Eccentric Training Improves Tendon Biomechanical Properties: A Rat Model

Abstract

BackgroundEven if eccentric exercises appear favourable in primary prevention of tendons lesions and, especially, in secondary prevention after tendinopathy, the biomechanical changes to the tissue are not yet clear.ObjectiveWe aimed to better define the biomechanical changes that affect healthy tendon after eccentric and concentric training.DesignRandomised controlled trial.SettingAnimal study.Participants18 Sprague-Dawley rats of 2 months.InterventionsThe 6 rats in the control group (U) were not subjected to physical exercise. The 12 remaining rats (6 in each group) ran on a treadmill set at a +15° incline for concentric training (C) or a −15° incline for eccentric training (E), at a speed of 17 m/min for 1 h, three times per week for 5 weeks.Main outcome measurementsThe tricipital, patellar and Achilles tendons were subsequently removed to perform a traction test until rupture, and a histological analysis was performed.ResultsThere was a significant improvement in the rupture force of the patellar and tricipital tendons between the U and E groups. The tricipital tendons in the control group presented a significantly smaller cross-section than the E- and C-trained groups, but none between E and C groups. No significant difference was observed for the mechanical stress at rupture per surface unit between the three groups for all three tendons. However, a tendency towards improvement these values was observed between the trained and the U groups for the patellar tendon. Histological studies demonstrated the tendency of the development of a greater number of blood vessels and a larger quantity of collagen in the eccentric group.ConclusionsThe mechanical properties of tendons in rats improve after specific training, especially following eccentric training. Our results partly explained how mechanical loading, especially in eccentric mode, could improve the tendon structure and perhaps prevent to tendon pathologies.

Tendon — function-related structure, simple healing process and mysterious ageing

“…Tendon cells affected by tendinopathy vary from healthy tenocytes and their metabolism is modified due to altered expression of almost 983 genes [4]. The etiology of tendinopathy seems to be multi-factorial, involving intrinsic and extrinsic factors [31]. As tendinopathy is related to tendons pathology, enthesopathy refers to pathology of tendon-bone junctions.…”

“…Tibialis posterior tendon disorders are common among runners, degenerative changes are also common in the elderly and often associated with valgus, flat-foot deformation, overpronation of the foot, impoverished vascularization in the area behind medial malleolus, ligamentous laxity [1]. Rotator cuff tendinopathy is a common pathology in the mid-aged and elderly patients, however it also often occur in swimmers, throwing sports such as javelin throwers, baseball, tennis, volleyball, American football players [1,31]. Triceps tendon disorders are common among throwing athletes [1].…”

“…Lateral epicondylitis (tennis elbow) and medial epicondylitis (golfer's elbow) are typical for activities demanding overhead or repetitive arm actions [31]. Achilles tendon is the biggest, the strongest and the most often injured tendon of human body.…”

“…This magnificent connective tissue structure is bearing the forces of 12,5 times of body weight during running [55]. Achilles tendinopathy occurs in 5.9%of seniors and 50% of elite athletes [31]. Degenerative alterations in Achilles tendon structure are commonly found among asymptomatic patients during ultrasound examination and may lead to spontaneous tendon rupture.…”

“…Inactive patients exposed to risk factors are also concern as prone to Achilles tendon disorders. 41% of patients with symptomatic Achilles tendon tendinopathy had an occurrence of symptoms in contraleteral extremity during 8-year period [31]. Tibialis posterior tendon disorders are common among runners, degenerative changes are also common in the elderly and often associated with valgus, flat-foot deformation, overpronation of the foot, impoverished vascularization in the area behind medial malleolus, ligamentous laxity [1].…”