The Acute Effects of Supramaximal High-Intensity Intermittent Exercise on Vascular Function in Lean vs. Obese Prepubescent Boys

2015 ◽  
Vol 27 (4) ◽  
pp. 503-509 ◽  
Author(s):  
Napasakorn Chuensiri ◽  
Hirofumi Tanaka ◽  
Daroonwan Suksom
Keyword(s):  
Energy Expenditure ◽  
Total Energy ◽  
Exercise Intensity ◽  
High Intensity ◽  
Vascular Function ◽  
Intermittent Exercise ◽  
Total Energy Expenditure ◽  
Obese Group ◽  
Acute Effects ◽  
Lean Group

Purpose:To determine the acute effects of high-intensity intermittent exercise (HIIE) on vascular function.Methods:Lean (n = 18, BMI = 17.1 ± 0.7) and obese (n = 17, BMI = 25.4 ± 0.8) prepubescent boys aged 10.2 ± 0.2 years were studied. HIIE consisted of 8 sets of 20 s of cycle ergometry at 100, 130, and 170% of VO2peak alternating with 10 s of rests.Results:The obese group had higher (p < .05) body mass, BMI, body fat percentage, waist-hip ratio than the lean group. Carotid artery wall thickness and arterial stiffness as assessed by brachial-ankle pulse wave velocity (baPWV) were greater in the obese than in the lean group (p < .05). Brachial artery flow-mediated dilation (FMD) was not different between the groups. Total energy expenditure increased gradually as the exercise intensity increased in both groups (p < .05). The obese group had significantly greater total energy expenditure in all three HIIE intensities than the lean group. FMD tended to be higher and baPWV lower as the exercise intensity increased in both groups. Only the HIIE at 170% demonstrated greater FMD compared with the baseline in both groups. baPWV decreased significantly after HIIE at 130 and 170% VO2peak in both groups.Conclusion:Supramaximal HIIE can be a feasible exercise modality for improving vascular function in obese prepubescent boys. Future exercise intervention studies are warranted.

scholarly journals Does skeletal muscle carnitine availability influence fuel selection during exercise?

2017 ◽  
Vol 77 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Francis B. Stephens
Keyword(s):  
Skeletal Muscle ◽  
Energy Expenditure ◽  
Total Energy ◽  
Exercise Intensity ◽  
Human Subjects ◽  
Maximal Oxygen Consumption ◽  
Fat Oxidation ◽  
Total Energy Expenditure ◽  
Fuel Selection

Fat and carbohydrate are the major fuel sources utilised for oxidative, mitochondrial ATP resynthesis during human skeletal muscle contraction. The relative contribution of these two substrates to ATP resynthesis and total energy expenditure during exercise can vary substantially, and is predominantly determined by fuel availability and exercise intensity and duration. For example, the increased ATP demand that occurs with an increase in exercise intensity is met by increases in both fat and carbohydrate oxidation up to an intensity of approximately 60–70 % of maximal oxygen consumption. When exercise intensity increases beyond this workload, skeletal muscle carbohydrate utilisation is accelerated, which results in a reduction and inhibition of the relative and absolute contribution of fat oxidation to total energy expenditure. However, the precise mechanisms regulating muscle fuel selection and underpinning the decline in fat oxidation remain unclear. This brief review will primarily address the theory that a carbohydrate flux-mediated reduction in the availability of muscle carnitine to the mitochondrial enzyme carnitine palmitoyltransferase 1, a rate-limiting step in mitochondrial fat translocation, is a key mechanism for the decline in fat oxidation during high-intensity exercise. This is discussed in relation to recent work in this area investigating fuel metabolism at various exercise intensities and taking advantage of the discovery that skeletal muscle carnitine content can be nutritionally increased in vivo in human subjects.

scholarly journals Effect of Change in VO2max on Daily Total Energy Expenditure in a Cohort of Norwegian Men: A Randomized Pilot Study

2015 ◽  
Vol 9 (1) ◽  
pp. 50-57 ◽  
Author(s):  
Nina Zisko ◽  
Dorthe Stensvold ◽  
Katrine Hordnes-Slagsvold ◽  
Øivind Rognmo ◽  
Javaid Nauman ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Exercise Training ◽  
Total Energy ◽  
Mitochondrial Function ◽  
High Intensity ◽  
Citrate Synthase ◽  
Interval Training ◽  
Total Energy Expenditure ◽  
Aerobic Interval Training ◽  
Daily Total

Objective: To investigate how a change in VO2max induced through 6 weeks of high intensity aerobic interval training affects daily total energy expenditure (TEE), active energy expenditure (AEE) and mitochondrial function in people not previously exposed to structured high intensity aerobic interval training (AIT). Methods: Thirty healthy males (39±6 yrs) not exposed to structured exercise training were randomized to either 1x4 min AIT (1-AIT), 4x4 min AIT (4-AIT), both at 90-95% maximum heart rate (HRmax) or 47 min of MCT at 70% HRmax. TEE, AEE, number of steps, active time, sedentary time, VO2max and mitochondrial function in m. vastus lateralis were measured before and after intervention. Results: TEE increased 14% (p=0.014) and AEE increased 43% (p= 0.004) after MCT. There was no change in TEE or AEE after 1-AIT or 4-AIT, but 1-AIT had significantly lower TEE (p=0.033) and step-count (p=0.011) compared to MCT post intervention. VO2max increased 7% after 1-AIT (p= 0.004) and 9% after 4-AIT (p=0.004), with no change after MCT. No change was observed in maximal mitochondrial respiration (VMAX) or Citrate Synthase (CS) activity within or between interventions. Basal respiration (V0) increased after 1-AIT (p=0.029) and 4-AIT (p=0.022), with no significant change after MCT. Conclusion: AIT interventions that increase VO2max, do not stimulate subjects to increase TEE or AEE. The intensity of exercise seems to play apart, as MCT increased TEE and AEE and AIT did not. Emphasis should be placed on the importance of maintaining everyday activities when introducing structured exercise training to untrained individuals.

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

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 &lt; 0.05) and a decreased fat oxidation (51 vs. 62 of total energy expenditure; P &lt; 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 &lt; 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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