Concept2 Forum

I found <a href='http://www.sciencedaily.com/releases/20 ... 232653.htm' target='_blank'>this article</a> from the Journal of the American College of Cardiology posted to Science Daily. Here are a few excerpts.<br /><!--QuoteBegin--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->In healthy volunteers, the equivalent of two cups of coffee reduced the body's ability to boost blood flow to the heart muscle in response to exercise. </td></tr></table><br /><!--QuoteBegin--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin--> Blood flow normally increases in response to exercise, and the results indicate that caffeine reduces the body's ability to boost blood flow to the muscle of the heart on demand. The ratio of exercise blood flow to resting blood flow, called the myocardial flow reserve, was 22 percent lower in the group at normal air pressure after ingesting caffeine. </td></tr></table><br /><!--QuoteBegin--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->"We now have good evidence that, at the level of myocardial blood flow, caffeine is not a useful stimulant. It may be a stimulant at the cerebral level in terms of being more awake and alert, which may subjectively give the feeling of having better physical performance. But I now would not recommend that any athlete drink caffeine before sports. It may not be a physical stimulant, and may even adversely affect physical performance," Dr. Kaufmann (Philipp A. Kaufmann, M.D., F.A.C.C., from the University Hospital Zurich and Center for Integrative Human Physiology CIHP in Zurich, Switzerland) said. </td></tr></table>

<!--QuoteBegin-arakawa+Jan 17 2006, 10:16 AM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(arakawa @ Jan 17 2006, 10:16 AM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->I found <a href='http://www.sciencedaily.com/releases/20 ... 232653.htm' target='_blank'>this article</a> from the Journal of the American College of Cardiology posted to Science Daily. Here are a few excerpts.<br /><!--QuoteBegin--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->In healthy volunteers, the equivalent of two cups of coffee reduced the body's ability to boost blood flow to the heart muscle in response to exercise. </td></tr></table><br /><!--QuoteBegin--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin--> Blood flow normally increases in response to exercise, and the results indicate that caffeine reduces the body's ability to boost blood flow to the muscle of the heart on demand. The ratio of exercise blood flow to resting blood flow, called the myocardial flow reserve, was 22 percent lower in the group at normal air pressure after ingesting caffeine. </td></tr></table><br /><!--QuoteBegin--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->"We now have good evidence that, at the level of myocardial blood flow, caffeine is not a useful stimulant. It may be a stimulant at the cerebral level in terms of being more awake and alert, which may subjectively give the feeling of having better physical performance. But I now would not recommend that any athlete drink caffeine before sports. It may not be a physical stimulant, and may even adversely affect physical performance," Dr. Kaufmann (Philipp A. Kaufmann, M.D., F.A.C.C., from the University Hospital Zurich and Center for Integrative Human Physiology CIHP in Zurich, Switzerland) said. </td></tr></table><br /><br />There's always someone to point out that the opposite of conventional is better, it seems. This certainly flies in the face of all the Red Bull ads and most endurance literature citing caffeine as one of maybe three ergogenic substances that actually has a measurable benefit, among the hundreds marketed.<br /><br />I'm not doubting you, or them. But did the article go further into the results of this myocardial blood flow inhibition, in terms of physical performance levels? Do they claim that caffein reduces the peak heart rate? Does it reduce stroke pressure and blood pressure? Wouldn't fit conventional understanding. Reduce stroke volume? Were the subjects tested aerobically in any way? Most output comparisons that I've heard of concluded that caffein was indeed a performance stumulant, and is why above a certain level it is included on banned substances lists.<br /><br />Its stimulating effect involves more physiology than I'd care to touch, but could it be that since the body is metabolizing fat and doing other things more efficiently, that the heart just doesn't need as much blood as it normally would?<br /><br />OK, just read the whole article. Another telling exerpt is "Dr. Kaufmann noted that this study was not designed to measure athletic performance.". So his claim that it won't aid physical performance and his recommendation not to use before sports is just not founded in any way. Blood to the heart is interesting. But there are dozens of other factors leading to physical performance. I think he's just part of the "If you like it, you can't do it." crowd.<br /><br />For my part, I'll enjoy my coffee, in moderation of course. There is one irrefutable risk accompanying the injestion of excessive coffee, and that is to do so before launching at the Head of the Charles, with over an hour to go before touching shore again, 250,000 spectators, and no place to pee. <br /> </td></tr></table><br />

<!--QuoteBegin-dougsurf+Jan 17 2006, 01:01 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(dougsurf @ Jan 17 2006, 01:01 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->There's always someone to point out that the opposite of conventional is better, it seems. This certainly flies in the face of all the Red Bull ads and most endurance literature citing caffeine as one of maybe three ergogenic substances that actually has a measurable benefit, among the hundreds marketed.[right] </td></tr></table><br />I just did a <a href='http://www.google.com/search?hl=en&lr=& ... tnG=Search' target='_blank'>Google search on caffeine and sports performance</a>. I didn't know so much research was done on the topic. I'm not, however, surprised.<br /><br /><!--QuoteBegin-dougsurf+Jan 17 2006, 01:01 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(dougsurf @ Jan 17 2006, 01:01 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->I'm not doubting you, or them. But did the article go further into the results of this myocardial blood flow inhibition, in terms of physical performance levels? Do they claim that caffein reduces the peak heart rate? Does it reduce stroke pressure and blood pressure? Wouldn't fit conventional understanding. Reduce stroke volume? Were the subjects tested aerobically in any way? Most output comparisons that I've heard of concluded that caffein was indeed a performance stumulant, and is why above a certain level it is included on banned substances lists.<br /><br />Its stimulating effect involves more physiology than I'd care to touch, but could it be that since the body is metabolizing fat and doing other things more efficiently, that the heart just doesn't need as much blood as it normally would?[right] </td></tr></table><br />You're now asking questions to which at least I do not have answers. Anyone with a medical background care to comment?<br /><br /><!--QuoteBegin-dougsurf+Jan 17 2006, 01:01 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(dougsurf @ Jan 17 2006, 01:01 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->OK, just read the whole article. Another telling exerpt is "Dr. Kaufmann noted that this study was not designed to measure athletic performance.". So his claim that it won't aid physical performance and his recommendation not to use before sports is just not founded in any way. Blood to the heart is interesting. But there are dozens of other factors leading to physical performance. I think he's just part of the "If you like it, you can't do it." crowd.[right] </td></tr></table><br />Although the researchers claimed to have measured cardiac <i>blood flow</i> using PET scans, they conjectured that caffeine "may block certain receptors in the walls of blood vessels, interfering with the normal process by which adenosine signals <i>blood vessels to dilate in response to the demands of physical activity</i> (italics mine)". One could argue that reduced blood vessel dilation in and of itself isn't a problem if blood flow volume is maintained (through higher pressure or greater blood velocity). Not being familiar with the limitations of PET scans, I don't know if it's actually possible to measure blood volume and the researchers are extrapolating reduced blood volume from a measured decrease in blood vessel dilation.<br /><br />I guess the bottom line is that, if it's legal, not harmful, and reduces your 2k time, why not - reduced dilation in cardiac blood vessels be damned!

<!--QuoteBegin-arakawa+Jan 17 2006, 12:13 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(arakawa @ Jan 17 2006, 12:13 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->I guess the bottom line is that, if it's legal, not harmful, and reduces your 2k time, why not - reduced dilation in cardiac blood vessels be damned! <br /> </td></tr></table><br /><br />My reading of the article left me with the feeling that this Dr. wanted to note his concern that caffiene may have an effect during exercise that could pose some risk to individuals with heart disease. The heart is just another muscle that needs O2 to function, and though it may not suffer any reduced function (cardiac output), and may even have a higher cardiac output when caffiene is used, it's not a bad thing to be aware that there are certain risks involved with chemical use. There have been cases where apparently healthy athletes have dropped dead just after finishing a race, adn no-one can say that they are happy when that happens. That said, we all engage in risky behavior every day, and likely wouldn't have it any other way.<br /><br />Now, how the heart can receive less blood and still provide output for improved overall performance, would be a very interesting question to have answered.

<!--QuoteBegin-PaulS+Jan 17 2006, 01:37 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(PaulS @ Jan 17 2006, 01:37 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin--><!--QuoteBegin-arakawa+Jan 17 2006, 12:13 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(arakawa @ Jan 17 2006, 12:13 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->I guess the bottom line is that, if it's legal, not harmful, and reduces your 2k time, why not - reduced dilation in cardiac blood vessels be damned! <br /> </td></tr></table><br /><br />My reading of the article left me with the feeling that this Dr. wanted to note his concern that caffiene may have an effect during exercise that could pose some risk to individuals with heart disease. The heart is just another muscle that needs O2 to function, and though it may not suffer any reduced function (cardiac output), and may even have a higher cardiac output when caffiene is used, it's not a bad thing to be aware that there are certain risks involved with chemical use. There have been cases where apparently healthy athletes have dropped dead just after finishing a race, adn no-one can say that they are happy when that happens. That said, we all engage in risky behavior every day, and likely wouldn't have it any other way.<br /><br />Now, how the heart can receive less blood and still provide output for improved overall performance, would be a very interesting question to have answered. <br /> </td></tr></table><br />Dr. Kaufmann noted that this study was not designed to measure athletic performance. So the Red Bull studies are not affected by this particular study vis-a-vis athletic performance.<br /><br />"Although these findings seem not to have a clinical importance in healthy volunteers, they may raise safety questions in patients with reduced coronary flow reserve, as seen in coronary artery disease, particularly before physical exercise and at high-altitude exposure," the researchers wrote.<br /><br />So if we're healthy, then not a problem, but since I trek at high altitude 17000 feet plus, this is good information to have -- no more caffeine at high altitude! (Athletic performance is not really at issue when you can hardly breath at altitude -- it's getting oxygen that matters; at least for me.)<br /><br />"Life is brought down to the basics: if you are warm, regular, healthy, not thirsty or hungry, then you are not on a mountain. . . . Climbing at altitude is like hitting your head against a brick wall - it's great when you stop." Chris Darwin ,The Social Climbers <br /><br />Thanks for bringing it to my attention.<br /><br />Mike