SLR - February 2019 - John Bonvillian
Activity-Induced Increase in Achilles Tendon Blood Flow Is Age and Sex Dependent
Reference: Wezenbeek E, Clercq D, Mahieu N, Willems T, Witvrouw E. Activity-Induced Increase in Achilles Tendon Blood Flow Is Age and Sex Dependent. Am J Sports Med. 2018 Sep;46(11):2678–2686.
Scientific Literature Review
Reviewed By: John Bonvillian, DPM
Residency Program: Wake Forest Baptist Health, Winston-Salem, NC
Podiatric Relevance: Injuries to the Achilles tendon are commonly encountered in middle-aged recreational male athletes. Previous studies have identified a decrease in the blood flow to the Achilles tendon immediately after running in the young adult population as a significant risk factor for development of Achilles tendinopathy. An increase in age is associated with a decreased tendon cellularity and vascularity. This decreased vascularity due to increased age, coupled with a decreased vascularity following activities may explain the increased prevalence of Achilles tendinopathy in the older population. The purpose of this study was to investigate the effect of age, sex and type of physical activity on the Achilles tendon blood flow.
Methods: A total of 63 study participants were divided into two groups: younger (18–25 years old) and older (40–55 years old). Blood flow measurements of 33 subjects in the younger group and 30 in the older group were obtained before and after four physical activities performed in randomized order: running, cycling, dynamic stretching and rope skipping. Blood flow measurements of the Achilles tendon were performed before, immediately after, five minutes after and ten minutes after the physical activities. Blood flow data was collected utilizing a noninvasive O2C device. Subjects were excluded if they had any history of Achilles tendinopathy, surgery of the lower extremity, severe trauma in the lower extremity in the past year or participated in more than three training sessions per week. The effect of age, sex and physical activities on the increase in blood flow was investigated with linear mixed models.
Results: The increase in blood flow after activity was significantly lower in the older population as compared with the younger population. Also, male participants in the older group showed a significantly lower increase in tendon blood flow when compared to females. The study also found that running, rope skipping and cycling resulted in a significant increase in tendon blood flow, whereas stretching did not.
Conclusions: This study is the first to investigate the effect of age and sex on Achilles tendon blood flow following physical activity. As patients age, increased vascular stiffness and impaired vasoconstrictor signaling may impair vascular conductance. With a decrease in tissue oxygenation, metabolic dysfunction occurs resulting in tendon damage. A decreased tendon vascularity is also thought to decrease the tensile strength of the tendon, increasing its susceptibility to tendon rupture or injury. This study claims that the decrease in blood flow in the older age group when compared to the younger group following physical activity may explain the increased risk of developing Achilles tendinopathy in older males. The authors recommend focusing on improving blood flow during physical activity in the physically active older male population to in an attempt to decrease the incidence of Achilles tendinopathy. Further research investigating the vascular response to treatment modalities, such as prostaglandins, nitrous oxide, heat and longer warm-up, is needed as previous studies only look at the response at the depth of the skin surface.