You’re running out of excuses to avoid tough hills. Uphill and downhill running doesn't seem to harm your Achilles tendon as much as previously thought, reports a study in the Journal of Sports Science and Medicine.
Your Achilles stretches and thins during any type of exercise, but it was previously assumed that the forces exerted on the tendon during downhill training could stretch it further, leading to possible long-term injury. Researchers from Brigham Young University used high-speed cameras and Doppler ultrasound imaging to prove that the Achilles maintains the same thickness during flat, uphill and downhill runs.
For the study, 20 experienced female runners completed three 10-minute treadmill sessions at a -6, 0, and +6 per cent grade. While the vertical force on the Achilles changed - at its highest on the downhill incline and lowest during the uphill incline - the Achilles adapted to maintain the same thickness no matter the grade. This is good news for runners looking to add elevation to their routine.
The Achilles naturally stretches on every run, storing elastic energy to reduce the workload of your muscles. Previous research indicates this constant stretching can lead to “micro-damage” in the tendon. The authors of the study hypothesised the Achilles would be more susceptible to injury on negative inclines because of the increased force on the heel, often from runners naturally using a rearfoot strike when navigating down hills to slow their momentum. Fortunately, it appears the Achilles is up for the job if you run regularly.
“Over time, runners adapt to the forces placed on their body, so even when the forces are higher (running downhill), if the adaptation process is gradual, the injury risk drops,” said Katy Andrews Neves, the study’s lead author, in a news release.
Neves, a former all-conference steeplechaser at Brigham Young University has made it her mission to root out the leading causes of Achilles injuries, which affect nearly 52 per cent of runners at some point in their career. With her latest research she says, “runners can know it is safe to transition to downhill running and include it in normal training and racing.”
The study does note that significant changes in training can lead to injury. The research was conducted on well-trained runners, each able to run faster than a 24-minute 5K, which may be why their Achilles tendons adapted so well to the changing incline. The authors recommend that new or low-mileage runners ready to attack more hills should add hill running gradually, giving the Achilles time to adapt.