Most runners are acutely aware of all of the different types of injuries that can occur. If they aren't , it's typically because they've been lucky enough to remain injury - free. But as we age, the possibility of injury continues to increase.
Achilles injuries are relatively common among runners. In the general population, middle-aged men are especially susceptible . Men over 40 years old have two times the injury rate of men 18-39 years old. The logical question that follows is: are middle-aged male runners more susceptible to Achilles injuries, or is running somehow protective against the aging factor?
A group of researchers investigated changes in the Achilles tendon properties of young and middle-aged male runners after a half marathon to address this question. Twenty-seven middle-aged (defined as 51 to 59 years old for this study) and 22 younger (25 to 29 year old) male recreational runners were recruited. The men had to be regularly running for the last 4-6 years (minimally 30km/week , but the average among the participants was 50km/week) and complete a minimum of two races in the last two years.
All of the runners ran a half marathon with the research team cycling alongside and with the instruction to "run as fast as possible at a self-selected pace." Four measurements of the Achilles tendon were taken: 1) 20-28 hours prior to the race, 2) immediately before, 3) immediately after, and 4) within 20 -28 hours after the race. Measurements included plantar flexion strength (the primary motion of the Achilles) as well as ultrasonography of the tendon to identify tendon stiffness.
The results showed that the middle-aged runners had decreased maximal plantarflexion strength and decreased tendon stiffness across the board ; not too unexpected. However, compared to their earlier measurements, their tendon stiffness was significantly worse immediately after the run. The older runners demonstrated an average of a 22% decrease in tendon stiffness after the run. This indicates the "older tendons" are less capable of resisting long - lasting cyclical mechanical loading (so, running) and as a result are more susceptible to injury.
Ackermans TMA Epro G McCrum C et al. “Aging and the effects of a half marathon on achilles tendon force-elongation relationship”. Eur J Appl Physiol 2016; 116:2281-2292.
Cathlin Fitzgerald, PT, DPT, CAFS, CSCS