Human running gaits exhibit various foot collision patterns based on which part of the foot contacts the ground first, such as the forefoot, midfoot, or heel. Therefore, a key aspect of analyzing running technique involves identifying foot strike patterns in athletes. Typically, the foot strike pattern is defined as a biomechanical analysis of how the foot contacts the ground. This analysis often distinguishes three foot strike patterns: heel strike, midfoot strike, and forefoot strike.
The storage and release of elastic energy in muscles and tendons improve the efficiency of running. This idea has led to the development of simple spring-mass models of human running, which help understand running mechanics, predict the energy cost of running, and examine the effects of fatigue. The main three plantar flexor muscles, the soleus, medial gastrocnemius, and lateral gastrocnemius, along with the Achilles tendon, significantly contribute to the mechanism of energy storage and return during running. The plantar flexors absorb energy during early stance and release energy during late stance. The elastic stretch and recoil of the Achilles tendon may account for up to 35% of the total energy storage and return during running (Yong et al., 2020).
Since the plantar flexor muscles and Achilles tendon span the ankle joint, their mechanics are influenced by foot strike patterns. Variations in heel, or rearfoot, versus forefoot striking suggest these patterns impact plantar flexor muscle-tendon mechanics. Forefoot striking increases peak stress and impulse in the Achilles tendon, resulting in higher force and strain, which likely enhances energy storage in the spring-like tendon (Yong et al., 2020).
The various strategies of human locomotion can be understood and explained through the principles of pendulums and springs. Humans possess four primary locomotive strategies: walking, jogging, running, and sprinting. These strategies exhibit a transition from a pendulum-like motion to a more spring-like behavior as speed and gravitational load increase and contact time decreases.
Running is characterized by a true 'spring-like' gait pattern, with the entire kinetic chain of the lower body functioning like a spring. At running speeds exceeding 10 mph (4.5 m/s), the biomechanical behavior of the foot and ankle typically shifts to a forefoot or midfoot loading pattern to maximize the elastic potential of the tendinous structures within the foot and ankle.
When transitioning from running to sprinting, the foot strike pattern changes to a forefoot striking pattern as a biomechanical necessity. This adjustment allows the body to create a stiffer spring to handle the increased forces associated with faster speeds. Sprinting differs biomechanically from running and occurs at speeds over 15-16 mph (7 m/s). It is characterized by a stride rate higher than 4 Hz and ground contact time less than 150 ms.
Evaluating the dynamics of the foot strike during running-based tasks with plantar pressure mapping technology serves a dual purpose:
In-shoe plantar pressure mapping technology, like XSENSOR's Intelligent Insoles, can provide objective information about the interaction between the foot and the ground and identify micromovement details otherwise undetectable with other measurement technologies.
To learn more about using plantar pressure mapping technology to identify and analyze foot strike patterns, contact one of our Human Performance experts to schedule a demonstration.