The Association Between Movement Variability And The Transient Achilles Tendon Thickness Loss In Runners

Introduction
It has been shown that runners with knee injuries present lower joint coordination variability than uninjured athletes. The authors suggested that less variable movements lead to a concentration of mechanical stress on few anatomical structures only, thereby leading to overuse injuries. Hence, the question arises whether this principle also applies to the genesis of Achilles tendinopathy (AT), given it is a frequent injury in runners. Considering that a single running bout leads to transient fluid expression out of the Achilles tendon, it is conceivable that less variable running patterns lead to increased transient tendon thickness loss and ultimately to AT.
Objective
To better understand the association between movement variability and the genesis of AT, this study investigates the correlation between the level of joint coordination variability and the acute loss of tendon thickness.
Method
Thirty runners are currently being recruited for this study. Eligibility criteria involve being aged 18-65 years of age, having a running experience of ≥1 year, with a minimum training volume of 5 km running distance per week on average, and feeling healthy. Participants receive longitudinal and transverse ultrasound scans of the Achilles tendon, then run on a treadmill for 30 minutes. Running kinematics are recorded using a 16-cameras optoelectronic motion capture system. After running, ultrasound scans are performed again. Statistical analysis will consist of calculating Pearson’s correlation between the average standard deviation in joint coordination (continuous relative phase) and the loss of tendon thickness.
Results
At this stage, data from 18 participants (11 males, 7 females) have been recorded. On average, they were 33 years old (range: 19-61), had a running experience of 13.8 years (range: 4-33), and an average weekly running distance of 43.4 km (range: 7-100). Seven were casual runners and 11 competed on regional or national level. Kinematic and sonographic data processing is currently being performed.
The findings could have implications for physicians, physiotherapists, and coaches. They could help identify individuals who are at risk of AT. Early detection appears to be crucial given the high chronification rate of AT and the need for preventive strategies. The findings could also form a basis for rehabilitation programs.