Walking is not as simple as it looks
Human locomotion refers to the way humans move, which encompasses different movement strategies such as crawling, walking, running. To most of us, walking is a simple task that we do every day. However, humans are virtually the only species that consistently use bipedal walking as the main form of locomotion. Human locomotion actually involves intricate and precise neural control mechanisms, and requires the integrity of almost all major body systems.
To enable the public to learn more about their bodies, the Hong Kong Science Museum begins a new exhibition entitled "Science of Human Locomotion" at its Science News Corner from today (May 8) to September 20. The exhibition highlights the role of different neutral structures in regulating locomotion and illustrates how different diseases or injuries may affect our walking function.
Development of human locomotion begins well before birth. As early as at the 10th week of the post-gestational stage, a baby starts to perform rhythmic stepping-like movements within the uterus. These movements are neither voluntary nor reflexive by nature. They are the responses of muscles to the neural signals generated by the spinal cord.
After birth, a newborn baby can typically demonstrate stepping behaviour when appropriate sensory stimuli to the legs are provided. This behaviour may be induced by firstly placing the newborn baby in an upright position by holding him/her on each side of the trunk, with the baby's feet making contact with a firm surface. Next, tilt the baby slightly forward to extend the hip joints. These will provide important sensory signals to the central nervous system to induce stereotypical and alternating stepping motions in the legs. This interesting phenomenon is referred to as the "stepping reflex".
The early stepping behaviour observed in the newborn baby may diminish or disappear between the second and the sixth months after birth, but will usually re-emerge about the seventh month. However, research studies show that if the parents continue to help the infant practise stepping, even as little as a few minutes a day, many infants will maintain the stepping response throughout infancy. As the higher centres of the central nervous system, for example, the cerebrum with its descending motor nerve tracts to the lumbar spinal cord, are far from mature before the age of one, it is asserted that this early stepping behaviour is controlled mainly by the spinal cord, and provides the basic building block for development of independent walking later.
Owing to ageing, functional decline may take place in many body systems, for instance, the visual, somatosensory, motor and musculoskeletal systems. The spinal joints may also become less flexible, leading to decreased trunk rotation and arm swing. In particular, worsened balance ability and leg muscle weakness are two of the major factors underlying gait changes in the elderly. Additionally, a good proportion of the elderly suffer from various kinds of chronic diseases, for example, arthritis and osteoporosis, which may further impair gait performance. Typically, the step length of the elderly becomes shorter, and the gait velocity becomes slower. This is particularly apparent when they attempt to make turns.
The elderly have an increased risk of falls during walking. Multiple factors, including physical, psychosocial and environmental, contribute to accidental falls in the elderly. Physical risk factors include decreased visual function, for example, visual acuity, contrast sensitivity and depth perception; impaired sensory function of the legs, leg muscle weakness and reduced balance ability. Psychosocial risk factors are exemplified by depression, decreased cognitive status and fear of falling. Other factors such as polypharmacy, and presence of environmental hazards, for instance, obstacles and slippery floor, are also common and important causes. However, some studies show that appropriate exercise training will have beneficial effects on balancing and walking functions as well as on psychological health of the elderly. An active lifestyle is thus of paramount importance for the elderly.
The Science Museum is located at 2 Science Museum Road, Tsim Sha Tsui East. It opens from 1pm to 9pm from Monday to Wednesday and on Fridays, and from 10am to 9pm on Saturdays, Sundays and public holidays. It is closed on Thursdays (except public holidays). Admission is $25 with half-price concession for full-time students, people with disabilities and senior citizens aged 60 or above. Admission is free on Wednesdays.
For enquiries, call 2732 3232 or visit the Science Museum's website at http://hk.science.museum
Ends/Friday, May 8, 2009