Foot strike pattern during running alters muscle-tendon dynamics of the gastrocnemius and the soleus

Abstract

Running is thought to be an efficient gait due, in part, to the behavior of the plantar flexor muscles and elastic energy storage in the Achilles tendon. Although plantar flexor muscle mechanics and Achilles tendon energy storage have been explored during rearfoot striking, they have not been fully characterized during forefoot striking. This study examined how plantar flexor muscle-tendon mechanics during running differs between rearfoot and forefoot striking. We used musculoskeletal simulations, driven by joint angles and electromyography recorded from runners using both rearfoot and forefoot striking running patterns, to characterize plantar flexor muscle-tendon mechanics. The simulations revealed that foot strike pattern affected the soleus and gastrocnemius differently. For the soleus, forefoot striking decreased tendon energy storage and fiber work done while the muscle fibers were shortening compared to rearfoot striking. For the gastrocnemius, forefoot striking increased muscle activation and fiber work done while the muscle fibers were lengthening compared to rearfoot striking. These changes in gastrocnemius mechanics suggest that runners planning to convert to forefoot striking might benefit from a progressive eccentric gastrocnemius strengthening program to avoid injury. The efficiency of running is enhanced by the storage and release of elastic energy in muscle and tendon. This concept has led to simple spring-mass models of human running 1 , which have been useful for understanding running mechanics 2 , predicting the energy cost of running 3 , and examining the effects of fatigue 4,5. The primary three plantar flexor muscles, the soleus, medial gastrocnemius, and lateral gastrocnemius, in conjunction with the Achilles tendon, are major contributors to energy storage and return during running 6. The plantar flexors absorb energy during early stance and release energy during late stance 7. The elastic stretch and recoil of the Achilles tendon may contribute as much as 35% of the total energy storage and return during running 8. The plantar flexor muscles and Achilles tendon span the ankle joint, suggesting that their mechanics would be affected by foot strike pattern. Rearfoot striking, characterized by landing on the heel, and forefoot striking, characterized by landing on the ball of the foot, are both naturally adopted foot strike patterns 9. Habitual rearfoot striking runners who transition to a forefoot striking pattern initially experience calf soreness 10,11 , indicating that altering foot strike pattern may affect the behavior of the plantar flexors. Previous research has focused on understanding plantar flexor mechanics during rearfoot striking 12-15 , but how plantar flexor mechanics are affected by converting to forefoot striking is unclear. Differences in kinematics and kinetics between rearfoot and forefoot striking indicate foot strike pattern may affect plantar flexor muscle-tendon mechanics. Forefoot striking increases peak stress 16 and impulse 17,18 in the Achilles tendon, suggesting...

Biomechanical Determinants of Knee Joint Loads Associated with Increased Anterior Cruciate Ligament Loading During Cutting: A Systematic Review and Technical Framework

“…Modification of foot-strike pattern may be useful, whereby adopting a more forefoot orientated “ankle dominant” strategy when cutting will reduce load and power absorption through the knee. This could have implications for the ankle joint, as forefoot striking has been reported to elicit considerable strain [ 73 ] and eccentric load [ 74 ] on the triceps surae muscle- tendon complex when running. During cutting, this would be amplified further by the large deceleration component present [ 33 ] and require substantial force production from the triceps to meet the demands of the task.…”

Human myoelectric spatial patterns differ among lower limb muscles and locomotion speeds

“…Additionally, the manner in which each subject's foot contacts the ground could influence EMG activity in the gastrocnemii, particularly during running. Due to the increased eccentric loading of the gastrocnemius muscle while braking, subjects who run with a forefoot strike pattern have shown increased muscle activation amplitude and muscle fiber force production than those who run with a heel strike pattern (Yong et al, 2020). We did not control for foot strike patterns in this study, and it is possible that regional differences in EMG-RMS amplitude may exist between these sub-groups of subjects.…”

Lower leg muscle–tendon unit characteristics are related to marathon running performance

“…But on the other hand, the majority of elite marathon runners are using rearfoot strike pattern 14 . Kinematic difference between rearfoot and forefoot strike pattern has been demonstrated 15,27,28 showing that ankle joint flexion is greater during forefoot strike which lead to a greater muscle tendon unit lengthening as well. In that case a thin tendon would be better since greater elastic energy could be stored by applying smaller muscle force compared to a thick tendon.…”

“…Also, because GAS contains dominantly fast twitch fibers 26 fatigue affects these muscles more, i.e. decreasing the mechanical output over time during running compared to SOL muscle [27][28][29] . Because muscle force generation capacity is related to CSA and the PCSA of the muscle 10,30,31 , greater force production could lead to morphological adaptations in the SOL.…”