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Foot/Ankle Joint and the Vertical Jump


This article will examine the effects of the foot/ankle joint on the vertical jump and what things we can do for our athletes (or ourselves) to improve this often overlooked link in the kinetic chain.

The most commonly overlooked area of the body and that of training is the feet. While general sport is taxing on the foot/ankle joint, not many coaches glance down and examine the feet of their athletes. Most examinations of the foot are left for podiatrists once a problem exists (i.e., plantar fasciitis, ankle sprain, shin splints, etc). The vertical jump is a complex multi-joint movement that requires muscle coordination best improved by specific skill development. Vertical jump performance is determined by a complex interaction among numerous factors, including the maximal force that the involved muscle can develop, how fast that can produce force and the neural coordination of the movement.

A portion of the power developed during a vertical jump is derived from the stretch-shortening cycle that enhances muscular force by evoking the stretch-reflex and utilizes elastic energy stored in the stretched tissues. Therefore, ankle mobility is very important during an initial jump stance. All movement is based on the level of efficiency of joint recruitment, so feet become a crucial player. The fewer number of joints that are utilized during movement, the lower the quality of that specific movement (i.e., jump).

Why the Ankle?

During the vertical jump, the muscles of the hip, knees and ankles act rapidly and with great force in an attempt to produce the greatest possible velocity of the body as it leaves the ground. Ultimately, the jump height is determined by the velocity. Eighty percent of the force is produced by the muscles around the hips. Therefore, if the ankle is restricted, there will be some loss of force. The force will then be applied at the knee and will generate solely from the hips, resulting in a poor jump. Conversely, if the ankle joint has excessive mobility, there is no rigid lever to produce force during a vertical jump.

So it makes sense to address the point of the kinetic chain that is closest to the object of force production (ground) when observing ways to improve vertical jump. In this case, we will look at the ankle and the fascia of the foot to determine what methods are helpful to increase mobility of in the ankle and provide enough force production to increase jump heights.

The height of a jump is initiated by a crouch or squat performed slowly (static) or rapidly (ballistic). During the initial squat, the feet are in total contact with the ground as the hips extend closer to the ground. In persons with poor ankle mobility and lower body tightness, this initial set-up is faltered and will result in a weak jump. In the past, coaches have looked at the height of the jump, meaning they always looked up. No one ever looked down. It is obvious that the ability to generate force is a major contributor to vertical jumping, and the feet are the first place to start observing.

Too Much Ankle Mobility (Hypermobile)

Many young athletes with undeveloped lower body muscles will demonstrate excessive ankle mobility, which leaves them prone to inversion sprains. Ankle sprains are a common cause of lost playing time and disability among athletes.

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 muscletendonius 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 plantar flexion 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. One quick observational assessment is the conventional calf raise stance. 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 First Metatarsal (L foot) Figure 2. Stable First Metatarsal (L Foot)

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 often 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.

How can the unstable first metatarsal effect jumping? An observation of the supinated foot shows that only the lateral half of the bottom surface contacts the floor. This leaves the other half of the bottom surface to lose rigidity, which can help produce a lever for the stretch-reflex.

In a study published by the Journal of Athletic Training in 2005, 16 individuals with either pronated, supinated or neutral feet were tested for static stability and dynamic stability. The results showed that stability was greater in pronators than in supinators but not in neutral types, suggesting that postural stability is affected by foot type under both static and dynamic conditions. These differences appear to be related to structural differences and not necessarily differences in peripheral input.

The unstable first metatarsal greatly influences supination of the foot and the initial crouch or squat position in a vertical jump greatly exaggerates this.

Figure 3

Figure 3 shows Supinated Crouch Stance. This is an often unseen abnormality in athletic testing (especially in vertical jump) because of footwear. The old adage, “Out of sight, out of mind” comes into effect.

One exercise that can be incorporated in those young athletes with unstable metatarsals is a simple static calf raise while maintaining firm pressure on the first metatarsal. This demands stabilization from the PL and can be held for time. Initially, this exercise can be performed bilaterally and progressed to being unilateral as stability improves. Hand support may be used to maintain proper positioning over the first metatarsal heads because insufficient stability will lead to a lateral displacement of bodyweight (see Figure 4).

Figure 4

Figure 4 shows how an excessive unstable first metatarsal can cause a lateral shift in bodyweight during propulsion (walking, jump, etc). Note that these observations are easily recognized when shoes are removed. A majority of young athletes exhibit this ankle dysfunction, however disguised under footwear, ankle wraps and socks.

An advancement to the static calf raise is placing a resistance band around the mid-foot and anchor laterally, away from the body (see Figure 5). The tension produced by the band induces a supination/inversion force at the ankle, attempting to shift away from the first metatarsal head and towards the lateral heads, which oppose the function of the PL.

Figure 5

Figure 5 illustrates the use of the resistance band to influence the function of the PL in stabilizing the first metatarsal.

Not Enough Ankle Mobility (Hypomobile)

The foot is the most distal segment in the lower extremity chain and represents a relatively small base of support on which the body maintains balance (particularly in single leg stance). Although it seems reasonable that even minor biomechanical alterations in the support surface may influence postural control strategies, the implications of a hypermobile or hypomobile foot on balance have received little attention to date. The issue of ankle mobility has been brought to light about two years ago by some prominent strength coaches and physical therapists and continues to fascinate more individuals today.

With a lack of mobility at the ankle joint, jumpers may suffer from a loss of force production in propulsion, and most coaches simply blame leg strength. Consequently, they instruct the young athlete to perform more leg presses, jump squats and lunges. When the athlete returns to test his/her vertical jump again and fails to increase height, the coach blames hypertonic muscles. So then the young athlete is forced to incorporate static stretching of the hamstrings, trunk and lower leg. This cycle of neglected observation of the ankle not only becomes frustrating for the athlete and coach but also becomes time consuming when preparing for a competitive season.

Supplemental movement preparation drills that can be incorporated in vertical jump assessment are foot rolls. Foot rolls allow for movement in all planes of motion and can quickly provide insight into the amount of influence they have on an individual. Foot rolls may cause extreme discomfort, which is a tell-tale sign that the ankle lacks mobility.

Figure 6

With foot rolls (see Figure 6), the individual should watch for increased tension throughout the body and work slowly to increase mobility.

Soft Tissue Work

The intrinsic muscles of the foot work synergistically to provide stability during tri-plane loading. By nature of the loads placed on the foot, the joints undergo transition from a loosely packed unit to absorb forces to a tightly packed lever during the propulsion phase. This repetitive mechanism stress causes soft tissues of the foot to influence the rest of the body and the body’s motion. There is an influence from the top down to the bottom up. In order to improve tissue quality of the foot, we incorporate self myofascial release (SMR) techniques using an ordinary tennis ball (Figure 7). The following illustrations depict areas of the foot bottom that can use SMR with the tennis ball. The ball is simply run on each part for approximately 20 to 40 seconds.

Figure 7 Figure 8 Figure 9

As we have examined the foot, now we must move our sights up to the lower leg. The tissue treatment of the anterior muscles is often overshadowed by the larger posterior muscles: gastrocnemius and soleus. However, more attention must be given to the superficial muscles of the front leg. A great tool that is often utilized in the athletic world is the Massage Stick. The Massage Stick is great because it is easily transported in a gym bag and can be used in movement prep work before any lower body exercise. The user gently rolls the stick on areas that present tension and poor tissue quality.

Figure 10 Figure 11

Putting It All Together

It is strongly suggested that the following exercises be incorporated in daily workouts and drills in order to enhance mobility and improve vertical jump. Some observatory assessments can be incorporated as exercises in the beginning of lower body workouts. For instance, the static calf raises (see Figure 2) can be included in a workout which would be held for time. It is important to emphasize first metatarsal stability with the calf raise. If stability is lost, the exercise is useless and may prohibit jump improvement. Using the band (see Figure 5) is a progression and should only be used when first metatarsal stability can be achieved without the assistance of hands and can be performed unilaterally.

Tissue work including foot rolls, tennis ball SMR and use of the Massage Stick can be completed prior to workouts or after or during “off” times. “Off” times being daily on upper body workout days or rest days. A proposed program design for improvement in the foot/ankle complex is as follows:

Figure 12 Figure 13

The purpose of this piece is to stress the important of the foot/ankle complex in the vertical jump. Many athletes and coaches overlook this adaptive lever system, which nearly effects all movement and musculoskeletal functions with the human body and every upright action of daily living and sport. By incorporating the exercises and drills, athletes will not only gain considerable improvement in the foot/ankle complex but observatory skills to help their peers.

References:

  1. Anderson, J. Steven, Acute Ankle Sprain. The Physician and Sportsmedicine, 2002
  2. www.physsportsmed.com/issues/2002/12_02/anderson.htm
  3. Bellew, W., James and Dunn, Sharon, Ankle Rehabilitation: A Reintroduction of the Peroneus Longus, August 2002, National Strength & Conditioning Association, Volume 24, Number 4, page 61-63
  4. Cote, P., Karen, Brunet, E., Michael, and Gansneder, M., Bruce, Effects of Pronated and Supinated Foot Postures on Static & Dynamic Postural Stability. Journal of Athletic Training, 2005 www.pubmedcentral.nih.gov/
  5. Henkin, Josh, Mobility Drills For a Better Vertical Jump, 2006. www.bodybuilding.com/fun/henkin35.htm
  6. Kraemer, J. William and Newton, U., Robert, Training For Improved Vertical Jump. Gatorade Sports Science Institute, 1994 www.gssiweb.com