Humans have walked and run barefoot for millions of years. Indirect evidence suggests that footwear emerged as recently as ~30 000 years ago. The majority of time since then, humans have worn minimalist footwear designed to protect the sole of the foot. The first indication of fashionable footwear beginning to alter the shape of the foot emerged a little over 100 years ago and the invention of the mass market cushioned athletic shoe is as recent as ~1970. Differences in foot structure between those who have never worn shoes and those who are habitually shod have been described for over a century. Emerging research has begun to demonstrate differences in movement and force absorption strategies between shod and barefoot populations. It is thought that these differences may contribute to the nature of injuries reported by shod and barefoot populations. Given that the aetiology of athletic injury is multifactorial and stretches far beyond footwear, the link between footwear, movement strategies and athletic injury may be better discussed in the context of certain types of athletes and or certain types of injuries. This invited symposium aims to unpick the role of footwear in the musculoskeletal development and movement strategies used by children and adults (Lecture A), discuss how the shoe-surface environment alters running mechanics and muscle recruitment in athletes (Lecture B) and subsequently, discuss the role that footwear may play in running injury (Lecture C).
ECSS Paris 2023: IS-AP04
Improvements of motor skills are basic processes of growth, maturation and development during childhood and adolescence. They are not only a direct consequence of learning processes but are also influenced by interactions between regular external (environmental) and internal (e.g. neuromuscular) factors. These include anthropometrical and muscular characteristics of the foot. It has been shown that different structural foot types such as high and low arches are associated with the performance of basic motor skills such as balancing, jumping or sprinting. Since the foot morphology differs between barefoot and shod populations, footwear habits have long been discussed to play an important role for motor learning and motor control. Evidence exists that compared to shod conditions, barefoot situations directly change gait biomechanics, postural control and jumping movements in children and adults. Individuals growing up barefoot also tend to have wider feet with a higher arch and smaller hallux angles. This emphasizes the hypothesis that the development of basic motor skills during childhood and adolescence partly depends on the amount of physical activity under barefoot conditions. A comparison of motor skills between habitually barefoot and shod individuals in the same setting is difficult, since barefoot habits seem to be influenced by sociocultural and regional factors. Individuals in western countries are used to wear shoes during almost all outdoor activities whereas especially children in some countries in the southern continents are often seen barefoot. The potential interaction between growing up barefoot or shod and performance in basic motor competencies during the different stages of childhood, adolescence and into adulthood will be discussed.
Read CV Astrid ZechECSS Paris 2023: IS-AP04
Unlike other primates, the human foot has an arch capable of both stiffness and deformation to varying degrees dependent on the terrain. It can store and release energy via springs (ligaments, aponeurosis, tendons) in order to make efficient use of muscle work during running. During running, muscles are continuously operating via both feedforward (in anticipation via vision) and feedback (in response via sensory physiology) mechanisms. Muscle responses will perhaps be most evident via kinematic changes at the major joints and the extent of muscle pre-activation in anticipation of the expected ground contact. In many runners, acutely and at submaximal speeds, barefoot running results in a reduction in stride length and increased plantar and knee flexion. Runners who are habitually barefoot demonstrate lower loading rates (force) compared with their shod counterparts. This is thought to be due to the optimisation of the limb position for ground contact and the pre-activation of muscles in anticipation. Previously shod runners who respond to a barefoot running intervention demonstrate increased biceps femoris and gluteus medius pre-activation, and decreased rectus femoris muscle activity between testing periods. The kinematic changes evident in some runners who transition to barefoot running seem to be similar to that experienced when running on an irregular surface. On an irregular surface, the knee and ankle appear to move in synchrony whereby the ankle stiffens and has a reduced rearfoot action. A spring-like ankle combined with an increase in knee flexion may increase impact attenuation. The task (barefoot running) and environmental (irregular surface) constraints may enhance the coordinated action of the spring-like function of the foot and the energy absorbing capacity of more proximal muscles. Subtle differences in ground deformation and subsequent foot placement will challenge the biotensegrity of foot structures and the plantar cutaneous nerve receptors to respond with variations of tensioning and stiffening. These variations facilitate a consistent outcome (running) using different patterns of joint relations, a concept known as dynamical systems. Lieberman and colleagues reported 72% of barefoot runners use a varied foot strike pattern compared with just 32% of shod runners. All runners used a more varied foot strike pattern on a softer surface. This lecture will aim to explore how the footwear we use and the surface we run on changes our biomechanics via altered muscle work.
Read CV Cassie OddyECSS Paris 2023: IS-AP04
For a relatively simple activity with numerous health benefits, the incidence of running injury is high compared to other aerobic activities. The debate amongst scientists about whether footwear plays a role in running injury and whether conventional, minimalist, or maximalist footwear is optimal toward injury prevention has moved on. Despite the high incidence of injury, there are many runners who do not get injured including those that run in conventional running shoes and with an infamous rear-foot strike. Indeed, most world championship marathon runners wear cushioned running shoes and use a rear-foot strike. However, in runners who do get injured, the top 5 injuries occur to non-contractile tissues (patellofemoral pain, shin splints, plantar fasciitis, achilles tendinopathy, iliotibial band), ill-equipped to absorb impact forces. There is a growing body of evidence which suggests the movement strategies used by these athletes are injurious in nature and are contributed to by footwear-surface interactions. As described in the introduction for this session, the human foot has undergone rapid changes in its footwear and surface environment in a very short space of time relative to human evolutionary history. Modern footwear is known to weaken the intrinsic muscles of the feet and encourage ‘heavier’ running mechanics (rear-foot strike) on what are now largely unyielding surfaces (roads, pavements, running tracks). Increasingly, scientists are beginning to view plantar fasciitis (chronic heel pain) as a mismatch disease, in other words a disease directly related to changes in the footwear-surface environments. This lecture will aim to provide insight into the role of footwear in running injury and make suggestions for how to run our way out of it.
Read CV Peter FrancisECSS Paris 2023: IS-AP04