AUTHOR=Risch Lucie , Stoll Josefine , Schomöller Anne , Engel Tilman , Mayer Frank , Cassel Michael 

TITLE=Intraindividual Doppler Flow Response to Exercise Differs Between Symptomatic and Asymptomatic Achilles Tendons

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.617497

DOI=10.3389/fphys.2021.617497

ISSN=1664-042X

ABSTRACT=<sec><title>Objective</title><p>This study investigated intraindividual differences of intratendinous blood flow (IBF) in response to running exercise in participants with Achilles tendinopathy.</p></sec><sec><title>Design</title><p>This is a cross-sectional study.</p></sec><sec><title>Setting</title><p>The study was conducted at the University Outpatient Clinic.</p></sec><sec><title>Participants</title><p>Sonographic detectable intratendinous blood flow was examined in symptomatic and contralateral asymptomatic Achilles tendons of 19 participants (42 ± 13 years, 178 ± 10 cm, 76 ± 12 kg, VISA-A 75 ± 16) with clinically diagnosed unilateral Achilles tendinopathy and sonographic evident tendinosis.</p></sec><sec><title>Intervention</title><p>IBF was assessed using Doppler ultrasound “Advanced Dynamic Flow” before (Upre) and 5, 30, 60, and 120 min (U5–U120) after a standardized submaximal constant load run.</p></sec><sec><title>Main Outcome Measure</title><p>IBF was quantified by counting the number (<italic>n</italic>) of vessels in each tendon.</p></sec><sec><title>Results</title><p>At Upre, IBF was higher in symptomatic compared with asymptomatic tendons [mean 6.3 (95% CI: 2.8–9.9) and 1.7 (0.4–2.9), <italic>p</italic> &lt; 0.01]. Overall, 63% of symptomatic and 47% of asymptomatic Achilles tendons responded to exercise, whereas 16 and 11% showed persisting IBF and 21 and 42% remained avascular throughout the investigation. At U5, IBF increased in both symptomatic and asymptomatic tendons [difference to baseline: 2.4 (0.3–4.5) and 0.9 (0.5–1.4), <italic>p</italic> = 0.05]. At U30 to U120, IBF was still increased in symptomatic but not in asymptomatic tendons [mean difference to baseline: 1.9 (0.8–2.9) and 0.1 (-0.9 to 1.2), <italic>p</italic> &lt; 0.01].</p></sec><sec><title>Conclusion</title><p>Irrespective of pathology, 47–63% of Achilles tendons responded to exercise with an immediate acute physiological IBF increase by an average of one to two vessels (“responders”). A higher amount of baseline IBF (approximately five vessels) and a prolonged exercise-induced IBF response found in symptomatic ATs indicate a pain-associated altered intratendinous “neovascularization.”</p></sec>