The "Z-angle" and the runner, cyclist and everyday posture - a really simple and important functional measure
During a deep knee squat, the foot, shin-bone and thigh can ideally create a "Z" pattern. If you are unable to create this pattern, this indicates short calves. This is a very common restriction in all populations be they active or sedentary.
In runners, over-training and sedentary desk jobs can lead to tightening calves that constant stretching won't release. People that run with their hip flexors, knee medial collapsers and overreachers typically have short calves. A big part of the solution is to strengthen the anterior shin compartment alongside the gluteal activation, and then the calves can afford to lengthen. The calf muscles shorten through walking flat city terrain, using elevated shoe heels and desk sitting. The buttock muscles weaken through the same mechanisms.
In the topic of achilles tendinopathy, I write about how insufficient calf conditioning for current demands increases tightness as well.
Recreating the Z-angle is an easy thing to try on yourself if you're active and pain-free: Get in front of a mirror, barefoot. Squat down while keeping your heels on the floor. Stop when you feel like tipping backwards. The ideal is to rest completely in the hips in a deep knee squat without needing to raise the heels off the floor. Watch out for the knee caps falling inwards, the medial foot arches rolling inwards, and feet turned outwards-that's a cheat to get past the ankle restriction.If you're all the way down, but hanging-on for dear life to stop falling over backwards using the front shin muscles for all they're worth, there's not enough range of motion.
When such a restricted individual is walking, you will note several possible compensations. The feet may splay outwards, or the arches collapse inwards mid-stance, the person "bounces" up and down trying to get over the restricted ankle, or they walk on the outer edge of the feet. Our bodies can do all sorts of things to get away from the restrictions.
The buttock muscles can't be fully used to extend at the hip in this situation. If the lateral foot columns at the ankles don't have 5-10 degrees range of motion, the gluteal muscles will have trouble fully extending the hip in the running motion. Hence the tight hip flexors since their full length is not accessed.
Weak gluteals and tight calves are classic aggravators of the low back. Patients with chronic low back pain may need to condition their calves (and create strength in the front shin muscles too), strengthen the gluteals, learn to re-integrate the gluteals into everyday activity, and keep the hip flexors open. Assessing competency in the Z-angle helps you self-assess your progress. One of the most accessible exercises to get all this happening is walking up hill gradients.
Walking a variety of gradients with 80% spent on small gradients and 20% on larger gradients is a decent mix. If this isn't likely to happen then the shuffle exercise and its varieties is a substitute in addition to appropriate hip extension exercise.
Managing to create the Z-angle comfortably is a great way to assess, progress and achieve functionality for running, cycling and general ambulation..