Background: Previous research of a young adult population identified a lower increase in Achilles tendon blood flow immediately after a running activity as a significant predictor for the development of Achilles tendinopathy (AT). Furthermore, advancing age is often mentioned as a risk factor for the development of AT, and the highest incidence for AT is reported to occur in middle-aged recreational male athletes.
Purpose: To investigate the effect of age, sex, and type of physical activity on the increase in Achilles tendon blood flow.
Study design: Controlled laboratory study.
Methods: Blood flow measurements of 33 subjects aged 18 to 25 years and 30 subjects aged 40 to 55 years were obtained before and after 4 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, 5 minutes after, and 10 minutes after the physical activities. The effect of age, sex, and physical activities on the increase in blood flow was investigated with linear mixed models.
Results: The results of this study identified that running, rope skipping, and cycling resulted in a significant increase in tendon blood flow ( P ≤ .001), whereas stretching did not. Prominent was the finding that the increase in blood flow after activity was significantly lower in the older population as compared with the younger population ( P < .001). Furthermore, male participants in the older group showed a significantly lower increase in tendon blood flow than did their female counterparts ( P = .019).
Conclusion: This study identified that sex and age significantly influence the increase in blood flow after activity, possibly explaining the increased risk for AT among middle-aged recreational athletes.
Clinical relevance: This study possibly identified one of the mechanisms explaining why an older male population is at increased risk for developing AT. Given that the lower increase in blood flow is an identified risk factor according to previous research, preventative measures should focus on improving this blood flow during physical activity in the physically active older male population. Registration: NCT03218605 ( ClinicalTrials.gov identifier).
Keywords: Achilles tendon; age; blood flow; physical activity; sex.