Benefits of a Firm Insert

Benefits of a Firm Insert

Written by Stacy Ciarleglio, a licensed athletic trainer and ultra runner.

What’s better, a soft insert or a firm insert? One of the most common misconceptions that I hear is that softer inserts are better because they provide more cushion. Recently, I have had quite a few people compare the inserts that we carry, Superfeet, to other over the counter inserts that they came in with. After standing on the Superfeet, which is a firm insert, they said, “oh yeah, this one is more comfortable, it’s softer.” They were surprised when I showed them the firm plastic that comprises the insert that they were standing on. Just because the inserts were comfortable, they figured they must be soft. That’s not necessarily true!

Over the counter inserts can be recommended to help stabilize the foot, provide shock absorption, and help customize the fit of a shoe. They are often used in conjunction with other rehabilitation modalities in the treatment of many common conditions from plantar fasciitis, achilles tendonosis, shin splints, bunions, neuromas, all the way up to knee and hip pain.

While there are certain conditions that might benefit from a soft insert, there are many advantages to a more firm insert versus a soft. To read about the advantages of a firm insert and to find out how the picture of the person walking on a beach relates to this article, click here.

The Calcaneal Fat Pad & Shock Absorption

On the bottom of our calcaneus (heel bone), there is about a 1” thick pad of fat between our skin and our bone. The purpose of the fat pad is to help our body absorb shock. The fat pad is divided into sections by baffles. The baffles help keep the fat pad from spreading out so it maintains its shock absorbing capabilities. Over time, or with certain injury, the baffles become stretched out, allowing the fat pad to spread. Spreading of the fat pad decreases its ability to absorb shock, which can lead to a bruised heel or heel pain.

How does a firm insert help in this case?

An insert with a deep, firm, heel cup will help to rectify this problem by keeping the fat pad together and dense.  A soft insert that doesn’t have a deep heel cup will still allow the fat pad to spread, even though it might feel soft and comfortable at first. A soft insert doesn’t do anything to help the body redeem its own shock absorbing qualities.

Foot Mobility versus Stability

Much of how the foot functions is dependent on the rearfoot (subtalar joint) and midfoot (midtarsal joint). If there are deficiencies throughout the foot, by the time we get to the “toe off” phase of gait, compensation must occur. Compensation, over time, can cause injury. There must be a balance of motion and stability. The foot has to be mobile enough that it can absorb shock and adjust to terrain, but stable enough to act as a rigid lever to propel us forward. Problems can arise when there is excessive motion in the midfoot. The foot becomes unstable and less efficient. When it comes time to push off of the big toe (1^st MTP joint), the foot is in a poor position.

Many common issues that we see when fitting customers can be traced back to poor positioning of the midfoot. One of the most common is the presence of a callus on the big toe. When the foot is out of alignment, it increases the sheer forces at the 1^st MTP joint. The foot will “twist” off of the ground, creating friction on the big toe which eventually results in a callus.

How does a firm insert help in this case?

A firm insert, such as Superfeet, stabilizes the rearfoot by cupping the calcaneus (another benefit of the deep heel cup) and provides support to the navicular bone, which is the keystone of the arch. By supporting the keystone, the rest of the mid foot and forefoot are placed in a better biomechanical position and can function more efficiently. If an insert was soft, it would allow the navicular bone to drop, which would cause the midtarsal joint to become unstable, in turn, putting the 1^st MTP joint in a poor position. 

When first stepping on a Superfeet insert, many people will say that they really don’t feel the support in the arch. They feel it more in the “heel” or “back of the arch.” They assume that is the wrong insert for them because it’s hitting them in the wrong spot. In fact, what they are feeling is the insert providing support to the keystone of the arch! By supporting the keystone, everything else will function better.

Walking on hard sand versus soft sand

Another helpful way to think about why a firm insert might work better for you versus a soft insert is to compare it to walking on the beach. The soft sand looks nice and feels nice to lay on, but try walking on it. It’s not easy! The firm sand is pretty easy to walk on. The soft sand actually makes the muscles of our foot and ankle work harder to stabilize and propel our body forward, while the firm sand provides a stable base of support to walk on. If you have a soft (or a gel) insert your shoe, with every step, you have to work harder to stabilize your foot. It might feel good for a few steps, but with 2,000 steps in a mile, that’s a lot of extra work over time!

Here’s something you can try at home if you have inserts. Stand barefoot on a single leg. Your foot muscles will engage to maintain foot contact with the ground and stability of your leg. Have someone observe how hard your foot is working. Are your toes “clawing” into the ground, is your big toe digging into the ground, is up in the air trying to find ground contact? This is what is going on inside of your shoe every time you take a step. Then, if you have a firm insert, stand on that and try single leg balance again. Your foot should be much more stable, which will allow the muscles of the foot to relax. A relaxed, stable, foot is much better for performance and injury prevention.  

If you always get that nagging callus on your big toe, or have a nagging injury that keeps returning, it might be worth considering the use of a firm insert if you never have before.