Wednesday, June 15, 2011

How Ankle Mobility Still Needs Stability for Power Production

With the rise of information coming out regarding ankle mobility, I began to wonder how can I help my clients prevent ankle sprains from reoccurring, while at the same time increase their ankle mobility? Years ago, I researched how the ankle joint--more specifically--the metatarsal head of the foot--can effect vertical jump power. I was amazed at what I dug up. I began to look at my client's lower legs and what faulty joint kinematics I could find. I began noticing the same things:

a.) People that sat all day had poor ankle mobility.

b.) De-condition and excessive weight gain caused a displacement of weight on the ankle that may place them at a high risk of future ankle sprains.

c.) Strength was a crucial factor in balance training--and not the gimmicky toys you see many people using for balance training.

In the initial squat position of the jump, most athletes show an ankle(s) in a position of low bony stability (plantar flexion, inversion); the ligaments have a more significant role in providing joint stability and are more likely to be injured or produce weak propulsion (as in a jump). The first corrective step in preventing excessive mobility is to look at the peroneus longus (PL) muscle. The PL is arises from the upper 2/3 of the lateral surface of the fibula and inserts on the base of the first metatarsal (big toe). The PL and the role of other muscle-tendonius tissue create a “pulley effect” which enables the PL to act as a stabilizer for the first metatarsal during push-off by exerting a plantar-flexion force. This assists in propulsion by creating a rigid lever for push-off.

During the vertical jump, electromyographic data confirm the role of the PL in stability and propulsion, as most of the PL activity is during the latter half of the initial stance phase. If the feet are excessively inverted or everted, the PL becomes inefficient in creating a plantarflexion movement and rigidity will not be formed during push-off. So the first step in improving vertical jump is assessing PL stability of the first metatarsal joint and observing propulsion stance.

On of the assessments I began using--and I actually disguised it as a conventional calf raise. With insufficient stabilization from the PL, the first metatarsal head will lose contact with the ground, the foot will supinate and the weight will shift to less the stable fourth and fifth metatarsal heads.
Figure 1: Unstable Metatarsals
Figure 1 shows what most therapists and coaches dismiss as a “conventional” supinated foot. The test is primarily a calf raise exercise initially performed bilaterally and progresses to being unilateral as stability improves. Most young athletes exhibit supinated feet due to improper footwear which provide insufficient support. Also, most young athletes develop poor gait patterns early on without proper intervention, which leaves the problem to manifest and eventually affect sport or physical activity.

Figure 2: Stable Metatarsals
Fixing the Problem

The easiest way I could think of to fix the problem in those that demonstrated excessive lateral shift at the ankle joint when standing on their toes, was isometric exercise. I came up with adding in a simple exercise that is challenging, yet helpful enough to address the peroneus longus muscle of the lower leg. As part of a active recovery or simply added to the end of a workout, I had clients performing Hindu Squats. I typically recommend simply standing against a wall and isometrically holding the metatarsal in a flexed position (as a calf raise without letting a lateral shift occur) for overweight clients before moving into a squatting position. However, for those that have the technique and coordination, we can get right into a Hindu Squat.

1.) Isometrically - Typically chosen for deconditioned and overweight people. Holds can range from 5 seconds to 30 second , to even 1 minute. Holds will depend largely on condition level and squat depth. Obviously, the deeper the depth, the more advanced the exercise becomes. To reiterate, maintaining body mass centered over the metatarsals is paramount.

2.) Repetitions - Once the isometric holds can be maintained optimally, move into reps of Hindu squats. Again, I like thee at the end of a workout or in between sets--simply using bodyweight to begin and later adding dumbbells. Reps can range from 10-20 for 2-3 sets.

Lastly, one aspect that is important for the fitness trainer is to identifying the deviation clearly. I recommend having your clients remove their shoes and socks for the initial assessment and when performing the exercises I outlined. It is important to "un-do" this poor neural pattern and strengthening the PL muscle. Simply holding a Hindu squat while the ankles are deviated (body mass centered over lateral aspect, rather than over each metatarsal) is irresponsible and a waste of time.

As a result of correcting and strengthening the ankle and lower leg, your clients should see a improvement in balance and power output. Over the years, I have had clients tell me their lateral speed in games like squash and tennis had improved and unilateral balance was substantially greater. 

1 comment:

  1. John

    Is there a fix for flat feet?

    I have come across clients quite a bit with knee issues. A common thread seems to be what therapists call 'flat feet'.

    They are typically advised to get insoles, and while this often 'fixes' the knee pain, I feel like it's a sticking plaster approach.

    I'd be interested to know if anyone has had success with this kind of problem and what approach was taken.


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