08 July, 2011
Plantar Flexion When Running
Your calf muscles plantar flexion your foot during running, which is also referred to as toe push-off or take-off. Many variables such as your shoes, calf strength and foot type influence the efficiency of your running mechanics including toe push-off. With proper training and exercises, you can achieve optimal running mechanics and avoid injury. Consult a physical therapist, athletic trainer or personal trainer for further guidance.
Running is separated into the stance phase and swing phase. The stance phase is when your foot is on the ground and swing phase is when your foot is off the ground. The stance phase is further broken down into heel-strike, mid-stance and toe push-off. When you step forward during running, your heel hits first and is therefore called heel-strike. Mid-stance follows as your weight shifts onto that foot, causing your foot to flatten or pronate as it absorbs the force. To keep your momentum moving forward, your calf muscles plantar flex your foot to push off the ground, finishing stance phase with toe push-off.
Many factors influence your running mechanics and toe push-off. Your shoes, for example, can inhibit normal toe flexibility and therefore resist plantar flexion. The stiffer your shoes, the more effort it takes to flex your foot. This is why running shoes are often flexible in the toe-box. Different running surfaces can have a similar affect. Ever try to run on a sandy beach? Sand shifts under the pressure of your foot, making plantar flexion more difficult. Additional factors include your calf strength and flexibility, flatfeet or high-arches, and your level of experience as a runner.
In one mile, your foot-strikes the ground approximately 1,200 times and the force of each foot-strike is 250 percent of your weight, according to Dr. Gregory P. Uchacz. This repetitive stress placed on your leg and foot can result in chronic injuries including plantar fasciitis, Achilles tendinitis, stress fractures, muscle strains and shinsplints. Running with injuries impair your running mechanics and toe push-off because of pain and reduced strength and flexibility. A 2000 University of Pennsylvania study found that prolonged immobilization of the ankle due to a fracture, decreased plantar flexion and impaired toe push-off. Fatigue, overtraining and previous injuries can further increase your risk of injury and lead to poor running mechanics.
Incorporate exercises such as toe walking, calf raises, calf stretches and plyometrics into your workout routine to improve your running gait and decrease your risk of injury. Toe walking and calf-raises increase calf strength and endurance, which prevents fatigue during running. Stretches improve muscle flexibility and joint mobility to allow more fluid movements. Plyometric exercises such as high skips and box jumps increase your quickness or explosiveness and therefore improve the efficiency between your heel-strike and toe push-off and between your swing and stance phases.
- “Principles of Athletic Training”; Sport Specific Conditions of The Foot; Daniel D. Arnheim, et al.; 2000
- “Basic Biomechanics”; The Biomechanics of The Human Lower Extremity; Susan J. Hall; 2003
- Chiropractor Performance and Sports Therapy Centre; Running Tips and Techniques; Dr. Gregory P. Uchacz
- “Physical Therapy”; Effects of Immobilization on Plantar-Flexion Torque, Fatigue Resistance, and Functional Ability Following an Ankle Fracture; Michael A. Shaffer, et al.; 2000
- American Medical Society For Sports Medicine; Achilles Tendonitis, Plantar Fasciitis, and Shin Splints; Karl B. Fields, M.D.
- Siri Stafford/Lifesize/Getty Images