Walking is the main gait of locomotion among legged animals, distinguished from running and other gaits. In humans, it is the fundamental form of bipedalism, a method of movement that involves using two legs. It is defined by a period of 'double support' where both feet are on the ground, a feature absent in running, as explained by the U.S. Centers for Disease Control and Prevention. The average human walking speed is about 5.0 kilometers per hour (3.1 mph).
Biomechanics
The human walking process is a complex interplay of the skeletal, muscular, and nervous systems. It is often described using the 'inverted pendulum' model, where the body vaults over a stiff leg with each step, as detailed in research published in the Journal of Experimental Biology. The gait cycle is the fundamental unit of walking and consists of two main phases for each leg:
- –Stance Phase: This phase constitutes about 60% of the gait cycle and occurs when the foot is in contact with the ground. It begins with the 'heel strike,' when the heel first touches the ground, and ends when the toe of the same foot lifts off.
- –Swing Phase: This phase makes up the remaining 40% of the cycle. It begins when the foot leaves the ground and ends just before the heel strikes again, allowing the limb to advance.
Efficient walking involves coordinated muscle contractions and the passive dynamics of the limbs to conserve energy. The central nervous system generates the basic walking rhythm, while sensory feedback from the limbs helps adapt the movement to varying terrain and obstacles.
Evolutionary History
The development of walking on two legs is a hallmark of human evolution. The transition to habitual bipedalism occurred in early hominins millions of years ago. Fossil evidence, such as the skeleton of 'Lucy' (Australopithecus afarensis), shows key anatomical adaptations for walking upright, including a broad pelvis, angled thigh bones, and arched feet, as documented by the Smithsonian National Museum of Natural History. These changes freed the hands for tool use and carrying, which is considered a critical step in the evolutionary path leading to modern humans, Homo sapiens.
Health and Well-being
Walking is one of the most accessible forms of physical activity and is widely recommended for its health benefits. Regular brisk walking can improve cardiovascular fitness, strengthen bones, reduce excess body fat, and boost muscle power and endurance according to the Mayo Clinic. It is associated with a reduced risk of developing chronic conditions such as heart disease, Type 2 diabetes, osteoporosis, and some cancers.
The World Health Organization recommends that adults engage in at least 150–300 minutes of moderate-intensity aerobic physical activity, such as brisk walking, per week. Beyond physical health, walking has also been shown to improve mental well-being by reducing anxiety, depression, and negative mood, and by improving self-esteem and cognitive function.
Forms and Cultural Significance
Walking takes many forms, from utilitarian transport to competitive sport. Different purposes have led to various specialized styles:
- –Recreational Walking: This includes activities like strolling, hiking (walking on trails in natural environments), and rambling. The practice of walking for pleasure became widespread in Europe during the 18th and 19th centuries, championed by figures of the Romantic movement.
- –Fitness Walking: Often called power walking or speed walking, this form involves walking at a brisk pace, sometimes using arm movements to increase intensity.
- –Racewalking: A competitive athletic discipline featured in the Olympic Games. It is a long-distance event where athletes must follow specific rules, most notably that one foot must appear to be in contact with the ground at all times.
In urban design, the concept of 'walkability' has gained prominence, referring to the extent to which the built environment is friendly to pedestrians. Cities with high walkability are associated with better public health outcomes, lower pollution, and stronger local economies, as noted by urban planning advocates like the Congress for the New Urbanism.