- 05-29-2006, 12:26 PM
Cortisol responses to mental stress, exercise, and meals following caffeine intake in men and women.
Lovallo WR, Farag NH, Vincent AS, Thomas TL, Wilson MF.
Veterans Affairs Medical Center, Department of Psychiatry and Behavioral Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
Caffeine elevates cortisol secretion, and caffeine is often consumed in conjunction with exercise or mental stress. The interactions of caffeine and stress on cortisol secretion have not been explored adequately in women. We measured cortisol levels at eight times on days when healthy men and women consumed caffeine (250 mgx3) and underwent either mental stress or dynamic exercise protocols, followed by a midday meal, in a double blind, placebo-controlled, crossover design. Men and women had similar cortisol levels at the predrug baselines, but they responded differently to mental stress and exercise. The cortisol response to mental stress was smaller in women than in men (p=.003). Caffeine acted in concert with mental stress to further increase cortisol levels (p=.011), the effect was similar in men and women. Exercise alone did not increase cortisol, but caffeine taken before exercise elevated cortisol in both men and women (ps<.05). After a postexercise meal, the women had a larger cortisol response than the men, and this effect was greater after caffeine (p<.01). Cortisol release in response to stress and caffeine therefore appears to be a function of the type of stressor and the sex of the subject. However, repeated caffeine doses increased cortisol levels across the test day without regard to the sex of the subject or type of stressor employed (p<.00001). Caffeine may elevate cortisol by stimulating the central nervous system in men but may interact with peripheral metabolic mechanisms in women.
I know a lot of guys drink coffee and such before and during their workout.
- 05-29-2006, 12:29 PM
Not good news but thanks for sharing. What was the year on this study?
- 05-29-2006, 12:32 PM
Hmm. Interesting stuff.
05-29-2006, 01:40 PM
the date on this study is March 2006
05-29-2006, 01:48 PM
yep, I've read various studies on caffeine and cortisol levels. I still drink my coffee I'll worry about it when I'm at 8% b.f. and need to get on a stage a 5%
05-29-2006, 07:33 PM
Damn... I can barely make it without my caffeine. I wonder if taking Lean Xtreme in conjunction with caffeine would make Cortisol levels essentially baseline?
05-30-2006, 06:11 AM
I would think lean extreme would help but it's something to think about if your a heavy coffee drinker before you workout. I know a lot of guys do it, how much it effects your muscle growth is probably not huge but every little bit helps
05-31-2006, 11:03 AM
Yeah, I love my AM coffee but my last cup is usually 4pm, and I dont workout until 9:30 pm or so.
Still something to be aware of.
Good posting Jminis!
05-31-2006, 12:30 PM
I dont drink much caffeine but my wife is an addict. I'll send her this article.
06-03-2006, 11:46 AM
Drinking coffee 'is good for the heart'
By Celia Hall, Medical Editor
One to three cups of coffee a day may protect people from heart disease and strokes, according to research which contradicts numerous studies that have suggested that coffee is bad for you.
The good news for coffee drinkers comes from a report in the American Journal of Clinical Nutrition and is based on a study of 27,000 older women, followed for 15 years.
It found a reduced risk of cardiovascular disease by about 30 per cent in women who had a moderate intake of coffee. The analysis, part of the Iowa Women's Health Study, found that up to 60 per cent of antioxidants in the diet may come from coffee.
Antioxidants protect cells from damage and reduce the inflammation that encourages arteries to narrow.
Active parts of coffee include caffeine and polyphenols. Polyphenols are also found in red wine and they too have been linked to a reduction in the risk of cardiovascular diseases in people who drink one to three glasses of red wine a day. The researchers in the Iowa study also pointed out that a Scottish survey of 11,000 men and women found that coffee drinking was associated with a reduction in deaths from all causes.
Dr Sarah Jarvis, a fellow of the Royal College of General Practitioners said: "This is a message about moderation. Too much exercise, too much coffee or too much alcohol are bad. In moderation they are beneficial."
Here's the original study data:-
Consumption of coffee is associated with reduced risk of death attributed to inflammatory and cardiovascular diseases in the Iowa Women's Health Study1,2,3,4
Lene Frost Andersen, David R Jacobs, Jr, Monica H Carlsen and Rune Blomhoff
1 From the Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway (LFA, DRJ, MHC, and RB), and the Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN (DRJ)
Background: Coffee is the major source of dietary antioxidants. The association between coffee consumption and risk of death from diseases associated with inflammatory or oxidative stress has not been studied.
Objective: We studied the relation of coffee drinking with total mortality and mortality attributed to cardiovascular disease, cancer, and other diseases with a major inflammatory component.
Design: A total of 41 836 postmenopausal women aged 55–69 y at baseline were followed for 15 y. After exclusions for cardiovascular disease, cancer, diabetes, colitis, and liver cirrhosis at baseline, 27 312 participants remained, resulting in 410 235 person-years of follow-up and 4265 deaths. The major outcome measure was disease-specific mortality.
Results: In the fully adjusted model, similar to the relation of coffee intake to total mortality, the hazard ratio of death attributed to cardiovascular disease was 0.76 (95% CI: 0.64, 0.91) for consumption of 1–3 cups/d, 0.81 (95% CI: 0.66, 0.99) for 4–5 cups/d, and 0.87 (95% CI: 0.69, 1.09) for 6 cups/d. The hazard ratio for death from other inflammatory diseases was 0.72 (95% CI: 0.55, 0.93) for consumption of 1–3 cups/d, 0.67 (95% CI: 0.50, 0.90) for 4–5 cups/d, and 0.68 (95% CI: 0.49, 0.94) for 6 cups/d.
Conclusions: Consumption of coffee, a major source of dietary antioxidants, may inhibit inflammation and thereby reduce the risk of cardiovascular and other inflammatory diseases in postmenopausal women.
06-03-2006, 11:48 AM
Caffeine increases exogenous carbohydrate oxidation during exercise
Sophie E. Yeo, Roy L. P. G. Jentjens, Gareth A. Wallis, and Asker E. Jeukendrup
Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
Submitted 10 February 2005 ; accepted in final form 14 April 2005
Both carbohydrate (CHO) and caffeine have been used as ergogenic aids during exercise. It has been suggested that caffeine increases intestinal glucose absorption, but there are also suggestions that it may decrease muscle glucose uptake. The purpose of the study was to investigate the effect of caffeine on exogenous CHO oxidation. In a randomized crossover design, eight male cyclists (age 27 ± 2 yr, body mass 71.2 ± 2.3 kg, maximal oxygen uptake 65.7 ± 2.2 ml·kg–1·min–1) exercised at 64 ± 3% of maximal oxygen uptake for 120 min on three occasions. During exercise subjects ingested either a 5.8% glucose solution (Glu; 48 g/h), glucose with caffeine (Glu+Caf, 48 g/h + 5 mg·kg–1·h–1), or plain water (Wat). The glucose solution contained trace amounts of [U-13C]glucose so that exogenous CHO oxidation could be calculated. CHO and fat oxidation were measured by indirect calorimetry, and 13C appearance in the expired gases was measured by continuous-flow IRMS. Average exogenous CHO oxidation over the 90- to 120-min period was 26% higher (P < 0.05) in Glu+Caf (0.72 ± 0.04 g/min) compared with Glu (0.57 ± 0.04 g/min). Total CHO oxidation rates were higher (P < 0.05) in the CHO ingestion trials compared with Wat, but they were highest when Glu+Caf was ingested (1.21 ± 0.37, 1.84 ± 0.14, and 2.47 ± 0.23 g/min for Wat, Glu, and Glu+Caf, respectively; P < 0.05). There was also a trend (P = 0.082) toward an increased endogenous CHO oxidation with Glu+Caf (1.81 ± 0.22 g/min vs. 1.27 ± 0.13 g/min for Glu and 1.12 ± 0.37 g/min for Wat). In conclusion, compared with glucose alone, 5 mg·kg–1·h–1 of caffeine coingested with glucose increases exogenous CHO oxidation, possibly as a result of an enhanced intestinal absorption.
06-03-2006, 12:03 PM
Did you know coffee has alot of protein in it too? I drink small amounts a caffiene, but just about every pre-wo stim has some form of it.
06-03-2006, 12:06 PM
I never knew that...that's pretty interesting.
Yeah you're right about every pre-w/o supp. having caffeine in it. I can't think of one that doesn't..
I think in conclusion, anything in moderation is ok.
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