Like any other type of pain, a sharp or aching pain in the ball of the foot can be distracting when you run. Although there are many conditions that can cause pain in the ball of the foot, there are only a few that are common among runners. Stress fractures are frequent, and may be worrisome, but differ from some other conditions. Unlike stress fractures that often seem to be related to more diffuse pain, several other conditions are easier to localize.
For example, if you have a bunion, you will know exactly where the pain is (at the big toe joint). If you push on that area when it is inflamed, it will hurt. Similarly, you can have very specific pain at the second toe joint. If you have a sharp pain on the bottom of the second toe joint, you may be suffering from a common condition called predislocation syndrome. As the name suggests, the condition is a syndrome that occurs before the toe begins to dislocate. In order for a toe to dislocate, the joint supporting structures must fail.
The bones in the toes (phalanges) connect to the bones in the foot (metatarsals) at joints appropriately called the metatarsophalangeal joints. The bones are held together and also allowed to move by a number of soft tissues attachments including the joint capsule (which holds the fluid in the joint to provide lubrication) and ligaments (that keep the joint stable). The toes mostly move up and don’t usually move very far down. As a result, the structures on the bottom of the metatarsophalangeal joints are more prone to stress, strain, and injury.
The most significant structure on the bottom these joints, is a thick reinforcing area called the plantar plate. Whenever you move or force the toes upward (such as when you stand up on your toes) the plantar plate resists this movement. Stress fractures result from increasing the duration of impact faster than the bones can develop the strength to withstand the impact. In a similar way, the soft tissues that support the bones can also become injured.
For example, if a runner is concerned about the impact of running and starts cross training excessively, injury can result. Elliptical trainers are a common culprits. The best feature of an elliptical trainer is that it is very low impact. The worse part is that with every swing of the trainer, the athlete’s foot is dealt an unnatural position that puts a great deal of pressure on the ball of the foot as the foot swings backward. With all of the repeated forcing of the foot up on the toes, the plantar plate on the bottom of the foot can become stressed to the point it develops very small tears. If not rested and allowed to heal these can get worse.
When most runners come to see me with this problem, they will describe pain in the ball of the foot that is significantly worse when on an elliptical trainer or walking barefoot of hard surfaces such as tile. It may ache after a run but usually does not hurt much during a run on flat ground. They will also usually describe a “fullness” in the ball of the foot, which they may or may not recognize as swelling. There is almost never any particular recall of how the problem began.
Sometimes, if the condition has been getting worse for a while, it appears that the second toe is sitting just a bit higher than the third toe. This indicates a weakness in the plantar plate and joint supporting structures on the bottom of the foot. If the inflammation is allowed to continue, these structures will become weaker. With the continued application of force (repeatedly forcing the toes up through the backswing of the elliptical trainer) the plantar plate may tear completely. Then, the toe dislocates.
Fortunately, I have only seen this one time. The patient came in with his second toe pointing at the ceiling and sitting on top of the metatarsal. He was in excruciating pain and required immediate surgery to reposition the toe and repair the torn structures.
All of this is, of course, preventable. Just remember that cross training is good, but it is possible to over do it. Elliptical trainers are great and highly recommended, but resist the temptation to set it at a steep angle. Although setting the machine on a steep angle can make the workout tougher, and hence shorter, it places enormous stress on the plantar plate. Do the same with your treadmill…keep it relatively flat to decrease strain on the ball of the foot.
If you do start to notice a sharp or aching pain in the ball of the foot, get it checked out ASAP. If you seek treatment early you will likely only need ice the area, take some anti-inflammatories, and tape the toe to stabilize it. You will almost certainly still be able to train and participate in your goal race. If you ignore what your body is trying to tell you, then you might end up working as a volunteer, handing out refreshments on the course.
Stay Fit. Go Long. Run Fast. Be Strong.