I was jogging along a trail in the woods and as I rounded the corner, a dog with his owner, distracted on his cell phone, lunged at me. I sort of hopped to my right to get out of the way but I didn't see the tree root bulging out of the ground. My foot hit the root at an odd angle and in a flash, I turned my ankle.
The dog was barking and jumping. The owner yanked the leash, kept talking on his cell phone and walked on.
I walked and limped along for about one hundred yards. Gradually, the pain subsided. I was lucky. No significant damage. Had it been my left ankle, I might have had to hop home on my right leg.
Scientists have recently discovered that people who have had prior ankle injuries seem to have a slower muscle response time to an inversion injury like the one I had on the jogging trail. In fact, it's about twice as slow. When you turn your ankle, the reaction time is in milliseconds; a lot faster than you can think. Your body responds to the sudden perturbation without you having to think about it but if you've had a prior injury your body seems to be on a coffee break. The typical response time by people without a prior ankle injury is 55 milliseconds. Those with an injury, 90 milliseconds (and for reference, an eye blink takes about 300 milliseconds).
A common approach to rebuilding a sprained ankle is to use strength training exercises using elastic bands for resistance on the foot and ankle in an open kinetic chain. The thinking is that the lateral muscles (peroneus longus) are weak and that by strengthening them, you'll recover function more quickly and reduce the risk of re-injury. But, the science behind this idea suggests that strength of the muscles isn't the main problem*. It's the reaction time.
Many clinicians understand this and use training techniques on an unstable surface such as an inflatable disc, foam roller, wobble board, etc. to address reaction time deficits. And, although unstable surface training may not be helpful for some other problems (such as squatting on foam pads to increase core strength), for chronic ankle sprains, it helps.
But, there are two other problems that follow an ankle sprain that sometimes are overlooked: weak hip abductors and loss of plantarflexion flexibility**.
Many of the clients we see at Sports Center with the diagnosis of an ankle sprain are well past the acute stage. They no longer battle swelling or an obvious loss of motion and most can function in day to day life reasonably well. The problems they face involve more dynamic tasks such as jogging, running, cutting, and hopping. So, they no longer have an ankle sprain. They have functional limitations of the lower extremity and sometimes the trunk. Many of them will have associated hip weakness and ankle inflexibility.
To solve this, we first collect certain information. In addition to standard orthopedic tests, we also often complete the following tests and procedures to help us better understand the person's functional capability and to direct our programming:
- Single leg stance. This should be at least 30 seconds.
- Single leg squat load tolerance. Expected values are 20% over body weight for 30 repetitions.
- Hip abduction strength measured with a digital muscle tester in an open kinetic chain.
- Hip rotation strength measured with a digital muscle tester in a closed kinetic chain.
- Plantarflexion flexibility. Active and passive. 50 degrees is expected.
- Hip rotation flexibility. 45 degrees is expected (external rotation).
- Running load tolerance. This is tested with the Newton Speed Trainer. Full body weight is the goal.
- Proprioception. Match the opposite side.
- Core endurance. We use the plank drill. Three minutes is the goal.
- Sweeper excursion. A "Sweeper" is a reverse lunge while sweeping the leg around behind the weight bearing limb. Full body weight with a squat of at least 70 degrees of knee flexion and equal excursion is the goal.
- Single leg hop for distance. 85% of the uninvolved side is the goal.
Once we have the data, we design the training program. The training programs are focused more on coordination, balance, reaction time than on strength although there are a few strength drills in the program. Some of the drills we use:
- Single Leg Stance. Play catch. This creates unexpected perturbations but can be kept within a "balance envelope" by how far away from the center of gravity you toss the ball and how heavy the ball is. If the Single Leg Stance Test is less than 30 seconds, we would add a light vector of force connected to a waist strap directed laterally (to the involved limb). This provides some assistance during the stance. If you apply a vector that runs toward the opposite hip, you make the drill considerably more difficult.
- Single Leg Squat. This is a strength drill so the repetition count is less than 15 reps per set. The load level is determined by the test. We start with a stable base and progress to less stable. And, there are variations off this that include adding vectors from a variety of angles to increase load and perturbation.
- Single Leg Squat and Reach. This is a squat with cones placed in a semi-circle. The client squats and touches a cone. We'll use anti-gravity equipment if needed.
- Sweeper. This is the same movement as in the test. We'll use anti-gravity equipment if needed so the client can perform the drill, control the motion and not hurt. As with the Single Leg Squat, progression moves toward an unstable base.
- Hip Burner. This is a classic hip abduction drill done in sidelying. The client lifts the involved limb up into abduction and then lowers only to the point of the leg being parallel to the floor. The drill is to repeat this small range of motion until the hip muscles "burn" - hence the name "hip burner".
- Perturbation. This is a variation of the Single Leg Stance. The client stands on the involved limb and holds a staff in both hands in front of his or her chest. The clinician gently and sporadically pushes the client from different directions. The client keeps track of how many "faults" he or she has in a defined period (a "fault is losing your balance).
- Sidelying Squats with a Training Shoe. I picked up this shoe from a equipment rep in California about 20 years ago. It is really a metal sandal that straps to the bottom of your shoe. On the bottom of the sandal is a metal hemisphere. This creates an unstable base - similar to a wobble board. Protruding from the toe area of the sandal is a small metal rod. You then add a small cylindrical weight to the rod. You perform the squats on a Total Gym lying on your side (involved side up). Place your foot on the platform of the Total Gym. Because the weight is attached to the metal rod, the sandal creates torque through the leg into the hip loading the external rotators. So, with this drill, you load the evertors of the foot and the external rotators of the leg.
- Superman with a Twist. This is a Yoga drill often referred to as Warrior III. We use a special portable pulley system known as an OnX to create a counter balance from behind to help the client balance on the involved leg. Then, the client turns his or her body right and left. As this the body turns, the foot inverts and everts and has to learn to stabilize itself.
Then, as their metrics improve (re-testing the above tests), we often add:
- Hopping. Four square, forward back, star drill. Anti-gravity if needed.
- Slide board. Start with a short distance and easy off the blocks. Progress to longer distances with explosive moves.
- Treadmill Drills (would prefer to have an indoor running surface but space always is an issue). This includes sideways, backward, skipping backward.
- Agility drills. Cone drills, three-line side to side drills.
Sometimes a client will need manual therapy; usually muscles in the hip or foot are too tight. But, if a client needs manual therapy after a session on in between sessions, then the session is probably too demanding.
There are a lot of drill choices. It comes down to matching the degree of difficulty of the drill with the capability of the client and making sure you "edge" both the drill choice and the client. Edging is critical. A client's ability can improve quickly. The drills need to keep up with the pace of improvement.
And, I'll offer one other drill I really like: Walk the Plank. Place an eight foot 2 x 4 on the ground. The client's challenge is to walk foot over foot down the 2 x 4. This may not seem hard but with after having had an ankle sprain, it's tough. You can frob the drill (and the first person who sends me the definition of the word "frob" gets a free copy of my book - make sure you send your contact info) with distractions, play catch, carry objects, squat up and down. Let your imagine go on this one.
We like our clients to reach certain functional goals (most of which are listed above in the section of tests and procedures) prior to discharge since many of them are not symptomatic in day to day life. Sometimes this can happen in 4 to 8 weeks and sometimes it's 6 to 8 months or longer. It depends on a number of factors such as the chronicity of the problem, are there other problems, how fit is the person, what's the objective long term (pro sports or run around the block), how adherent will the person be (that's code for following directions).
There are a lot of options when it comes to designing programs for people following an ankle sprain. My advice is to organize the drills around balance, reaction and timing and not worry about open chain ankle strength drills so much. I think you'll find that clients enjoy the sessions more, show up more often, and when you have those things going for you, the outcome is usually better.
DK
*Munn, J., D. J. Beard, et al. (2003). "Eccentric muscle strength in functional ankle instability." Med Sci Sports Exerc 35(2): 245-50.
** Friel, K., N. McLean, et al. (2006). "Ipsilateral hip abductor weakness after inversion ankle sprain." J Athl Train 41(1): 74-8.
