How to Prevent Ankle Sprains – Risk Factors (Part 3)

There have been numerous studies about how ankle sprains are caused and what factors increase your risk for ankle sprains. In this article I will go over some of the more and less common risk factors for incurring an ankle sprain. While ankle sprains can occur in anybody who walks or runs, they occur most frequently in athletes. There are several proposed risk factors for ankle sprains in athletes. While it can be difficult for researchers to design good studies of risk factors there are a few that are generally accepted for ankle sprains.

History of Ankle Sprain. The strongest predictor of ankle sprains is a previous history of ankle sprains. This conclusion is shared by nearly every study conducted on the subject [1], [2], [3], [4]. The people with the highest risk after they have previously sprained their ankle are those who did not proper rehabilitate the injury. An unrehabilitated ankle can be unstable afterward and is open to being sprained over and over again. The reason for this, some researchers think, is that when an ankle injury occurs some of the nerves that tell your body what position your ankle is in are damaged. These nerves are called proprioceptors and the ability to determine the position of your body parts is called proprioception. When these nerves are injured it can be more difficult for your body to know how to position your foot to keep it safe.

Balance. Lack of balance (also referred to as Postural Sway), may indicate a lack of proprioception due to ankle stability. A study of ankle sprain risk factors identified athletes with poor balance as those who could not maintain a single-leg stance for at least 15 seconds without touching down the unplanted foot to remain steady [5]. These people had an increased occurrence of ankle sprain injuries. Another researcher studied high school basketball players using a specially designed machine to identify those with poor balance [6]. Players with low pre-season testing scores experienced nearly 7 times more ankle sprains than those with normal balance.

Height and Weight. There is not much agreement as to whether height and weight are significant factors for ankle sprains. Studies of soldiers in basic training exercises indicated that being taller and heavier were risk factors. Another research study, however, experienced different results and determined that height, by itself, was not a risk factor [7]. This was based on a study of 1,601 West Point cadets who participated in basketball with no history of ankle sprain or instability. There were no findings to indicate height and weight as something that would increase or decrease the risk of an ankle sprain. Until more research is done it is unclear whether taller or heavier people have a greater risk for spraining an ankle.

Foot Shape / Joint Laxity. You might expect a lax ankle joint to be at a greater risk for ankle sprains. However, evidence indicates that this is not the case. One research study evaluated ankle joint laxity using orthopedic testing [8]. Based on these results it was not possible to predict an increased likelihood for ankle sprains based on the mobility of the joint. Other factors like the shape of the foot or whether it over-pronated during running or walking, did not indicate a higher risk for sprains. However, over- and under-pronation may indicate some degree of foot instability.

Gender. Males and females tend to experience the same frequency of ankle sprains. When all other risk factors are taken out of the equation, neither gender is at a greater risk for an ankle sprain.

Muscle Strength and Reaction Time. Muscle strength and reaction time are not risk factors for ankle sprains. The muscles in your legs control the position of your foot. Researchers have studied the velocity and forces necessary to sprain an ankle [9], [10]. In order to rupture a ligament in the ankle complex the speed required is greater than the speed with which your muscles react to the stimulus that your ankle is about to go too far in one direction or another. In addition it takes even longer for your muscles to reach full contraction. By the time this happens your ligaments could be long gone. What reaction time and muscle strength do affect is the positioning of your foot before it hits the ground. This positioning can be very influential when it comes to increasing you risk of ankle sprain [11].

Shoe Type. Shoes may increase or decrease your risk for ankle sprains. Some researchers theorize that certain types, such as high-top basketball shoes, may increase proprioceptive feedback from the ankle joint [12]. There is also some evidence that shoes offer some resistance to the excessive range of motion in the ankle [13]. One study was done of over 10,000 recreational / elite basketball players to determine some ankle sprain risk factors. In a questionnaire distributed to players who had suffered an ankle sprain they asked several questions about shoes including: cut (high, mid, low-top), cost, brand / model, and condition (good, fair, poor). When they noticed a high frequency of players wearing more expensive shoes also suffered ankle injuries they looked at other commonalities in the high priced shoes. The most common feature of these shoes was the presence of air cushions in the heel portion of the shoe. From this research they conclude that these air cushions increase the likelihood of an ankle sprain. The same may be true for shoes with energy return systems like Nike Shox. There are four key features of a shoe that will help limit ankle injury. These are lateral (side-to-side) stability, torsional (twisting) flexibility, cushioning, and traction control. The most significant of these features is traction control [14]. Among soccer and football players, cleat length and design has been linked to an increase in ankle injuries [15]. The increased traction increases foot fixation. This foot fixation increases the vulnerability of all of the lower joints of the leg, in particular, the ankle.

Surface conditions. The quality and condition of the playing surface is a risk factor for ankle sprains. Any surface that has friction which is not optimal (too high or too low) increases an athlete's risk for injury. For instance artificial turf increases friction, while water on a court surface may drastically decrease it. High friction will hold the contact foot stationary while the momentum of the rest of the body will create great stress on the joints and ligaments of the ankle. Low friction will cause the contact foot to slip from under the body causing excessive motion at the ankle joint, thereby stressing the ligaments. With these risk factors in mind it is possible to greatly reduce your likelihood of suffering and ankle sprain. Some risk factors can not be avoided. To help protect yourself in these situations there are some proven methods for decreasing your risk of ankle sprain. Now with this information in mind we are ready to discuss the top three methods for preventing ankle sprains: taping, braces, and exercises.

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