Intramyocellular triacylglycerol in prolonged cycling with high- and low-carbohydrate availability

2003 ◽  
Vol 94 (4) ◽  
pp. 1365-1372 ◽  
Author(s):  
N. A. Johnson ◽  
S. R. Stannard ◽  
K. Mehalski ◽  
M. I. Trenell ◽  
T. Sachinwalla ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Time Trial ◽  
Exercise Bout ◽  
Whole Body ◽  
Strenuous Exercise ◽  
Resonance Spectroscopy ◽  
Double Blind ◽  
Low Carbohydrate ◽  
Before And After ◽  
Experimental Trials

Vastus lateralis intramyocellular lipid (IMCL) content was assessed by1H-magnetic resonance spectroscopy before and after prolonged time trial cycling bouts of ∼3-h duration. Six highly trained male cyclists completed a double-blind, randomized, crossover design of two experimental trials after a strenuous exercise bout and 48 h of high (HC) (9.32 ± 0.08 g · kg−1 · day−1) and low (LC) (0.59 ± 0.21 g · kg−1 · day−1) dietary carbohydrate. Resting IMCL content was significantly higher after LC vs. HC ( P < 0.01) and was reduced during exercise by 64 and 57%, respectively. IMCL was not different between conditions after exercise ( P > 0.05). The approximately twofold increase in IMCL degradation in LC compared with HC suggests that higher rates of whole body lipid metabolism in LC were in part attributable to a greater IMCL utilization. Four subjects experienced reductions of IMCL in excess of 70% during exercise. To our knowledge, this is the first study to report near depletion of IMCL during prolonged cycling, indicating that IMCL, presumably the triacylglycerol component, may be exhausted by prolonged strenuous exercise.

scholarly journals n-3 Polyunsaturated Fatty Acids Do Not Alter Immune and Inflammation Measures in Endurance Athletes

2009 ◽  
Vol 19 (5) ◽  
pp. 536-546 ◽  
Author(s):  
David C. Nieman ◽  
Dru A. Henson ◽  
Steven R. McAnulty ◽  
Fuxia Jin ◽  
Kendra R. Maxwell
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Exercise Performance ◽  
Time Trial ◽  
Exercise Bout ◽  
Double Blind ◽  
Epa And Dha ◽  
Before And After ◽  
Plasma Cytokines ◽  
Exercise Induced

The purpose of this study was to test the influence of 2.4 g/d fish oil n-3 polyunsaturated fatty acids (n-3 PUFA) over 6 wk on exercise performance, inflammation, and immune measures in 23 trained cyclists before and after a 3-d period of intense exercise. Participants were randomized to n-3 PUFA (n = 11; 2,000 mg eicosapentaenoic acid [EPA], 400 mg docosahexaenoic acid [DHA]) or placebo (n = 12) groups. They ingested supplements under double-blind methods for 6 wk before and during a 3-d period in which they cycled for 3 hr/d at ~57% Wmax with 10-km time trials inserted during the final 15 min of each 3-hr bout. Blood and saliva samples were collected before and after the 6-wk supplementation period, immediately after the 3-hr exercise bout on the third day, and 14 hr postexercise and analyzed for various immune-function and inflammation parameters. Supplementation with n-3 PUFA resulted in a significant increase in plasma EPA and DHA but had no effect on 10-km time-trial performance; preexercise outcome measures; exercise-induced increases in plasma cytokines, myeloperoxidase, blood total leukocytes, serum C-reactive protein, and creatine kinase; or the decrease in the salivary IgA:protein ratio. In conclusion, 6 wk supplementation with a large daily dose of n-3 PUFAs increased plasma EPA and DHA but had no effect on exercise performance or in countering measures of inflammation and immunity before or after a 3-d period of 9 hr of heavy exertion.

Carbohydrate and Protein Co-Ingestion Postexercise Does Not Improve Next-Day Performance in Trained Cyclists

2021 ◽  
pp. 1-9
Author(s):  
Hilkka Kontro ◽  
Marta Kozior ◽  
Gráinne Whelehan ◽  
Miryam Amigo-Benavent ◽  
Catherine Norton ◽  
...  
Keyword(s):  
Whey Protein ◽  
Protein Hydrolysate ◽  
Insulin Response ◽  
Time Trial ◽  
Exercise Bout ◽  
Whey Protein Concentrate ◽  
Glucose Disposal ◽  
Double Blind ◽  
Time Trial Performance ◽  
Trial Performance

Supplementing postexercise carbohydrate (CHO) intake with protein has been suggested to enhance recovery from endurance exercise. The aim of this study was to investigate whether adding protein to the recovery drink can improve 24-hr recovery when CHO intake is suboptimal. In a double-blind crossover design, 12 trained men performed three 2-day trials consisting of constant-load exercise to reduce glycogen on Day 1, followed by ingestion of a CHO drink (1.2 g·kg−1·2 hr−1) either without or with added whey protein concentrate (CHO + PRO) or whey protein hydrolysate (CHO + PROH) (0.3 g·kg−1·2 hr−1). Arterialized blood glucose and insulin responses were analyzed for 2 hr postingestion. Time-trial performance was measured the next day after another bout of glycogen-reducing exercise. The 30-min time-trial performance did not differ between the three trials (M ± SD, 401 ± 75, 411 ± 80, 404 ± 58 kJ in CHO, CHO + PRO, and CHO + PROH, respectively, p = .83). No significant differences were found in glucose disposal (area under the curve [AUC]) between the postexercise conditions (364 ± 107, 341 ± 76, and 330 ± 147, mmol·L−1·2 hr−1, respectively). Insulin AUC was lower in CHO (18.1 ± 7.7 nmol·L−1·2 hr−1) compared with CHO + PRO and CHO + PROH (24.6 ± 12.4 vs. 24.5 ± 10.6, p = .036 and .015). No difference in insulin AUC was found between CHO + PRO and CHO + PROH. Despite a higher acute insulin response, adding protein to a CHO-based recovery drink after a prolonged, high-intensity exercise bout did not change next-day exercise capacity when overall 24-hr macronutrient and caloric intake was controlled.

scholarly journals Effects of Monomeric and Oligomeric Flavanols on Kidney Function, Inflammation and Oxidative Stress in Runners: A Randomized Double-Blind Pilot Study

Nutrients ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1634 ◽  
Author(s):  
Khrystyna O. Semen ◽  
Antje R. Weseler ◽  
Marcel J. W. Janssen ◽  
Marie-José Drittij-Reijnders ◽  
Jos L. M. L. le Noble ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Kidney Function ◽  
Randomized Study ◽  
Kidney Injury ◽  
Strenuous Exercise ◽  
Vitis Vinifera L ◽  
Grape Seeds ◽  
Double Blind ◽  
Before And After ◽  
And Oxidative Stress

Nonsteroidal anti-inflammatory drugs are frequently used by athletes in order to prevent musculoskeletal pain and improve performance. In combination with strenuous exercise, they can contribute to a reduction of renal blood flow and promote development of kidney damage. We aimed to investigate whether monomeric and oligomeric flavanols (MOF) could reduce the severity of kidney injuries associated with the intake of 400-mg ibuprofen followed by the completion of a half-marathon in recreational athletes. In this double-blind, randomized study, the original MOF blend of extracts from grape seeds (Vitis vinifera L.) and pine bark (Pinus pinaster L.) or placebo were taken for 14 days preceding the ibuprofen/half-marathon. Urine samples were collected before and after the ibuprofen/half-marathon, and biomarkers of kidney injury, inflammation and oxidative stress were assessed. Intake of MOF significantly reduced the incidence of post-race hematuria (p = 0.0004) and lowered concentrations of interleukin (IL)-6 in the urine (p = 0.032). Urinary neutrophil-associated lipocalin, creatine, albumin, IL-8 and malondialdehyde tended to decrease. The supplementation with MOF in recreational runners appears to safely preserve kidney function, reduce inflammation and promote antioxidant defense during strenuous exercise and intake of a single dose of ibuprofen.

scholarly journals Caffeine Supplementation for 4 Days Does Not Induce Tolerance to the Ergogenic Effects Promoted by Acute Intake on Physiological, Metabolic, and Performance Parameters of Cyclists: A Randomized, Double-Blind, Crossover, Placebo-Controlled Study

Nutrients ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2101
Author(s):  
Anderson Pontes Morales ◽  
Felipe Sampaio-Jorge ◽  
Thiago Barth ◽  
Anna Paola Trindade Rocha Pierucci ◽  
Beatriz Gonçalves Ribeiro
Keyword(s):  
Time Trial ◽  
Minute Volume ◽  
Controlled Study ◽  
Performance Parameters ◽  
Double Blind ◽  
Double Blind Placebo ◽  
Ergogenic Effects ◽  
And Performance ◽  
Experimental Trials ◽  
Acute Intake

The present study investigated whether the caffeine supplementation for four days would induce tolerance to the ergogenic effects promoted by acute intake on physiological, metabolic, and performance parameters of cyclists. A double-blind placebo-controlled cross-over design was employed, involving four experimental trials; placebo (4-day)-placebo (acute)/PP, placebo (4-day)-caffeine (acute)/PC, caffeine (4-day)-caffeine (acute)/CC and caffeine (4-day)-placebo (acute)/CP. Fourteen male recreationally-trained cyclists ingested capsules containing either placebo or caffeine (6 mg∙kg−1) for 4 days. On day 5 (acute), capsules containing placebo or caffeine (6 mg∙kg−1) were ingested 60 min before completing a 16 km time-trial (TT). CC and PC showed improvements in time (3.54%, ES = 0.72; 2.53%, ES = 0.51) and in output power (2.85%, ES = 0.25; 2.53%, ES = 0.20) (p < 0.05) compared to CP and PP conditions, respectively. These effects were accompanied by increased heart rate (2.63%, ES = 0.47; 1.99%, ES = 0.34), minute volume (13.11%, ES = 0.61; 16.32%, ES = 0.75), expired O2 fraction (3.29%, ES = 0.96; 2.87, ES = 0.72), lactate blood concentration (immediately after, 29.51% ES = 0.78; 28.21% ES = 0.73 recovery (10 min), 36.01% ES = 0.84; 31.22% ES = 0.81), and reduction in expired CO2 fraction (7.64%, ES = 0.64; 7.75%, ES = 0.56). In conclusion, these results indicate that caffeine, when ingested by cyclists in a dose of 6 mg∙kg−1 for 4 days, does not induce tolerance to the ergogenic effects promoted by acute intake on physiological, metabolic, and performance parameters.

scholarly journals Dexamethasone in resting and exercising men. I. Effects on bioenergetics, minerals, and related hormones

1999 ◽  
Vol 87 (1) ◽  
pp. 175-182 ◽  
Author(s):  
P. Marquet ◽  
G. Lac ◽  
A. P. Chassain ◽  
G. Habrioux ◽  
F. X. Galen
Keyword(s):  
Ventilatory Threshold ◽  
Exercise Bout ◽  
Random Order ◽  
Blood Levels ◽  
High Dose ◽  
Double Blind ◽  
Men I ◽  
Before And After ◽  
Blood Pressures ◽  
Rest And Exercise

A placebo and a low and a high dose of dexamethasone (Dex) were administered for 4.5 days, at 3-wk intervals, to 24 healthy men, following a double-blind, random-order, crossover procedure. After the last dose the subjects performed a maximal cycling exercise, during which respiratory exchanges, electrocardiogram, and blood pressures were monitored. Blood was sampled just before and after each exercise bout. Dex showed no significant effect on fitness, sleep, exhaustion during exercise, maximal O2 consumption, ventilatory threshold, maximal blood lactate, or rest and exercise blood pressures. On the contrary, both doses of Dex significantly decreased heart rate at rest and during maximal exercise. Blood glucose at rest was higher after both doses of Dex than after placebo; the opposite was found during exercise. Blood levels of ACTH, β-endorphin, cortisol, and cortisol-binding globulin were lowered by Dex at rest and after exercise. Dex stimulated the increase in atrial natriuretic factor during exercise and lowered rest and postexercise aldosterone. Finally, no difference between “fit or trained” and “less fit or untrained” subjects could be found with respect to Dex effects.

Carbohydrate Supplementation Attenuates Muscle Glycogen Loss during Acute Bouts of Resistance Exercise

2000 ◽  
Vol 10 (3) ◽  
pp. 326-339 ◽  
Author(s):  
G. Gregory Haff ◽  
Alexander J. Koch ◽  
Jeffrey A. Potteiger ◽  
Karen E. Kuphal ◽  
Lawrence M. Magee ◽  
...  
Keyword(s):  
Resistance Exercise ◽  
Body Mass ◽  
Muscle Glycogen ◽  
Vastus Lateralis ◽  
Placebo Treatment ◽  
Double Blind ◽  
Isokinetic Test ◽  
Before And After ◽  
Leg Exercise ◽  
Wet Weight

The effects of carbohydrate (CHO) supplementation on muscle glycogen and resistance exercise performance were examined with eight highly resistance trained males (mean ± SEM, age: 24.3 ± 1.1 years, height: 171.9±2.0 cm, body mass: 85.7 ± 3.5 kg; experience 9.9 ± 2.0 years). Subjects participated in a randomized, double blind protocol with testing sessions separated by 7 days. Testing consisted of an initial isokinetic leg exercise before and after an isotonic resistance exercise (IRT) session consisting of 3 leg exercises lasting ~39 min. Subjects consumed a CHO (1.0 g CHO ·kg body mass−1) or placebo treatment (PLC), prior to and every 10-min (0.5 g CHO ·kg body mass−1) during the IRT. Muscle tissue was obtained from the m vastus lateralis after a supine rest (REST) immediately after the initial isokinetic test (POST-ISO) and immediately after the IRT (POST-IRT). The CHO treatment elicited significantly less muscle glycogen degradation from the POST-ISO to POST-IRT (126.9 ± 6.5 to 109.7 ± 7.1 mmol·kg wet weight−1) compared to PLC (121.4±8.1 to 88.3±6.0 mmol·kg wet weight−1). There were no differences in isokinetic performance between the treatments. The results of this investigation indicate that the consumption of a CHO beverage can attenuate the decrease in muscle glycogen associated with isotonic resistance exercise but does not enhance the performance of isokinetic leg exercise.

scholarly journals Hepatic steatosis, inflammation, and ER stress in mice maintained long term on a very low-carbohydrate ketogenic diet

2011 ◽  
Vol 300 (6) ◽  
pp. G956-G967 ◽  
Author(s):  
Joel R. Garbow ◽  
Jason M. Doherty ◽  
Rebecca C. Schugar ◽  
Sarah Travers ◽  
Mary L. Weber ◽  
...  
Keyword(s):  
Ketogenic Diet ◽  
Western Diet ◽  
Whole Body ◽  
Resonance Spectroscopy ◽  
Chow Diet ◽  
High Fat ◽  
Low Protein ◽  
Low Carbohydrate ◽  
Term Administration

Low-carbohydrate diets are used to manage obesity, seizure disorders, and malignancies of the central nervous system. These diets create a distinctive, but incompletely defined, cellular, molecular, and integrated metabolic state. Here, we determine the systemic and hepatic effects of long-term administration of a very low-carbohydrate, low-protein, and high-fat ketogenic diet, serially comparing these effects to a high-simple-carbohydrate, high-fat Western diet and a low-fat, polysaccharide-rich control chow diet in C57BL/6J mice. Longitudinal measurement of body composition, serum metabolites, and intrahepatic fat content, using in vivo magnetic resonance spectroscopy, reveals that mice fed the ketogenic diet over 12 wk remain lean, euglycemic, and hypoinsulinemic but accumulate hepatic lipid in a temporal pattern very distinct from animals fed the Western diet. Ketogenic diet-fed mice ultimately develop systemic glucose intolerance, hepatic endoplasmic reticulum stress, steatosis, cellular injury, and macrophage accumulation, but surprisingly insulin-induced hepatic Akt phosphorylation and whole-body insulin responsiveness are not impaired. Moreover, whereas hepatic Pparg mRNA abundance is augmented by both high-fat diets, each diet confers splice variant specificity. The distinctive nutrient milieu created by long-term administration of this low-carbohydrate, low-protein ketogenic diet in mice evokes unique signatures of nonalcoholic fatty liver disease and whole-body glucose homeostasis.

Fatigue and exhaustion in chronic hypobaric hypoxia: influence of exercising muscle mass

1994 ◽  
Vol 76 (2) ◽  
pp. 634-640 ◽  
Author(s):  
B. Kayser ◽  
M. Narici ◽  
T. Binzoni ◽  
B. Grassi ◽  
P. Cerretelli
Keyword(s):  
Hypobaric Hypoxia ◽  
Vastus Lateralis ◽  
Lactate Concentration ◽  
Exercise Bout ◽  
Vastus Lateralis Muscle ◽  
O2 Uptake ◽  
Before And After ◽  
Leg Exercise ◽  
Muscle Groups ◽  
Forearm Exercise

Exhaustive dynamic exercise with large muscle groups in chronic hypobaric hypoxia may be limited by central (nervous) rather than peripheral (metabolic) fatigue. Six males [32 +/- 4 (SD) yr] at sea level (SL) and after 1-mo acclimatization at 5,050 m (HA) performed exhaustive dynamic forearm exercise at a constant absolute load, requiring regional maximum aerobic power at SL, and exhaustive cycle exercise at prevailing maximal O2 uptake (HA approximately equal to 80% SL). Exhaustion time (t(ex)), blood O2 saturation (SaO2), and heart rate (HR) were measured during each exercise bout. Before and after both arm and leg exercise, lactate concentration ([La]), PO2, PCO2, and pH were measured in arterialized blood samples. Integrated electromyogram activity (IEMG) and mean (MPF) and centroid (CPF) power frequencies of the EMG power spectrum during exercise were calculated for forearm flexors and vastus lateralis muscle. t(ex) for forearm exercise at the same absolute load was the same at SL and HA. Similar increases of IEMG (+214% at SL vs. +172% at HA) and decreases of CPF (-13% at SL vs. -16% at HA) and MPF (-22% at SL vs. -21% at HA) were observed. By contrast, at HA, for similar t(ex), leg exercise had to be performed at the same relative (i.e., prevailing maximal O2 uptake) but lower absolute load (approximately equal to 80% of SL).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Intramyocellular Lipid Changes in Men and Women during Aerobic Exercise: A 1H-Magnetic Resonance Spectroscopy Study

2003 ◽  
Vol 88 (12) ◽  
pp. 5638-5643 ◽  
Author(s):  
Lesley J. White ◽  
Michael A. Ferguson ◽  
Sean C. McCoy ◽  
HeeWon Kim
Keyword(s):  
Body Composition ◽  
Imaging System ◽  
Vastus Lateralis ◽  
Region Of Interest ◽  
Whole Body ◽  
Resonance Spectroscopy ◽  
Whole Body Imaging ◽  
Intramyocellular Lipid ◽  
Men And Women ◽  
Magnetic Resonance Spectroscopy Study

Abstract This study was designed to compare intramyocellular lipid (IMCL) changes during 60 min of submaximal exercise in men and women. Eighteen moderately active (18–38 yr) men (n = 9) and women (n = 9) were recruited. Maximum oxygen consumption (V̇O2max) and body composition were used to match subjects for aerobic fitness and body composition. Subjects performed cycle ergometry for 1 h at 65% of V̇O2max. Expired gases were collected throughout exercise to determine caloric expenditure and substrate use. Blood samples were collected before and after exercise to evaluate markers of lipid metabolism. Pre- and postexercise proton spectra were acquired from the vastus lateralis using a 3-T whole-body imaging system. Spectra were acquired from an 18-mm3 region of interest (echo time = 45 msec; repetition time = 2000 msec) for IMCL evaluation. IMCL decreased significantly with exercise (11.5–28.5% for men and 17.1–21.7% for women) (P &lt; 0.05); however, there were no significant differences between men and women. Although changes were found for many plasma variables [free fatty acids, glycerol, and norepinephrine (P &lt; 0.05)], group differences were only evident for norepinephrine. In conclusion, a significant decrease in IMCL was observed during 60 min of cycling in matched men and women.

N-acetylcysteine alters substrate metabolism during high-intensity cycle exercise in well-trained humans

2013 ◽  
Vol 38 (12) ◽  
pp. 1217-1227 ◽  
Author(s):  
Adam J. Trewin ◽  
Aaron C. Petersen ◽  
Francois Billaut ◽  
Leon R. McQuade ◽  
Bernie V. McInerney ◽  
...  
Keyword(s):  
Power Output ◽  
High Intensity ◽  
Repeated Measures ◽  
Vastus Lateralis ◽  
Venous Blood ◽  
Time Trial ◽  
Peak Power Output ◽  
Mean Power ◽  
Double Blind ◽  
Substrate Metabolism

We investigated the effects of N-acetylcysteine (NAC) on metabolism during fixed work rate high-intensity interval exercise (HIIE) and self-paced 10-min time-trial (TT10) performance. Nine well-trained male cyclists (V̇O2peak, 69.4 ± 5.8 mL·kg−1·min−1; peak power output (PPO), 385 ± 43 W; mean ± SD) participated in a double-blind, repeated-measures, randomised crossover trial. Two trials (NAC supplementation and placebo) were performed 7 days apart consisting of 6 × 5 min HIIE bouts at 82% PPO (316 ± 40 W) separated by 1 min at 100 W, and then after 2 min of recovery at 100 W, TT10 was performed. Expired gases, venous blood, and electromyographic (EMG) data were collected. NAC did not influence blood glutathione but decreased lipid peroxidation compared with the placebo (P < 0.05). Fat oxidation was elevated with NAC compared with the placebo during HIIE bouts 5 and 6 (9.9 ± 8.9 vs. 3.9 ± 4.8 μmol·kg−1·min−1; P < 0.05), as was blood glucose throughout HIIE (4.3 ± 0.6 vs. 3.8 ± 0.6 mmol·L−1; P < 0.05). Blood lactate was lower with NAC after TT10 (3.3 ± 1.3 vs. 4.2 ± 1.3 mmol·L−1; P < 0.05). Median EMG frequency of the vastus lateralis was lower with NAC during HIIE (79 ± 10 vs. 85 ± 10 Hz; P < 0.05), but not TT10 (82 ± 11 Hz). Finally, NAC decreased mean power output 4.9% ± 6.6% (effect size = –0.3 ± 0.4, mean ± 90% CI) during TT10 (305 ± 57 W vs. 319 ± 45 W). These data suggest that NAC alters substrate metabolism and muscle fibre type recruitment during HIIE, which is detrimental to time-trial performance.

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