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Ground Contact

By Russ Ebbets, D.C., Track Coach Editor

 

    If one had the desire and time to page through the numerous strength and conditioning books on the market one would be hard pressed to find any information pertaining to strengthening the foot.
    Yet ground contact is initiated with the foot, the body briefly balances on the foot during mid-stance and the foot is a significant source of power with toe-off. Yet if asked about strengthening the foot most coaches would answer---"Why?"
    Although the foot is taken for granted it shouldn't be. It is through ground contact that we generate power. But the foot must also dissipate the shock of ground contact. Running produces the stress of 4-7 times body weight. Jim Hay found that ground reaction forces could be as high as 22 times body weight in the triple jump. World class shot putters generate more horse power than any other human activity. It's tough to do any of these with a sore foot.

    Americans are particularly susceptible to a weak foot. The two main culprits are shoes and surfaces. The technological innovations shoes have made in the last two decades are fantastic. In the 70's choice was limited to size. Now you can get shoes that are molded, gelled, aired, pumped and glow in the dark. Makes you wonder how Roger Bannister ever did it.
    But while the advances in today's shoes offer greater protection there is a negative side effect. Scott Christensen briefly touched on this in his article in Track Coach #152. Today's well-constructed shoes essentially represent a soft cast for the foot and lead to atrophy of the small intrinsic muscles of the foot. Weak intrinsics mean an unstable base and a "wobble" at the moment of power generation. It is the wobble, on a cellular level, that initiates the tearing of the musculo-tendinous junctions that through overuse becomes an injury.
    Overuse injuries develop from decreased proprioception from a weak foot. Balance sense and proprioception come about because of sensory receptors in the muscles, tendons and ligaments in and around the joint capsules. With a poorly developed muscular system one's nerve pathways are "less clear." Less clear translates into slower transmission times from the brain to the foot, the longest pathway in the body. Power = force x time.

    The central player in this scenario is the subtalar joint. The subtalar joint is between the calcaneus and the talus bones in the foot. The subtalar joint allows one to pronate and supinate the foot as one walks and runs. If you balance on one foot for a minute the quiver you feel coming from the foot is proprioceptive input from the subtalar joint.

    How does this relate to anything? To a greater or lesser degree all events require one to stand on one leg, single support, for a portion of time. However brief this single-support ground contact may be, the "quiver" (lateral movement at the subtalar joint or an attempt by the body to find itself in space through proprioceptive input) represents lost time.
    So what, you say. It is not a long time. You are right, but if the "quiver" only lasts 1/100th of a second (it takes 14/100ths to blink your eyes) and you run the 100m in 50 steps, that insignificant "quiver" has cost you 50/100ths or-a half second. The time significance becomes even greater in the distances.
    The solution to the problem is simple. The foot can be significantly strengthened (thus increasing the balance sense) by doing six foot exercises and spending as little as 30 seconds a day on a balance or wobble board.
    The six drills are done barefooted or in stocking feet. Walk 25 meters on the outside and inside of the feet, 25m toeing in and out, 25m backward on the toes and with the shoes back on walk 25m on the heels. These exercises will strengthen the intrinsic muscles of the foot in addition to challenging and clarifying the major nerve pathways to the foot.
    Your athletes should note positive results in about three weeks. Changes will be subtle. They may feel they can "corner" better on their distance runs, run stronger turns or have more bounce in their approach.

    A secondary benefit is that consistent use of these drills will all but eliminate shin splints, Achilles tendinitis, plantar fasciitis and knee problems. I've lost count of the number of coaches who've seen me demo the drills at a clinic, used the drills and had great results. We are talking about three minutes of practice time per day.
    Success starts with simple things.

 

FROM: TRACK COACH 153

 

 

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