| Factor |
Childhood |
Adolescence |
Adulthood and changes with aging |
| Skeletal muscle mass |
- Number of muscle cells is established at an early age: however, a large change in muscle size is possible via the mechanism of muscle fiber hypertrophy (increase in size).
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- In males, puberty initiates rapid hypertrophy of muscle fiber. In females, do not exhibit any disproportionate muscle growth during adolescence. Adolescent females have approximately 30 % less muscle mass than males, due to two reasons smaller stature and muscle fiber size.
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- After age 30 muscle strength begins to decline.Howerver,the loss of strength is not linear, most of the decline occurs after 50, by age 80,loss of strength is usually in the range of 30 to 40 %.
- Fast twitch fibers are particularly suscep -tible to atrophy(decrease muscle size) in aging humans. Aging is also associated with decrease in metabolic rate.
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| Bone deveolpment |
- Human skeletal system begins to develop in the embryo as the process of endochondral ossification.
- In long bones,ossification begins in the diaphysis,long bones continue to grow in length until the response to hormonal changes occurring at about 16-18 years of age.
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- In men,Bone loss begins by age 65;over all bone mineral content is about 10 % lower than the peak value.
- In women,bone loss begins by as early as 30-35 years of age and rate is accelerated following menopause.
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| Reaction time and co-ordination |
- By the age 6 yrs, most children have mastered basic skills such as throwing and jumping.
- There is sudden decrease in reaction time around 8 yrs of age.
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- Speed of movement improves during adolescence.
- During adolescence, In females performance of skills requiring strength plateaus whereas boys continue to improve.
- During adolescence, performance of sophisticated skills improves.(sports)
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- many neurophysiological changes occur with aging that affect motor performance ,including
- Decreased visual capacity.
- Hearing loss
- Deterioration of short term memory.
- Inability to handle too many information.
- Decrease in muscle mass.
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| Tolerance of extreme environments |
- Childrens are less efficient than adults at temp regulations.
- Sweating rate for children is lower than adults.
- Childrens acclimatize to hot environments less efficiently and at a slower rate.
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- Aging does not effect on sweating Mechanism, but there is general reduction Total cellular water content.
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| Maximum oxygen consumption(VO2 MAX) |
- VO2max increases during childhood.
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- There is large increase in VO2 max in adolescent boys corresponding to growth spurt as compare to girls.
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- VO2 max decreases with aging.
- the assessment of the effect of aging on VO2 max is complicated by factors such as physical inactivity, increase in fat mass, decrease in lean mass and development of diseases.
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| Bodycomposition (change in Fat and muscle percentage) |
- Fat tissue accounts for about 16 % of body mass in the full term newborn infant.
- Total fat content increases through out childhood(depends upon food choice and physical activity)
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- In males, fat per kg, decreases during puberty to approximately 12-13% of total body weight.
- In females, fat per kg increases during puberty to about 20-25% of total body weight.
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- After 70 yrs of age, body mass begins to lose,by 1-2 kgs in eight decade and accelerating thereafter,Represents a loss of fat free mass.
- Physically active life style effects Positively on Body composition .exercise Training can reduce body fatt any age.
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