Increasing skeletal muscle carnitine content in older individuals increases whole‐body fat oxidation during moderate‐intensity exercise

Intramuscular triacylglycerols (IMTG) are proposed to be an important metabolic substrate for contracting muscle, although this remains controversial. To test the hypothesis that reduced plasma free fatty acid (FFA) availability would increase IMTG degradation during exercise, seven active men cycled for 180 min at 60% peak pulmonary O2 uptake either without (CON) or with (NA) prior ingestion of nicotinic acid to suppress adipose tissue lipolysis. Skeletal muscle and adipose tissue biopsy samples were obtained before and at 90 and 180 min of exercise. NA ingestion decreased ( P < 0.05) plasma FFA at rest and completely suppressed the exercise-induced increase in plasma FFA (180 min: CON, 1.42 ± 0.07; NA, 0.10 ± 0.01 mM). The decreased plasma FFA during NA was associated with decreased ( P < 0.05) adipose tissue hormone-sensitive lipase (HSL) activity (CON: 13.9 ± 2.5, NA: 9.1 ± 3.0 nmol·min−1·mg protein−1). NA ingestion resulted in decreased whole body fat oxidation and increased carbohydrate oxidation. Despite the decreased whole body fat oxidation, net IMTG degradation was greater in NA compared with CON (net change: CON, 2.3 ± 0.8; NA, 6.3 ± 1.2 mmol/kg dry mass). The increased IMTG degradation did not appear to be due to reduced fatty acid esterification, because glycerol 3-phosphate activity was not different between trials and was unaffected by exercise (rest: 0.21 ± 0.07; 180 min: 0.17 ± 0.04 nmol·min−1·mg protein−1). HSL activity was not increased from resting rates during exercise in either trial despite elevated plasma epinephrine, decreased plasma insulin, and increased ERK1/2 phosphorylation. AMP-activated protein kinase (AMPK)α1 activity was not affected by exercise or NA, whereas AMPKα2 activity was increased ( P < 0.05) from rest during exercise in NA and was greater ( P < 0.05) than in CON at 180 min. These data suggest that plasma FFA availability is an important mediator of net IMTG degradation, and in the absence of plasma FFA, IMTG degradation cannot maintain total fat oxidation. These changes in IMTG degradation appear to disassociate, however, from the activity of the key enzymes responsible for synthesis and degradation of this substrate.

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Menopause is associated with decreased whole body fat oxidation during exercise

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00492.2012 ◽

2013 ◽

Vol 304 (11) ◽

pp. E1227-E1236 ◽

Cited By ~ 37

Author(s):

J. Abildgaard ◽

A. T. Pedersen ◽

C. J. Green ◽

N. M. Harder-Lauridsen ◽

T. P. Solomon ◽

...

Keyword(s):

Skeletal Muscle ◽

Energy Expenditure ◽

Body Fat ◽

Pyruvate Dehydrogenase ◽

Premenopausal Women ◽

Exercise Bout ◽

Fat Oxidation ◽

Whole Body ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor

The purpose of this study was to examine if fat oxidation was affected by menopausal status and to investigate if this could be related to the oxidative capacity of skeletal muscle. Forty-one healthy women were enrolled in this cross-sectional study [premenopausal ( n = 19), perimenopausal ( n = 8), and postmenopausal ( n = 14)]. Estimated insulin sensitivity was obtained from an oral glucose tolerance test. Body composition was measured by dual-energy X-ray absorptiometry and magnetic resonance imaging. Fat oxidation and energy expenditure were measured during an acute exercise bout of 45 min of ergometer biking at 50% of maximal oxygen consumption (V̇o2 max). Muscle biopsies from the vastus lateralis of the quadriceps muscle were obtained before and immediately after the exercise bout. Postmenopausal women had 33% [confidence interval (CI) 95%: 12–55] lower whole body fat oxidation ( P = 0.005) and 19% (CI 95%: 9–22) lower energy expenditure ( P = 0.02) during exercise, as well as 4.28 kg lower lean body mass (LBM) than premenopausal women. Correction for LBM reduced differences in fat oxidation to 23% ( P = 0.05), whereas differences in energy expenditure disappeared ( P = 0.22). No differences between groups were found in mRNA [carnitine palmitoyltransferase I, β-hydroxyacyl-CoA dehydrogenase (β-HAD), peroxisome proliferator-activated receptor-α, citrate synthase (CS), pyruvate dehydrogenase kinase 4, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α)], protein [phosphorylated AMP-activated protein kinase (AMPK), vascular endothelial growth factor, pyruvate dehydrogenase-1Eα, cytochrome oxidase I], or enzyme activities (β-HAD, CS) in resting skeletal muscle, except for an increased protein level of cytochrome c in the post- and perimenopausal women relative to premenopausal women. Postmenopausal women demonstrated a trend to a blunted exercise-induced increase in phosphorylation of AMPK compared with premenopausal women ( P = 0.06). We conclude that reduced whole body fat oxidation after menopause is associated with reduced LBM.

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A reduced lactate mass explains much of the glycogen sparing associated with training

Journal of Applied Physiology ◽

10.1152/jappl.1996.81.1.362 ◽

1996 ◽

Vol 81 (1) ◽

pp. 362-367 ◽

Cited By ~ 9

Author(s):

M. A. Crowley ◽

W. T. Willis ◽

K. S. Matt ◽

C. M. Donovan

Keyword(s):

Endurance Training ◽

Exercise Bout ◽

Fat Oxidation ◽

Whole Body ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Pentobarbital Sodium ◽

Long Evans ◽

Glycogen Sparing

Endurance training is associated with glycogen (Gly) sparing, generally attributed to less carbohydrate (CHO) oxidation. However, untrained individuals commit a greater fraction of CHO to lactate (La), accounting for a portion of the Gly "spared." We examined the effects of training (running 1 h/day at 30 m/min up an 8 degrees grade) on whole body CHO distribution and oxidation. Female Long Evans rats (n = 27) were assigned to control (Untr) and trained (Tr) groups. Two days before the experiment, animals were chronically catheterized. On the day of the experiment, animals ran for 20 min at a speed of 28 m/min and were killed with an overdose of pentobarbital sodium injection while running. Whole carcasses were then promptly freeze-clamped with a liquid N2-cooled press. Whole body carcass powder was assayed for La, Gly, and glucose. Resting whole body values were not different between groups (La = 0.78 +/- 0.06 vs. 0.83 +/- 0.07, Gly = 4.46 +/- 0.62 vs. 3.77 +/- 0.35, glucose = 0.19 +/- 0.07 vs. 0.23 +/- 0.09 mmol/body for Tr and Untr rats, respectively). However, postexercise La was higher in Untr vs. Tr group (2.01 +/- 0.28 vs. 1.13 +/- 0.09 mmol/body), and Gly was lower in the Untr vs. Tr rats (1.58 +/- 0.25 vs. 3.42 +/- 0.43 mmol/body). Similarly, Untr animals displayed higher epinephrine levels than Tr at the end of the exercise bout (4.9 +/- 1.0 vs. 1.7 +/- 0.4 ng/ml). Differences between groups in La and glucose masses (postexercise minus rest data) accounted for 60% of the Gly differences. Gly spared from oxidation and replaced by increased fat oxidation only accounted for 40% of the differences in Gly levels between Tr and Untr animals. We conclude that untrained mammals commit a significant portion of their CHO pool to La, which accounts for almost one-half of the apparent Gly spared during moderate-intensity exercise in the trained state.

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Moderate intensity exercise training combined with inulin-propionate ester supplementation increases whole body resting fat oxidation in overweight women

Metabolism ◽

10.1016/j.metabol.2019.154043 ◽

2020 ◽

Vol 104 ◽

pp. 154043 ◽

Cited By ~ 2

Author(s):

Dalia Malkova ◽

Thelma Polyviou ◽

Eleni Rizou ◽

Konstantinos Gerasimidis ◽

Edward S. Chambers ◽

...

Keyword(s):

Exercise Training ◽

Fat Oxidation ◽

Whole Body ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Overweight Women

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Acetate Does Not Affect Palmitate Oxidation and AMPK Phosphorylation in Human Primary Skeletal Muscle Cells

Frontiers in Endocrinology ◽

10.3389/fendo.2021.659928 ◽

2021 ◽

Vol 12 ◽

Author(s):

Manuel A. González Hernández ◽

Ellen E. Blaak ◽

Nicole T. H. Hoebers ◽

Yvonne P. G. Essers ◽

Emanuel E. Canfora ◽

...

Keyword(s):

Skeletal Muscle ◽

Body Fat ◽

Muscle Cells ◽

Fat Oxidation ◽

Skeletal Muscle Cells ◽

Whole Body ◽

Mediated Effects ◽

Male Donor ◽

Underlying Mechanisms

Our recent in vivo human studies showed that colonic administration of sodium acetate (SA) resulted in increased circulating acetate levels, which was accompanied by increments in whole-body fat oxidation in overweight-obese men. Since skeletal muscle has a major role in whole-body fat oxidation, we aimed to investigate effects of SA on fat oxidation and underlying mechanisms in human primary skeletal muscle cells (HSkMC). We investigated the dose (0–5 mmol/L) and time (1, 4, 20, and 24 h) effect of SA on complete and incomplete endogenous and exogenous oxidation of 14C-labeled palmitate in HSkMC derived from a lean insulin sensitive male donor. Both physiological (0.1 and 0.25 mmol/L) and supraphysiological (0.5, 1 and 5 mmol/L) concentrations of SA neither increased endogenous nor exogenous fat oxidation over time in HSkMC. In addition, no effect of SA was observed on Thr172-AMPKα phosphorylation. In conclusion, our previously observed in vivo effects of SA on whole-body fat oxidation in men may not be explained via direct effects on HSkMC fat oxidation. Nevertheless, SA-mediated effects on whole-body fat oxidation may be triggered by other mechanisms including gut-derived hormones or may occur in other metabolically active tissues.

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Protein consumption following aerobic exercise increases whole-body protein turnover in older adults

Applied Physiology Nutrition and Metabolism ◽

10.1139/h10-047 ◽

2010 ◽

Vol 35 (5) ◽

pp. 583-590 ◽

Cited By ~ 16

Author(s):

Cheryl Murphy ◽

Benjamin F. Miller

Keyword(s):

Older Adults ◽

Aerobic Exercise ◽

Protein Turnover ◽

Whole Body ◽

Moderate Intensity ◽

Older Individuals ◽

Moderate Intensity Exercise ◽

Body Protein ◽

Healthy Older Adults ◽

Postexercise Recovery

Research measuring whole-body protein turnover (WBPT) after both exercise and nutrition has generally focused on resistance exercise; however, there is a paucity of data regarding the effect of postaerobic exercise nutrition, especially in older adults. It is not known if postexercise protein feeding has a beneficial effect on protein turnover after low- to moderate-intensity exercise. We investigated whether consuming protein plus carbohydrate (PRO) immediately after an acute bout of aerobic exercise has an additive effect over carbohydrate alone (CHO) on WBPT in older individuals. Twelve healthy older adults (age, 59 ± 4 years) were studied on 2 separate occasions after 1 h of exercise at approximately 50% of maximal rate of oxygen uptake, followed by 4 h of recovery. Immediately following exercise, subjects ingested a CHO (60 g) or an isocaloric PRO beverage (40 g carbohydrate, 20 g whey protein). Whole-body protein metabolism was determined using [1-13C]leucine infusion (60 mg prime; 75 mg·h–1 continuous), and sampling blood and expired breath. Rates of whole-body leucine appearance and oxidation, and nonoxidative leucine disposal during the third and fourth hours of postexercise recovery were higher in the PRO group (2.51 ± 0.55, 0.78 ± 0.37, and 1.71 ± 0.44 µmol·kg–1·min–1, respectively) than in the CHO group (1.81 ± 0.27, 0.33 ± 0.14, and 1.47 ± 0.25 µmol·kg–1·min–1, respectively; p = 0.001). Our results indicate that consumption of a PRO beverage after aerobic exercise increased WBPT to a greater extent than a CHO beverage.

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