CALF LENGTH FOOT PUMP SOCKS FOR RUNNERS:
Many runners find calf-length compressive socks useful for several calf issues, including recurrent calf strains and Achilles tendinitis (tendinopathy). They can also prove to be extremely beneficial in preventing and helping to resolve the most common cause of shin pain, known as medial tibial stress syndrome or MTSS.
MTSS is one of the most common problems suffered by endurance/ distance runners. It presents as a diffuse discomfort running along the inner side of the shin close to and upon the medial-anterior edge of the tibia bone. It affects an area over 5cm in length. Pain is usually initially noted as occurring after sport, but it slowly becomes present towards the end of a run, as well as afterwards. If left unresolved, it can become very problematic preventing further participation in any significant running.
What is MTSS?
Pathologically, MTSS causes the tibia bone’s tissue and surrounding bone membrane to become damaged over a relatively large area of its inner side. In time, the tibia becomes increasingly troubled with bone fluid inside the bone that builds up with further damage, until the marrow at the very centre of the bone becomes full of fluid under pressure. This prevents normal free fluid flow through the bone tissues that keep them healthy.
What causes MTSS?
Presently, the cause of MTSS remains debated. Some clinicians claim it results from internal bone strains becoming too high during running. However, the inner tibia is not a location associated with high bone stresses compared to other areas. It appears more likely that MTSS may develop as a result of one of the human’s distinct shock-absorbing mechanisms.
When the leg impacts the ground, it creates a shockwave across the soft tissues. Running creates far greater impact forces and soft tissue shockwaves than walking. In long-distance running, these high-impact events are repeated over and over again. The soft tissues’ motion from shockwaves tensions and stretches the surrounding tough membrane called the deep fascia, which holds soft tissues in place. Because these membranes are made of stiff, yet slightly elastic tissues that can recoil to compress the tissues back into place after impact, the soft tissue motion process helps absorb impact energies. This means the soft tissue shockwaves are able to act as extra shock absorbers.
Most of this soft tissue displacement is horizontal rather than vertical. Some soft tissues can move over 4cm. The larger the amount of soft tissue within an area of the leg, the greater the soft tissue shock absorption possible. Therefore, the buttocks and thigh areas vibrate the most at impact. This motion creates a fair old tug on the surrounding fascia that binds muscles down onto the bone. The deep fascia forms a continuous structure that surrounds individual muscles and bundles of muscles to bind the soft tissues together like a tight Lycra suit, but one that binds through the muscles to the membrane that covers bone.
A problem with fatigue during running
Apart from the deep fascia restraining the soft tissue motion passively, muscles contracting in the leg at the time of impact also help to limit how far the soft tissues move, controlling the tensions put into the deep fascia. When legs are tired (fatigued), the muscular control can reduce and then soft tissue displacement is greater.
The knee as a shock absorber
The knee is the primary shock absorber of the lower limb. Its ability to flex in a controlled manner reduces impact forces travelling toward the rest of the body and head. In running, the knee must work much harder than during walking because impact forces are so much higher. As a result, muscles that control knee flexion motion and extension power (mainly the quadriceps muscles) can easily become fatigued, especially if a runner increases pace and/or distance too quickly.
Humans are unusual animals by having a lot of muscle mass low down on their legs (the calf muscles in particular). Calf soft tissues lie below the knee, meaning there is a lot of soft tissue that can displace close to the point of impact on the foot. This means that soft tissue shock waves can help absorb impact energies to protect the knee. However, it also means they are not as well protected by the knee as those above the knee, even when knee muscles are strong and unfatigued. If calf muscles fatigue, soft tissues in the calf will start to move greater distances under the power of impact shockwaves.
To prevent an issue with soft tissue shockwaves in the calf, the local deep fascia is particularly complex. The deep fascia that holds the big fleshy triceps surae muscles located under the skin moves the most during a shockwave. Therefore, their deep fascia is relatively flexible and elastic. However, the muscles deep beneath the triceps surae are bound down by much stiffer fascia. This prevents these important foot-supporting deep muscles from bouncing around with the large fleshy muscle above them. This allows the big fleshy muscles to provide most of the shock absorption, without pulling the deeper muscles away from the back of the tibia bone.
These mechanically different areas of deep fascia have an important junction to the bone membrane along the inner edge of the tibia. This union is required to hold the muscle mass to the bone next to an area of bone not covered by muscle, which is commonly known as the ‘shin bone’. Yes, the bit that hurts so much when you knock it and why footballers use a shin guard. This has a very stiff area of deep fascia closely attached to the bone’s membrane. You will note that your skin cannot move much in this area.
Where materials with different mechanical properties join, there is always a weak point. This is true where soft tissues and bones join, as they present a union between tissues that can stretch and recoil easily and those that cannot. If soft tissues pull away from the bone with too much stress and strain and over too many repetitions, damage to the bone tissues and their membranes will happen. What compounds the problem along the inner side of the shin is that one of the fascial layers is flexible and the other stiff, so more mechanical differences occur across this junction.
As long as strong muscle contractions in the lower leg control to reduce the soft tissue displacements and keep tension stresses at the fascial-bone interface within tolerance, the fascia, bone and its membrane should be safe. However, when muscles fatigue during repetitive high impacts, the soft tissues can start to increase their displacement, and then the trouble can start with too much soft tissue shockwave pulling too hard on the bone beneath.
Compressive solution
HealthyStep’s knee-length Foot Pump compression socks offer part of the solution. By restraining the amounts of horizontal soft tissue displacement from the impact shockwave on the lower leg, tensions on the fascia being passed to the soft tissue-bone interface are reduced. Even if the leg muscles become fatigued.
Insole assistance
The X-line Run can be used with the calf-length foot pump socks to resolve and prevent MTSS. If you have MTSS, always apply the rearfoot posts provided with the insoles. This is because MTSS is associated with the speed of the hindfoot and ankle rolling inwards after heel strike. Running requires that the leg swings more under the body than walking, creating a much narrower base of support. This causes the ankle and rearfoot to roll inwards faster to compensate, which can fatigue calf muscles earlier. The posts reduce the speed of this motion, making life easier for the muscles.
Other helpful hints
To avoid MTSS, keep your stride length short as this will make it easier for the knee to shock-absorb and will create an impact force directed more vertically, rather than posteriorly directed into your body. This can reduce the shock wave effect.
Build up your running distance very slowly. No more than 10% in any week. Avoid trying to increase pace and distance at the same time. Do one or the other only, and do expect your pace to initially drop as you increase your distance. A slower pace is your body trying to avoid fatigue. Do not try to override this adaptation. You can concentrate on pace once you are happy that you can easily complete a certain distance.
Be aware, there are other causes of shin pain
Not all shin splints are a result of MTSS. Anterior shin ache can be caused by tibialis anterior strain. This is commonly developed after taking up running or having to walk very quickly on a hard surface. Strengthening the tibialis anterior usually resolves this problem easily.
Chronic exercise-induced compartment syndrome is more serious and can develop through poorly managed MTSS. It results because the deep fascia enclosing a muscle group cannot expand when muscles are being exercised, causing compartment pressures to rise and effectively preventing blood from entering the muscles sufficiently. Most frequently, it occurs in the anterior muscle compartment, which has a less flexible deep fascia enclosing tibialis anterior and the long digital extensors. The other compartment more frequently affected is the deep posterior muscle compartment containing tibialis posterior and the long digital flexors. Pain develops in the whole compartment after a period of sport and goes away rapidly when the sport stops. Do not use compression socks in this condition.
Tibial fatigue (stress) fractures produce pain during exercise, which rapidly stops soon after sport ends. The pain’s location is very point specific to the fracture site, usually on the anterior or deep posterior tibial surface. Asking a patient to jump/hop on the single affected leg often provokes the pain (try and only do this test with just one jump to prevent damaging the fracture further). Do not exercise until the issue is resolved, then try and establish why it happened to prevent it from happening again. You likely require some clinical guidance for this