The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws and/or nails.
Running is a method of terrestrial locomotion by which humans and other animals move rapidly on foot. Running is a gait with an aerial phase in which all feet are above the ground. This is in contrast to walking, where one foot is always in contact with the ground, the legs are kept mostly straight, and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion. A feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride co-occur, with energy storage accomplished by springy tendons and passive muscle elasticity. The term "running" can refer to a variety of speeds ranging from jogging to sprinting.
The leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula. The thigh is between the hip and knee, while the calf (rear) and shin (front) are between the knee and foot.
The Achilles tendon or heel cord, also known as the calcaneal tendon, is a tendon at the back of the lower leg, and is the thickest in the human body. It serves to attach the plantaris, gastrocnemius (calf) and soleus muscles to the calcaneus (heel) bone. These muscles, acting via the tendon, cause plantar flexion of the foot at the ankle joint, and flexion at the knee.
A gait is a manner of limb movements made during locomotion. Human gaits are the various ways in which humans can move, either naturally or as a result of specialized training. Human gait is defined as bipedal forward propulsion of the center of gravity of the human body, in which there are sinuous movements of different segments of the body with little energy spent. Varied gaits are characterized by differences such as limb movement patterns, overall velocity, forces, kinetic and potential energy cycles, and changes in contact with the ground.
In humans and some other mammals, the soleus is a powerful muscle in the back part of the lower leg. It runs from just below the knee to the heel and is involved in standing and walking. It is closely connected to the gastrocnemius muscle, and some anatomists consider this combination to be a single muscle, the triceps surae. Its name is derived from the Latin word "solea", meaning "sandal".
The triceps surae consists of two muscles located at the calf – the two-headed gastrocnemius and the soleus. These muscles both insert into the calcaneus, the bone of the heel of the human foot, and form the major part of the muscle of the posterior leg, commonly known as the calf muscle.
The gastrocnemius muscle is a superficial two-headed muscle that is in the back part of the lower leg of humans. It is located superficial to the soleus in the posterior (back) compartment of the leg. It runs from its two heads just above the knee to the heel, extending across a total of three joints.
Foot drop is a gait abnormality in which the dropping of the forefoot happens due to weakness, irritation or damage to the deep fibular nerve, including the sciatic nerve, or paralysis of the muscles in the anterior portion of the lower leg. It is usually a symptom of a greater problem, not a disease in itself. Foot drop is characterized by inability or impaired ability to raise the toes or raise the foot from the ankle (dorsiflexion). Foot drop may be temporary or permanent, depending on the extent of muscle weakness or paralysis and it can occur in one or both feet. In walking, the raised leg is slightly bent at the knee to prevent the foot from dragging along the ground.
Barefoot running, also called "natural running", is the act of running without footwear. With the advent of modern footwear, running barefoot has become less common in most parts of the world but is still practiced in parts of Africa and Latin America. In some Western countries, barefoot running has grown in popularity due to perceived health benefits.
Pronation is a natural movement of the foot that occurs during foot landing while running or walking. Composed of three cardinal plane components: subtalar eversion, ankle dorsiflexion, and forefoot abduction, these three distinct motions of the foot occur simultaneously during the pronation phase. Pronation is a normal, desirable, and necessary component of the gait cycle. Pronation is the first half of the stance phase, whereas supination starts the propulsive phase as the heel begins to lift off the ground.
Orthotics is a medical specialty that focuses on the design and application of orthoses, sometimes known as braces or calipers. An orthosis is "an externally applied device used to influence the structural and functional characteristics of the neuromuscular and skeletal systems." Orthotists are professionals who specialize in designing these braces.
Terrestrial locomotion by means of a running gait can be accomplished on level surfaces. However, in most outdoor environments an individual will experience terrain undulations requiring uphill running. Similar conditions can be mimicked in a controlled environment on a treadmill also. Additionally, running on inclines is used by runners, both distance and sprinter, to improve cardiovascular conditioning and lower limb strength.
Neuromechanics of orthoses refers to how the human body interacts with orthoses. Millions of people in the U.S. suffer from stroke, multiple sclerosis, postpolio, spinal cord injuries, or various other ailments that benefit from the use of orthoses. Insofar as active orthoses and powered exoskeletons are concerned, the technology to build these devices is improving rapidly, but little research has been done on the human side of these human-machine interfaces.
Minimalist shoes are shoes intended to closely approximate barefoot running or walking conditions in comparison to traditional shoes. Minimalist shoes are defined as providing "minimal interference with the natural movement of the foot, because of its high flexibility, low heel to toe drop, weight and stack height, and the absence of motion control and stability devices." Minimalist shoes provide more sensory contact for the foot on the ground while simultaneously providing the feet with some protection from ground hazards and conditions. Research shows that wearing a minimalist shoe can help improve running economy, foot strength and arch function.
Proportional myoelectric control can be used to activate robotic lower limb exoskeletons. A proportional myoelectric control system utilizes a microcontroller or computer that inputs electromyography (EMG) signals from sensors on the leg muscle(s) and then activates the corresponding joint actuator(s) proportionally to the EMG signal.
Cutaneous, superficial, or skin reflexes, are activated by skin receptors and play a valuable role in locomotion, providing quick responses to unexpected environmental challenges. They have been shown to be important in responses to obstacles or stumbling, in preparing for visually challenging terrain, and for assistance in making adjustments when instability is introduced. In addition to the role in normal locomotion, cutaneous reflexes are being studied for their potential in enhancing rehabilitation therapy (physiotherapy) for people with gait abnormalities.
Running injuries affect about half of runners annually. The frequencies of various RRI depend on the type of running, such as speed and mileage. Some injuries are acute, caused by sudden overstress, such as side stitch, strains, and sprains. Many of the common injuries that affect runners are chronic, developing over longer periods as the result of overuse. Common overuse injuries include shin splints, stress fractures, Achilles tendinitis, Iliotibial band syndrome, Patellofemoral pain, and plantar fasciitis.
The function of the lower limbs during walking is to support the whole-body against gravitational forces while generating movement patterns which progress the body forward. Walking is an activity that is primarily confined to the sagittal plane, which is also described as the plane of progression. During one gait cycle, there are two major phases: stance and swing. In a healthy individual walking at a normal walking speed, stance phase makes up approximately 60% of one gait cycle and swing makes up the remaining 40%. The lower limbs are only in contact with the ground during the stance phase, which is typically subdivided into 5 events: heel contact, foot flat, mid-stance, heel off, and toe off. The majority of stance phase (~40%) takes place in single-limb support where one limb is in contact with the ground and the contralateral limb is in swing phase. During this time interval, the lower limb must support constant changes in alignment of body weight while propelling forward. The hip, knee, and ankle joints move through cyclical kinematic patterns that are controlled by muscles which cross these joints. As postural changes occur, the body adapts by motor tuning an efficient muscular pattern that will accomplish the necessary kinematics required to walk.
