Effects of training duration on substrate turnover  and oxidation during exercise

Phillips, Stuart M.; Green, H. J.; Tarnopolsky, Mark A.; Heigenhauser, George J. F.; Hill, Robert E.; Grant, Sue

doi:10.1152/jappl.1996.81.5.2182

Cited by 234 publications

(218 citation statements)

References 25 publications

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“…In contrast to results of net glycerol release and glycerol turnover studies, data from FFA turnover and indirect calorimetry, as well as muscle biopsies measuring IMTG, suggest that training may increase reliance on IMTG at a given absolute workload (18,25,29). Martin et al (25) used the difference between whole body FFA oxidation calculated from pulmonary RER and isotopically determined FFA rate of disposal (R d ) to indirectly estimate IMTG utilization.…”

Section: Glycerol Exchangementioning

confidence: 99%

“…exertion; free fatty acid; glucose; lactate; crossover concept; substrate shuttling EFFECTS OF EXERCISE intensity and training state on muscle lipid metabolism in humans are unclear, as the relatively few studies have utilized different experimental approaches. Some investigations have employed isotopic tracers and indirect calorimetry (25,29,33), whereas others have utilized arteriovenous (a-v) balance methods (17,22,35) and muscle biopsies (18,22 …”

mentioning

confidence: 99%

“…isotopic tracers and indirect calorimetry (25,29,33), whereas others have utilized arteriovenous (a-v) balance methods (17,22,35) and muscle biopsies (18,22). In addition, longitudinal and cross-sectional designs have been employed that have tested trained and untrained subjects at either the same absolute or relative exercise intensity, but rarely both.…”

mentioning

confidence: 99%

“…Recently, several groups of investigators used FFA isotope tracers and indirect calorimetry to estimate the contribution of intramuscular lipid stores to total lipid oxidation (25,29,33). Because the difference between whole body FFA oxidation measured by indirect calorimetry and tracer-measured FFA flux was greater after training, the data were interpreted to mean that training increased reliance on intramuscular triglycerides (IMTG; see Refs.…”

mentioning

confidence: 99%

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An Evaluation of Exercise and Training on Muscle Lipid Metabolism

Bergman

Butterfield

Wolfel

et al. 1998

Medicine & Science in Sports & Exercise

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. Evaluation of exercise and training on muscle lipid metabolism. Am. J. Physiol. 276 (Endocrinol. Metab. 39): E106-E117, 1999.-To evaluate the hypothesis that endurance training increases intramuscular triglyceride (IMTG) oxidation, we studied leg net free fatty acid (FFA) and glycerol exchange during 1 h of cycle ergometry at two intensities before training [45 and 65% of peak rate of oxygen consumption (V O 2 peak )] and after training [65% pretraining V O 2 peak , same absolute workload (ABT), and 65% posttraining V O 2 peak , same relative intensity (RLT)]. Nine male subjects (178.1 Ϯ 2.5 cm, 81.8 Ϯ 3.3 kg, 27.4 Ϯ 2.0 yr) were tested before and after 9 wk of cycle ergometer training, five times per week at 75% V O 2 peak . The power output that elicited 66.1 Ϯ 1.1% of V O 2 peak before training elicited 54.0 Ϯ 1.7% after training due to a 14.6 Ϯ 3.1% increase in V O 2 peak . Training significantly (P Ͻ 0.05) decreased pulmonary respiratory exchange ratio (RER) values at ABT (0.96 Ϯ 0.01 at 65% pre-vs. 0.93 Ϯ 0.01 posttraining) but not RLT (0.95 Ϯ 0.01). After training, leg respiratory quotient (RQ) was not significantly different at either ABT (0.98 Ϯ 0.02 pre-vs. 0.98 Ϯ 0.03 posttraining) or RLT (1.01 Ϯ 0.02). Net FFA uptake was increased at RLT but not ABT after training. FFA fractional extraction was not significantly different after training or at any exercise intensity. Net glycerol release, and therefore IMTG lipolysis calculated from three times net glycerol release, did not change from rest to exercise or at ABT but decreased at the same RLT after training. Muscle biopsies revealed minor muscle triglyceride changes during exercise. Simultaneous measurements of leg RQ, net FFA uptake, and glycerol release by working legs indicated no change in leg FFA oxidation, FFA uptake, or IMTG lipolysis during leg cycling exercise that elicits 65% pre-and 54% posttraining V O 2 peak . Training increases working muscle FFA uptake at 65% V O 2 peak , but high RER and RQ values at all work intensities indicate that FFA and IMTG are of secondary importance as fuels in moderate and greaterintensity exercise. exertion; free fatty acid; glucose; lactate; crossover concept; substrate shuttling EFFECTS OF EXERCISE intensity and training state on muscle lipid metabolism in humans are unclear, as the relatively few studies have utilized different experimental approaches. Some investigations have employed isotopic tracers and indirect calorimetry (25,29,33), whereas others have utilized arteriovenous (a-v) balance methods (17,22,35) and muscle biopsies (18,22

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Section: Glycerol Exchangementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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An Evaluation of Exercise and Training on Muscle Lipid Metabolism

Bergman

Butterfield

Wolfel

et al. 1998

Medicine & Science in Sports & Exercise

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“…There are metabolic conditions that stimulate fat oxidation. Acute conditions of stress, such as fasting, severe trauma, sepsis (Wolfe et al, 1983), and exercise of long duration (Phillips et al, 1996) are characterized by a stimulation of lipolysis, a rise in plasma free fatty acid (FFA) levels, and a stimulation of fat oxidation. Chronic conditions such as obesity and type II diabetes which are described as insulin-resistant states, are also characterized by increased lipolysis, elevated plasma FFA levels in the postabsorptive state, and stimulation of fat oxidation (Golay et al, 1995).…”

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Response to and range of acceptable fat intake in adults

Jéquier

1999

Eur J Clin Nutr

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Cellular energy metabolism depends on two main energy substrates: glucose and fatty acids. The major determinants of the fuel mix oxidized are glucose availability and insulin secretion that both promote glucose oxidation. Fatty acid oxidation occurs mainly when glucose availability is reduced, for instance during the postabsorptive period, or when energy expenditure is increased, for instance during exercise of long duration. When eucaloric diets with high carbohydrate and low fat content are ingested, de novo lipogenesis is stimulated in adults, but the rate of conversion of glucose to fatty acids is low, which means that carbohydrate intake does not have much in¯uence on fat requirements. The lower limit of fat intake depends on three factors: the fat requirement to meet energy needs, the need for essential fatty acids, and the amount of fat in the diet that is necessary to absorb fat-soluble vitamins. The lower limit of fat intake to meet the energy needs of adults is assumed to be between 10 and 15% of dietary energy, provided that enough carbohydrates are available. For adults, the requirement for essential fatty acids is in the range of 3 ± 5% of dietary energy for linoleic acid, and 0.5 ± 1.0% of dietary energy for linolenic acid. Fat energy should not be below 10% of total energy intake in order to ensure an unrestricted absorption of fat-soluble vitamins, particularly vitamins A and E. The recommendations on upper limits of fat intake for adults must take into account the degree of physical activity. International recommendations indicate that active individuals in energy balance may consume up to 35% of their total energy intake as dietary fat, whereas sedentary individuals should not consume more than 30% of their energy from fat. Saturated fatty acids should not exceed 10% of the energy intake. IntroductionWhile protein and energy requirements have been studied extensively in humans (Scrimshaw et al, 1972), the relative contribution of carbohydrates and fats to cover energy needs has received less attention. In many rural communities of developing countries, carbohydrates contribute between 70 and 75% to total energy intake, while fat intake contributes only 12 ± 15% (FAOUN, 1970). By contrast, the traditional adult Eskimo diet in the last century contained about 7% carbohydrate and 50% fat energy (Bang et al, 1980). A range of fat intake between 12 and 50% of total energy intake appears to be compatible with a normal body composition and the maintenance of good health in individuals who are adapted to these types of diets and to their environment. This does not imply, however, that these extreme values of fat and carbohydrate intakes can be recommended for adults of developed countries with a sedentary lifestyle. Lower limit of fat intake in adultsThe lower limit of fat intake depends on three factors: the fat requirement to meet energy needs, the need for essential fatty acids, and the amount of fat in the diet that is necessary to absorb the fat soluble vitamins.Fat requirement to meet energy nee...

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Metabolism during Exercise – Energy Expenditure and Hormonal Changes

Henriksson¹,

Sahlin²

2003

Textbook of Sports Medicine

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Effects of training duration on substrate turnover and oxidation during exercise

Cited by 234 publications

References 25 publications

An Evaluation of Exercise and Training on Muscle Lipid Metabolism

An Evaluation of Exercise and Training on Muscle Lipid Metabolism

Response to and range of acceptable fat intake in adults

Metabolism during Exercise – Energy Expenditure and Hormonal Changes

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