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- Saltin, Bengt, et al.
(författare)
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Free fatty acids and exercise.
- 1993
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Ingår i: American Journal of Clinical Nutrition. - 0002-9165 .- 1938-3207. ; 57:5 Suppl, s. 752S-757S; discussion 757S
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Tidskriftsartikel (refereegranskat)abstract
- Although the great explorers were well aware that eating fat was an efficient way to meet their large energy demand, it was not until some decades into this century that it could be demonstrated that lipids are metabolized directly by contracting skeletal muscles. The 1950s produced the first studies with [14C]-tagged fatty acids (FAs), proving that fat is transported into the cell as FAs. An FA-transporting protein that is present in the sarcolemma and in the cytoplasma has been identified. For FA transport into the mitochondria, carnitine and carnitine transferase are needed. It is still unclear how the use of lipids as an energy source for the muscle during exercise is limited. The supply of free fatty acids (FFAs) far exceeds what is taken up by the muscle. Seldom more than 2-4% of the amount of FFAs delivered to an exercising limb is taken up by the muscles and only part of it is oxidized. Physical training induces changes that enhance the uptake of FAs by the contracting muscles, and a larger fraction of this uptake is oxidized, but it is not yet clear which mechanism is behind this adaptation. What is known is that this uptake occurs despite no elevation in the amount of FA supplied to the limb.
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| 2. |
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| 3. |
- Åstrand, PO
(författare)
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J.B. Wolffe Memorial Lecture. "Why exercise?".
- 1992
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Ingår i: Medicine & Science in Sports & Exercise. - 0195-9131 .- 1530-0315. ; 24:2, s. 153-62
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Tidskriftsartikel (refereegranskat)abstract
- There is a pronounced plasticity and adaptability in the structural and/or functional properties of cells, tissues, and organ systems in the human body when exposed to various stimuli. While there is unanimous agreement that regular exercise is essential for optimal function of the human body, it is evident that extrinsic factors, such as diet and exercise habits, are reflected in the morbidity and mortality statistics, especially in the aged. Aging is obligatorily associated with reduced maximal aerobic power and reduced muscle strength, i.e., with reduced physical fitness. As a consequence of diminished exercise tolerance, a large and increasing number of elderly persons will be living below, at, or just above "thresholds" of physical ability, needing only a minor intercurrent illness to render them completely dependent. Physical training can readily produce a profound improvement of functions essential for physical fitness in old age. Adaptability to regular physical activity serves to cause less disruption of the cell's "milieu interieur" and minimizes fatigue, thereby enhancing performance and the economy of energy output during exercise.
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| 4. |
- Åstrand, PO
(författare)
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Physical activity and fitness.
- 1992
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Ingår i: American Journal of Clinical Nutrition. - 0002-9165 .- 1938-3207. ; 55:6 Suppl, s. 1231S-1236S
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Tidskriftsartikel (refereegranskat)abstract
- There is unanimous agreement that regular exercise is essential for optimal function of the human body. It is evident that extrinsic factors, such as diet and exercise habits, are reflected in the morbidity and mortality statistics, especially in aging. Aging is obligatorily associated with reduced maximal aerobic power and reduced muscle strength, ie, with reduced physical fitness. As a consequence of diminished exercise tolerance, a large and increasing number of elderly people will be living below, at, or just above "thresholds" of physical ability, needing only a minor intercurrent illness to render them completely dependent. Physical training can readily produce a profound improvement of functions also essential for physical fitness in old age. From a nutritional viewpoint one advantage of physical activity, and increased metabolic rate, is that a higher energy intake can better secure an adequate intake of essential nutrients.
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