al., 2024). Both protocols showed beneficial effects on the Achilles and patellar tendons, and their associated muscles (triceps surae and vastus lateralis, respectively), and showed large to very large improvements in clinical outcomes, including pain (ECC: -37.5%, HSRT: -54.6%), muscle strength (ECC: 7.8%, HSRT: 17.0%), and the VISA questionnaire (ECC: 31.2%, HSRT: 32.6%).
Conclusions
As both protocols reduced pain and increased function significantly, HSRT could be a promising time-saving alternative to ECC training for the rehabilitation of tendinopathies, when the latter is not possible. Further research is needed to elucidate if ECC or HSRT is superior to the other. Matching and standardizing training parameters when prescribing resistance training is the first step to try and elucidate the real effects of both interventions on tendon characteristics.
References
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