Oxidation rate of exogenous carbohydrate during  exercise is higher in boys than in men

To determine whether the relative utilization of exogenous carbohydrate (CHOexo) differs between children and adults, substrate utilization during 60 min of cycling at 70% peak O2 uptake was studied in 12 pre- and early pubertal boys (9.8 ± 0.1 yr) and 10 men (22.1 ± 0.5 yr) on two occasions. Subjects consumed either a placebo or a13C-enriched 6% CHOexo beverage (total volume per trial: 24 ml/kg). Substrate utilization was calculated for the final 30 min of exercise. During both trials, total fat oxidation was higher (5.4 ± 0.5 vs. 3.0 ± 0.4 mg · kg−1 · min−1, P < 0.001) and total CHO oxidation lower (27.4 ± 1.5 vs. 34.8 ± 1.2 mg · kg−1 · min−1, P < 0.001) in boys than in men, respectively. During the CHOexo trial, CHOexo oxidation was higher ( P < 0.001) in boys (8.8 ± 0.5 mg · kg−1 · min−1) than in men (6.2 ± 0.5 mg · kg−1 · min−1) and provided a greater ( P < 0.001) relative proportion of total energy in boys (21.8 ± 1.4%) than in men (14.6 ± 0.9%). These results suggest that, although endogenous CHO utilization during exercise is lower, the relative oxidation of ingested CHO is considerably higher in boys than in men. The greater reliance on CHOexo in boys may be important in preserving endogenous fuels and may be related to pubertal status.

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Influence of age and pubertal status on substrate utilization during exercise with and without carbohydrate intake in healthy boys

Applied Physiology Nutrition and Metabolism ◽

10.1139/h07-004 ◽

2007 ◽

Vol 32 (3) ◽

pp. 416-425 ◽

Cited By ~ 43

Author(s):

Brian W. Timmons ◽

Oded Bar-Or ◽

Michael C. Riddell

Keyword(s):

Stable Isotope ◽

Energy Expenditure ◽

Aerobic Power ◽

Fat Oxidation ◽

Substrate Utilization ◽

Maximal Aerobic Power ◽

Chronological Age ◽

Pubertal Status ◽

Oxidation Rates ◽

Pubertal Boys

Substrate utilization during exercise is known to differ between children and adults, but whether these differences are related to pubertal status is unclear. The objective of this study was to investigate the effects of pubertal status on endogenous (CHOendo) and orally ingested exogenous (CHOexo) carbohydrate and fat oxidation rates during exercise. Twenty boys at the same chronological age (12 y) were divided into three pubertal groups (pre-pubertal, PP: n = 7; early-pubertal, EP: n = 7; mid- to late-pubertal, M-LP: n = 6) and consumed either a placebo or13C-enriched 6% CHO drink while cycling for 60 min at ~70% of their maximal aerobic power (VO2 max). Another group of 14-year-old boys (pubertal, n = 9) completed all procedures. Substrate utilization was calculated for the final 15 min of exercise using indirect calorimetry and stable isotope methodology. CHOexodecreased fat (p < 0.001) and increased total CHO (p < 0.001) oxidation, irrespective of group. Fat oxidation was higher (p = 0.01) in younger boys than in older boys, but similar (p ≥ 0.33) among PP, EP, and M-LP boys. CHOexocontributed to ~30% of energy expenditure (EE) in PP and EP, but to only 24% in M-LP (p = 0.02), which was identical to the older boys (24%). CHOexooxidation rate as a percentage of EE was inversely related to testosterone levels (r = −0.51, p = 0.005, n = 29). It was concluded that reliance on CHOexoduring exercise is particularly sensitive to pubertal status, with the highest oxidation rates observed in pre- and early-pubertal boys, independent of chronological age.

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β-Adrenergically Stimulated Fat Oxidation Is Diminished in Middle-Aged Compared to Young Subjects*

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.84.10.6043 ◽

1999 ◽

Vol 84 (10) ◽

pp. 3764-3769

Author(s):

E. E. Blaak ◽

M. A. van Baak ◽

W. H. M. Saris

Keyword(s):

Skeletal Muscle ◽

Energy Expenditure ◽

Total Energy ◽

Fat Oxidation ◽

Substrate Utilization ◽

Total Energy Expenditure ◽

Adrenergic Stimulation ◽

Middle Aged ◽

Older Subjects ◽

Young Subjects

Abstract The effect of aging on β-adrenergically mediated substrate utilization was investigated in nine young (25.2 ± 1.7 yr old) and eight older males (52.9 ± 2.1 yr old), matched for body weight and body composition. In a first experiment, the nonselectiveβ -agonist isoprenaline (ISO) was infused in increasing standardized doses, and during each infusion period energy expenditure and substrate utilization were determined by indirect calorimetry. In a second experiment, forearm skeletal muscle metabolism was studied during a standardized infusion dose of ISO (19 ng/kg fat-free mass·min). During β-adrenergic stimulation there was an increased carbohydrate oxidation (at an ISO infusion dose of 24 ng/kg fat-free mass·min, 31% vs. 21% of total energy expenditure; P < 0.05) and a decreased fat oxidation (51 vs. 62 of total energy expenditure; P < 0.05) in older compared to young subjects. Skeletal muscle lactate release significantly increased in the older subjects (from −175 ± 32 to −366 ± 66 nmol/100 mL forearm tissue·min), whereas there was no change in young subjects (from− 32 ± 21 to 23 ± 57 nmol/100 mL forearm tissue·min; interaction group × ISO, P < 0.01). Additionally, there was a tendency toward a blunted ISO-induced increase in nonesterified fatty acid uptake in the older subjects (interaction group × ISO, P = 0.062). Thus, middle-aged subjects have a blunted ability to oxidize fat during β-adrenergic stimulation compared to young subjects. This diminished fat oxidation may be an important etiological factor in the age-related increase in body fatness and obesity by favoring fat storage above oxidation.

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Energy substrate utilization with and without exogenous carbohydrate intake in boys and men exercising in the heat

Journal of Applied Physiology ◽

10.1152/japplphysiol.00535.2016 ◽

2016 ◽

Vol 121 (5) ◽

pp. 1127-1134 ◽

Cited By ~ 1

Author(s):

Gabriela T. Leites ◽

Giovani S. Cunha ◽

Lisa Chu ◽

Flavia Meyer ◽

Brian W. Timmons

Keyword(s):

Total Energy ◽

Oxidation Rate ◽

Substrate Utilization ◽

Fat Free Mass ◽

Energy Yield ◽

Total Carbohydrate ◽

Relative Contribution ◽

Endogenous Substrate ◽

Oxidation Efficiency ◽

Over Time

Little is known about energy yield during exercise in the heat in boys compared with men. To investigate substrate utilization with and without exogenous carbohydrate (CHOexo) intake, seven boys [11.2 ± 0.2 (SE) yr] and nine men (24.0 ± 1.1 yr) cycled (4 × 20-min bouts) at a fixed metabolic heat production ( Ḣ p) per unit body mass (6 W/kg) in a climate chamber (38°C and 50% relative humidity), on two occasions. Participants consumed a 13C-enriched 8% CHO beverage (CARB) or placebo beverage (CONT) in a double-blinded, counterbalanced manner. Substrate utilization was calculated for the last 60 min of exercise. CHOexo oxidation rate (2.0 ± 0.3 vs. 2.5 ± 0.2 mg·kg fat-free mass−1·min−1, P = 0.02) and CHOexo oxidation efficiency (12.8 ± 0.6 vs. 16.0 ± 0.9%, P = 0.01) were lower in boys compared with men exercising in the heat. Total carbohydrate (CHOtotal), endogenous CHO (CHOendo), and total fat (Fattotal) remained stable in boys and men ( P > 0.05) during CARB, whereas CHOtotal oxidation rate decreased ( P < 0.001) and Fattotal oxidation rate increased over time similarly in boys and men during CONT ( P < 0.001). The relative contribution of CHOexo to total energy yield increased over time in both groups ( P < 0.001). In conclusion, endogenous substrate metabolism and the relative contribution of fuels to total energy yield were not different between groups. The ingestion of a CHO beverage during exercise in the heat may be as beneficial for boys as men to spare endogenous substrate.

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Substrate utilization and enzymes in skeletal muscle of extremely endurance-trained men

Journal of Applied Physiology ◽

10.1152/jappl.1987.62.3.999 ◽

1987 ◽

Vol 62 (3) ◽

pp. 999-1005 ◽

Cited By ~ 135

Author(s):

E. Jansson ◽

L. Kaijser

Keyword(s):

Vastus Lateralis ◽

Relative Proportion ◽

Plasma Free Fatty Acid ◽

Fat Oxidation ◽

Substrate Utilization ◽

Acid Extraction ◽

Vo2 Max ◽

Muscle Lactate ◽

Carbohydrate Utilization ◽

O2 Extraction

Substrate utilization during exercise at 65% of maximal O2 uptake (VO2 max) and biochemical characteristics of vastus lateralis were compared between five endurance-trained (T) and five untrained subjects (U). The oxidative enzyme activities were 100% greater in T than in U, and VO2 max was 50% higher. A greater proportion of ATP regeneration occurred through oxidative processes in T than in U (smaller leg lactate release and smaller muscle lactate accumulation). The respiratory exchange ratio together with the local leg respiratory quotient indicated a greater contribution of fat to oxidative metabolism in T than U (53 vs. 33%). No difference, however, in the ratio of plasma free fatty acid extraction to O2 extraction by the working legs was found between T and U. Thus it could be calculated that a greater fraction of fat oxidation would have been covered by intramuscular triglycerides in T than in U (34 vs. 15%, P less than 0.05). T in comparison to U were further characterized by a smaller glycogen breakdown and a smaller glucose uptake, which may have been one contributing factor that prevented the blood glucose level from falling in T. The greater leg muscle citrate concentration in T could have been one factor mediating a lower carbohydrate utilization as a response to an increase in the relative proportion of fat oxidation.

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Acute p-synephrine ingestion increases fat oxidation rate during exercise

British Journal of Clinical Pharmacology ◽

10.1111/bcp.12952 ◽

2016 ◽

Vol 82 (2) ◽

pp. 362-368 ◽

Cited By ~ 19

Author(s):

Jorge Gutiérrez-Hellín ◽

Juan Del Coso

Keyword(s):

Oxidation Rate ◽

Fat Oxidation

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Substrate oxidation during exercise in taekwondo athletes: impact of aerobic fitness status

Comparative Exercise Physiology ◽

10.3920/cep200012 ◽

2020 ◽

Vol 16 (5) ◽

pp. 371-376

Author(s):

B. Taati ◽

H. Rohani

Keyword(s):

Aerobic Fitness ◽

Oxidation Rate ◽

Fat Oxidation ◽

Potential Effect ◽

Substrate Oxidation ◽

Training Experience ◽

Male Athletes ◽

Fitness Level ◽

Oxidation Rates ◽

Maximal Fat Oxidation

The present study aimed to investigate the potential effect of different aerobic fitness levels on substrate oxidation in trained taekwondo athletes. 57 male athletes (age 21.10±7.79 years; VO2max 50.67±6.67 ml/kg/min) with regular weekly taekwondo training and training experience of at least three years completed a graded exercise test to exhaustion on a treadmill. Maximal fat oxidation (MFO), the exercise intensity related to MFO (Fatmax), and carbohydrate (CHO) oxidation rate were measured using indirect calorimetry methods. The athletes then were divided into a low (<50 ml/kg/min, n=18) and high (>50 ml/kg/min, n=39) VO2max group. The average MFO was higher in the high VO2max group than in the low VO2max group (0.46±0.19 vs 0.28±0.11 g/min; P<0.001). Although Fatmax tended toward higher values in the high VO2max group, no difference was observed between the groups (49.15±15.22 vs 42.42±12.37% of VO2max; P=0.18). It was also shown that the high VO2max group had a lower CHO oxidation rate and a higher fat oxidation rate at given exercise intensities. In conclusion, it seems that MFO and substrate oxidation rates in taekwondo athletes can be influenced by aerobic fitness level such that the athletes with higher VO2max appeared to use more fat as a fuel source for energy supply during a given exercise.

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Abstract 653: Muscle Ring Finger-1 (MuRF1) Expression Shifts Cardiomyocyte Substrate Utilization from Fatty Acids to Glucose

Circulation ◽

10.1161/circ.116.suppl_16.ii_120-c ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Monte S Willis ◽

Jon Schisler ◽

Holly McDonough ◽

Cam Patterson

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Fatty Acid Oxidation ◽

Glucose Oxidation ◽

Relative Proportion ◽

Substrate Utilization ◽

Acid Oxidation ◽

Protective Mechanism ◽

Dependent Manner ◽

Dose Dependent

Previous work has suggested that MuRF1, a cardiac-specific protein, regulates metabolism by its interactions with proteins that regulate ATP transport, glycolysis, and the electron transport chain. We recently identified that MuRF1 is cardioprotective in ischemia reperfusion injury. In the current study, we investigated the effects of MuRF1 expression on metabolic substrate utilization and found that MuRF1 shifts substrate utilization from fatty acids to glucose in a dose-dependent manner. Isolated neonatal ventricular cardiomyocytes were treated with an adenovirus expressing MuRF1 (Ad.MuRF1) or GFP (Ad.GFP) at a range of 0–25 MOI (Multiplicity Of Infection). 14C-Oleate or 14C-glucose were added to cells for 1 hour and 14C-CO2 release was determined using the CO2-trapping method. Trapped 14CO2 and acid soluble metabolites were used to calculate total fatty acid oxidation. Cardiomyocytes treated with 5–25 MOI Ad.MuRF1 demonstrated a dose dependent decrease in fatty acid oxidation of 10.5 +/− 2.3(5 MOI), 8.5 +/− 1.9 (10 MOI), 6.6 +/− 1.6 (15 MOI), and 5.1 +/− 1.3 (25 MOI) nmol oleate/mg protein/h. Compared with control cardiomyocytes treated with 5–25 MOI Ad.GFP (average of 5–25 MOI=13.5 +/− 0.7 nmol oleate/mg protein/h), this represents a 22.2%– 62.2% decrease in fatty acid oxidation. Inversely, glucose oxidation increased with increasing MuRF1 expression. Cardiomyocytes infected with 25 MOI Ad.MuRF1 oxidized 184% more glucose (28.9 +/− 4.6 nmol glucose/mg protein/h) compared to control cells treated with 25 MOI Ad.GFP (15.7 +/− 1.3 nmol glucose/mg protein/h). Increasing MuRF1 expression resulted in no net gain or loss of calculated ATP production (1699 +/− 157 vs. 1480 +/− 188 nmol ATP/mg protein/h). The co-utilization of glucose and fatty acids as substrates for the production of ATP allows the heart to adapt to both environmental stress and disease. Increasing the relative proportion of glucose oxidation in relationship to fatty acids is a known protective mechanism during cardiac stress, and may represent one mechanism by which MuRF1 is cardioprotective.

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Body Fat has No Effect on the Maximal Fat Oxidation Rate in Young, Normal, and Overweight Women

The Journal of Strength and Conditioning Research ◽

10.1519/jsc.0000000000000512 ◽

2014 ◽

Vol 28 (8) ◽

pp. 2121-2126 ◽

Cited By ~ 5

Author(s):

Ashley N. Blaize ◽

Jeffrey A. Potteiger ◽

Randal P. Claytor ◽

Douglas A. Noe

Keyword(s):

Body Fat ◽

Oxidation Rate ◽

Fat Oxidation ◽

Overweight Women ◽

Maximal Fat Oxidation

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Effect of Acute Caffeine Intake on the Fat Oxidation Rate during Exercise: A Systematic Review and Meta-Analysis

Nutrients ◽

10.3390/nu12123603 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3603

Author(s):

Daniel Collado-Mateo ◽

Ana Myriam Lavín-Pérez ◽

Eugenio Merellano-Navarro ◽

Juan Del Coso

Keyword(s):

Systematic Review ◽

Oxidation Rate ◽

Meta Analysis ◽

Fat Oxidation ◽

Caffeine Intake ◽

Fasting Period ◽

Fitness Level ◽

Recreational Athletes ◽

Other Substances ◽

Dose Response Effect

A number of previous investigations have been designed to determine the effect of acute caffeine intake on the rate of fat oxidation during exercise. However, these investigations have shown contradictory results due to the differences in the exercise protocols used or the co-ingestion of caffeine with other substances. Hence, to date, there is no consensus about the effect of caffeine on fat oxidation during exercise. The purpose of this study was to conduct a systematic review followed by a meta-analysis to establish the effect of acute intake of caffeine (ranging from 2 to 7 mg/kg of body mass) on the rate of fat oxidation during exercise. A total of 19 studies published between 1978 and 2020 were included, all of which employed crossover experimental designs in which the ingestion of caffeine was compared to a placebo. Studies were selected if the exercise intensity was consistent in the caffeine and placebo trials and if these were preceded by a fasting protocol. A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD). The meta-analysis revealed that caffeine significantly (p = 0.008) increased the fat oxidation rate (SMD = 0.73; 95% CI = 0.19 to 1.27). This increment was consistent with a significant (p = 0.04) reduction of the respiratory exchange ratio (SMD = −0.33; 95% CI = −0.65 to −0.01) and a significant (p = 0.049) increase in the oxygen uptake (SMD = 0.23; 95% CI = 0.01 to 0.44). The results also showed that there was a dose–response effect of caffeine on the fat oxidation rate, indicating that more than 3.0 mg/kg is necessary to obtain a statistically significant effect of this stimulant on fat oxidation during exercise. Additionally, the ability of caffeine to enhance fat oxidation during exercise was higher in sedentary or untrained individuals than in trained and recreational athletes. In conclusion, pre-exercise intake of a moderate dose of caffeine may effectively increase fat utilization during aerobic exercise of submaximal intensity performed after a fasting period. However, the fitness level of the participant may modulate the magnitude of the effect of caffeine on fat oxidation during exercise.

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