Over the last few years, sports medicine professionals examining injuries have increasingly looked at what they call the kinetic chain, or the body parts that work together during an athletic movement. (In layperson's terms, the hip bone's connected to the knee bone, and so on.) For example, it's now widely believed that hip weakness and instability increases the risk of developing runner's knee.
A similar link might exist between pain in and around the Achilles tendon and how your glute muscles fire when you run, suggests a study that will be published in Medicine & Science in Sports & Exercise.
Australian researchers gathered two groups of male runners who were similar except that one group had been free of Achilles problems for at least the last year, while the runners in the other group had Achilles tendon pain when they ran and did other activities. While the men did short runs at about 6:40 per mile pace, the researchers measured the runners' neuromuscular control of the glutes–that is, when the muscles were activated, and for how long.
In the men with Achilles pain, glute activation in relation to heel strike occurred later than in the pain-free men, and glute activation lasted for a shorter time.
This is potentially significant because poorer glute activation can cause increased hip internal rotation and adduction (movement toward the middle of the body). That instability in the hips, in turn, can lead to more pronation, which is thought to contribute to Achilles problems.
The researchers note that it's unclear from their study whether the runners' Achilles pain caused a change in their glute muscle activation, or vice versa. Still, they write, retraining glute muscles, including by strengthening, should be considered for runners with Achilles injuries.
The video below shows a short, simple glute-strengthening routine.