Eccentric Training Decreases Paratendon Capillary Blood Flow and Preserves Paratendon Oxygen Saturation in Chronic Achilles Tendinopathy

Abstract

STUDY DESIGN: A controlled, randomized, prospective study, OBJECTIVE: To assess the changes in paratendon microcirculation after 12 weeks of daily painful eccentric training in individuals with chronic Achilles tendinopathy. BACKGROUND: Changes in tendon and paratendon microcirculation are evident in insertional and midportion Achilles tendinopathy. Whether the paratendon is involved in eccentric training response is not known. METHODS: Twenty patients with chronic Achilles tendinopathy were recruited for a prospective, controlled trial using eccentric exercise. A laser Doppler system assessed capillary blood flow (flow), tissue oxygen saturation (SO2), and postcapillary venous filling pressure (rHb) at 8 paratendon locations at depths of 2 and 8 mm. RESULTS: Pain in the eccentric-training group was reduced by 48% (from a mean of 4.1 +/- 2.9 to 2.1 +/- 2.2, P<.05). Deep paratendon blood flow decreased at the midportion paratendon location (P<.05). Superficial blood flow at the medial distal midportion position (by 31%, P = .008) and the lateral proximal midportion location (by 45%, P = .016) were significantly decreased postintervention, No significant change of superficial or deep paratendon oxygenation was found after intervention as compared to baseline. Deep paratendon postcapillary venous filling pressures were significantly reduced following eccentric training (P<.05). CONCLUSION: An eccentric-training program performed daily over 12 weeks reduced the increased paratendinous capillary blood flow in Achilles tendinopathy by as much as 45% and decreased pain level based on a visual analog scale. Local paratendon oxygenation was preserved while paratendinous postcapillary venous filling pressures were reduced after 12 weeks of eccentric training, which appears to be beneficial from the perspective of microcirculation.