Awareness of Fluid Losses Does Not Impact Thirst during Exercise in the Heat: A Double-Blind, Cross-Over Study

Background: Thirst has been used as an indicator of dehydration; however, as a perception, we hypothesized that it could be affected by received information related to fluid losses. The purpose of this study was to identify whether awareness of water loss can impact thirst perception during exercise in the heat. Methods: Eleven males participated in two sessions in random order, receiving true or false information about their fluid losses every 30 min. Thirst perception (TP), actual dehydration, stomach fullness, and heat perception were measured every 30 min during intermittent exercise until dehydrated by ~4% body mass (BM). Post exercise, they ingested water ad libitum for 30 min. Results: Pre-exercise BM, TP, and hydration status were not different between sessions (p > 0.05). As dehydration progressed during exercise, TP increased significantly (p = 0.001), but it was the same for both sessions (p = 0.447). Post-exercise water ingestion was almost identical (p = 0.949) in the two sessions. Conclusion: In this study, thirst was a good indicator of fluid needs during exercise in the heat when no fluid was ingested, regardless of receiving true or false water loss information.

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Exercise-induced GH secretion is enhanced by the oral ingestion of melatonin in healthy adult male subjects

Acta Endocrinologica ◽

10.1530/eje.0.1410022 ◽

1999 ◽

Vol 141 (1) ◽

pp. 22-26 ◽

Cited By ~ 23

Author(s):

DR Meeking ◽

JD Wallace ◽

RC Cuneo ◽

M Forsling ◽

DL Russell-Jones

Keyword(s):

Initial Period ◽

Area Under The Curve ◽

Random Order ◽

Controlled Study ◽

Double Blind ◽

Post Exercise ◽

Gh Secretion ◽

Exercise Induced ◽

Male Subjects ◽

Peak Increase

There is evidence that melatonin may play a role in modulating pituitary secretion, although the mechanisms are unclear. We examined the effects of a single dose of oral melatonin (5mg) on exercise-induced GH secretion. In a randomised, double-blind, placebo-controlled study, seven healthy male subjects undertook an initial period of graded bicycle ergometric exercise to determine maximum workload and oxygen uptake (VO(2max)). Subjects were subsequently studied on two further occasions, receiving either melatonin or placebo in random order at the onset of each study (-60min). At 0 min a period of bicycle exercise was performed for 8 min at a workload corresponding to 70% of that achieved at VO(2max). Serum GH and IGF-binding protein-1 (IGFBP-1) concentration was measured at 15-min intervals from the onset of the study until 120 min post-exercise. Blood was also sampled for the measurement of plasma glucose, insulin, non-esterified fatty acids, IGFBP-3, melatonin and vasopressin concentration. There was an exercise-induced increase in GH concentration following melatonin which was greater compared with placebo as assessed by both area under the curve (P<0.01) and peak increase in GH levels (P<0.01). The peak increase in IGFBP-1 levels post-exercise was also significantly greater following melatonin compared with placebo (P<0. 01) but did not quite reach levels of significance as measured by area under the curve (P=0.07). Since exercise-induced GH secretion is thought to be mediated predominantly through a hypothalamic pathway, it seems likely that melatonin facilitates GH secretion at a hypothalamic level.

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Rehydration with a Caffeinated Beverage during the Nonexercise Periods of 3 Consecutive Days of 2-a-Day Practices

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.14.4.419 ◽

2004 ◽

Vol 14 (4) ◽

pp. 419-429 ◽

Cited By ~ 22

Author(s):

Kelly A. Fiala ◽

Douglas J. Casa ◽

Melissa W. Roti

Keyword(s):

Body Fat ◽

Hydration Status ◽

Double Blind ◽

Psychological Measures ◽

Mild Heat ◽

Urine Color ◽

Significant Difference ◽

Before And After ◽

Time Point

The purpose of this study was to assess the influence of rehydration with a caffeinated beverage during non exercise periods on hydration status throughout consecutive practices in the heat. Ten (7 women, 3 men) partially heat-acclimated athletes (age 24 ± ly, body fat 19.2 ± 2%, weight 68.4 ± 4.0 kg, height 170 ± 3 cm) completed 3 successive days of 2-a-day practices (2 h/ practice, 4 h/d) in mild heat (WBGT = 23 °C). The 2 trials (double-blind, random, cross-over design) included; 1) caffeine (CAF) rehydrated with Coca-Cola® and 2) caffeine-free (CF) rehydrated with Caffeine-Free Coca-Cola®. Urine and psychological measures were determined before and after each 2-h practice. A significant difference was found for urine color for the post-AM time point, F = 5.526, P = 0.031. No differences were found among other variables (P > 0.05). In summary, there is little evidence to suggest that the use of beverages containing caffeine during non exercise might hinder hydration status.

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Influence of Carbohydrate Supplementation on Plasma Cytokine and Neutrophil Degranulation Responses to High Intensity Intermittent Exercise

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.12.2.145 ◽

2002 ◽

Vol 12 (2) ◽

pp. 145-156 ◽

Cited By ~ 41

Author(s):

Nicolette C. Bishop ◽

Michael Gleeson ◽

Ceri W. Nicholas ◽

Ajmol Ali

Keyword(s):

High Intensity ◽

Intermittent Exercise ◽

Plasma Concentrations ◽

Neutrophil Function ◽

Moderate Intensity ◽

Post Exercise ◽

Carbohydrate Supplementation ◽

Tnf Α ◽

Neutrophil Degranulation ◽

Factor Α

Ingesting carbohydrate (CHO) beverages during prolonged, continuous heavy exercise results in smaller changes in the plasma concentrations of several cytokines and attenuates a decline in neutrophil function. In contrast, ingesting CHO during prolonged intermittent exercise appears to have negligible influence on these responses, probably due to the overall moderate intensity of these intermittent exercise protocols. Therefore, we examined the effect of CHO ingestion on plasma interIeukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and lipopolysaccharide (LPS)-stimuIated neutrophil degranulation responses to high-intensity intermittent running. Six trained male soccer players performed 2 exercise trials, 7 days apart, in a randomized, counterbalanced design. On each occasion, they completed six 15-min periods of intermittent running consisting of maximal sprinting interspersed with less intense periods of running and walking. Subjects consumed either CHO or artificially sweetened placebo(PLA) beverages immediately before and at 15-min intervals during the exercise. At 30 min post-exercise, CHO versus PLA was associated with a higher plasma glucose concentration (p< .01), a lower plasma cortisol and IL-6 concentration (p < .02), and fewer numbers of circulating neutrophils (p < .05). Following the exercise, LPS-stimulated elastase release per neutrophil fell 31 % below baseline values on the PLA trial (p = .06) compared with 11% on the CHO trial (p = .30). Plasma TNF-α concentration increased following the exercise (main effect of time, p < .001) but was not affected by CHO. These data indicate that CHO ingestion attenuates changes in plasma IL-6 concentration, neutrophil trafficking, and LPS-stimulated neutrophil degranulation in response to intermittent exercise that involves bouts of very high intensity exercise.

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Effect of exercise timing on elevated postprandial glucose levels

Journal of Applied Physiology ◽

10.1152/japplphysiol.00608.2016 ◽

2017 ◽

Vol 123 (2) ◽

pp. 278-284 ◽

Cited By ~ 5

Author(s):

Yoichi Hatamoto ◽

Ryoma Goya ◽

Yosuke Yamada ◽

Eichi Yoshimura ◽

Sena Nishimura ◽

...

Keyword(s):

Blood Glucose ◽

Effect Size ◽

Exercise Intervention ◽

Intermittent Exercise ◽

Random Order ◽

Postprandial Glucose ◽

Glucose Levels ◽

Exercise Timing ◽

Daily Exercise ◽

Blood Glucose Concentrations

There is no consensus regarding optimal exercise timing for reducing postprandial glucose (PPG). The purpose of the present study was to determine the most effective exercise timing. Eleven participants completed four different exercise patterns 1) no exercise; 2) preprandial exercise (jogging); 3) postprandial exercise; and 4) brief periodic exercise intervention (three sets of 1-min jogging + 30 s of rest, every 30 min, 20 times total) in a random order separated by a minimum of 5 days. Preprandial and postprandial exercise consisted of 20 sets of intermittent exercise (1 min of jogging + 30 s rest per set) repeated 3 times per day. Total daily exercise volume was identical for all three exercise patterns. Exercise intensities were 62.4 ± 12.9% V̇o2peak. Blood glucose concentrations were measured continuously throughout each trial for 24 h. After breakfast, peak blood glucose concentrations were lower with brief periodic exercise (99 ± 6 mg/dl) than those with preprandial and postprandial exercise (109 ± 10 and 115 ± 14 mg/dl, respectively, P < 0.05, effect size = 0.517). After lunch, peak glucose concentrations were lower with brief periodic exercise than those with postprandial exercise (97 ± 5 and 108 ± 8 mg/dl, P < 0.05, effect size = 0.484). After dinner, peak glucose concentrations did not significantly differ among exercise patterns. Areas under the curve over 24 h and 2 h postprandially did not differ among exercise patterns. These findings suggest that brief periodic exercise may be more effective than preprandial and postprandial exercise at attenuating PPG in young active individuals. NEW & NOTEWORTHY This was the first study to investigate the effect of different exercise timing (brief periodic vs. preprandial vs. postprandial exercise) on postprandial glucose (PPG) attenuation in active healthy men. We demonstrated that brief periodic exercise attenuated peak PPG levels more than preprandial and postprandial exercise, particularly in the morning. Additionally, PPG rebounded soon after discontinuing postprandial exercise. Thus, brief periodic exercise may be better than preprandial and postprandial exercise at attenuating PPG levels.

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Disposition of MDMA and Metabolites in Human Sweat Following Controlled MDMA Administration

Clinical Chemistry ◽

10.1373/clinchem.2008.117093 ◽

2009 ◽

Vol 55 (3) ◽

pp. 454-462 ◽

Cited By ~ 21

Author(s):

Allan J Barnes ◽

Bruno S De Martinis ◽

David A Gorelick ◽

Robert S Goodwin ◽

Erin A Kolbrich ◽

...

Keyword(s):

Solid Phase ◽

Random Order ◽

Research Unit ◽

Sweat Test ◽

Test Results ◽

Double Blind ◽

Scientific Database ◽

Sweat Testing ◽

Clinical Research Unit ◽

Sweat Tests

Abstract Background: Understanding the excretion of 3,4-methylenedioxymethamphetamine (MDMA) and metabolites in sweat is vital for interpretation of sweat tests in drug treatment, criminal justice, and workplace programs. Methods: Placebo, low (1.0 mg/kg), and high (1.6 mg/kg) doses of oral MDMA were given double-blind in random order to healthy volunteers (n = 15) with histories of MDMA use. Participants resided on the closed clinical research unit for up to 7 days after each dose. Volunteers wore PharmChek® sweat patches (n = 640) before, during, and after controlled dosing. Patches were analyzed by solid phase extraction and GC-MS for MDMA, methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxyamphetamine (HMA), and 4-hydroxy-3-methoxymethamphetamine (HMMA). Limits of quantification (LOQ) were 2.5 ng/patch for MDMA and 5 ng/patch for HMA, HMMA, and MDA. Results: MDMA was the primary analyte detected in 382 patches (59.7%), with concentrations up to 3007 ng/patch. MDA was detected in 188 patches (29.4%) at <172 ng/patch, whereas no HMMA or HMA was detected; 224 patches (35.0%) and 60 patches (9.4%) were positive for MDMA and MDA, respectively, at the 25-ng/patch threshold proposed by the Substance Abuse and Mental Health Services Administration. Conclusions: Sweat testing was shown to be an effective and reliable method for monitoring MDMA use in this controlled MDMA administration study. However, variability in sweat excretion suggests that results should be interpreted qualitatively rather than quantitatively. These data provide a scientific database for interpretation of MDMA sweat test results.

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Abstract 803: Diesel Exhaust Inhalation Enhances Thrombus Formation In Man

Circulation ◽

10.1161/circ.116.suppl_16.ii_155-a ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Andrew J Lucking ◽

Magnus Lundback ◽

Nicholas L Mills ◽

Dana Faratian ◽

Fleming Cassee ◽

...

Keyword(s):

Myocardial Infarction ◽

Acute Myocardial Infarction ◽

Air Pollution ◽

Platelet Activation ◽

Diesel Exhaust ◽

Intermittent Exercise ◽

Ex Vivo ◽

Thrombus Formation ◽

Ex Vivo Model ◽

Double Blind

Background: Transient exposure to traffic-derived air pollution may be a trigger for acute myocardial infarction although the mechanism is unclear. The aim of this study was to investigate the effect of diesel exhaust inhalation on thrombus formation in man using an ex vivo model of thrombosis. Methods and Results: In a double-blind randomized cross-over study, 20 healthy volunteers were exposed to diluted diesel exhaust (300 μg/m3) or filtered air during intermittent exercise for 1 or 2 hours. Thrombus formation, coagulation, platelet activation and inflammatory markers were measured at 2 and 6 hours after exposure. Thrombus formation was measured using the Badimon ex vivo perfusion chamber at low (212 /s) and high (1,690 /s) shear rates with porcine aortic tunica media as the thrombogenic substrate. Specimens were fixed, stained and thrombus area measured using computerized planimetry. Compared to filtered air, diesel exhaust increased thrombus formation in the low and high shear chambers by 24.2% (p<0.001) and 19.1% (p<0.001) respectively. This increased thrombogenicity was seen at two and six hours, and using two different types of diesel exposure. Although there were no effects on coagulation variables, diesel exhaust inhalation increased platelet-neutrophil (6.5% to 9.2%; P<0.05) and platelet-monocyte (21.0% to 25.0%; P<0.05) aggregates 2 hours following exposure. Conclusions: Inhalation of diesel exhaust increases ex vivo thrombus formation and causes platelet activation in man. These findings provide a potential mechanism that links exposure to traffic-derived air pollution with acute atherothrombotic events including acute myocardial infarction.

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Analysis of acute naproxen administration on memory in young adults: A randomized, double-blind, placebo-controlled study

Journal of Psychopharmacology ◽

10.1177/0269881117724406 ◽

2017 ◽

Vol 31 (10) ◽

pp. 1374-1376

Author(s):

Jack H Wilson ◽

Amy H Criss ◽

Sean A Spangler ◽

Katherine Walukevich ◽

Sandra Hewett

Keyword(s):

Young Adults ◽

Healthy Adult ◽

Adult Population ◽

Critical Role ◽

Random Order ◽

Controlled Study ◽

High Dose ◽

Short Term ◽

Double Blind ◽

Inflammatory Drugs

Nonsteroidal anti-inflammatory drugs work by non-selectively inhibiting cyclooxygenase enzymes. Evidence indicates that metabolites of the cyclooxygenase pathway play a critical role in the process of learning and memory. We evaluated whether acute naproxen treatment impairs short-term working memory, episodic memory, or semantic memory in a young, healthy adult population. Participants received a single dose of placebo or naproxen (750 mg) in random order separated by 7–10 days. Two hours following administration, participants completed five memory tasks. The administration of acute high-dose naproxen had no effect on memory in healthy young adults.

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Nociceptive mechanisms modulate ozone-induced human lung function decrements

Journal of Applied Physiology ◽

10.1152/jappl.1998.85.5.1863 ◽

1998 ◽

Vol 85 (5) ◽

pp. 1863-1870 ◽

Cited By ~ 38

Author(s):

Anthony N. Passannante ◽

Milan J. Hazucha ◽

Philip A. Bromberg ◽

Elston Seal ◽

Larry Folinsbee ◽

...

Keyword(s):

Lung Function ◽

Intermittent Exercise ◽

Forced Expiratory Volume ◽

Endogenous Opioids ◽

Functional Responses ◽

Double Blind ◽

C Fibers ◽

Impaired Lung Function ◽

Opioid Receptor Agonists ◽

Double Blind Crossover Study

We have previously suggested that ozone (O3)-induced pain-related symptoms and inhibition of maximal inspiration are due to stimulation of airway C fibers (M. J. Hazucha, D. V. Bates, and P. A. Bromberg. J. Appl. Physiol. 67: 1535–1541, 1989). If this were so, pain suppression or inhibition by opioid-receptor agonists should partially or fully reverse O3-induced symptomatic and lung functional responses. The objectives of this study were to determine whether O3-induced pain limits maximal inspiration and whether endogenous opioids contribute to modulation of the effects of inhaled O3 on lung function. The participants in this double-blind crossover study were healthy volunteers (18–59 yr) known to be “weak” (WR; n = 20) and “strong” O3 responders (SR; n = 42). They underwent either two 2-h exposures to air or two 2-h exposures to 0.42 parts/million O3 with moderate intermittent exercise. Immediately after post-O3 spirometry, the WR were randomly given either naloxone (0.15 mg/kg iv) or saline, whereas SR randomly received either sufentanil (0.2 μg/kg iv) or saline. O3 exposure significantly ( P < 0.001) impaired lung function. In SR, sufentanil rapidly, although not completely, reversed both the chest pain and spirometric effects (forced expiratory volume in 1 s; P < 0.0001) compared with saline. Immediate postexposure administration of saline or naloxone had no significant effect on WR. Plasma β-endorphin levels were not related to an individual’s O3responsiveness. Cutaneous pain variables showed a nonsignificant weak association with O3responsiveness. These observations demonstrate that nociceptive mechanisms play a key role in modulating O3-induced inhibition of inspiration but not in causing lack of spirometric response to O3 exposure in WR.

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Plasma irisin levels progressively increase in response to increasing exercise workloads in young, healthy, active subjects

Acta Endocrinologica ◽

10.1530/eje-14-0204 ◽

2014 ◽

Vol 171 (3) ◽

pp. 343-352 ◽

Cited By ~ 83

Author(s):

Stella S Daskalopoulou ◽

Alexandra B Cooke ◽

Yessica-Haydee Gomez ◽

Andrew F Mutter ◽

Andreas Filippaios ◽

...

Keyword(s):

Pilot Study ◽

Energy Demand ◽

Acute Exercise ◽

Therapeutic Potential ◽

Maximal Oxygen Consumption ◽

Random Order ◽

Time Frame ◽

Main Study ◽

Post Exercise ◽

Beneficial Effects

BackgroundIrisin, a recently discovered myokine, has been shown to induce browning of white adipose tissue, enhancing energy expenditure and mediating some of the beneficial effects of exercise. We aimed to estimate the time frame of changes in irisin levels after acute exercise and the effect of different exercise workloads and intensities on circulating irisin levels immediately post-exercise.MethodsIn a pilot study, four healthy subjects (22.5±1.7 years) underwent maximal workload exercise (maximal oxygen consumption, VO2 max) and blood was drawn at prespecified intervals to define the time frame of pre- and post-exercise irisin changes over a 24-h period. In the main study, 35 healthy, non-smoking (23.0±3.3 years) men and women (n=20/15) underwent three exercise protocols ≥48-h apart, in random order: i) maximal workload (VO2 max); ii) relative workload (70% of VO2 max/10 min); and iii) absolute workload (75 W/10 min). Blood was drawn immediately pre-exercise and 3 min post-exercise.ResultsIn the pilot study, irisin levels increased by 35% 3 min post-exercise, then dropped and remained relatively constant. In the main study, irisin levels post-exercise were significantly higher than those of pre-exercise after all workloads (all,P<0.001). Post-to-pre-exercise differences in irisin levels were significantly different between workloads (P=0.001), with the greatest increase by 34% following maximal workload (P=0.004 vs relative and absolute).ConclusionsCirculating irisin levels were acutely elevated in response to exercise, with a greater increase after maximal workload. These findings suggest that irisin release could be a function of muscle energy demand. Future studies need to determine the underlying mechanisms of irisin release and explore irisin's therapeutic potential.

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Post-Exercise Whole Body Cryotherapy (−140 °C) Increases Energy Intake in Athletes

Nutrients ◽

10.3390/nu10070893 ◽

2018 ◽

Vol 10 (7) ◽

pp. 893

Author(s):

Chihiro Kojima ◽

Nobukazu Kasai ◽

Chika Kondo ◽

Kumiko Ebi ◽

Kazushige Goto

Keyword(s):

Energy Intake ◽

Intermittent Exercise ◽

Rest Period ◽

Whole Body ◽

Strenuous Exercise ◽

Acylated Ghrelin ◽

Meal Test ◽

Male Athletes ◽

Post Exercise ◽

Whole Body Cryotherapy

PURPOSE: The purpose of the present study was to investigate the effect of whole-body cryotherapy (WBC) treatment after exercise on appetite regulation and energy intake. METHODS: Twelve male athletes participated in two trials on different days. In both trials, participants performed high-intensity intermittent exercise. After 10 min following the completion of the exercise, they were exposed to a 3-min WBC treatment (−140 °C, WBC trial) or underwent a rest period (CON trial). Blood samples were collected to assess plasma acylated ghrelin, serum leptin, and other metabolic hormone concentrations. Respiratory gas parameters, skin temperature, and ratings of subjective variables were also measured after exercise. At 30 min post-exercise, energy and macronutrient intake were evaluated during an ad libitum buffet meal test. RESULTS: Although appetite-regulating hormones (acylated ghrelin and leptin) significantly changed with exercise (p = 0.047 for acylated ghrelin and p < 0.001 for leptin), no significant differences were observed between the trials. Energy intake during the buffet meal test was significantly higher in the WBC trial (1371 ± 481 kcal) than the CON trial (1106 ± 452 kcal, p = 0.007). CONCLUSION: Cold exposure using WBC following strenuous exercise increased energy intake in male athletes.

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