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The human body consists of the following six main regions: the head, the upper extremities, the torso and the lower extremities. Each of these body regions has its own functions and consists of its own set of tissues, such as connective tissue and muscle tissue, needed to perform those functions. As the weight of the tissues forming the various body regions differ from one region to another, the weights of the body regions themselves also differ.
From a kinesiological perspective, the two hands, two lower extremities, trunk and head participate in various movements and thus can be broadly regarded as components of the musculoskeletal system. Knowing the weight (or the mass, to be exact) of each body region is very important when scientifically assessing the mechanical role of each body region during movement and their contribution to postural control. Studies that measured the weights of body regions, however, have all been based on data from cadavers in which the weight of each body region was measured after it was dismembered from the body (Dempster & Gaughran, 1967; Mozumdar & Roy, 2004), and no reports on the weighing of body segments on living bodies could be found. Thus, while the current way of measuring body weight throughout the world is to stand on a scale to determine whole body weight, the weights of and weighing methods of one’s separate body regions, which is more important information as far as body movements in everyday life are concerned, are at present largely unknown.
Meanwhile, the rate of aging is accelerating in Japan,, as shown in Table 1, and according to the Ministry of Internal Affairs and Communications, the number of people aged 65 years or older is 32.96 million as of September 2014, accounting for an unprecedented 25.9% of the total population, with one in eight people now aged 75 years or older.
Table 1. Changes in the elderly population in Japan
| Year | Total Population | Aged People (Over 65 Years of Age) | Percentage of Aged People (%) |
| 1970 | 103,720,000 | 7,330,000 | 7.1 |
| 1980 | 117,060,000 | 10,650,000 | 9.1 |
| 1990 | 123,610,000 | 14,930,000 | 12.1 |
| 2000 | 126,930,000 | 22,040,000 | 17.4 |
| 2010 | 128,060,000 | 29,480,000 | 23.0 |
| 2020 | 124,100,000 | 36,120,000 | 29.1 |
| 2030 | 116,620,000 | 36,850,000 | 31.6 |
Data source: Bureau of Statistics, Ministry of Internal Affairs and Communications, 2014.
Key Terms in this Chapter
Seven Body Regions: Outwardly, the human body is made up of six regions: the head, the upper extremities, the trunk and the lower extremities. The torso, however, can be divided into upper and lower parts, giving an upper trunk region and a lower trunk region; thus, the six regions of the body become seven.
Healthy Life Expectancy: The period of living without any health problems. Specifically, the average period of life with no limitations to activities of daily living, or the average period in which people are aware that they are healthy.
Health Management on an Individual Level: Individual people looking after their own exercise, diet, and body weight in order to maintain everyday health.
Body-Region Separately Weighing Method: A system that individually measures the weights of the body regions that form the human body. Note that the sum of the regional weights must always match the whole body weight measured in a standing position.
Assessing Separate Weights of the Main Musculoskeletal Components: Assessing weights of the hands and feet, principal parts of the musculoskeletal apparatus, are needed in order to evaluate efficient or effective motor activities.
Weights of Separate Body Regions: This means the weight of each body region that make up the human body with respect to whole body weight.
LS. Abbreviation for Locomotive Syndrome: Locomotive should be taken to mean “pertaining to movement.” Based on the idea that the musculoskeletal system provides a wide framework for an individual’s health, the Japanese Orthopaedic Association coined this new expression to refer to the state of requiring long-term care (or the state of being at risk of requiring long-term care) due to a musculoskeletal disorder.