Why do people get Achilles tendonitis and plantar fasciitis???
There are many factors that can contribute to Achilles tendonitis and plantar fasciitis. The number one factor is usually an overuse of the gastroc-soleus complex. The two muscles in your calf join together at the Achilles tendon in the back of the heel. When this structure gets overused, it can pull the heel bone (calcaneus) in a way that irritates the plantar fasciitis in addition to it just getting irritated right at the Achilles tendon.
The real question we ask as physical therapists is “Why Are You Using Your Calf So Much!?” Ironically, your calf being tight may be the immediate source of your pain but more often than not your pain is probably coming from a lack of strength or range of motion somewhere else entirely. I have found throughout my experience in physical therapy and taking two intensive courses on running injuries that there are two main places that can cause an overuse of your calf muscle: 1. Hip Extension Range Of Motion and 2. Great Toe Extension Range Of Motion
In the gait and running cycle, we have phases called “terminal stance” and “pre-swing,” which is when our toe just barely comes off the ground to take that next step forward. This particular position requires a certain range of motion at the hip and big toe. The hip should be able to achieve at least 10 degrees of extension and the big toe should be able to achieve at least 60 degrees (if walking) and up to 90 degrees (if running) of great toe extension.
If you take a look at this picture, you can see that the femur (thigh bone) is angled slightly behind a totally vertical line (imagine a straight line from the pelvis down to the ground) and that the big toe is starting to extend or bend as the foot/ankle rolls through. This position allows optimal contraction of our gluteus maximus muscle - the huge power generating muscle of the entire lower kinetic chain. When the range of motion is limited in the big toe, we cut the terminal stance and pre-swing phase of gait short. This means we get off of the foot more quickly and we don’t access the range of motion that allows the glute to work. Thus, we use something else - the CALF. The same principle applies with limited hip range of motion. If we can’t get our femurs to extend beyond neutral and into that 10 degrees of extension, the glute cannot properly fire so we again ask the calf to help with power more than we normally would. As luck would have it, when I have a patient come in with plantar fasciitis or Achilles tendonitis, they are usually lacking BOTH hip range of motion and toe range of motion - double whammy.
Can it be fixed?! YES! My approach to treating plantar fasciitis and Achilles tendonitis is to treat locally first. This means treating calf tightness to help with symptom management right away - massage, dry needling, stretching, etc. As the calf responds to treatment, we are able to shift gears to the actual origin of the injury. This usually includes manual therapy to the big toe or the hip to improve any limitations noted. Whilst improving the range of motion is a big component to improving the motor efficiency in your gait cycle, there needs to be accompanying functional exercises to promote muscle activation in the appropriate positions. This is where physical therapy can get really fun and creative using balance equipment, speed adjustments, plyometrics, and sport-specific exercises.
There is this concept we discuss in physical therapy where we describe being strong throughout the available range of motion. What this means is that even if we improve your flexibility and range of motion, you’re still at risk for injury if you don’t know how to CONTROL that new range of motion. But once you learn to do this, your risk of re-injury is significantly less - assuming you keep up with your homework!
This blog was meant to discuss the most common reasons plantar fasciitis and Achilles tendonitis may occur, but is certainly not all-inclusive. Overall, I want to remind all patients that the longer plantar fasciitis or Achilles tendonitis are bothering you, the longer it takes to heal. Don’t wait too long to get it checked out! Key identifying factors are sharp pain felt in the center of the heel, pain felt along the inside of the heel, pain in the arch of the foot, pain in your Achilles tendon, and pain with your first steps out of bed in the morning. If you feel like you have any of these nagging pains, let us know and we can get you started on your road to recovery!
Lisa Corken, PT, DPT
Bob Cranny, PT